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Background: The Micheli technique for anterior cruciate ligament (ACL) reconstruction (ACLR) has proven to be a reliable method with a minimal risk for growth disturbance among skeletally immature patients. Purposes: To evaluate the Micheli technique of iliotibial band (ITB) graft passage for ACLR using cadaveric knee models and to measure the distance between the surgical instrument tip and the neurovascular bundle in the posterior knee joint: specifically, the peroneal nerve, tibial nerve, and popliteal artery. Study Design: Descriptive laboratory study. Methods: Gross dissection was performed on 17 pediatric cadaveric knees (12 male and 5 female) aged between 4 and 12 years. To simulate ITB graft passage, we passed a curved-tip hemostat clamp through the posterior capsule, with the knee flexed from 90° to 100°. Next, clinical photographs were taken, and digital imaging software was used to measure the distance in centimeters from the clamp tip to each respective neurovascular structure. Results: The mean distances from the clamp tip to the tibial nerve, popliteal artery, and peroneal nerve were 0.875 cm (range, 0.468-1.737 cm), 0.968 cm (range, 0.312-1.819 cm), and 1.149 cm (range, 0.202-2.409 cm), respectively. Mean values were further calculated for age groups of ≤8, 9-10, and 11-12 years. The mean distance from the clamp tip to the peroneal nerve was 1.400 cm larger for 11- to 12-year-old specimens than for ≤8-year-old specimens (95% CI, 0.6-2.2 cm; P = .005). Conclusion: The neurovascular structures in the posterior knee were in close proximity to the path of graft passage, with distances Clinical Relevance: As the incidence of ACL tears is continuously increasing within the pediatric population, there are a larger number of ACLR procedures being performed. Although neurovascular injuries during ACLR are rare, this study clarifies the close proximity of neurovascular structures during ITB graft passage using the Micheli technique of ACLR.

Background:An increased posterior tibial slope (PTS) results in greater force on the anterior cruciate ligament (ACL) and is a risk factor for ACL injuries. Biomechanical studies have suggested that a reduction in the PTS angle may lower the risk of ACL injuries. However, the majority of these investigations have been in the adult population.Purpose:To assess the mean medial and lateral PTS on pediatric cadaveric specimens without known knee injuries.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 39 pediatric knee specimens with computed tomography scans were analyzed. Specimens analyzed were between the ages of 2 and 12 years. The PTS of each specimen was measured on sagittal computed tomography slices at 2 locations for the medial and lateral angles. The measurements were plotted graphically by age to account for the variability in development within age groups. The anterior medial and lateral tibial plateau widths were measured. The distance between the top of the tibial plateau and the physis was measured. The independent-samples t test and analysis of variance were used to analyze the measurements.Results:The mean PTS angle for the medial and lateral tibial plateaus was 5.53° ± 4.17° and 5.95° ± 3.96°, respectively. The difference between the PTS angles of the medial and lateral tibial plateaus was not statistically significant ( P > .05). When plotted graphically by age, no trend between age and PTS was identified.Conclusion:This data set offers values for the PTS in skeletally immature specimens without a history of ACL injury and suggests that age may not be an accurate predictive factor for PTS.

Background:The Hospital for Special Surgery Pediatric Functional Activity Brief Scale (HSS Pedi-FABS) has demonstrated normally distributed scores in children aged 10 to 18 years. It has been used to evaluate knee injuries; however, there is limited information regarding its use in evaluating other injury types.Purpose:To (1) assess the validity and utility of HSS Pedi-FABS in youth athletes with injuries to different parts of the body and (2) evaluate the association between the HSS Pedi-FABS and the Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Global Health 7 (PGH), as well as PROMIS–Pain Interference (PGH-PI) and PROMIS-Fatigue (PGH-F) components.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:The authors performed a retrospective review of youth athletes aged 10 to 18 years who completed the HSS Pedi-FABS as part of their previsit intake questionnaire between April 2016 and July 2020. HSS Pedi-FABS score distributions were compared and evaluated for ceiling effects in cohorts determined by demographic, injury characteristic, and sports participation variables; a ceiling effect was determined to be present if >15% of respondents received the highest possible score. HSS Pedi-FABS scores were analyzed for a correlation with PGH, PGH-PI, and PGH-F components.Results:Included were 2274 patients (mean age, 14.6 ± 2.1 years; 53.0% female) participating in 21 distinct primary sports for 9.6 ± 7.9 hours per week. The mean HSS Pedi-FABS scores by injury group were as follows: elbow (22.7 ± 6.7), shoulder (21.0 ± 8.7), ankle (20.2 ± 8.8), knee (19.5 ± 9.1), and hip (15.4 ± 10.4) ( P < .001). Broad distribution was seen in each cohort, with no floor or ceiling effects. The HSS Pedi-FABS score correlated with patient-reported hours per week ( r = 0.33), days per week ( r = 0.33), and years of participation ( r = 0.21) ( P < .001 for all). All 3 PROMIS components correlated with HSS Pedi-FABS: PGH ( r = 0.28), PGH-PI ( r = –0.11), and PGH-F ( r = –0.15) ( P < .001).Conclusion:Study findings indicated that the HSS Pedi-FABS is a valid tool for measuring physical activity level in most injured youth athletes, not just those with knee injuries. The correlation of HSS Pedi-FABS with the PGH suggests a positive relationship of childhood physical activity with general health.

Objectives: The public health opioid abuse epidemic has led to nationwide interest in judicious use and close monitoring of opioid pain medication. Knee arthroscopy(KA) and anterior cruciate ligament reconstruction(ACLR) are common procedures in adolescent patients for which narcotics have been historically utilized for post-operative pain management. The purpose of this study is to investigate pain management strategies following basic KA or ACLR by pediatric sports surgeons who contribute to a multi-center quality improvement initiative(SCORE). Methods: Surgeon participants in SCORE represent fifteen U.S. institutions from primarily academic teaching hospitals who specialize in pediatric sports medicine. Surgeons contribute all ACLR and other KA-related cases. A RedCap survey was distributed to all SCORE surgeon participants in December 2019. A KA (defined as a knee arthroscopy that does not include a ligament reconstruction or a cartilage procedure other than chondroplasty) represented a less invasive procedure, while the ACLR represented a more invasive procedure. Survey results were collected and analyzed for both practice patterns of regional anesthesia utilization and post-operative narcotic prescribing volumes. Results: Twenty-eight SCORE surgeon participants completed the survey, a 100% response rate. A planned prescription of a mean of 16.4 pain pills (range 0-40 pills) were reported for pain management following a KA, only 32.1% of surgeons reported adjunctive regional anesthesia techniques for this procedure in addition to general anesthesia. Following an ACLR, surgeons reported a planned prescription of a mean 23.8 pain pills (range 0-40 pills) and most (92.3%) reported utilization of regional anesthesia for their peri-operative analgesia strategy. Of those using adjunctive regional anesthesia, significant variability was reported: 30.7% reported indwelling catheter placement for peripheral nerve block following ACLR as opposed to a single shot injection method, and several block locations were reported to be utilized of which adductor canal (67.9%) block was the most common (see Figure 1). For both procedure types, variability in multi-modal pain management was noted, with incomplete adoption of the use of additional non-narcotic medication (acetaminophen, 64.2%; and NSAIDS, 75%). Cryotherapy devices were applied/prescribed in 75.0% of knee arthroscopy procedures and 92.8% of ACLR. Conclusions: Despite evidence for effective adjunctive pain management strategies, incomplete adoption of multi-modal techniques and reliance on narcotic medication remains a significant component of pediatric sports surgical practice; with on average > 15 pills prescribed following these procedures. Opportunities for reducing practice variability, adoption of multi-modal analgesia strategies, and decreasing post-operative narcotic use following common adolescent knee procedures exist for this subset of pediatric sports medicine specialists

Background: Understanding the morphology of cartilage/bony maturation in preadolescents may help explain adult trochlear variation. Purpose: To study trochlear morphology during maturation in children and infants using magnetic resonance imaging (MRI). Study Design: Descriptive laboratory study. Methods: Twenty-four pediatric cadaveric knees (10 male and 14 female knees; age, 1 month to 10 years) were included. High-resolution imaging of the distal femoral secondary ossification center was performed using 7-T or 9.4-T MRI scanners. Three-dimensional MRI scans were produced, and images were reformatted; 3 slices in the axial, sagittal, and coronal planes images were analyzed, with coronal and sagittal imaging used for image orientation. Biometric analysis included lateral and medial trochlear height (TH); cartilaginous sulcus angle (CSA); osseous sulcus angle (OSA); trochlear depth; and trochlear facet (TF) length symmetry. Sex comparisons were considered when ≥1 specimen from both sexes of the same age was available; these included 11 knees spanning 4 age groups (ages 1, 3, 4, and 7 years). Results: The analysis of trochlear morphology showed a lateral TH greater than the medial TH at all ages. The thickest cartilage was found on the lateral TF in the younger specimens. Regarding the development of osseous and cartilaginous trochlear contour, a cartilaginous sulcus was present in the 3-month-old specimen and continued to deepen up to the age of 4 years. The shape of the osseous center evolved from round (1 month) to oval (9 months) to rectangular (2 years); no distinct bony trochlear sulcus was present, although a well-formed cartilaginous sulcus was present. The first evidence of formation of a bony sulcus was at 4 years. By the age of 7 to 8 years, the bony contour of the adult distal femur resembled its cartilaginous contour. Female samples had a shallower CSA and OSA than did the male ones in all samples that had a defined OSA. Conclusion: Female trochlear grooves tended to be shallower (flatter). The lateral trochlea was higher (TH) and wider (TF length) during growth than was the medial trochlea in both sexes; furthermore, the development of the osseous sulcus shape lagged behind the development of the cartilaginous sulcus shape in the authors’ study population. Clinical Relevance: Bony anatomy of the trochlear groove did not match the cartilaginous anatomy in preadolescent children, suggesting that caution should be used when interpreting bony anatomy in this age group.

Background: The most common presentation of knee osteochondritis dissecans (OCD) is a stable lesion on the lateral aspect of the medial femoral condyle (MFC) in an adolescent or pre-adolescent athlete. Standard of care for conservative treatment, include activity modification and weight bearing protection. Failed conservative management often leads arthroscopy and drilling of the lesion. Two different primary drilling techniques have been utilized, but no prospective studies have compared their relative effectiveness. Hypothesis/Purpose: The study hypothesis was that trans-articular (TAD) and retro-articular drilling (RAD) would demonstrate similar rates of healing, times to return to sports, and patient-reported outcome scores (PROs). Methods: Skeletally immature (n=113) patients presenting with radiograph indicated stable OCD of the MFC who did not demonstrate healing despite a minimum of 3 months of non-operative treatment were prospectively enrolled and randomized to TAD or RAD, for which 17 surgeon-investigators (at 14 centers, representing all major regions in the U.S.). Serial radiographs were obtained every 6 weeks to assess healing, and PROs were obtained at 6 months, 12 months, and 24 months. Twelve patients were due to lesion instability detected at the time of surgery, Results: Ninety-one study subjects were included, consisting of 51 TAD and 40 RAD patients, with the two groups being of similar age (12.6 years vs. 11.9 years), sex distribution (45% vs. 27% female, p=0.081), and 2-year PRO response rate (both 90%). No significant difference between TAD and RAD was detected in follow-up Pedi-IKDC, Lysholm, Marx knee activity score, or KOOS QOL scores (Table 1). Revision/additional OCD surgery occurred in 10% of patients in RAD and 4% in TAD. 71% of TAD patients reached a ‘healed’ status at a mean of 1.15 years, compared with 58% RAD patients at a mean of 1.06 years. Conclusion: While both primary forms of OCD drilling (TAD and RAD) showed consistent post-operative healing, achieving a completely ‘healed’ status was often a more prolonged process, taking approximately 1 year, despite clinical improvement being achieved much sooner. While PROs were similar between drilling techniques, revision surgery rates were more than twice as common with RAD compared with TAD but the overall risk was low and the Absolute Risk was only 6%. [Table: see text]

Background: The most common modern procedure for medial patellar stabilization involves reconstruction of the medial patellofemoral ligament (MPFL) and involves reconstructed ligament attachment to the femur and patella. However, cases of patellar fracture have been reported, particularly in the smaller anatomy of the pediatric population, leading to further investigations of patella stabilizing structures. The medial quadriceps tendon femoral ligament has been identified as a separate structure, connecting the patella to the femur and playing a significant role in patella stability. Reconstruction of this ligament may serve a role in patellar stabilization similar to pedicled quadriceps tendon medial ligamentous reconstructions. The anatomy and relationship of the MQTFL attachment to the quadriceps tendon and proximal pole of the patella has not been described in pediatric specimens. Purpose: To determine the anatomical relationship and attachment of the medial quadriceps tendon femoral ligament (MQTFL) on the patella and quadriceps tendon. Methods: Six pediatric cadaveric knee specimens were dissected to identify the patellar and quadriceps attachment site of the MQTFL. Dissection was facilitated by lateral arthrotomy and identification of the MQTFL thickened fibers from the undersurface of the ligament. Results: Six specimens included patients a mean age of 6 years at time of patient death (three 10-year-old specimens, one 4-year-old, and one 2-month-old specimen). The MQTFL was identified in all specimens. As identified from the undersurface of the everted extensor mechanism, it was found to insert a mean distance of 10.5 mm (range 3.9 – 18.2) from the superior pole of the patella. The attachment distally along the edge of the bony patella measured a mean of 12.7 mm (range 5.4-19.4). Total patellar length, as measured from the posterior articular surface, was a mean of 24.5 mm (range 11.0-35.6). Attachment to the quadriceps tendon averaged 47% of total attachment to both the quadriceps tendon and patella; conversely, direct patellar measurement averaged 53%. Conclusion: This study provides quantitative anatomy to attachment of the MQTFL to the patella and quadriceps tendon. Precise knowledge of these structures will assist to more precisely define the complex relationship between stabilizing structures to the medial patellofemoral joint and assist in patella stabilization procedures, particularly in skeletally immature patients. A lower risk of patellar fracture may be one of the key benefits of this procedure, compared with MPFL reconstruction. FIGURES [Figure: see text] References Fulkerson JP, Edgar C. Medial quadriceps tendon-femoral ligament: Surgical anatomy and reconstruction technique to prevent patella instability. Arthrosc Tech 2013;2:e125- e128. Joseph SM, Fulkerson JP. Medial Quadriceps Tendon Femoral Ligament Reconstruction Technique and Surgical Anatomy. Arthroscopy techniques. 2019 Jan 1;8(1):e57-64. Parikh SN, Wall EJ. Patellar fracture after medial patel- lofemoral ligament surgery: A report of five cases. J Bone Joint Surg Am 2011;93. e97(1-8) Dhinsa BS, Bhamra JS, James C, Dunnet W, Zahn H. Patella fracture after medial patellofemoral ligament reconstruction using suture anchors. Knee 2013;20:605- 608. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med 2012;40:1916-1923 Tanaka MJ. The anatomy of the medial patellofemoral complex. Sports Med Arthrosc 2017;25:e8-e11. Kruckeberg BM, Chahla J, Moatshe G, et al. Quantitative and qualitative analysis of the medial patellar ligaments: An anatomic and radiographic study. Am J Sports Med 2017. 363546517729818 LaPrade RF, Engebretsen AH, Ly TV, Johansen S, Wentorf FA, Engebretsen L. The anatomy of the medial part of the knee. J Bone Joint Surg Am 2007;89:2000- 2010. Mochizuki T, Nimura A, Tateishi T, Yamaguchi K, Muneta T, Akita K. Anatomic study of the attachment of the medial patellofemoral ligament and its characteristic relationships to the vastus intermedius. Knee Surg Sports Traumatol Arthrosc 2013;21:305-310. Nelitz M, Williams SR. Anatomic reconstruction of the medial patellofemoral ligament in children and adolescents using a pedicled quadriceps tendon graft. Arthroscopy techniques. 2014 Apr 1;3(2):e303-8.

Background: Radial head subluxation, known as pulled elbow or Nursemaid’s elbow, is a common pediatric condition that occurs when a longitudinal traction force is applied to an elbow that is pronated and extended. Although the stability of the proximal radioulnar joint has been previously examined in cadaveric models, there are no current studies quantifying the biomechanics of nursemaid’s elbow. The purpose of our study was to demonstrate and quantify the axial traction force required to produce a nursemaid’s elbow in a pediatric cadaver specimen. Methods: Two fresh-frozen cadaveric elbows from a single 3 year-old male donor were dissected by a fellowship-trained orthopedic surgeon. An Instron 5944 testing machine with a 2 kN load cell was used to perform uniaxial testing. The radius and humerus were mounted to the Instron machine, and loaded in the axial direction with the elbow in full extension. Loading occurred at a rate of 10 mm/sec for 4 seconds, during which the force and actuator displacement were continuously recorded. The local instantaneous load and extension displacement at the time of subluxation were recorded, and data was synced with high-frame-rate video footage used to confirm the annular ligament subluxation. Results: The load to failure required to produce the nursemaid’s elbow injury in the first elbow was 31N, with a failure displacement of 4.6mm. The second elbow demonstrated a load to failure of 26N, with a failure displacement of 4.6mm. After subluxation, we reduced the annular ligament from the first specimen. The elbow was then re-tested and demonstrated a load to failure of 20N, with a failure displacement of 2.6mm. Conclusion: Axial traction applied to a pediatric cadaver specimen results in subluxation of the annular ligament into the radiocapitellar joint. The mean load to failure is 28.5N, and a lower load to failure was required to produce a recurrent subluxation in a previously injured specimen. Lower load for a recurrent subluxation may be attributed to damage on the annular ligament due to the first subluxation. [Figure: see text]

Objectives: The most common presentation of knee osteochondritis dissecans (OCD) is a stable lesion on the lateral aspect of the medial femoral condyle (MFC) in an adolescent or pre-adolescent athlete. The standard of care for primary treatment is non-operative, and includes rest/activity modification and often weight bearing protection or bracing. Failed conservative management often leads arthroscopy and drilling of the lesion. Two different primary drilling techniques have been utilized, but no prospective studies have compared their relative effectiveness. The study hypothesis was that retro-articular drilling (RAD), the slightly newer technique, would not be inferior to trans-articular (TAD), with regard to rate of healing, time to return to sports (RTS), and patient-reported outcome scores (PROs). Methods: Skeletally immature (n=113) patients presenting with MRI-confirmed stable OCD of the MFC who did not demonstrate substantial healing after a minimum of 3 months of non-operative treatment were prospectively enrolled by one of seventeen surgeon-investigators (at 14 centers, representing all major geographic regions in the U.S.) and randomized to TAD or RAD. Post-operatively, serial radiographs were obtained every 6 weeks to assess healing, and PROs were obtained at 6 months, 12 months, and 24 months. Twelve patients were closed out at time of surgery due to lesion instability detected during arthroscopy. Power analysis determined that in order to detect a difference in 2-year IKDC score between RA and TA groups with 80% power, sample sizes of 37 subjects per group would be required if the true standard deviation were 15. This analysis was based on conducting an independent samples Student’s t-test with alpha set to 5%. Results: Ninety-one study subjects were included, consisting of 51 TAD and 40 RAD patients, respectively, with the two groups being similar in age (12.6 years vs. 11.9 years), sex distribution (45% vs. 27% female, p=0.081), and 2-year PRO response rate (both 90%). No significant differences between TAD and RAD were detected in follow-up Pedi-IKDC, Lysholm, Marx knee activity score, or KOOS QOL scores (Table 1). Revision/additional OCD surgery occurred in 10% of patients in RAD and 4% in TAD (p=0.40). 73% of TAD patients reached a ‘healed’ status at a mean of 1.15 years, compared with 60% RAD patients at a mean of 1.21 years. Conclusions: While both primary forms of OCD drilling (TAD and RAD) showed consistent post-operative healing, achieving a completely ‘healed’ status was often a more prolonged process, taking approximately 1 year, despite clinical improvement and RTS being achieved much sooner. PROs were similar between drilling techniques. Significantly higher powered studies are needed to better elucidate the greater revision surgery rates in RAD compared with TAD, but overall risk is low and absolute risk only 6%. The current data support either drilling technique, which may be technically simpler, without the need for fluoroscopy, with TAD, and may be more protective of the chondral articular surface with RAD.

Background: For patients with significant growth remaining, the Iliotibial Band ACL reconstruction technique has proven to be reliable procedure with minimal risk for growth disturbance. Recent dissection studies confirm the neuro-vascular bundle is within 1 cm of the ACL graft over the top position, confirming the importance of careful graft passage technique to avoid neurovascular injury. Purpose: The purpose of this study was to evaluate the over the top graft passage technique using pediatric 3-D knee models. Instrument placement for graft passage was assessed for its proximity to the posterior aspect of the femur, maintaining a safe distance from the neurovascular bundle. Materials and Methods: 3D knee models (ages 7, 9, 11 years) were printed from high resolution knee CT scans, including a hinge/pivot mechanism to allow for simulation of knee position during flexion and extension. Various curved tip instruments were used to evaluate the path of the graft passage, with several goals: 1. Allow the instrument to create a graft path through the posterior capsule in the most anatomic femoral position. 2. Keep the tip of the instrument close to posterior and lateral cortex of the femur, to avoid neurovascular injury. The instruments varied in design, arc of curvature, overall length, diameters. Results: Clamp passage was performed using a retrograde approach, i.e. through the notch, passing outside the periosteum of the postero-lateral femur (Figure 1). For some clamps, the arc of the curvature allowed for passage of the instrument with minimal risk of neurovascular injury. For some clamp configurations, the clamps deviated significant from the posterior aspect of the femur during graft passage, which may increase the risk of neurovascular bundle injury. In each case, an instrument was identified that met the criteria for safe passage, but different instruments were required based upon the size of the knee joint. Conclusions: The ITB ACL reconstruction is one of the best options for ACL reconstruction in the skeletally immature. The neurovascular structures are very close to the path for over the top graft placement. Due to the wide range of knee dimensions in this group, different clamp designs may be necessary for optimal over the top graft passage. 3D knee models may guide surgeons for procedure technique and optimal instrument selection for safe graft passage. [Figure: see text]

Objectives: Determining bone age in skeletally immature patients is critical for proper management and surgical planning. Pennock et al. recently created and validated a bone age atlas using the ossification pattern of the knee on MRI in pediatric patients, obfuscating the need for a hand radiograph and its associated cost, radiation exposure, and clinical inefficiency. This aim of this study was to create and validate a shorthand method of bone age determination using knee MRI. Methods: We identified patients who underwent both knee MRI and hand bone age radiograph within a ninety-day period. From the findings of Pennock et al., a stepwise algorithm for predicting bone age on knee MRI was developed for males and females separately, in collaboration with a pediatric musculoskeletal radiologist. Six raters at varying levels of training used the algorithm to assign a bone age to each knee MRI. Intraclass correlation coefficient (ICC) was used to compare each rater’s predicted knee bone age to the Greulich and Pyle (G&P) hand bone age and validate the shorthand algorithm. Inter- (two-way random, absolute agreement) and intra-rater (two-way mixed, absolute agreement ) reliability were also calculated using ICC. Results: Thirty-eight patients (44.7% females) underwent a knee MRI at a mean age of 12.8 years (range 9.3-15.7). The mean time between hand bone age x-ray and knee MRI was 20.2 days (range 0-88). The inter-rater reliability for the application of our shorthand algorithm was 0.81 (95% CI: 0.72 – 0.88), indicating good inter-observer agreement. The shorthand algorithm was also shown to be a reliable predictor of hand bone age across level of training, as medical students (ICC 0.77, 95% CI 0.60-0.88), residents (ICC 0.80, 95% CI 0.65-0.89), and attending physicians (ICC 0.80, 95% CI 0.63-0.89) all achieved strong correlation between predicted knee bone age and G&P hand bone age. All respondents also demonstrated consistency, with intra-rater ICCs between 0.85-0.93. Conclusion: This shorthand algorithm is a consistent, reliable and valid way to determine skeletal maturity using knee MRI in patients aged 10 to 15 and can be utilized across different levels of orthopaedic and radiographic expertise. We believe this method is readily applicable in a clinical setting and may reduce the need for routine hand bone age radiographs. Figure 1. Table 1. Correlation between knee MRI bone age and hand radiograph bone age (G&P) for each rater, as determined using intraclass correlation coefficients (ICC). Note: Intra-rater reliability has not been competed for “Resident 2” at this time. Validity of MRI Knee Bone Age and Hand Bone Age Intra-Rater Reliability Rater ICC 95% CI ICC 95% CI Student 1 0.75 0.57-0.86 0.93 0.79-0.97 Student 2 0.73 0.53-0.86 0.93 0.87-0.97 Resident 1 0.73 0.54-0.85 0.85 0.73-0.92 Resident 2 0.78 0.60-0.88 - - Attending 1 0.74 0.54-0.85 0.86 0.70-0.93 Attending 2 0.80 0.63-0.89 0.86 0.72-0.93

Background: The medial and lateral ligamentous complexes of the elbow provide static restraint to the elbow and serve as important components of posteromedial and posterolateral rotatory instability. Many collateral ligament and medial epicondylar injuries require surgical repair in those with open physes. Little is known about the anatomy of the pediatric elbow and the relationship between these ligaments and physes. Purpose: To evaluate the anterior bundle of the medial collateral ligament complex, lateral ulnar collateral ligament, annular ligament, and relationships to the joint surfaces and physes. Methods: Two cadaveric elbows from a 3 year-old donor were dissected. Collateral and annular ligaments were isolated and left intact at their osseous attachment. Pins were placed at the origins and insertions and CT scans were used to establish precise anatomic relationships. All dissections and measurements were performed by a single orthopedic surgeon with specialization in pediatric sports medicine. Results: The MUCL origin was a mean 4.10 mm distal and anterior to the medial epicondyle, 10.09 mm from the distal humeral articular surface, and 9.01 mm distal to the medial physis. The distal insertion of the MUCL spanned a mean 3.09 mm and was posterior and medial to the sublime tubercle. In the longitudinal axis, the MUCL insertion footprint spanned the tubercle. The origin was a mean 1.20 mm proximal to the sublime tubercle and the distal extent averaged 2.53 mm distal to the tubercle. The center of the MUCL insertional footprint was 0.38 mm distal to the tubercle. The center of the MUCL was 3.87 mm from the olecranon articular surface. The annular ligament had consistent medial and lateral attachments to the ulna. Distance from the annular ligament attachments to the tip of the coronoid averaged 4.6 mm (4.46 & 4.74 lateral and medial for left; 4.80 & 5.27 lateral and medial for right). The LUCL origin was distal and anterior to the lateral epicondyle. It was 3.43 mm from the lateral epicondyle, 7.51 mm from the articular surface and 0.74 mm distal to the physis. Conclusions: This study is the first to describe anatomy of the elbow collateral and annular ligaments in pediatric cadaveric specimens, through a reliable, CT-based identification method. Knowledge of the precise ligamentous attachments and relationships to the physis and to the joint surface is important for reconstructive procedures. A better understanding of these relationships may assist with surgical planning that preserves adjacent physeal growth regions.

Background: Despite advances in surgical techniques, implant technology, and biological augmentation, one innate limitation to meniscus healing is lack of vascularity. Ability to quantify meniscal vascularity has been limited with previous techniques, and minimal data exists describing differential vascular zones in the skeletally immature meniscus. Purpose/Hypothesis: The objective of this study is to use quantitative contrast-enhanced magnetic resonance imaging (MRI) to compare meniscal vascularity in pediatric cadaveric specimens to adults. We hypothesize that the developing meniscus has greater and more uniform vascularity throughout all zones. Methods: We utilized 10 fresh-frozen human cadaveric knees (5 immature knees, age 0-6 months; 5 mature knees, age 34-67 years). Gadolinium-enhanced MRI was performed using a previously established vascularity quantification protocol. Regions of interest corresponding to peripheral and central zones of the meniscus were identified on pre-contrast coronal images, and signal enhancement (normalized against background tissue) was compared between pre-and post-contrast images (Figure 1). Results: Quantitative MRI demonstrated increased perfusion in the peripheral zones compared to the central zones (2.3:1 in immature knees and 3:1 in mature knees) in the medial and lateral menisci separately, and both menisci aggregated. Overall, the medial and lateral menisci had similar levels of perfusion in all specimens (45.9% ± 8.3% medial vs. 54.1% ± 8.3% lateral in immature knees; 50.5% ± 11.3% medial vs. 49.5% ± 11.3% lateral in mature knees). Immature specimens demonstrated greater overall normalized meniscal signal uptake, with the 0-month specimen demonstrating the greatest proportional signal enhancement. Conclusion: While blood flow to peripheral zones is greater than to central zones in both immature and adult menisci, younger menisci receive proportionally greater overall blood flow compared to adults, including greater blood flow to the inner zone, challenging the conventional wisdom of the central zone being avascular. As younger patients become increasingly active in sports, thorough understanding of the immature meniscus is required. Greater overall vascularity, including centrally, to the developing meniscus suggests improved healing potential following injury, and further encourages meniscal preservation when possible. Figure 1. Analysis of meniscal vascularity using contract-enhanced magnetic resonance imaging. A:Schematic drawing of peripheral and central zones of the medial and lateral menisci used for quantification.B:Mid-coronal images showing pre-and post contract images with ROIs delineated in adult and pediatric specimens; there is significatly increased perfusion to the epiphysis in the immature knee. Figure 2. Quantification of mensical vascularity in each specimen Comparsion of relative vascularity of peripheral versus central zones shows significantly greater blood flow to outer zone across all specimens.Quantification of total vascular contribution from the medial and lateral menisci aggregated showed a trend towards greater proportional blood flow in younger specimens.

Background: Although the available evidence generally supports surgical treatment of unstable osteochondritis dissecans (OCD) lesions of the elbow, the optimal surgical management lacks consensus. Given the myriad of options available for skeletally immature patients, the purpose of this study was to identify preferred surgical procedures based upon patient and OCD characteristics among a group of high volume surgeons. Hypothesis/Purpose: To understand current treatment practices for experts on OCD of the elbow. Methods: A survey evaluating the surgical treatment strategies for twenty-three clinical vignettes of skeletally immature patients with OCD of the elbow was created and distributed electronically to members of the Research on Osteochondritis Dissecans (ROCK) study group using REDCap. Each vignette described an OCD lesion of varying location, size, degree of cartilage involvement, and depth. Multiple-choice answers related to specific treatment strategies and technique were provided for each lesion. Standard descriptive statistics were used to summarize and compare responses for each vignette. Results: Fifteen surgeons treating OCD of the elbow participated in the study. All respondents were attending-level surgeons. One-third of responding surgeons treat elbow OCD weekly, 53% monthly, and 13% every six months. In skeletally immature patients with stable, intact elbow OCD lesions, 80% of surgeons would treat with transarticular (58%), retroarticular (33%), or combined trans/retroarticular (8%) drilling. For full-thickness (FT) osteochondral defects occupying 33% or 66% of capitellar width, the preferred treatment modality varied substantially based on lesion depth. Overall, the preferred strategies for these lesions were (1) debridement with marrow stimulation for FT defects with 1-2 mm subchondral bone loss and (2) internal fixation for trap-door lesions with either trace or > 4 mm of subchondral bone. There was substantial heterogeneity with respect to treatment strategy for FT defects with > 4 mm bone loss. For a lesion occupying 33% of capitellar width, 47% of surgeons would treat with debridement and marrow stimulation, 47% would treat with an osteochondral transfer, and 6% would perform both. For larger lesions of 66% width, slightly more would treat with osteochondral transfer (47% vs. 40%). Ultimately, > 75% agreement was only reached in 19% of the vignettes, highlighting the high degree of variability in the treatment of elbow OCD. Conclusion: For elbow OCD in skeletally immature patients, the greatest agreement exists for (1) the drilling of stable OCD lesions, though there is variability with respect to technique (transarticular/retroarticular/combined) and (2) internal fixation for trap-door lesions with > 5mm of subchondral bone. Nonetheless, high-quality clinical data to guide decision-making is currently lacking for capitellar OCD. Even among a group of experienced experts, there is significant disagreement regarding preferred surgical methods. Our study ultimately highlights the need for multicenter, prospective investigations to evaluate the clinical outcomes of various treatment strategies for OCD of the elbow. Table I. Preferred intra-operative treatment principles and techniques for a central, full-thickness OCD lesion of the capitellum. Lesion Depth Treatment Principle % of Surgeons Central, Contained 33% Width of Capitellum Full-Thickness Defect 4 mm Bone Loss Transarticular/Retroarticular Drilling 0 Debridement +/- Marrow Stimulation 46.7 Debridement Only 0 Debridement + Marrow Stimulation 100 Drilling of Full-Thickness Defect 28.6 Awl 42.9 Abrasion 14.3 Other 14.3 Internal Fixation 0 Osteochondral Transfer 46.7 Allograft 28.6 Autograft 71.4 Biopsy and ACI 0 Figure 1. Treatment principles and techniques for skeletally immature patients with central, contained OCD lesions occupying 33% width of the capitellum with varying articular cartilage and subchondral bone involvement. (FT = full-thickness; TD = trap-door)

Background: Pediatric athletes commonly sustain inversion-type ankle fractures.1,2 Approximately 1% will form post-traumatic subfibular ossicles (SO), especially after tip avulsion fractures.3,4 Athletes with SOs can have pain and recurrent sprains.5,6,7 Here we show the utility of magnetic resonance imaging (MRI) in clinical decision-making for athletes with ankle symptoms and the presence of a SO. Our hypothesis is that MRI can predict which athletes have a stable SO and will respond to non-operative management, and which athletes have an unstable SO and will need surgery. Methods: We performed an IRB approved retrospective cohort study. Children were eligible from our practices if (1) they had radiographic evidence of a SO, (2) they had symptoms of pain and recurrent sprains, and (3) they had undergone MRI during their clinical evaluation. We identified 19 eligible children (20 ankles;) eight girls and eleven boys, ages 5–19 years. Nine involved the left ankle; 11 the right ankle. Most frequent sport was soccer (12/16) followed by basketball (3/14.) From the radiograph we determined ossicle size and location. MRI images were considered positive if fluid-sensitive sequences showed a high-intensity signal between the SO and the fibular epiphysis. Main outcome was treatment (non-surgical or surgical) relative to the MRI findings. Results: Size shape and location: Size and shape were variable. Width ranged from 2 – 10.4 mm and length from 4 – 13.5 mm. Concerning location all were in the distal 1/3 pf the epiphysis. Six were anterior and 14 were anterior-inferior to the fibular tip. MRI findings: Sixteen of the 20 ankles (80%) had positive MRI findings (figure 1), and 4 had negative findings (figure 2). The ATFL attached directly to the fragment in 11 of the 16 MRI positive ankles. Clinical decision making: All athletes with negative MRI findings responded to non-operatively management. Ten of the 16 ankles with positive MRIs have had surgery. Eight had excision of the ossicle and two had internal fixation based on the size of the ossicle. Surgical findings confirmed attachment of the ATFL to the fragment (figure 3.) Six athletes with positive MRIs continue to be under observation. Conclusions The results support our hypothesis that MRI has predictive value in clinical decision-making for symptomatic athletes with a SO. When fluid-sensitive MRI sequences show high signal intensity between the ossicle and the fibular epiphysis, and when the ATFL attaches to the ossicle, the athlete has a poor prognosis for non-operative management. [Figure: see text][Figure: see text] References: Su AW, Larson AN. Pediatric ankle fractures: Concepts and treatment principles. Foot Ankle Clin. 2015;20(4):705-719. Pommering TL, Kluchurosky L, Hall SL. Ankle and foot injuries in pediatric and adult athletes. Prim Care 2005;32(1):133-161. Han SH, Choi WJ, Kim S, Kim S-J, Lee JW. Ossicles associate with chronic pain around the malleoli of the ankle. 2008;90-B:1049-1054. Gamble JG, Sugi M, Tileston KR, Chan CM, Livingston KS. The natural history of type VII all-epiphyseal fractures of the lateral malleolus. Orthop J Sports Med. 2019; 7(3) (suppl 1) DOI 10.1177/2325967119S00116. Pill SG, Hatch M, Linton JM, Davidson RS. JBJS 2013;95: e115(1-6). Han SH, Choi WJ, Kim S, Kim SJ, Lee JW. Ossicles associated with chronic pain around the malleoli of the ankle. J Bone Joint Surg Br. 2008;90(8):1049-1054. Danielsson LG. Avulsion fracture of the lateral malleolus in children. Injury 12:165-167

Background: Determining bone age in skeletally immature patients is critical for proper management and surgical planning. Pennock et al. recently created and validated a bone age atlas using the ossification pattern of the knee on MRI in pediatric patients, obfuscating the need for a hand radiograph and its associated cost, radiation exposure, and clinical inefficiency. Hypothesis/Purpose: We sought to validate and demonstrate reliability of a novel shorthand method of bone age determination using knee MRI across multiple levels of medical training. Methods: We identified patients who underwent knee MRI and hand bone age radiograph within a ninety-day period. In collaboration with a pediatric musculoskeletal radiologist, stepwise algorithms for predicting bone age on knee MRI were developed- one for males and one for females. Six raters at varying levels of training used the algorithm to assign a bone age for each patient. Intraclass correlation coefficient (ICC) was used to compare each rater’s predicted knee bone age to the Greulich and Pyle (G&P) hand bone age and validate the shorthand algorithm. Inter-rater reliability was also calculated using ICC. Results: Thirty-eight patients (44.7% female) underwent a knee MRI at a mean age of 12.8 years (range 9.3-15.7). The mean time between hand bone age x-ray and knee MRI was 20.2 days (range 0-88). The inter-rater reliability for the application of our shorthand algorithm was 0.81 (95% CI: 0.72 – 0.88), indicating good inter-observer agreement. The shorthand methos was shown to be a good predictor of G&P hand bone age, both for each individual rater (ICC range: 0.73 – 0.80) and the mean knee MRI bone age across all raters (ICC 0.81; 95% CI 0.65 – 0.90). It was also shown to be a consistent predictor of hand bone age across level of training, as medical students (ICC 0.77, 95% CI 0.60-0.88), residents (ICC 0.80, 95% CI 0.65-0.89), and attending physicians (ICC 0.80, 95% CI 0.63-0.89) all achieved strong correlation between predicted knee MRI bone age and G&P hand bone age. Conclusions: This novel shorthand algorithm is a reliable and valid way to determine skeletal maturity using knee MRI. It can be utilized clinically across different levels of radiographic and orthopaedic expertise and reduces the need for hand bone age radiographs and consequential radiation exposure in children. Figure 1. Shorthand Algorithm for Knee Bone Age Using MRI for Males Figure 2. Shorthand Algorithm for Knee Bone Age Using MRI for Females Table 1. Correlation between knee MRI bone age and hand radiograph bone age (G&P) for each rater, as determined using intraclass correlation coefficients (ICC). Rater ICC 95% CI Student 1 0.75 0.57 – 0.86 Student 2 0.73 0.53 – 0.86 Resident 1 0.73 0.54 – 0.85 Resident 2 0.78 0.60 – 0.88 Attending 1 0.74 0.54 – 0.85 Attending 2 0.80 0.63 – 0.89 Mean 0.83 0.68 – 0.91

Background: Young athletes have the highest rates of primary and recurrent anterior cruciate ligament (ACL) tears, and recent research has identified graft diameter as a predictor of graft failure. Newer ACL reconstruction techniques have been developed to increase graft diameter and reduce re-rupture rates. Graft diameter can be modified based upon graft length, number of graft strands/configuration, and native ACL length. While the ACL has been well-studied in adult populations, there is limited research examining the ACL dimensional characteristics in a pediatric population. Appropriate preoperative anatomic dimensions may help surgeons plan for optimal graft length, diameter and bundle arrangement Purpose: To develop MRI-based predictors of native ACL graft length in pediatric populations and enhance preoperative planning to optimize graft length, strand configuration and graft diameter to lower the risk of recurrent ACL injury. Methods: One hundred and ten subjects were included from the STRIDE database (64 females and 46 males, median age 10 years, range 1-13 years). Our exclusion criteria were if the subjects had musculoskeletal diseases or history of knee injury. Using MRIs, researchers evaluated ACL length, sagittal and coronal inclination of the ACL, inclination and width of the intercondylar notch, depth and width of the femoral condyles, and the medial and lateral tibial slopes. Association between measurements, sex, and age were investigated using linear and multivariate regression models. Results: When examining the predictors for ACL length by sex, the best predictor (R⁁2 = 0.65) for female ACL lengths was the depth of the lateral femoral condyle taken in the sagittal view (pConclusion: When predicting the ACL length in pediatric populations, femoral condylar depth and width, and patient age may be valuable predictors for those undergoing ACL reconstructions. Surgical planning to maximizing graft diameter is contingent upon native ACL graft length, and the use of this information to optimize graft utilization may lower the rates of ACL graft failure in the highest risk pediatric populations. Tables/Figures: [Table: see text][Figure: see text][Figure: see text]

Background: Quantifying native cartilage thickness in pediatric and adolescent knees can help match donor and recipient sites for articular cartilage restoration procedures such as osteochondral autograft transplantation (OATS) and osteochondral allograft transplantation (OCA). Hypothesis/Purpose: The purpose of the current study was to quantify articular cartilage thickness in pediatric and adolescent knees using magnetic resonance imaging (MRI). We hypothesized that cartilage thickness is inversely correlated with skeletal maturity and age. Methods: One hundred and twenty MRI scans were evaluated in a cohort of patients 9 to 18 years old without osteochondral lesions, chondral wear or pathology, intraarticular fractures, history of knee surgery, or inflammatory arthropathy. Measurements of articular cartilage thickness at the medial femoral condyle, lateral femoral condyle, lateral trochlea, and patella were made on axial, coronal, and sagittal MRI scans (Figure 1). Skeletal maturity was categorized as ‘open’, ‘closing’, or ‘closed’ based on the status of the proximal tibial and distal femoral growth plates. Descriptive statistics was used to evaluate cartilage thickness by age and sex. Independent samples t-test, analysis of variance (ANOVA), and linear regression were performed to investigate for associations with sex, skeletal maturity, and age. Results: On the femur, cartilage was thickest at the lateral trochlea with mean articular thickness of 4.2 ± 1.4 mm in males and 3.6 ± 1.3 mm in females (p=0.015) (Table 1). Skeletally immature patients with open physes had significantly thicker cartilage at the medial femoral condyle, lateral femoral condyle, and lateral trochlea compared to patients with closing and closed physes (Figure 2). Linear regression analysis also revealed a significant association between femoral cartilage thickness and age (Figure 3). Age explained 63% of the variance at the medial femoral condyle (B=6.1, p

Background: Arthroscopy may be utilized for treatment of septic arthritis of the pediatric knee, with success reported in ages from 3 months to 12 years. There is limited data on the ability to arthroscopically assess articular structures and ensure adequate evaluation without arthrotomy. Hypothesis/Purpose: The purpose of this study is: (1) utilize arthroscopy in small cadaveric knees to improve qualitative and quantitative knowledge of pediatric articular structures and (2) to obtain pilot data for common procedures performed in pediatric patients Methods: Five small pediatric cadaveric specimens (1-4 years) underwent arthroscopy (2.7 mm Stryker arthroscope). Medial and lateral compartments were assessed for meniscus size/mobility/height, compartmental joint space, ACL insertion, patellar chondral height and length, and position of the medial patellofemoral ligament were recorded. Utilizing standard anterior medial and lateral portals, the ability to visualize the structures of the posteromedial and posterolateral compartments was recorded. Procedures pertinent to immature ACL reconstruction and meniscal repair (unstable discoid) were critically evaluated to provide source data for future work. Results: Prior to arthroscopy, all specimens underwent volume-assessed knee insufflation (average 11.4 cc normal saline). Arthroscopic visualization of the menisco-capsular attachment was possible posteromedially in 4/6, and posterolaterally in 5/6 knees. Qualitative arthroscopic relationships were similar to adult references; including patellar-trochlear articulation and lateral meniscal positional relationship to the ACL insertion (see Figure 1). The ACL center was within 2 mm of the posterior aspect of the anterior horn of the lateral meniscus in all specimens. The average height of the medial compartment space under valgus load was 1.5 mm (1 – 2 mm), and lateral space under varus was 2.2 mm (2-3 mm); further emphasizing the need for small joint instruments. The width of the medial and lateral menisci are noted in Table 1. All-inside meniscal devices designed for skeletally mature specimens should be used with caution (Figure 1). Traditionally described inside-out technique for immature ACL reconstruction with an iliotibial band demonstrated significant proximity of the passing device to the neurovascular bundle (Figure 1). Conclusion: The entirety of the small knee is assessable via standard diagnostic arthroscopy, when a 2.7mm arthroscope is utilized. These findings suggest that intra-articular pathology can be reliably identified utilizing this surgical technique. However, the ability to work on the infant meniscus and cartilage with standard arthroscopic instruments is likely limited given the constraints of joint height. Table 1. Meniscal width of the medial and lateral meniscus as measure by a microprobe. Figure 1. Arthroscopic and gross images of an infant cadaveric knee 11 year old). (A) ACL insertion into the tibia. Note the relationship of the anterior horn of the lateral meniscus to the ACL Insertion. (B) The patellocrochiear articulation with a well formed troctilea, (C) Medial patellofemoral ligament as it inserts onto the patella. Marking in the ligament 1') indicates centroid of the ligament based on superficial anatomy. (D) Pilot study of placement of an all-inside meniscal repair device (Stryker AIR) The size of implant is 70% of the height of the lateral meniscus, .1E) Image of a dissected popliteal fossa of a small knee. Curved clamp )black arrow) was placed as if to facilitate passage of the !Thin a extra-articular ACL reconstruction with the dicta:fiat hand. Note the proximity to the posterior neurovascular structures (Yellow = artery; blue = nerve).

Background: The anatomy of the trochlea plays a significant role in patella stability. Surgical approaches to alter the anatomy of the trochlea and associated structures to influence patella tracking continue to evolve. Unlike the development of the pediatric hip joint which has been well studies for decades, the developmental anatomy of the trochlea and its relationship to patella stability remains poorly understood. An improved understanding of trochlear growth and development may alter both the timing and type of surgical procedures for patella stability. Purpose: The purpose of this study was to describe the developmental changes of the osseous and cartilage trochlear morphology in skeletally immature specimens. Methods: Fifty-five skeletally immature cadaveric knees between the ages of 2 months and 11 years were evaluated using 0.625mm computed tomography scans. In the axial plane, measurements included medial and lateral osseous condylar height, medial and lateral cartilaginous condylar height, osseous and cartilaginous sulcus angles, osseous and cartilaginous condylar height asymmetry, and trochlear depth. Results: Analysis of trochlear morphology using osseous and cartilaginous measurements of condylar height, condylar height asymmetry, and trochlear depth demonstrated an increase in the size of the medial and lateral trochlea as age increased. The osseous and cartilaginous sulcus angles decreased (became deeper) with age until around age 8 and then plateaued. This corresponded with an increase in trochlear depth that plateaued also around age 8. In contrast, medial and lateral condylar height continued to increase through age 11. Cartilaginous condylar asymmetry rose slightly with age with the lateral condyle consistently larger than the medial condyle. Osseous condylar asymmetry increased with age but flipped from a larger medial condyle to a larger lateral condyle around age 8. Conclusions: This cadaveric analysis demonstrated that there is an increase in the medial and lateral trochlear height as age increased by all measurements analyzed. These changes in height continue to be seen through age 11 suggesting a still developing trochlea past this age. By age 8, a plateau in sulcus angle and sulcus depth suggests more proportionate growth after this point. Access to pediatric cadaveric specimens is exceptionally rare. This study provides a unique evaluate of the developing trochlea in young children, especially those under age 7, who rarely receive advanced imaging. [Figure: see text][Figure: see text]

Background: The medial patellofemoral complex (MPFC) is comprised of the medial quadriceps tendon-femoral ligament (MQTFL) superiorly and the medial patellofemoral ligament (MPFL) inferiorly. The anatomy of the pediatric MPFL has been well-described, however, the MPFC in skeletally immature patients and its relationship to the quadriceps tendon and superior patellar border has yet to be described. Purpose: To evaluate the relationship between the MPFC attachment and quadriceps tendon and patella in skeletally immature patients. Methods: 16 pediatric knees were dissected to analyze the MPFC insertion on the quadriceps tendon. Dissection was performed using a lateral parapatellar arthrotomy followed by eversion of the extensor mechanism to evaluate the MPFC fibers from its undersurface. The patellar articular length (PL), patellar width, and quadriceps tendon attachment (QTA) of the MPFC above the superior pole of the patella were measured using the ImageJ program. Additionally, the ratio of quadriceps tendon attachment to patellar length was calculated as a percent (QTA/PL%). Two sample t-tests were used to identify significant differences. Results: The average age of the specimens included in this study was 9.6 years. Specimens were divided into two cohorts: a younger cohort (4-8 years), and an older cohort (9-12 years). The QTA above the patella averaged 10.6 mm in the younger cohort and 13.4 mm in the older cohort with no significant difference between the two groups (Figure 1). There was no significant difference in average QTA/PL% which was found to be 47.8% and 48% for the younger and older cohorts respectively (Figure 1). PL was significantly longer in the older cohort (Figure 1). As shown in Figure 2, the insertion of the proximal MPFC into the quadriceps tendon can be variable across specimens. Conclusion: This study clarifies the anatomy of the pediatric MPFC in exceptionally rare pediatric specimens. The MQTFL relationship to the quadriceps tendon is important to guide surgical reconstructions of the medial stabilizers of the patellofemoral joint. Primary and recurrent patella instability remains a significant problem in those under 20 years. A better understanding of the MPFC (both the MQTFL and MPFL components) will support anatomic reconstructions to stabilize the joint. [Figure: see text][Figure: see text]

Background: For patients with significant growth remaining, the Micheli-Kocher (iliotibial band) ACL reconstruction technique has proven to be a reliable procedure with minimal risk for growth disturbance. Recent cadaveric studies have demonstrated that graft passage over the top of the femur may bring the graft and instrument close to the critical neurovascular structures. Purpose: The purpose of this study was to evaluate the over-the-top graft passage technique using pediatric cadaveric knees, and measure the distance between instruments and the peroneal nerve, tibial nerve, popliteal artery. Methods: Seventeen skeletally immature cadaveric knees between the ages of 4 and 12 years old were dissected and prepared for visualization of iliotibial band graft passage procedure. A curved hemostat clamp was used, creating a path through the posterior capsule. To avoid neurovascular injury, the tip of the instrument was kept close to the posterior and lateral cortex of the femur. Once the clamp was safely positioned in the posterior knee joint, photographs were taken. Digital imaging software was used to measure the distance in centimeters from clamp tip to peroneal nerve laterally, and the popliteal artery and tibial nerve medially for all specimens, FIGURE 1. Distances were averaged and stratified to assess differences in age, FIGURE 2. Results: The average distances from clamp to neurovascular bundle were 0.875cm (range: 0.468-1.737cm), 0.968cm (range: 0.312-1.819cm), and 1.149cm (range: 0.202-2.409cm) for tibial nerve, popliteal artery and peroneal nerve, respectfully. Means were further calculated for age groups ≤8, 9-10, and 11-12 years old. Conclusion: Iliotibial band graft ACL reconstruction is one of the best options in the skeletally immature, as it has the lowest risk of growth plate complications and growth arrest. The neurovascular structures are very close to the path for over-the-top graft clamp placement with distances

Background: The HSS Pedi-FABS activity scale has become increasingly used in children age 10-18 since its development in 2013. Research reports on the utility of the measure in general youth athletes with knee injuries, however limited information is available regarding use in evaluating a variety of joint injuries, athletes who participate in sports with disparate biomechanics, or specialized competitive athletes. Hypothesis/Purpose: This study assessed the sensitivity and distribution of Pedi-FABS in an athletic youth population. Secondarily, this study evaluated Pedi-FABS association with PROMIS® Pediatric Global Health 7(PGH7) with Pain Interference(PGHPI) and Fatigue(PGHF) components. Methods: A retrospective review of youth athletes age 10-18 presenting for evaluation at a single pediatric sports medicine clinic between 4/2016-7/2020 was performed. Participants were included if they completed a pre-visit intake questionnaire and Pedi-FABS. Descriptive statistics were used to analyze Pedi-FABS for normal distribution and the presence of a floor or ceiling effect in subgroups determined by demographics, injury characteristics, and sports participation. A floor or ceiling effect was determined to be present if more than 15% of respondents scored the lowest or highest possible score. A Kruskal-Wallis test used to compare average scores in each subgroup. Spearman’s Correlations were calculated to assess the association of PGH with Pedi-FABS scores. Results: 2274 sports medicine patients(14.6±2.1 years; 53.0% females) were included. Of these, 2010 youth athletes reported participating in sports for 9.6±7.9 hours per week during 32.3±15.7 weeks per year with 6.2±3.4 years of participation in 21 distinct primary sports. 80.3% of patients reported participation in only one sport. Pedi-FABS Score differences were found across demographic(Table 1) and sport participation(Table 2) subgroups. Broad distribution was seen in each subgroup with no floor or ceiling effects. Pedi-FABS score correlated with hours per week(r=0.20), days per week(r=0.28), weeks per year(r=0.12), and years of participation(r=0.16/pConclusion: Correlations with multiple forms of self-reported activity without floor or ceiling effects demonstrates the validity and sensitivity of Pedi-FABS for use in athletes with a variety of primary sports and injury types. Additionally, mean differences between demographic and sport participation subgroups, as well as associations with days to presentation and a commonly used patient reported outcome measure, may demonstrate the utility of Pedi-FABS for sports medicine clinicians. [Table: see text][Table: see text]

Background: Meniscal injury in skeletally immature patients is increasingly reported. During meniscal repair, all-inside devices may protrude beyond the posterior limits of the meniscus, putting the neurovascular structures at risk. Purpose: The purposes of this study were (1) to examine the relationship between the popliteal artery and the posterolateral and posteromedial aspects of the menisci, (2) to examine the relationship of the peroneal nerve to the posterolateral meniscus, and (3) to develop recommendations for avoiding neurovascular injury during posterior meniscal repair in pediatric patients. Study Design: Descriptive laboratory study. Methods: A total of 26 skeletally immature knee cadaveric specimens (7 females and 19 males) were included. Specimens were divided into age groups: 2-4, 5-8, and 9-11 years. The most posterior extent of the lateral and medial menisci was identified via sagittal and axial views on computed tomography (CT) scans. The shortest distance from the most posterior aspect of the lateral and medial menisci to the popliteal artery and the shortest distance from the posterior aspect of the lateral menisci to the anterior rim of the peroneal nerve were measured, and 3-dimensional models of representative specimens were re-created through use of CT scans. Results: For the age groups 2-4, 5-8, and 9-11 years, the mean minimum distance from the posterolateral meniscus to the popliteal artery was 5.2, 6.7, and 8.2 mm, respectively, and the mean minimum distance from the posteromedial meniscus to the popliteal artery was 12.7, 15.4, and 20.3 mm, respectively. In all groups, the distance between the posteromedial meniscus and the popliteal artery was greater than that between the posterolateral meniscus and the popliteal artery. The mean distance from the peroneal nerve to the lateral meniscus was 13.3, 15.0, and 17.9 mm for the respective groups. Conclusion: Many all-inside meniscal repair devices have sharp tips that penetrate posterior to the meniscus and capsule. This study demonstrated that the distance between the posterior meniscus and popliteal artery is relatively small in pediatric patients, especially for the lateral meniscus region. Clinical Relevance: Because of the higher potential for meniscal healing, meniscal repair is more likely to be performed in pediatric patients. The data in this study regarding the proximity of the lateral meniscus and neurovascular structures may be used to guide safe surgical repair of posterior meniscal tears during the use of all-inside meniscal repair devices in these patients.

Background: The close proximity of the popliteal neurovascular bundle to the posterior horn of the lateral meniscus puts it at risk of compromise during lateral meniscal repair. This is particularly important in smaller pediatric patients, who are commonly treated for lateral meniscal abnormalities in isolation (discoid meniscus) or concomitantly with anterior cruciate ligament reconstruction. Purpose: To quantify the distance between the posterior horn of the lateral meniscus and the popliteal neurovascular bundle along the path of meniscal repair and to investigate for associations with age, sex, height, weight, body mass index (BMI), and skeletal maturity. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 144 magnetic resonance imaging scans were evaluated in a cohort of patients aged 10 to 18 years without meniscal or ligament abnormalities. Measurements were made along a line from the anterolateral portal between the popliteal neurovascular bundle and the free edge, midpoint, and meniscocapsular junctions of the posterior horn of the lateral meniscus. In addition to descriptive statistics of these distances by age and sex, analyses of variance and linear regression analyses were performed to investigate for associations with age, sex, height, weight, BMI, and skeletal maturity. Results: Male participants had a significantly larger mean free edge distance (14.4 ± 2.5 vs 13.1 ± 2.5 mm, respectively; P = .005) and midpoint distance (9.6 ± 2.2 vs 8.9 ± 1.8 mm, respectively; P = .011) than female participants but not a significantly larger meniscocapsular distance (5.2 ± 1.6 vs 4.6 ± 1.4 mm, respectively; P = .096). Linear regression analyses revealed significant associations between these distances and age, height, weight, and BMI ( P < .001 for all). There were statistically significant pairwise differences for free edge and midpoint distances to the neurovascular bundle between patients with open and closed physes. Conclusion: The distance between the posterior horn of the lateral meniscus and the popliteal vasculature along a trajectory from the standard anterolateral arthroscopic portal increases linearly throughout development between the ages of 10 and 18 years. There were also significant associations between height, weight, BMI, and skeletal maturity and these anatomic distances. Knowing the safe distance to the popliteal vasculature will increase the safety of arthroscopic lateral meniscal repair in children, especially with all-inside devices that require setting the penetration depth for the advancement of a sharp delivery device beyond the posterior capsule.

Background:The quadriceps tendon (QT) is increasingly considered for primary and revision anterior cruciate ligament reconstruction in skeletally immature patients, as it may be harvested as a purely soft tissue graft with considerable tissue volume. Because of distinct rectus tendon (RT) separation from the QT complex, the potential for RT retraction exists and could lead to QT weakness after QT graft harvest.Purpose:To describe the anatomy of the pediatric QT and clarify decussation of the RT and QT to avoid the risk of delayed RT retraction and QT weakness after QT graft harvest.Study Design:Descriptive epidemiology study.Methods:Nine cadaveric knee specimens (aged 4-11 years) underwent gross dissection. Coronal-plane width and depth of the QT were measured at intervals proximal to the superior pole of the patella at distances of 0.0, 0.5, 1.0, and 1.5 times the length of the patella. The distance was measured from the superior patellar pole to the point of RT separation from the remainder of the deeper/posterior QT.Results:The median patellar length was 28 mm (interquartile range, 26-37 mm). The coronal-plane width of the QT was larger superficially/anteriorly when closest to the patella but wider when measured deeper/posteriorly as the tendon extended proximally. The median distance between the superior pole of the patella and RT separation from the QT was 0.95 times the patellar length. The distance to widening of the deeper/posterior aspect of the QT was 1.14 times the patellar length proximal to the patella.Conclusion:The RT begins a distinct separation from the QT above the superior pole of the patella at a median of 0.95 times the patellar length in skeletally immature specimens. The deeper/posterior aspect of the QT begins to increase in coronal-plane width proximally after a distance of 1.14 times the patellar length above the knee, while the superficial/anterior aspect of the tendon continues to narrow. Awareness of the separation of the RT from the QT, and the coronal-plane width variation aspects of the QT proximally, is important for surgeons utilizing the QT as a graft to avoid inadvertent release of the RT from the rest of the QT complex.

Background: Knowledge of the medial patellofemoral ligament (MPFL) size and positional relationship to the articular cartilage is not well understood in pediatrics. The purpose of this study was to analyze the size and position of the MPFL relative to the articular surface of the pediatric patella. Methods: 39 pediatric cadaveric knee specimens (age range 1 month-11 years, 24 male) were dissected by fellowship-trained, pediatric orthopedic surgeons to expose the MPFL insertion to the patella (Figure 1A). Digital calipers (Mahr, MarCal 16EWRi) were used to record the proximal to distal cartilaginous articular surface length and the proximal to distal extent (zone) of MPFL patellar insertion. The ratio of the patellar articular cartilage length covered by the zone of MPFL patellar insertion was calculated. The center-point of the zone of MPFL patellar insertion was also recorded as a percentile distance from the superior margin of the articular cartilage of the patella. These measures were analyzed by age and Spearman’s Correlation coefficients were calculated. Results: Both patellar articular cartilage length (pConclusion: In pre-ambulatory and early childhood years, the MPFL inserts on a large portion of the medial border of the patella, covering a distance >50% of the articular surface length and centered above the mid-point of the articular cartilage. During maturation, the length of the articular cartilage of the patella increases at a rate greater than the MPFL, resulting in an MPFL insertion averaging 45% the length of the articular surface and centered near the center-point of the articular cartilage (mean = 49th percentile from the superior border) in school age, pre-adolescents. Significance: Knowledge of the MPFL position relative to the articular cartilage length in children may add to understanding of the development of patellar instability, and aid in the accurate reconstruction of the ligament during treatment. [Figure: see text][Figure: see text]

Background: While access to pediatric tissue for cartilage conditions is limited, recent research on the use of pediatric cartilage tissue for implantation has shown promising results. These pediatric grafts may include bulk osteochondral allografts, morselized cartilage, or cellular manipulation products. The purpose of this study was to evaluate the parameters of cartilage thickness in different regions of the pediatric knee from a larger pediatric knee specimen research database. Methods: CT Scans of 12 skeletally immature knees ranging from ages 7 to 11 were evaluated. Cartilage thickness measurements were taking in the following regions: 1. Femoral Condyles - Cahill Zones 1, 2, 4, and 5 (Fig. 1) on coronal plane CT images, the region of greatest cartilage thickness on medial and lateral femoral condyles using coronal plane CT images, and Cahill Zones A, B, and C on sagittal plane CT images (Fig. 2). 2. Tibial Plateau – the region of greatest cartilage thickness identified on the medial and lateral sides of the tibial plateau using coronal plane CT images (Fig. 1). 3. Patella – the region of greatest cartilage thickness identified on axial and sagittal CT images (Fig. 3 and 4). Results: The cartilage on the medial femoral condyle had an average thickness of 4.86 mm ± 0.61 mm at its thickest point and the cartilage on lateral femoral condyle had an average thickness of 3.71 mm ± 0.52 mm at its thickest point. The cartilage on the medial tibial plateau had an average thickness of 2.80 mm ± 0.26 mm at its thickest point and the cartilage on the lateral tibial plateau had an average thickness of 3.29 mm ± 0.45 mm at its thickets point. The cartilage on the midpoints of Cahill zones 1, 2, 3, and 4 had an average thickness of 2.93 mm ± 0.62 mm, 3.42 mm ± 0.66 mm, 2.81 mm ± 0.46 mm, and 3.30 mm ± 0.73 mm respectively. The cartilage on the midpoints of Cahill zones A, B, and C had an average thickness of 3.81 mm ± 0.68 mm, 4.40 mm ± 0.49 mm, and 3.82 mm ± 0.68 mm respectively. The cartilage at its thickest point on the patella had an average thickness of 4.53 mm ± 0.38 mm from an axial view and 4.40 mm ± 0.49 mm from a sagittal view (Fig. 5 and 6). Conclusion: Pediatric knees demonstrate relatively thick cartilage regions in multiple zone of the knee, compared with adult specimens. Increasing access to and use of this tissue for cartilage grafts, non-manipulated tissue, and manipulated tissue offer significant opportunity to address cartilage loss. Osteochondral allograft procedures may benefit from access to such tissue, with relatively high volume and thickness of normal articular cartilage. [Figure: see text][Figure: see text][Figure: see text][Figure: see text][Figure: see text][Figure: see text]

Background: The relative influence of patella and trochlear shape on the development of each structure is poorly understood. Articular morphology is felt to be an important factor influencing patellar instability. The purpose of this study was to evaluate the development of patellar facets in relation to age and sulcus depth in the pediatric knee. Methods: Dissection of 57 immature knees (1 month – 11 years; 36 male) was performed by fellowship-trained orthopaedic surgeons. A coordinated laser scanner, and analysis software (Hexagon Romer V3 CMM; Polyworks) were used to record cartilage anatomy. Patellar facets were identified as distinct regions of surface contour. In a subset of 30 specimens (2 years – 11 years; 22 male) trochlear cartilage sulcus angles were analyzed at points on the trochlea in relation to orientation angle from the femoral axis [F90° (perpendicular to the femoral axis, correlated to the posterior condylar axial slice), F120° (30° flexion), and F150° (60° flexion)]. Spearman’s correlations and nonparametric Mann-Whitney tests were evaluated for specimen age, patellar articular surface lengths, and trochlear sulcus angles. Results: There was strong correlation of patellar facet development with the angle of the cartilaginous femoral sulcus at 30° of flexion (pConclusion: Complex patellar morphology with multiple facets present is not uncommon in early pediatric development, with patellar width and the femoral sulcus angle at 30° as correlates. Significance: Patellar maturation may occur early and further investigation of the relationship of patellofemoral dysplasia on the early development of the corresponding structures is warranted. [Figure: see text]

Background: Previous work on adult specimens have demonstrated some differential thickness of the iliotibial band (ITB) tissue in different areas. The purpose of this study was twofold: 1) to quantitatively and qualitatively describe the relevant surgical anatomy of the ITB, at the level of the knee, in pediatric cadaveric specimens in which either an iliotibial band tenodesis or extraphyseal reconstruction would be considered, and 2) to provide recommendations that allow the surgeon to obtain the ideal graft in terms of tissue width and location on the larger ITB structure. Methods: Pediatric cadaveric specimens (n=24) were dissected by a group of fellowship trained pediatric orthopaedic surgeons. Digital photography of each specimen was obtained prior to collecting quantitative data of the ITB and its three main divisions using digital calipers and a coordinated measurement device (Hexagon Romer Absolute V3 CMM). Measurements included thickness, surface area, length, and width of each branch; surface area and length of each insertion; and distance of insertion in relation to other pertinent anatomical landmarks. Specimens were grouped into four age groups (Group 1: 2 year olds, Group 2: 3 and 4 year olds, Group 3: 5-7 year olds, and Group 4: 9-11 year olds). The four age groups were compared utilizing ANOVA and nonparametric Kruskal-Wallis tests with post-hoc analysis using the Tukey method. In order to correlate measurements and age, a Spearman’s correlation was used. Results: All specimens (mean age 4.7 years; range 2-11) contained a visible ITB with a direct primary arm to Gerdy’s tubercle. Sixteen specimens (66.6%) had a visible trifurcation point, in which the aggregate of ITB fibers diverge into three distinct branches: a direct arm, the iliopatellar branch, and the iliotendinous branch (Figure 1). Fibers from the central third of the iliotibial band, as described as the primary site for harvest, do not terminate on Gerdy’s tubercle, but diverge to the patella, patellar tendon and a portion of Gerdy’s tubercle. The length from the trifurcation point to the insertion of the direct arm at Gerdy’s tubercle increased with each age group (21.3 mm, 29.9 mm, 31.5 mm, and 41.8 mm, respectively) with a significant difference seen between Group 1 and 4 (pConclusion: The ITB is a consistent, well-defined structure in pediatric specimens. While some longitudinal changes in the ITB and its insertions were seen with increasing age, the thickness and width of the direct arm of the ITB, typically harvested for extra-physeal ACL reconstruction, does not appear to differ between age groups and does not represent the thickest distal branch of the ITB. The location of ITB harvest may influence the impact that the extra-articular “capsular tightening” has on joint mechanics, including altering the compression across the joint, and/or the impact on the Pivot-Shift/rational laxity of the knee undergoing ITB reconstructions. Further study of the graft location/harvest and its impact on knee biomechanics is warranted. [Figure: see text]

Background: Quadriceps tendon (QT) turndowns are an alternative method for medial patellofemoral ligament (MPFL) reconstruction, with several distinct advantages: 1. Avoids the use of patella bone tunnels, which have been associated with patella fracture, 2. Avoids the use of separate incision for hamstring tendon harvest, and 3. Avoids the use of allograft tissue, which adds a significant cost. The disadvantage of the Quad Tendon graft is that the most distal reflection point on the patella may not duplicate the patella origin of the native MPFL. The purpose of this study was to determine whether a QT graft for MPFL reconstruction is anatomically analogous to the native MPFL origin in a skeletally immature population. Methods: Three skeletally immature cadaveric knee specimens (ages 10 and 11, 11) were dissected to reveal the MPFL and QT origins on the patella. The proximal and distal extent of the MPFL was marked on the medial border of the patella. The medial aspect of the quad tendon was reflected as far as possible in both a medial and distal position on the patella, to function as the MPFL graft. The distance was measured between the midpoint of the patellar origin of the MPFL in the coronal plane, and the most distal aspect of the patellar origin of the reflected quad tendon. Results: In the 10, 11, and 11 year-old specimens, the distance between the midpoint of MPFL patellar origin and the QT patellar origin was 3.4 cm, 4.3, and 3.7 mm. In all cases, the QT reflected origin was at least 7 mm anterior to the to native MPFL origin on the medial border of the patella. Conclusion: A disparity exists between the patellar origin of the MPFL and the patellar origin of the quad tendon, with the patellar origin of the MPFL being more medial, more distal, and more posterior than the reflected patellar origin of the QT graft. Surgeons performing MPFL reconstructions may find this anatomically valuable as they attempt to duplicate the normal anatomy of the patella stabilizers during surgical reconstruction. While the QT remains a good graft choice for MPFL reconstruction, attachment of the QT graft at the native origin of the MPFL may better reproduce the anatomy of the MPFL. Figures: [Figure: see text][Figure: see text]

Background: The arterial supply to the chondroepiphysis is of paramount importance for proper nutrition and development. Previous animal studies had demonstrated that ischemic necrosis of the chondroepiphysis plays an important role in subsequent development of osteochondritis dissecans (OCD). Previous studies using susceptibility weighted imaging, a magnetic resonance image (MRI) sequence, demonstrated a pattern of disappearance of the arterial system over time at predilection sites for OCD lesions. The purposed of this study is to quantify distribution of the arterial perfusion in different zones of the immature distal femoral chondroepiphysis. Methods: We utilized 5 fresh frozen skeletally immature human cadaver knees (aged 0-6 months). The superficial femoral artery was cannulated proximal to the knee joint and major arteries distal to the knee joint were tied off. For volumetric analysis, comparisons were performed between contrast-enhanced and pre-contrast MRI. Regions of interest were developed to quantify the contrast enhancement in different zones of the chondroepiphysis, excluding the secondary ossification center. (Fig.1) Results: Quantitative MRI analysis demonstrated equivalent enhancement within the medial and lateral condyles in the 5 month and one of the 2 month specimens. The 0 month and 6 month specimens demonstrated greater enhancement in the medial condyle. One of the 2 months specimen demonstrated greater perfusion in the lateral condyle. The distal condyle analysis demonstrated equivalent enhancement in the 0 month, one of the 2 months and the 6 months specimens. The 5 month specimen demonstrated greater enhancement in the lateral distal condyle. The other 2 months specimen demonstrated greater enhancement in the medial distal condyle. The posterior condyle analysis demonstrated greater enhancement in the posterior lateral condyle in one of the 2 month specimen, and the 5 month and the 6 month specimens. The 0 month specimen demonstrated greater enhancement in the medial side. The other 2 month specimen demonstrated equivalent enhancement between medial and lateral side. Analyzing the medial condyle revealed equivalent enhancement in the medial and lateral zone in the 5 month and 6 month specimens. The 0 month specimen demonstrated greater enhancement laterally. Both 2 months specimens demonstrated greater enhancement in the medial side. Conclusion: This study expands the knowledge on the vascularity of the developing distal femoral chondroepiphysis, which may have an impact on our future understanding of OCD etiology, physeal growth, and peri-articular infections. The majority of the specimens demonstrated diminished perfusion in the posterior aspect of the medial femoral condyle when compare to the lateral posterior condyle. This is where the predilected area for the development of OCD lesions is located. Future studies in human and other mammals susceptible to knee OCD, along with the ongoing development of animal models of OCD will benefit from this information.

Background: Anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injuries in skeletally immature patients are increasingly recognized and surgically treated. However, the relationship between the footprint anatomy and the physes are not clearly defined. The purpose of this study was to identify the origin and insertion of the ACL and MCL, and define the footprint anatomy in relation to the physes in skeletally immature knees. Methods: Twenty-nine skeletally immature knees from 16 human cadaver specimens were dissected and divided into two groups: Group A (ages 2-5 years), and Group B (ages 7-11 years). Metallic markers were placed to mark the femoral and tibial attachments of the ACL and MCL. CT scans were obtained for each specimen used to measure the distance from the center of the ligament footprints to the respective distal femoral and proximal tibial physes. Results: Median distance from the ACL femoral epiphyseal origin to the distal femoral physis was 0.30 cm (interquartile range, 0.20 cm to 0.50 cm) and 0.70 cm (interquartile range, 0.45 cm to 0.90 cm) for Groups A and B, respectively. The median distance from the ACL epiphyseal tibial insertion to the proximal tibial physis for Groups A and B were 1.50 cm (interquartile range, 1.40 cm to 1.60 cm) and 1.80 cm (interquartile range, 1.60 cm to 1.85 cm), respectively. Median distance from the MCL femoral origin on the epiphysis to the distal femoral physis was 1.20 cm (interquartile range, 1.00 cm to 1.20 cm) and 0.85 cm (interquartile range, 0.63 cm to 1.00 cm) for Groups A and B, respectively. Median distance from the MCL insertion on the tibial metaphysis to the tibial physis was 3.05 cm (interquartile range, 2.63 cm to 3.30 cm) and 4.80 cm (interquartile range, 3.90 cm to 5.10 cm) for Groups A and B, respectively. Conclusion: Surgical reconstruction is a common treatment for ACL injury, and occasionally MCL reconstruction or repair is also required. Cadaveric dissection and CT scanning of exceptionally rare pediatric tissue clearly defines the location of the ACL and MCL with respect to the femoral and tibial physes, and may guide surgeons for physeal respecting procedures for both ACL reconstruction, and ACL repair procedures. Clinical Relevance: In addition to ACL reconstruction, recent basic science and clinical research suggest that ACL repair may be more commonly performed in the future. MCL repair and reconstruction is also occasionally required in skeletally immature patients. This information may be useful to help surgeons avoid or minimize physeal injury during ACL/MCL reconstructions and/or repair in skeletally immature patients. [Figure: see text][Figure: see text][Figure: see text][Figure: see text]

INTRODUCTION: An increased rate of pediatric and adolescent patients undergoing ACL reconstruction has clearly been established, and now considered one of the most common arthroscopic procedures performed in youth patients. Little knowledge exists on whether these trends truly represent an increase in ACL injury, identification, or surgical management. Trends, including surgeon training, meniscus treatment, or geographic differences, have not been reported. The purpose of this study was to review data from ACL reconstructions performed in patients under the age of 17 years, that were submitted to the American Board of Orthopaedic Surgeons (ABOS) Part 2 examination, with a goal of evaluating national treatment trends over a 16-year period. METHODS: A query to the ABOS SCRIBE database was submitted for all ACL reconstructions performed in patients less than 17 years old between 2002 and 2016. The query was designed to search for CPT procedure codes submitted by each applicant. Query data included geographic region, fellowship training of the applicant, age and sex of the patients, and associated procedures. Each case had an associated applicant number, and thus, the total number of ACL reconstructions performed by each surgeon during board collection was provided. Trends were reviewed for the aggregate data and a Mann-Whitney test was used for comparison of data between 2002 – 2009 (Early-ACL) and 2010-2016 (Recent-ACL) groups. RESULTS: Since 2002, there has been a 2.6% increase in pediatric ACL reconstructions performed by candidates applying for Part 2 of the ABOS examination. Additionally, a 193% increase in dual pediatric and sports medicine fellowship trained candidates performing pediatric ACL reconstruction since 2010 was seen. A majority of pediatric ACL procedures were performed by sports medicine trained surgeons (75.9%). During this time period, a total of 362 (or 8.3%) of pediatric ACL procedures were performed by surgeons with neither sports medicine nor pediatric orthopaedic fellowship training. Following 2009, a 44% increase in pediatric ACL reconstructions performed was noted (Figure 1A). Additionally, an increase in reconstructions performed in female patients compared to males was noted (Figure 1B). A majority of pediatric ACL reconstructions did not require additional meniscal treatment, however, meniscus repair was more likely to be performed after 2009 (p=0.0012). The number of meniscal repair procedures reported in the setting of ACL reconstruction generally increased over the study period. In 2002, 24% of ACL reconstructions required a meniscal repair compared to 41% in 2016 (Figure 1C). A majority of these repairs were performed by surgeons with sports medicine fellowship training. Geographic trends reported are based on patients CONCLUSION: Since 2009, pediatric ACL reconstructions are more likely to be female and are more likely to undergo a meniscal repair. Geographic variation is noticeable, with more surgeries reported to be performed in the South. Dual pediatric and sports medicine fellowship trained candidates performing ACL reconstruction have significantly increased over time, although those surgeons who are only sports medicine fellowship trained continue to perform the bulk of ACL reconstructions in young patients.

Background: Recent research has identified posterior tibial slope as a risk factor for anterior cruciate ligament (ACL) injury, due to increased forces on the ACL with this tibial anatomy. Biomechanical studies suggest that altering a patient’s posterior tibial slope may lower the risk of ACL injury. Due to the presence of an open physis, guided growth may be used to reduce the posterior tibia slope in this high risk skeletally immature population. The primary purpose of this study was to quantify and measure the posterior tibial slope in pediatric knees. Methods: Forty-four pediatric knee CT scans were analyzed using OsiriX, an imaging software. Specimens analyzed were between the ages of 2 and 12 years of age. The proximal tibial slope for each specimen was measured on CT scan sagittal slices at 2 locations: 1) At the medial tibial plateau at the mid region of the medial femoral condyle, as determined on a coronal slice through the femoral condyle; 2) At the lateral tibial plateau at the mid region of the lateral femoral condyle, as determined on the coronal slice through the femoral condyle. The measurement of the posterior tibial slope was determined by placing two lines parallel to the diaphysis of the tibia, one located in the middle of the diaphysis and one located at the most posterior aspect of the diaphysis. The most proximal aspect of both the medial and lateral tibial plateau were then identified and angle measurements were taken in reference to the parallel lines. The angle measurements were plotted graphically by age in order to account for variability in development within age groups. The anterior medial and lateral tibia plateau widths were measured by identifying the mid region of the respective plateaus. From this point, the distance between the top of the tibial plate and the physis was measured. Results: The average posterior tibial slope angle for the medial and lateral tibial plateau were (5.53° ± 4.17°) and (5.95° ± 3.96°) respectively. Independent samples t-test and ANOVA indicate the difference between the posterior tibial slope angle of the medial and lateral tibial plateau were not statistically significant (p < 0.05). When plotted graphically by age, a slight negative trend between age and posterior tibial slope was identified. As age increases, the medial and lateral posterior tibial slope decreases. The mean anterior medial tibial plateau width and lateral tibial plateau width were .99 cm and 1.19 cm respectively. Discussion/Conclusion: ACL primary and secondary injury occur at very high rates in the skeletally immature, especially in females at age 11 and older, and in males at age 13 and older. This data set offers some preliminary values for posterior tibial slope in patients without a history of ACL injury, allowing for comparisons to patients with ACL Injury. Increased tibial slope is a risk factor for ACL injury. In the skeletally immature, one option to alter the tibial slope is the use of guided growth with implants to slow the anterior growth of the proximal tibia, reducing the posterior slope of the tibia, and possibly lower the risk of ACL injury in this high-risk population. [Figure: see text][Figure: see text][Figure: see text][Figure: see text][Figure: see text][Table: see text][Table: see text]

Background: Discoid meniscus epidemiology remains poorly defined for race and sex, in part, due to limitations of retrospective studies and small case series. A better understanding of epidemiology may improve clinical care and diagnostic precision. Purpose: Our purpose is to better define the epidemiology of discoid meniscus by analyzing a large, national database for incidence rates by sex and race. Methods: Analysis was conducted on the national-scale Clinformatics Data Mart Database by Optum. Proportions of the database’s racial categories (Asian, Black, Hispanic, White, and Unknown) in the total population of diagnosed discoid meniscus cases (n = 1,006) were calculated and compared via chi-squared tests to the total database population (n = 65,759,970). This analysis was repeated for the population of patients who received knee arthroscopies (81,205). Incidence rates were calculated from these populations as well. Finally, a multivariable logistic regression analysis based on the population of arthroscopy-receiving patients was performed to control for age, reported gender, and income. Results: Proportions of Asian, Black, Hispanic, and White racial categories in the discoid meniscus group were 5.7%, 7.3%, 20.6%, 66.4%, respectively; the proportions of each racial category in the total population were 5.2%, 10.3%, 13.5%, 71.0%, respectively. Incidence rates (per 10,000) for these groups in the arthroscopy population were 72.9, 25.6, 49.2, 25.6, respectively. Our logistic regression model indicated that race was not a statistically significant predictor for our dataset after income adjusting. Adjusting for other covariates, the odds of a discoid meniscus diagnosis decreased by 6% for each increase in age (p < 0.001) and were 41% lower for males compared to females (p < 0.001). Conclusion: Prior studies have suggested that race (Asian and Hispanic, is a predictor of higher incidence of discoid meniscus – this study did not show a difference in incidence based upon race. Patient sex and age was identified as significant predictors for discoid meniscus, and increasing age showed a decreasing incidence of this condition. This study’s analysis of a large, national claims database allows for a comprehensive epidemiological study on this topic, offering proportions and incidence rates by race appropriate for application to the US population. Its conclusions promote patient sex and age as significant predictors and question the beliefs on race-associated incidence often based on comparing results from the corpus of single-site cohort studies. Tables/Figures: [Table: see text]

Background: Health Systems routinely make investments in clinically driven outreach programs to build for future community needs, improve health outcomes, and serve their community mission. Many community sports programs have limited access to sports medicine care, including access to athletic trainers. Hypothesis/Purpose: The primary purpose of this study was to evaluate the impact of a clinically integrated Certified Athletic Trainer (ATC) Community Sports Outreach Program, by evaluating the outreach into the community, sports clubs, schools, covered events. Methods: The ATC Community Outreach Program monitored key metrics over a 3 and 1/2-year period. Metrics included the partnerships developed with local clubs and schools, number of athletes covered in each organization, games covered and hours spent supporting organizations. Categories were divided into fiscal years (FY) running from September to August. Fiscal Year 2016 was calculated from January – August, as it was the first year of the program. The percentage of growth of the amount of games covered was calculated from the adjacent FY. Results: Over the first 3 and 1/2 years (FY2016-FY2019), the number clubs, schools, programs covered grew from 10, 19, 25, to 31 from FY2016 - FY2019. Number of athletes from 7,363, 12,552, 15,104, to 19,794 from FY2016 - FY2019. The number of community outreach events grew from 6, 11, 57, to 190 from FY2016 - FY2019 (Table/Figure 1.1). The percentage of growth of games covered grew from 183%, 518% to 333% between FY2016 and FY2019. Discussion/Conclusion: Building, maintaining a sports medicine practice is a complex undertaking, and represents a significant investment for the health system and community. In many communities, access to sports medicine care for athletes is very limited. A clinically integrated ATC program can generate a significant impact on the community by building relationships with local sports clubs/schools and improving sports medicine care access to young athletes. Tables/Figures: [Table: see text][Figure: see text]

Background: As regards anterior cruciate ligament (ACL) reconstruction (ACLR), graft diameter has been identified as a major predictor of failure in skeletally mature patients; however, this topic has not been well-studied in the higher risk pediatric population. Hamstring tendon autograft configuration can be adjusted to increase graft diameter, but tendon length must be adequate for ACLR. Historical parameters of expected tendon length have been variable, and no study has quantified pediatric ACL morphology with other osseous parameters. Purpose: To develop magnetic resonance imaging (MRI)–derived predictors of native ACL graft length in pediatric patients so as to enhance preoperative planning for graft preparation in this skeletally immature patient population. Study Design: Cross-sectional study; Level of evidence, 3. Methods: MRI scans of 110 patients were included (64 girls, 46 boys; median age, 10 years; range, 1-13 years). Patients with musculoskeletal diseases or prior knee injuries were excluded. The following measurements were taken on MRI: ACL length; sagittal and coronal ACL inclination; intercondylar notch width and inclination; and femoral condyle depth and width. Associations between these measurements and patient sex and age were investigated. Univariate linear regression and multivariable regression models were created for each radiographic ACL measure to compare R 2. Results: Female ACL length was most strongly associated with the depth of the lateral femoral condyle as viewed in the sagittal plane ( R 2 = 0.65; P < .001). Other statistically significant covariates of interest included distal femoral condylar width, age, and coronal notch width ( P < .05). For males, the ACL length was most strongly associated with the distal femoral condyle width as viewed in the coronal plane ( R 2 = 0.70; P < .001). Other statistically significant covariates of interest for male ACL lengths were lateral femoral condyle depth, age, and coronal notch width ( P < .05). Conclusion: In pediatric populations, femoral condylar depth/width and patient age may be valuable in assessing ACL size and determining appropriate graft dimensions and configuration for ACLRs. The use of this information to optimize graft diameter may lower the rates of ACL graft failure in this high-risk group.

Objectives: The menisci of the knee (Figure 1) play a critical role in maintaining structural integrity, as well as in load bearing and shock absorption. In adolescent patients, meniscal tear is a very common sports injury, and is frequently associated with concomitant traumatic injuries including tibial eminence fracture or ACL tear. Depending on the severity of meniscal tear, surgical treatment options include arthroscopic partial or total meniscectomy, with a reported 78-88% success rate. Given the high incidence of pediatric meniscal injuries and reliance on landmarks to guide arthroscopic meniscus repair, surprisingly few human pediatric cadaveric studies are reported in the current literature. The primary purpose of our research was to evaluate the rates at which different zones of the meniscus rim lengthen with age during early adolescence. Our null hypothesis was that meniscus rim length is unrelated to patient age, tibial plateau width, or to lateral-medial meniscus width. Methods: From images of 29 dissected cadaveric knee specimens between 1 month and 132 months of age obtained on a copy stand (14 left knee, 15 right knee), we made direct length measurements from the inner to outer meniscus rim at 45 degree intervals (12, 1:30/10:30, 3:00/9:00, 4:30/7:30 o’clock, 6 o’clock) using Autodesk Fusion 360 software (Figure 2). We also measured width between the outer medial and lateral meniscus rims, as well as CT measurements of coronal and sagittal width of the tibial plateau using OsiriX DICOM software. Generalized linear models were used to evaluate the associations of meniscal length measurements with age, tibial width, and meniscal width measurements. All statistical analyses were completed with a two-sided level of significance of 0.05. Results: All meniscal length measurements were predicted to increase significantly as age increases (p < 0.01 for all), as coronal tibial width increases (p < 0.05 for all), and as lateral-medial meniscal width increases (p < 0.001 for all). Other than the lateral 3 o’clock measurement (p = 0.119), all meniscal length measurements were predicted to increase significantly as sagittal tibial width increases (p < 0.05 for the rest). Interestingly, the posterior zones of the medial meniscus (6 o’clock and 4:30/7:30 o’clock) were found to increase in length at a faster rate than the anterior zones (Figure 3), which supports our hypothesis that increased weight bearing is correlated with meniscus growth. The same length correlation was not identified in the lateral meniscus. Furthermore, the anterior zones of the medial meniscus (12 o’clock and 1:30/10:30 o’clock) were found to have the slowest rate of growth, presumably due to reduced weight bearing function anteriorly. Conclusions: We reject our null hypothesis that meniscus rim length is unrelated to age, tibial plateau width, or to lateral-medial meniscus width. Surprisingly, the posterior zones of the medial meniscus were found to grow at a faster rate with age compared to the anterior zones, which we attribute to the effect of increased weight bearing experienced by the posterior zones during knee bending exercise. Additionally, the anterior, lesser-weight bearing regions of the medial meniscus were found to develop at the slowest rate out of all zones measured. Further studies are underway to generalize these observations to all adolescent patients. This information will be useful for meniscus repair and transplantation surgical planning.

Objectives: Discoid lateral meniscus (DLM) is a congenital anomaly of the knee where the normally “O” shaped lateral meniscus has redundant tissue filling the “O” and covering the lateral tibial plateau. The redundant tissue can degenerate and cause mechanical symptoms and pain. Treatment of symptomatic DLM is arthroscopic saucerization to reshape the meniscus to a more normal contour. Enough tissue must be removed to eliminate mechanical symptoms but not too much as to create instability. The residual width of the meniscus is crucial at the popliteus hiatus because here the peripheral rim is unattached to the capsule. The literature recommends a residual width of 6-8 mm. The primary purpose of this research was to determine the width of the meniscus at the popliteal hiatus in normal specimens. Our null hypothesis was that a residual width of 6-8 millimeters will be sufficient for saucerization of DLM. Methods: We made direct measurements of lateral meniscus radial width from the outer rim at the popliteus hiatus to the inner edge (Figure 1) in 19 specimens (ages 2 months to 11 years.) We measured one four-year-old specimen with bilateral complete DLM (Figure 2.) We also measured 39 digital images of specimens (ages 1-month to 12-years) using ImageJ. Finally, we made direct measurements of 8 skeletally mature specimens. Results: Figure 3 shows the relationship of meniscus width as a function age. The average width of specimens Conclusions: We rejected our null hypothesis. Direct measurements suggest that a residual width of 6-8mm is insufficient for children 8-years and older. A width of at least a full centimeter more closely approximates our findings, and for adolescents consider a residual rim of 15 mm. For children less than six-years-old a residual width of 6-8mm is sufficient.

Background: Although anterior cruciate ligament (ACL) tears have received the most attention, the medial collateral ligament (MCL) is thought to be the most commonly injured knee ligament overall. The lateral collateral ligament (LCL) and posterior collateral ligament (PCL) are less frequently compromised but can be involved in severe multiligament injuries. The paucity of information on the native properties of these ligaments in the pediatric population hinders the overall optimization of treatment for these injuries. Purpose: To characterize the mechanical and microstructural properties of pediatric MCLs, LCLs, and PCLs using a rare cadaveric cohort (mean age, 9.2 years). Study Design: Descriptive laboratory study. Methods: MCLs, LCLs, and PCLs were harvested from 5 fresh-frozen pediatric knee specimens (3 male, 2 female) and were subjected to a tensile loading protocol. A subset of contralateral tissues from a single donor was analyzed using bright-field, polarized light, and transmission electron microscopy to measure collagen fiber morphology. Results: The pediatric MCL exhibited values for ultimate stress (11.7 ± 6.7 MPa), ultimate strain (18.2% ± 6.8%), and the Young modulus (93.7 ± 56.5 MPa) that were similar to values for the LCL (11.4 ± 11.5 MPa, 27.7% ± 12.9%, and 64.4 ± 76.6 MPa, respectively). The PCL demonstrated decreased ultimate stress (4.2 ± 1.8 MPa), increased ultimate strain (28.8% ± 11.9%), and a decreased Young modulus (19.8 ± 10.4 MPa) when compared with the MCL and LCL. All 3 ligaments had similar mean crimp wavelengths (MCL, 32.8 ± 3.6 µm; LCL, 27.2 ± 3.5 µm; PCL, 25.8 ± 3.5 µm) and collagen fibril diameters (MCL, 88.0 ± 26.0 nm; LCL, 93.3 ± 34.6 nm; PCL, 90.9 ± 34.0 nm); however, the fibril distribution profiles exhibited different modalities. Conclusion: The pediatric MCL and LCL possessed similar mechanical properties, while the pediatric PCL was weaker but capable of withstanding higher amounts of strain. All 3 of these pediatric structures were weaker than what has been reported in studies with adult cohorts. Clinical Relevance: Results from this study can be considered preliminary mechanical and microstructural data for healthy pediatric collateral and posterior cruciate ligaments that can be used to guide further laboratory and clinical research.

Background: Combination analgesics are among the most commonly prescribed pain medications in pediatric orthopedic patients. However, combined analgesics do not allow for individual medication titration, which can increase the risk of opioid misuse and hepatoxicity from acetaminophen. Increasingly, the risks of combined analgesics associated with opioid misuse and hepatotoxicity are recognized by the FDA and other organizations. Given these risks, consideration should be made for independent administration of acetaminophen and opioids. Hypothesis/Purpose: The primary aim was to alter the prescribing habits of pediatric orthopedic providers at our institution from postoperative combined opioid/acetaminophen medicines to independent opioids and acetaminophen. Methods: The study took place at a children’s hospital level one trauma center. A multidisciplinary team of health professionals utilized lean methodology to develop a project plan. Guided by a key driver diagram, (1) combination oxycodone/acetaminophen products were removed from hospital formulary, (2) a revised inpatient and outpatient electronic order set was implemented, and (3) multiple education efforts (emails, in person meetings) were conducted. Outcomes included inpatient and outpatient percent combined opioid/acetaminophen orders by surgical providers over twenty-seven months. Statistical process control charts were used to measure combination opioid prescribing practices for orthopedic and other surgical specialties. Results: Prior to intervention, inpatient combination opioid/acetaminophen products were prescribed for an average of 46% of all opioid prescriptions for orthopedic patients. After intervention and multiple educational efforts, the percent of combined opioid/acetaminophen products dropped to 31% and then to 3% by end of the investigational period. For outpatient prescriptions, the combined products accounted for 88% prior to intervention and dropped to 15% at project completion. Conclusion: By removing combined oxycodone/acetaminophen products from hospital formulary, educating the medical staff, and employing electronic order sets, the inpatient/outpatient prescribing practice of pediatric orthopedic surgeons changed from the common use of combined opioid/acetaminophen products to independent medications. This project demonstrates that changing medication prescription practice can be accomplished with 3 steps within a hospital system. Reducing the use of combination opioid/acetaminophen products may have further positive impacts on opioid misuse and hepatoxicity.

Background: The anatomy of the anterolateral ligament (ALL) has been controversial, with modern studies varying in their description of the precise origin and insertion, as well as relation to surrounding structures on the lateral femur and anterolateral tibia Regardless of such controversy, principles of reconstruction, even non-anatomic, require a clear understanding of the referenced anatomy and surrounding structures. Due to high rates of primary and recurrent ACL tears in pediatric/adolescent patients, the use of ALL reconstruction is increasing in these groups. No pediatric cadaveric study to date has clearly identified the locations of the known surrounding structures of the anterolateral ligamentous complex. Purpose: The purpose of this study was to quantitatively assess the anatomy of the pediatric lateral collateral ligament (LCL) origin, the popliteus origin, and in the tibial insertion of the iliotibioband (ITB). Methods: Nine pediatric cadaveric knee specimens were dissected to identify the ligamentous femoral origin of the LCL, popliteus, and tibial insertion of the ITB.. Marking pins were used to localize the central footprint of these structures, followed by CT Scans. Results: LCL & Popliteus: On the femur, the popliteus was consistently found deep to the LCL and inserted both distally and anteriorly to the LCL a mean distance of 4.6 mm (range 1.9 to 7.6 mm; std dev 2.0). The LCL measured a mean of 12.5 mm to the joint line while the popliteus measured a mean of 8.2 mm from the joint line. Both the LCL and popliteus were consistently distal to the physis. The LCL was a mean distance of 4.4 mm (range 1.0 - 9.5 ) and the popliteus was a mean distance of 8.2 (range 1.7 – 12.5), respectively. ITB insertion: The ITB insertion at Gerdy’s tubercle had an average footprint measuring 28.2 mm2 (range 10.3-58.4), and the ITB center was found proximal to the physis in 6 specimens and distal in 3 specimens. Mean distance from the footprint center to the physis was 1.6 mm proximal (range 7.1 mm proximal to 2.2 mm distal). Conclusion: This study provides quantitative anatomy to structures on the lateral femur and anterolateral tibia, commonly referenced in descriptions of the ALL and lateral extraarticular reconstruction techniques. Knowledge of these structures will define the anterolateral complex and guide extra-articular procedures that provide extraarticular anterolateral rotatory stabilization in the pediatric patients. [Figure: see text][Figure: see text]

Background:Osteochondritis dissecans (OCD) of the elbow is a disorder of subchondral bone and articular cartilage, of which the incidence among children is not clearly known.Purpose:To assess the demographics and epidemiology of OCD of the elbow among children.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A retrospective chart review of an integrated health system for the years 2007 through 2011 was performed for patients with elbow OCD aged 2 to 19 years. Lesion location, laterality, and all patient demographics were recorded. OCD incidence was determined for the group as a whole as well as by sex and age group (2-5, 6-11, 12-19 years). Patient differences based on age, sex, and ethnicity were analyzed, and multivariable logistic regression models were used to assess the risk of elbow OCD by group.Results:A total of 37 patients with 40 OCD lesions fit the inclusion criteria. No lesion was found among 2- to 5-year-olds. A majority of lesions (n = 39, 97.5%) were in the capitellum, and 1 (2.5%) was in the trochlea. Twenty-five patients (67.6%) had right-sided lesions; 9 (24.3%), left-sided; and 3 (8.1%), bilateral. The incidence of elbow OCD for patients aged 6 to 19 years was 2.2 per 100,000 overall and 3.8 and 0.6 per 100,000 for males and females, respectively. The majority of OCD cases were seen in those aged 12 to 19 years, with an incidence of 3.4 per 100,000 versus 0.38 among 6- to 11-year-olds. Multivariable logistic regression analysis revealed a 21.7-times increased odds ratio of elbow OCD among patients aged 12 to 19 years versus 6 to 11 years, and males had a 6.8-times greater odds ratio of elbow OCD than females ( P < .0001 for both). Based on race and ethnicity, non-Hispanic whites had the highest incidence of elbow OCD as compared with all other ethnic groups.Conclusion:In this population-based cohort study of pediatric elbow OCD, males had almost 7 times the risk of elbow OCD as compared with females, and 12- to 19-year-olds had nearly 22 times the risk of elbow OCD versus 6- to 11-year-olds. In keeping with many prior studies, the majority of patients had right-sided lesions.

Objectives: To study trochlear morphology during maturation in children using MR imaging. Methods: The study population consisted of 22 knees (11 M/11 F) from pediatric cadavers, aged 1 month to 10 years (provided by Allosource, Inc.) An IRB waiver approval applied. MR Sequence: 3D-GRE sequence for Susceptibility-Weighted Magnetic Resonance Imaging: a non-invasive technique allowing precise distinction between cartilage vs. osseous morphology. For each sample, the MRI biometric analysis was conducted on the axial/sagittal/coronal views analyzing three slices; the most proximal slice corresponding to the location of full cartilage trochlear groove coverage. Patellar measurements were not performed due its absence in many specimens. Biometric analysis included lateral/media/central trochlear height, cartilaginous sulcus angle (CSA), osseous sulcus angle (OSA), trochlear depth (TD), and trochlear facet length asymmetry. Sex comparisons were considered when one or more specimens from both sexes of the same age were available; 12 knees total spanning 4 age groups (ages 1, 3, 4 and 7 years). Results: Four samples were excluded due to low quality images. Morphology: Both lateral and medial condylar height increased by 12% from distal slices to proximal slices; lateral trochlear height > medial trochlear height at all ages. There was a discrepancy between lateral and medial trochlear facet length which was more evident in older samples (lateral > medial). The thickest cartilage was present on the lateral condylar facet in the younger specimens. Comparative trends between male/females: Female samples had a shallower cartilaginous sulcus (CSA) and osseous sulcus (OSA) than males. Development of osseous and cartilaginous trochlear contour: A cartilaginous sulcus is present in the 3mo. old specimen and continues to deepen up to the age of 4 years. The shape of the osseous center evolves from round (1 month), to oval (9 month), to square (2 years), with no distinct bony trochlear sulcus, although a well formed cartilaginous sulcus already is in place. At 5 years the shape of the osseous center resembles aviator glasses, with the first evidence of a sulcus forming. The bony contour of the adult distal femur resembles the cartilaginous contour at 7-8 years. Discussion: From the earliest stage of the development, the female trochlea is flatter with less groove depth than that of males. The development of the shape of the OSA does not follow that of the CSA, suggesting that other forces (possibly from the patella) dictate the contour of the mature bony trochlear groove. Conclusion: Our sample suggests: 1) a developmental tendency for females to have shallower (i.e., more dysplastic) grooves; 2) the lateral trochlea is higher (trochlear height) and wider (trochlear facet length) during growth than the medial in both sexes; and 3) The development of the osseous sulcus shape lags behind the development of the cartilagenous sulcus shape in our sample population. The anatomic findings are consistent with clinical studies on trochlear dysplasia in females, and suggests that trochlear development differences may play a critical role in patella instability. [Figure: see text]

Objectives: Over the last 50 years, the genesis of OCD lesions has been thought secondary to a primary bone necrosis origin. This theory has been challenged recently, as histological studies performed on specimens obtained from asymptomatic mammals, have revealed that ischemic necrosis of epiphyseal cartilage (rather than bone) is the precursor lesion of osteochondrosis dissecans (OCD) in several animal species. The earliest lesion identified histologically is osteochondrosis (OC) latens, in which the area of necrosis is confined to epiphyseal cartilage. As the ossification front advances, the area of necrosis causes a delay/failure in endochondral ossification that is visible radiographically and by CT and is termed OC manifesta. Juvenile osteochondritis dissecans (JOCD) in children has many similarities to OCD in animals; however, subclinical disease in children has not been studied due to the invasive nature of this work and the difficulty in obtaining appropriate cadaveric specimens. Lesions of OC latens are not recognized in children, and lesions resembling OC manifesta identified by CT are often considered to be normal ossification variants. Previous work by our group identified 32 suspected OC manifesta lesions in the medial and lateral femoral condyles (MFC and LFC) and the lateral trochlear ridge (LTR) in 14 cadaveric specimens from children ranging in age from 7 to 11 years. Our aim was to determine if skeletally immature human knees contained histological evidence of delayed endochondral ossification occurring secondary to ischemic necrosis of epiphyseal cartilage. Methods: Eleven sites (4 MFC, 4LFC, 3LTR) containing suspect OC manifesta lesions identified on CT from five male children (age range 7-11 years) were decalcified in 10% EDTA. Areas corresponding to the CT lesions were trimmed into 3-mm thick slabs (n=2-4 slabs/site), processed into paraffin, sectioned at 5 µm, and stained with hematoxylin and eosin. All sections (n= 30 total) were examined by four veterinary pathologists/radiologists with extensive experience in the study of OC in pigs and horses. Results: All sites examined contained at least one section containing histological evidence of one or more areas of OC manifesta Lesions were evidenced by focal failure of endochondral ossification accompanied by remnants of necrotic blood vessels, chondrocyte necrosis with matrix degeneration. Some lesions were accompanied by evidence of repair/healing response, including chondrocyte clusters, proliferating blood vessels, and fibrous connective tissue. Conclusion: Similar to other mammals, human OCD lesions appear to develop as a primary defect secondary to avascular necrosis of epiphyseal cartilage, rather than primary avascular necrosis in bone. Our findings strongly support a common pathogenesis of OCD in humans and mammals. Historically, ossification variants have been considered a developmental anomaly with a benign clinical course. Our histologic findings suggest that ‘ossification variants’ may in face be delayed presentations of a continuum of OCD lesion development that starts years earlier due to primary epiphyseal cartilage necrosis. Some of these ‘variants’ may progress to healing, but many may progress to frank ‘osteochondritis dissecans’, suggesting that these lesions that are idenfitifed on xray or with MRI sequences require close follow-up.

Background:Rates of anterior cruciate ligament (ACL) reconstruction among pediatric and adolescent patients are increasing. Limited knowledge exists about population-level rates of concomitant meniscal surgery in this age group.Purpose/Hypothesis:This study sought to examine trends in concomitant meniscal procedures and describe short-term complications in pediatric and adolescent patients undergoing ACL reconstruction. We hypothesized that overall meniscal surgery rates are increasing and that the likelihood of performing meniscal repair or meniscectomy is associated with patient- and surgeon-specific factors.Study Design:Cross-sectional study.Methods:We queried ACL procedures in patients younger than 19 years reported by American Board of Orthopaedic Surgery (ABOS) part II examination candidates from 2000 to 2016. Regression models examined associations between patient and surgeon characteristics, year of surgery, follow-up time, meniscal procedure type, and number and type of complications.Results:A total of 9766 cases were identified. Females represented 46% (n = 4468) of included cases. Mean patient age was 16.1 years (SD, 1.62 years; range, 0-18 years). The rate of concomitant ACL-meniscal procedures increased from the years 2000 to 2016 (49%-60%; P = .005). Surgeons with sports medicine (+7.0%) or pediatric orthopaedic fellowship (+6.6%) training had a higher likelihood of reporting a concomitant ACL-meniscal procedure ( P = .003 and .006, respectively). Sports medicine–trained surgeons were more likely to perform meniscal repair compared with meniscectomy (+3.0%; P = .016). Younger patient age was associated with increased likelihood of undergoing meniscal repair compared with meniscectomy. Overall reported complication rate was 12.8%. Notable reported complications included infection (1.61%), arthrofibrosis (1.14%), and deep venous thrombosis or pulmonary embolism (0.11%). Sports medicine and pediatric orthopaedic fellowship training was associated with higher rates of reporting postoperative stiffness and/or arthrofibrosis.Conclusion:Among ABOS part II candidates, concomitant ACL-meniscal surgery has become more common than isolated ACL procedures. Procedures involving sports medicine fellowship–trained surgeons and younger patients were associated with increased rates of meniscal repair compared with meniscectomy. Pediatric orthopaedic and sports medicine training was associated with a greater likelihood of being involved in a concomitant ACL-meniscal procedure of any kind, and surgeons with such training also reported a higher incidence of postoperative stiffness and/or arthrofibrosis in patients.

Background: Tibial spine fractures, although relatively rare, account for a substantial proportion of pediatric knee injuries with effusions and can have significant complications. Meyers and McKeever type II fractures are displaced anteriorly with an intact posterior hinge. Whether this subtype of pediatric tibial spine fracture should be treated operatively or nonoperatively remains controversial. Surgical delay is associated with an increased risk of arthrofibrosis; thus, prompt treatment decision making is imperative. Purpose: To assess for variability among pediatric orthopaedic surgeons when treating pediatric type II tibial spine fractures. Study Design: Cross-sectional study. Methods: A discrete choice experiment was conducted to determine the patient and injury attributes that influence the management choice. A convenience sample of 20 pediatric orthopaedic surgeons reviewed 40 case vignettes, including physis-blinded radiographs displaying displaced fractures and a description of the patient’s sex, age, mechanism of injury, and predominant sport. Surgeons were asked whether they would treat the fracture operatively or nonoperatively. A mixed-effects model was then used to determine the patient attributes most likely to influence the surgeon’s decision, as well as surgeon training background, years in practice, and risk-taking behavior. Results: The majority of respondents selected operative treatment for 85% of the presented cases. The degree of fracture displacement was the only attribute significantly associated with treatment choice ( P < .001). Surgeons were 28% more likely to treat the fracture operatively with each additional millimeter of displacement of fracture fragment. Over 64% of surgeons chose to treat operatively when the fracture fragment was displaced by ≥3.5 mm. Significant variation in surgeon’s propensity for operative treatment of this fracture was observed ( P = .01). Surgeon training, years in practice, and risk-taking scores were not associated with the respondent’s preference for surgical treatment. Conclusion: There was substantial variation among pediatric orthopaedic surgeons when treating type II tibial spine fractures. The decision to operate was based on the degree of fracture displacement. Identifying current treatment preferences among surgeons given different patient factors can highlight current variation in practice patterns and direct efforts toward promoting the most optimal treatment strategies for controversial type II tibial spine fractures.

Background: Meniscal injuries in the skeletally immature have been increasingly reported. Many meniscal repair surgeries involve the approximation of the meniscus tissue to the peripheral meniscus capsule. This peripheral fixation may not be ideal for some meniscus tear patterns, and may contribute to ‘peripheralization’ of the meniscus during the healing process, which may alter the weight bearing distribution function of the meniscus/articular cartilage complex. Surgical procedures that do not periperalize the meniscus are being developed, which may better replicate the normal meniscus anatomy. Purpose: The primary purpose of this study was to evaluate the coronary ligament attachments of the meniscus, and how this may influence further development of anatomic repair techniques and implants to address meniscus injury. The secondary purpose of this study was to determine the distance between the tibial insertion of the coronary ligament and the proximal tibial physis. Methods: 10 skeletally immature knee cadaver specimens between the ages of 3 months and 11 years (3 female, 7 male) were included in this study. Prior to CT, pins were placed in the tibias marking the coronary ligament insertion at designated points surrounding both the medial and lateral menisci (Figure 1). Using OsiriX, a medical imaging software, the distances between the proximal tibial physis and the coronary ligament insertion sites were measured at 10 points (5 lateral: anterior root, 12 o’clock, 3/9 o’clock, 6 o’clock, and posterior root, and 5 medial: anterior root, 12 o’clock, 3/9 o’clock, 6 o’clock, and posterior root). Axial view was used confirm proper pin measurement and the measurements were gathered in either the sagittal and coronal view depending on the pin’s placement. The specimen were divided into two groups for analysis- Group 1: ages 3 months- 2 years, Group 2: ages 10-11 years. Results: Medial Meniscus The average distance from the proximal tibial physis to the posterior medial root of the coronary ligament was 0.48 ± 0.08 cm and 1.02 ± 0.10 cm for Group 1 and Group 2, respectively. The average distance from the physis and the 6 o’clock pin was 0.37 ± 0.19 cm and 0.78 ± 0.23 cm. The average distance from the physis and the 3/9 o’clock pin was 0.32 ± 0.13 cm and 0.73 ± 0.22 cm. The average distance from the physis to the 12 o’clock pin was 0.14 ± 0.22 cm and 0.65 ± 0.45 cm. The average distance from the physis to the anterior pin was 0.21 ± 0.30 cm and 1.01 ± 0.62 cm. Lateral Meniscus The average distance from the proximal tibial physis to the posterior lateral root of the coronary ligament was 0.48 ± 0.11 cm and 1.62 ± 0.29 cm for Group 1 and Group 2, respectively. The average distance from the physis and the 6 o’clock pin was 0.38 ± 0.16 cm and 1.72 ± 0.25 cm. The average distance from the physis and the 3/9 o’clock pin was 0.17 ± 0.15 cm and 0.1.41 ± 0.19 cm. The average distance from the physis to the 12 o’clock pin was -0.04 ± 0.20 cm and 0.60 ± 0.14 cm. The average distance from the physis to the anterior pin was 0.16 ± 0.07 cm and 0.31 ± 0.16 cm. Conclusions: Our results show an increase in the distance between the proximal tibial physis and the insertion points of the coronary ligament as age increases. For all measurements, medial and lateral, Group 1 (the younger specimen’s) tibial insertion of the coronary ligament was less than 1 cm away from the physis. Group 2’s coronary ligament insertion points were further away from the physeal line, however still less than 2 cm away, and sometimes even as close as Clinical Significance: This study of pediatric cadaveric specimens allowed for direct visualization of the coronary ligament anatomy on the tibia. This information is clinically significant as it detailed the developmental pattern of coronary ligament anatomy in pediatrics and can be used by surgeons performing meniscal injury reconstructions and repairs in patients with open physes. [Figure: see text]

Background: In skeletally immature patients, the MPFL femoral origin as near or below the physis in most age groups. Although MPFL reconstruction procedures that employ patella drill holes facilitate graft tension adjustment, recent research demonstrates significant risk of patella fractures if patella drill holes are utilized. For this reason, the use of patella drill holes may be best avoided, but this technical alteration makes graft tension fixation more challenging during MPFL reconstruction in the skeletally immature. The purpose of this study was to evaluate the feasibility of developing a physeal respecting femoral drill for the MPFL origin with surgical model simulation, which allows for graft tensioning during MPFL reconstruction. Methods: Pediatric cadaveric specimens (n=5) were dissected by a group of fellowship trained pediatric and/or sports orthopaedic surgeons, and these specimens were then subject to CT Scans for the creation of 3D models. Specimens, aged 7, 9, 10, 11 and 11 years, were used to develop surgical simulations. CT Scans were loaded into Osyrix, converted to appropriate file structure, and then 3D models were loaded into Blender (Stichting Blender Foundation, Buikslotermeerplein 161, 1025 ETAmsterdam, the Netherlands). These models were used to evaluate 3D models of the knee, with placement of medial femoral condyle drill holes starting at the MPFL femoral origin, and entering the joint just anterior to the PCL femoral origin. The anatomic goals of the surgical simulation include: 1. Place drill hole at the MPFL origin on the femur. 2 Enter the intercondylar notch region of the femur anterior to the PCL origin allowing for arthroscopic visualization. 3. avoiding the articular cartilage on the medial femoral condyle. 4. Avoid the femoral physis throughout the course of drilling from the femoral MPFL Origin point to the entry location into the intercondylar notch. In the specimens, a full length drill hole was placed with either a 4 or 5 mm drill hole. Results: All specimens were subject to the surgical modeling and simulated drill hole placement. In each case, a drill hole was successfully placed meeting all the goals of the simulation: 1. Starting Point at MPFL, 2. Exit point anterior the PCL origin, 3. Exit point posterior to the articular cartilage, and 4. Avoidance of direct physeal injury. Figures 1 and 2. Conclusion: Setting graft tension during MPFL reconstruction is one of the significant technical challenges during MPFL reconstruction, and appropriate graft position and tension may be the most critical elements of successful MPFL reconstruction. Historically, graft tension has been set on the patella, using drill holes for the MPFL attachment point on the patella, but this technique has been associated with patella fractures. In order to allow for adjustment of graft tension on the femoral side of the MPFL graft during surgical reconstruction, a surgical simulation was developed to confirm the anatomic appropriateness and safety of placement of femoral drill holes which allow for adjustment of graft tension. This surgical simulation model confirms that MPFL femoral origin anatomy can be reproduced with injury to the physis, the PCL, or the articular cartilage of the femoral condyle. This drill hole and graft can be visualized arthroscopically and allow for appropriate graft tensioning during the procedure. [Figure: see text][Figure: see text]