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The lateral patellofemoral joint soft tissues contain key structures that surround and balance the joint. These structures can affect joint tracking, stability, and force distribution. It is important to understand the lateral patellofemoral anatomy and biomechanics, and their relationship with patellofemoral instability, anterior knee pain, and osteoarthritis. Lateral-sided surgical procedures such as lateral release, lateral retinacular lengthening, and partial lateral patellar facetectomy can be useful in the treatment of such patellofemoral problems.

Objectives There are limited data on Western Ontario Rotator Cuff (WORC) Index scores in a population without shoulder pathology. The primary purpose was to provide normative reference values for the WORC in an adult population with healthy shoulders. The secondary purpose was to identify demographic factors and comorbidities that may impact WORC scores. Methods The WORC survey was completed by patients and family members at a suburban outpatient orthopaedic centre. Patients with current shoulder injury or former upper extremity surgery were excluded. Percentage scores were calculated for total and subscale measures. Demographic factors and comorbidities were evaluated to identify possible risk factors for an abnormal baseline score (less than 100). Results There were 988 participants (434 men, 554 women). Overall WORC median (IQR) was 98.64 (94.3 to 100). Each subscale was greater than 96 for all sex-based and age-based subgroups. Median WORC scores were greater than those reported in previous literature following surgery for shoulder pathology. Demographic risk factors for poor WORC scores included body mass index (BMI) greater than 30 (p Conclusions This study provides baseline values for the WORC survey in a US suburban population across a range of age groups, demonstrating that surgery for shoulder pathology often results in improved WORC scores, but may not return patients to baseline. Demographic risk factors for lower scores include smoking, BMI above 30, history of shoulder problems or history of shoulder injection. Level of evidence Descriptive epidemiology study; Level of evidence: III.

Objective Investigate the patellar force-displacement profile (ligament stiffness) of patellofemoral disorders. Methods Fifty-two knees from 34 consecutive patients (mean 31.6 years and 53% male) were analysed including 24 knees with patellofemoral pain (PFP), 19 with potential patellofemoral instability (PPI) and 9 with objective patellofemoral instability (OPI). Physical examination, patient-reported outcome measures (Kujala and Lysholm Scores), standard radiography and MRI or CT were performed in all patients. Instrumented stress testing (Porto Patella testing device) concomitantly with imaging (MRI or CT) was performed to calculate ligament stiffness. Results The force-displacement curves in patients with PPI and OPI displayed a similar pattern, which was different from that of the PFP group. Patients with PPI showed higher ligament stiffness (a higher force was required to displace the patella) than the patients in the OPI group. Patients with OPI had a statistically significant shallower trochlear groove and increased lateral tilt. More than half of the PPI and OPI population presented with at least one classic risk factor (patella alta, trochlear dysplasia, increased quadriceps vector, lateral tilt). In the PPI group, at least two risk factors were found in 37% of patients, whereas at least 33% of patients in the OPI group had three risk factors present. None of the patients presented with all four anatomical risk factors. Conclusion Patients presenting with patellofemoral instability (PPI and OPI) display similar ligament stiffness patterns (force-displacement curve). Patients with PFP and PPI showed higher ligament stiffness as compared with patients with OPI. Level of evidence Level V, case series.

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.

Purpose To better define the epidemiology of discoid meniscus by analyzing a large, national database for incidence rates and associations with demographic variables. Methods From Optum’s Clinformatics® Data Mart Database, incidence rates and proportions of reported racial categories - Asian, Black, Hispanic, and Caucasian - of diagnosed discoid meniscus cases (n = 198) in the study population of patients receiving arthroscopic meniscectomy or repair procedures (n = 60,042) were calculated and compared via chi-square tests to the total population. To control for age, sex, and socioeconomic factors such as income, multivariable logistic regression analysis was performed. Results Proportions of discoid meniscus patients who were Asian, Black, Hispanic, or Caucasian were

For iliotibial band (ITB) lateral extra-articular tenodesis or anterolateral ligamentous/capsular reconstruction with anterior cruciate ligament reconstruction, a clear understanding of the referenced anterolateral knee anatomy is critical-especially given the risk of injury to the physis or key anterolateral structures in the paediatric population, which is at high-risk for primary and secondary anterior cruciate ligament injury. The purpose of this study was to quantitatively assess the anatomy of the knee physes, paediatric lateral collateral ligament (LCL) origin, popliteus origin and ITB tibial insertion.Nine paediatric cadaveric knee specimens with average age 4.2 years (range 2 months-10 years) underwent dissection to identify the LCL's and popliteus' femoral origins and the ITB's tibial insertion. Metallic marking pins demarcated precise anatomic attachment sites, and subsequent computerised tomography scans enabled quantified measurements among them.LCLPopliteus: On the femur, the popliteus origin lay consistently deep to the LCL and inserted both distally and anteriorly to the LCL, a mean distance of 4.6 mm (range 1.9-7.6; standard deviation 2.0). From the joint line, the LCL lay a mean distance of 12.5 mm proximally while the popliteus measured a mean of 8.2 mm. Both 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) from the physis. ITB insertion: The ITB insertion at Gerdy's tubercle had an average footprint measuring 28.2 mmThis study describes relative and quantitative positions of the femoral LCL and popliteus origins and tibial ITB attachment and their respective physeal relationships. Knowledge of paediatric anterolateral knee anatomy will help guide essential future research and procedures providing extra-articular anterolateral rotatory stabilisation and may help reduce iatrogenic physeal injury risk.N/A (descriptive anatomic study).

Juvenile osteochondritis dissecans (JOCD) is a developmental disease characterized by formation of intra-articular (osteo)chondral flaps or fragments. Evidence-based treatment guidelines for JOCD are currently lacking. An animal model would facilitate study of JOCD and evaluation of diagnostic and treatment approaches. The purpose of this study was to assess the suitability of miniature pigs as a model of JOCD at the distal femur. First, stifle (knee) joints harvested from three juvenile miniature pigs underwent magnetic resonance imaging (MRI) to establish the vascular architecture of the distal femoral epiphyseal cartilage. Second, vessels supplying the axial or abaxial aspects of the medial femoral condyle were surgically interrupted in four additional juvenile miniature pigs, and the developing epiphyseal cartilage lesions were monitored using three consecutive MRI examinations over nine weeks. The miniature pigs were then euthanized, and their distal femora were harvested for histological evaluation. Vascular architecture of the distal femoral epiphyseal cartilage in the miniature pigs was found to be nearly identical to that of juvenile human subjects, characterized by separate vascular beds supplying the axial and abaxial aspects of the condyles. Surgical interruption of the vascular supply to the abaxial aspect of the medial femoral condyle resulted in ischemic cartilage necrosis (a precursor lesion of JOCD) in 75% (3/4) of the miniature pigs. Cartilage lesions were identified during the first MRI performed 3 weeks post-operatively. No clinically apparent JOCD-like lesions developed. In conclusion, miniature pigs are suitable for modeling JOCD precursor lesions. Further investigation of the model is warranted to assess induction of clinically apparent JOCD lesions. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2130-2137, 2019.

Acknowledgements: The authors would like to acknowledge Drs. Matthew Milewski, Yi-Meng Yen, and Adam Yanke for their contributions. Background: Surgical decision-making and pre-operative planning for children and adolescents with patellofemoral instability relies heavily on skeletal maturity status. In order to be clinically useful, radiologic assessments of skeletal maturity must demonstrate acceptable interrater reliability and accuracy. Purpose: The purpose of this study was to evaluate the interrater reliability among surgeons of varying experience levels and specialty training backgrounds when evaluating skeletal maturity in the distal femur and proximal tibia of children and adolescents with patellofemoral instability. Study Design: Cross-sectional study Methods: Six fellowship-trained orthopedic surgeons (4 pediatric orthopedic, 2 sports medicine) who perform a high volume of patellofemoral instability surgery examined 20 blinded and randomized knee radiographs and MR images. They assessed these images for clinically relevant growth (open physis) or clinically insignificant growth (closing/closed physis) remaining in the distal femoral and proximal tibial physes. Fleiss’s kappa was calculated for each measurement. After initial ratings, raters discussed consensus methods to improve reliability and assessed the images again in order to determine if training and new criteria improved interrater reliability. Results: Reliability for initial assessments of distal femoral and proximal tibial physeal status was poor (Kappa range: 0.01 – 0.58). After consensus building, all assessments demonstrated almost perfect interrater reliability (Kappa = 0.99 for all measurements). Conclusion: Surgical decision-making and pre-operative planning for children and adolescents with patellofemoral instability relies heavily on radiologic assessment of skeletal maturity. This study found that initial interrater reliability of physeal status and clinical decision making was unacceptably low. However, with the addition of new criteria, a consensus-building process, and training, these variables became highly reliable. Clinical Relevance: Lack of assessment reliability can jeopardize patient care, both when determining surgical indications as well as choosing an appropriate procedure based upon skeletal maturity. Surgeons should focus on using reliable imaging metrics in children and adolescents with patellofemoral instability, and measurements that remain unreliable after consensus building and training should be removed from clinical decision-making algorithms. What is known about the subject: Treatment of patellofemoral instability heavily relies on skeletal maturity status. Physeal assessments of the knee must be reliable and clinically relevant to ensure optimal patient care. What this study adds to existing knowledge: Physeal assessment of the knee without training can be unreliable among fellowship trained orthopedic surgeons. With consensus building and training in the use of the methods described in this manuscript, physeal assessments can demonstrate almost perfect reliability.

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: 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]

➤ Osteochondritis dissecans occurs most frequently in the active pediatric and young adult populations, commonly affecting the knee, elbow, or ankle, and may lead to premature osteoarthritis. ➤ While generally considered an idiopathic phenomenon, various etiopathogenetic theories are being investigated, including local ischemia, aberrant endochondral ossification of the secondary subarticular physis, repetitive microtrauma, and genetic predisposition. ➤ Diagnosis is based on the history, physical examination, radiography, and advanced imaging, with elbow ultrasonography and novel magnetic resonance imaging protocols potentially enabling early detection and in-depth staging. ➤ Treatment largely depends on skeletal maturity and lesion stability, defined by the presence or absence of articular cartilage fracture and subchondral bone separation, as determined by imaging and arthroscopy, and is typically nonoperative for stable lesions in skeletally immature patients and operative for those who have had failure of conservative management or have unstable lesions. ➤ Clinical practice guidelines have been limited by a paucity of high-level evidence, but a multicenter effort is ongoing to develop accurate and reliable classification systems and multimodal decision-making algorithms with prognostic value.

Objectives: Anatomic meniscus repair is frequently performed in young patients to maximize joint preservation and long-term joint health. Increasingly, surgeons are considering the role and function of the meniscotibial ligament structures during meniscus repair and transplant. The purpose of this study was to determine the distance between the tibial insertion of the meniscotibial ligament capsular attachment and the proximal tibial physis in skeletally immature subjects. Methods: 14 pediatric knee cadaver knee specimens (ages 3 months to 11 years) were dissected to clarify the relationship physis and meniscus/meniscotibial ligament complex. Metallic markers were placed marking the meniscotibial ligament capsular attachment in specific domains (Figure 1). The specimens underwent CT scanning to evaluate pin placement and relationship to the physis. OsiriX was used to measure the distances between the proximal tibial physis and the pins (placed at 5 points on both the lateral and medial meniscus- anterior root, 12 o’clock, 3/9 o’clock, 6 o’clock and posterior root). Specimens were divided into two groups for analysis- Group 1: ages 3 months- 2 years (10 pediatric knee specimens: 8 male, 2 female), and Group 2: ages 10-11 years (4 pediatric knee specimens: 2 male, 2 female). Results: There was an increase in the distance between the proximal tibial physis and the insertion points of the meniscotibial ligament with increasing specimen age. For both the medial and lateral menisci, Group 1’s meniscotibial ligament insertion points were less than 10mm away from the physis. Group 2’s meniscotibial ligament insertion points tended to be further away from the physis, but less than 20mm away, and sometimes even as close as Conclusions: This anatomic study defines the relationship between the physis and meniscotibial ligament capsular attachments that increases with age. These anatomic parameters can be considered as future meniscus repair and reconstruction techniques seek to restore the meniscus anatomy, stability, and mobility provided by the meniscotibial ligament structures. This anatomic information and may be used by surgeons to develop techniques to perform meniscal repair/reconstruction in patients that utilize the meniscotibial ligament structures. Avoiding direct physeal injury during menisco-tibial ligament repair is possible. [Figure: see text][Figure: see text]

Objectives: Endochondral ossification is a skeletal developmental process in children by which the embryonic cartilaginous model of bones undergoes gradual ossification over time until skeletal maturity is reached. Juvenile Osteochondritis Dissecans (JOCD) is a developmental disease characterized by focal areas of chondronecrosis within the epiphyseal cartilage and subsequent delay of the ossification front. JOCD lesions can become loose bodies and lead to premature Osteoarthritis. The etiology of JOCD is not yet well understood, however, there is mounting evidence of a genetic predisposition. Recently, positive familial history, including familial OCD and a genome-wide association study in humans identified genetic loci related to juvenile OCD. In this longitudinal pilot study, we examined siblings of JOCD patients utilizing clinical 3T MRI data to evaluate morphological integrity of the epiphyseal cartilage and the advancing ossification front in the distal femoral condyles in bilateral knees. We hypothesized that asymptomatic, clinically “silent” JOCD lesions could be detected in young siblings of patients affected by JOCD. Methods: In this longitudinal study, 44 MRI datasets from seven skeletally immature participants with no clinical symptoms (7 siblings of JOCD patients; 3 females; 12 bilateral knees; average age at first visit=8.7 years; range=6-10 years) were evaluated. This study was approved by the institutional review board and informed consent was obtained. All images were acquired at 3T MRI system with a 1Tx/15Rx knee coil. Sagittal PD-weighted TSE images without fat suppression (TR/TE = 3900/40 ms, resolution = 0.36x0.36 mm2, scanning time = 1min:49s) and with fat suppression (TR/TE = 3530/40 ms, resolution = 0.36x0.36 mm2, scanning time = 3min:46s) were acquired bilaterally at first visit and at multiple MRI follow-up studies ranging from 6-21 months. The images were reviewed by an experienced musculoskeletal radiologist using the following MRI criteria: (i) integrity of the ossification front; (ii) presence/absence of bone marrow edema; (iii) intact/disrupted secondary physis; and (iv) T2 hyperintensity in epiphyseal cartilage. Results: Five of seven participants (71%) met at least one of the MRI criteria defining a JOCD lesion. Six of the seven participants (86%) had an irregular ossification front at the distal aspect of the medial and/or lateral femoral epicondyles, focal areas of T2 hyperintensities in the epiphyseal cartilage, and a disrupted secondary physis. Of the 13 imaged knees, two knees (both lateral and medial epicondyle) from the same participant and two knees (only lateral epicondyle) had no abnormal MRI findings (= 6 normal epicondyles). Abnormal findings in the medial and lateral epicondyles of the remaining bilateral knees resolved over time in 11 epicondyles (Fig. 1), whereas in the remaining 9 epicondyles the abnormal findings persisted or progressed (Fig. 2). Conclusions: The most important finding of this pilot study is the high prevalence (6 out of 7, 86%) of morphological changes during skeletal development in this group of first-degree relatives of JOCD patients. Furthermore, 71% (5 out of 6) of participants met the imaging criteria for early JOCD lesions at least at one time point during the study without developing any clinical symptoms. There is mounting evidence of a genetic contribution to the etiology of JOCD. In the literature, so called ossification variants are considered morphological variants of bone shape with an overall prevalence of 12% and are believed to resolve naturally over time. While 55% of the epicondyles with abnormalities in the ossification front in our cohort resolved over time on MRI, during the course of this study – typically 8-21 months, the remaining 45% did not resolve or occurred at the last imaging time point with associated marrow edema and needed clinical surveillance. A high incidence of MRI abnormalities in the ossification front, epiphyseal cartilage and secondary physis in a clinically asymptomatic study group of first degree relatives of patients with JOCD supports the hypothesis a) that there is a strong genetic predisposition for this disease, b) clinically “silent” initial stages of the disease could be overlooked, challenging the common current understanding of normal physiologic “ossification variants”. [Figure: see text][Figure: see text]

Orthopaedic practices have been markedly affected by the emergence of the COVID-19 pandemic. Despite the ban on elective procedures, it is impossible to define the medical urgency of a case solely on whether a case is on an elective surgery schedule. Orthopaedic surgical procedures should consider COVID-19-associated risks and an assimilation of all available disease dependent, disease independent, and logistical information that is tailored to each patient, institution, and region. Using an evidence-based risk stratification of clinical urgency, we provide a framework for prioritization of orthopaedic sport medicine procedures that encompasses such factors. This can be used to facilitate the risk-benefit assessment of the timing and setting of a procedure during the COVID-19 pandemic.

Background: Immature articular cartilage (a.k.a. articular epiphyseal cartilage complex, AECC), serves dual functions as an articulating layer and surface growth plate. The AECC originates from an uninterrupted cartilaginous template during embryogenesis, presumably stemming from the same pool of progenitors, but it is unclear how the articulating layer is maintained throughout life, while the surface growth plate undergoes endochondral ossification. Hypothesis: The function and fate of chondrocytes in the AECC are not predetermined in the embryo, but instead can be influenced during development by biochemical and/or biomechanical stimuli in the cellular microenvironment. Methods: Microenvironments of the articulating layer and surface growth plate were switched in an in vivo goat model. Twelve 3-week-old goats were used. Osteochondral autografts were harvested from medial and lateral condyles and trochlea of the distal femur. Subchondral bone was removed (Figures 1A and 1B). Grafts were inverted and press-fit into select sites, which were full (condyles) or low (trochlea) weightbearing (Figures 1C through 1E). Animals were allowed ambulation and range of motion as tolerated. Two goats each were euthanized at 1, 2, 3, 6, 12, and 24 weeks postoperatively. Distal femurs were harvested and grafts were analyzed with trichrome staining and in situ hybridization for Col10, Col2, and Prg4. Results: All animals survived surgery, ambulated within 24 hours, and none exhibited signs of surgical site infection. Macroscopically, grafts at the trochlea and lateral condyle maintained a more cartilaginous appearance than those at the medial condyle, but all eventually developed an osseous appearance. Histologically, there was healing over time, with early grafts often containing areas of hemorrhage and occasionally necrosis, followed by formation of granulation tissue and subjacent myelofibrosis, with eventual invasion and ossification. At later timepoints, there was better graft incorporation at the articular surface without replacement by fibrosis at the medial condyle (Figure 2). In situ hybridization demonstrated some Prg4 positive cells and a decrease in Col10 expression at the articular surface (Figure 3). Conclusions: The synovial microenvironment may play a protective role against endochondral ossification. Some incorporation of epiphyseal cartilage into articular cartilage occurred at sites subjected to both compressive and shear forces. Data suggest the existence of local cytokines and/or matrix effects on chondrocytes that stimulate different cell functions and fates. A limitation of this study is its observational nature. Further understanding of articular chondrocyte differentiation and identification of key biochemical and/or biomechanical stimuli hold therapeutic promise for articular cartilage regeneration, repair, and replacement. Figure 1A. through 1E. Osteochondral autografts measuring 4.75 x 7 mm harvested from donor (lateral condyle and distal trochlea) and recipient (medial condyle and proximal trochlea) sites at the distal femur (Figure 1A). Separation of subchondral bone from the AECC (Figure 1B). Grafts inverted and inserted at select sites (Figures 1C through 1E). Experimental control with 13 gauge bone biopsies harvested and inserted in original orientation (Figures 1C through 1E). Figure 2. Histology with trichrome staining showing the articular surface of osteochondral autografts transplanted to the medial femoral condyle at 1, 2, 3, 6, 12, and 24 weeks postoperatively. Figure 3. In situ hybridization of Col2, Col10, and Prg4 gene expression of an osteochondral autograft transplanted to the femoral trochlea at 3 weeks postoperatively.

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 pathogenesis of human juvenile osteochondritis dissecans (JOCD) remains poorly understood, with multiple factors implicated, including ischemia, repetitive trauma, and genetic predisposition. Similarities in the predilection site and the diagnostic and clinical features of JOCD to the well-characterized veterinary counterpart, osteochondrosis dissecans, suggest that, similar to the animal disease, the pathogenesis JOCD may also be initiated in the first few years of life, when disruption of blood supply to the epiphyseal growth cartilage leads to failure of endochondral ossification. To gather data in support of the hypothesis that JOCD and osteochondrosis dissecans have a shared pathogenesis, biopsy specimens obtained from predilection sites of JOCD in juvenile human cadavers were histologically examined to determine whether they contained lesions similar to those found in animals diagnosed with subclinical osteochondrosis dissecans. Methods In this descriptive laboratory study, 59 biopsy specimens (6 mm in diameter) were harvested from the central aspect (i.e., the notch side) of the femoral condyles of 26 human cadavers (1 month to 11 years old). Specimens were histologically evaluated for the presence of areas of cartilage necrosis and the morphology of cartilage canal blood vessels. Results Locally extensive areas of necrotic epiphyseal cartilage were identified in 4 specimens obtained from 3 donors (ages 2 to 4 years). Areas of cartilage necrosis accompanied by focal failure of endochondral ossification or surrounded by subchondral bone were identified in biopsy specimens from 4 donors (ages 4 to 9 years). Conclusions The identification of epiphyseal cartilage necrosis identical to that described in animals with subclinical osteochondrosis, found in biopsy specimens obtained from femoral predilection sites of JOCD in pediatric cadavers, suggests a shared pathogenesis of JOCD in humans and osteochondrosis dissecans in animals. Clinical relevance These findings imply that the pathogenesis of human JOCD likely starts 5 to 10 years prior to the development of clinical symptoms. Enhanced understanding of the temporal features of JOCD pathogenesis provides an opportunity for earlier diagnosis and treatment, likely resulting in improved outcomes for this condition in the future.

Background: Few studies have documented early functional recovery after anterior cruciate ligament (ACL) reconstruction. Purpose: To quantify the time to early functional milestone achievement and change in function over 12 weeks after ACL reconstruction and to identify demographic characteristic predictors of the outcomes. Study Design: Prospective, longitudinal, observational study. Level of Evidence: Level 4. Methods: A total of 182 patients (95 females, 87 males; mean ± SD age, 28 ± 12 years; mean ± SD body mass index [BMI], 25 ± 4 kg/m2) who received primary, unilateral, ACL reconstruction were included. Testing occurred before surgery as well as 1, 2, 4, 8, and 12 weeks postsurgery. Outcomes included demographic characteristics, self-reported functional milestone achievements and responses on the Short Musculoskeletal Function Assessment (SMFA) questionnaire. Time to functional milestone achievement was calculated, and patients were categorized into “faster” or “prolonged” recovery groups based on the median value. Longitudinal change in SMFA subscale scores (daily activities and mobility) as well as demographic predictors of functional recovery group assignment and postsurgical change in SMFA subscale scores were examined. Results: Median time for discontinuing narcotic pain medication was 9 days, while that for discontinuing crutches was 15 days. Time to return to work occurred at a median of 11 days, return to school at 7 days, and return to driving at 11 days. Both SMFA subscale scores significantly decreased (improved) over time, with the greatest change occurring between 1 and 4 weeks postsurgery. The demographic predictor of faster functional recovery for discontinuation of narcotic pain medication was surgery with allograft; those for return to work were higher age, male sex, decreasing BMI, and sedentary/light occupational demand; and those for return to driving were higher age, male sex, and surgery on the left side of the body. Conclusion: Functional recovery occurs rapidly over the first month after ACL reconstruction for most patients. Nonmodifiable demographic characteristics may influence recovery time for specific functional milestones. Clinical Relevance: Results can be used to counsel patients on early functional recovery after ACL reconstruction.

Background: We introduce a quantitative measure of epiphyseal cartilage vascularity and examine vessel networks during human skeletal maturation. Understanding early morphological changes in the distal femoral condyle is expected to provide information on the pathogenesis of developmental diseases such as juvenile osteochondritis dissecans. Methods: Twenty-two cadaveric knees from donors ranging from 1 month to 10 years of age were included in the study. Images of bone, cartilage, and vascularity were acquired simultaneously with a 3-dimensional gradient-recalled-echo magnetic resonance imaging (MRI) sequence. The secondary ossification center volume and total epiphysis cartilage volume ratio and articular-epiphyseal cartilage complex and epiphyseal cartilage widths were measured. Epiphyseal cartilage vascularity was visualized for 9 data sets with quantitative susceptibility mapping and vessel filtering, resulting in 3-dimensional data to inform vessel network segmentation and to calculate vascular density. Results: Three distinct, non-anastomosing vascular networks (2 peripheral and 1 central) supply the distal femoral epiphyseal cartilage. The central network begins regression as early as 3 months and is absent by 4 years. From 1 month to 3 years, the ratio of central to peripheral vascular area density decreased from 1.0 to 0.5, and the ratio of central to peripheral vascular skeletal density decreased from 0.9 to 0.6. A narrow, peripheral vascular rim was present at 8 years but had disappeared by 10 years. The secondary ossification center progressively acquires the shape of the articular-epiphyseal cartilage complex by 8 years of age, and the central areas of the medial and lateral femoral condyles are the last to ossify. Conclusions: Using cadaveric pediatric knees, we provide quantitative, 3-dimensional measures of epiphyseal cartilage vascular regression during skeletal development using vessel image features. Central areas with both early vascular regression and delayed ossification correspond to predilection sites of juvenile osteochondritis dissecans in this limited case series. Our findings highlight specific vascular vulnerabilities that may lead to improved understanding of the pathogenesis and better-informed clinical management decisions in developmental skeletal diseases. Clinical Relevance: This paradigm shift in understanding of juvenile osteochondritis dissecans etiology and disease progression may critically impact future patient management. Our findings highlight specific vascular vulnerabilities during skeletal maturation in a group of active young patients seen primarily by orthopaedic surgeons and sports medicine professionals.

Summary Objective Evaluate articular cartilage by magnetic resonance imaging (MRI) T2∗ mapping within the distal femur and proximal tibia in adolescents with juvenile osteochondritis dissecans (JOCD). Design JOCD imaging studies acquired between August 2011 and February 2019 with clinical and T2∗ mapping MRI knee images were retrospectively collected and analyzed for 31 participants (9F/22M, 15.0 ± 3.8 years old) with JOCD lesions in the medial femoral condyle (MFC). In total, N = 32 knees with JOCD lesions and N = 14 control knees were assessed. Mean T2∗ values in four articular cartilage regions-of-interest (MFC, lateral femoral condyle (LFC), medial tibia (MT), and lateral tibia (LT)) and lesion volume were measured and analyzed using Wilcoxon-rank-sum tests and Spearman correlation coefficients (R). Results Mean ± standard error T2∗ differences observed between the lesion-sided MFC and the LFC in JOCD-affected knees (28.5 ± 0.9 95% confidence interval [26.8, 30.3] vs 26.3 ± 0.7 [24.8, 27.7] ms, P = 0.088) and between the affected- and control-knee MFC (28.5 ± 0.9 [26.8, 30.3] vs 28.5 ± 0.6 [27.1, 29.9] ms, P = 0.719) were nonsignificant. T2∗ was significantly increased in the lesion-sided MT vs the LT for the JOCD-affected knees (21.5 ± 0.7 [20.1, 22.9] vs 18.0 ± 0.7 [16.5, 19.5] ms, P = 0.002), but this same difference was also observed between the MT and LT in control knees (21.0 ± 0.6 [19.7, 22.3] vs 18.1 ± 1.1 [15.8, 20.4] ms, P = 0.037). There was no significant T2∗ difference between the affected- and control-knee MT (21.5 ± 0.7 [20.1, 22.9] vs 21.0 ± 0.6 [19.7, 22.3] ms, P = 0.905). T2∗ within the lesion-sided MFC was not correlated with patient age (R = 0.20, P = 0.28) or lesion volume (R = 0.06, P = 0.75). T2∗ values were slightly increased near lesions in later-stage JOCD subjects but without statistical significance. Conclusions T2∗ relaxations times were not significantly different from control sites in the articular cartilage overlying JOCD lesions in the MFC or adjacent MT cartilage in early-stage JOCD.

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: 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: 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:Surgical decision making and preoperative planning for children and adolescents with patellofemoral instability rely heavily on a patient’s skeletal maturity. To be clinically useful, radiologic assessments of skeletal maturity must demonstrate acceptable interrater reliability and accuracy.Purpose:The purpose of this study was to examine the interrater reliability among surgeons of varying experience levels and specialty training backgrounds when evaluating the skeletal maturity of the distal femur and proximal tibia of children and adolescents with patellofemoral instability.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:Six fellowship-trained orthopaedic surgeons (3 pediatric orthopaedic, 2 sports medicine, and 1 with both) who perform a high volume of patellofemoral instability surgery examined 20 blinded knee radiographs and magnetic resonance images in random order. They assessed these images for clinically relevant growth (open physis) or clinically insignificant growth (closing/closed physis) remaining in the distal femoral and proximal tibial physes. Fleiss’ kappa was calculated for each measurement. After initial ratings, raters discussed consensus methods to improve reliability and assessed the images again to determine if training and new criteria improved interrater reliability.Results:Reliability for initial assessments of distal femoral and proximal tibial physeal patency was poor (kappa range, 0.01-0.58). After consensus building, all assessments demonstrated almost-perfect interrater reliability (kappa, 0.99 for all measurements).Conclusion:Surgical decision making and preoperative planning for children and adolescents with patellofemoral instability rely heavily on radiologic assessment of skeletal maturity. This study found that initial interrater reliability of physeal patency and clinical decision making was unacceptably low. However, with the addition of new criteria, a consensus-building process, and training, these variables became highly reliable.

Background: In patients who have undergone anterior cruciate ligament reconstruction (ACLR), the effect of neuromuscular re-education (NMR) programs on standard hop tests outcomes, including limb symmetry indices (LSIs), is unknown. Hypothesis: Both legs will show improvement in hop test–measured units after neuromuscular training, but the involved leg will show relatively greater improvement leading to improved limb symmetry. Patients younger than 18 years will show more improvement than patients who are older. Study Design: Retrospective cohort study. Level of Evidence: Level 3. Methods: Patients self-selected their participation in this NMR program, which was completed after traditional outpatient physical therapy. Pre– and post–hop test scores were recorded as the primary outcome measure. Results: Seventy-one patients met the inclusion criteria and completed hop testing. Overall, the involved leg showed significant improvements (pretest/posttest) for single-leg hop (138.30 cm/156.89 cm), triple crossover hop (370.05 cm/423.11 cm), and timed hop (2.21 s/1.99 s). Similarly, on the uninvolved leg, improvements were seen for the single-leg hop (159.30 cm/171.87 cm) and triple crossover hop (427.50 cm/471.27 cm). Overall mean limb symmetry improved across all 4 hop tests, but there was significant improvement only on the single-leg hop (87% pretest to 92% posttest). Patients younger than 18 years showed mean significant LSI improvement on the triple crossover hop. Conclusion: Utilizing an intensive 6-week NMR program after ACLR prior to return to sport can improve quantitative hop test measurements. Patients younger than 18 years had greater improvement than those 18 years and older. Clinical Relevance: Advanced NMR programs can be successfully utilized in the postoperative ACLR setting to improve quantitative limb symmetry.

Rationale and Objectives In this retrospective case series, we utilize arthroscopy as the gold standard to determine if magnetic resonance imaging (MRI) of the knee can predict osteochondritis dissecans (OCD) lesion stability, the most important information to guide patient treatment decisions. It is hypothesized that the classification system of the International Cartilage Repair Society (ICRS) will allow for improved assessment of lesion grade and stability in OCD. Materials and Methods Routine MRI studies of 46 consecutive patients with arthroscopically proven OCD lesions (mean age: 23.7 years; 26 male, 16 female) were assessed by three radiologists who were blinded to arthroscopic results. Arthroscopic images were evaluated by two orthopedic surgeons in consensus. The OCD criteria of the ICRS were applied to arthroscopy and imaging interpretations. Inter-rater correlation statistics and accuracy of magnetic resonance (MR) grading with respect to arthroscopy were determined. Results Only 56% of the available MR reports assigned a label of stable or unstable to the lesion description. Of these, 58% of the lesions were deemed unstable and 42% were stable. Accuracy was 53% when reports addressed stability. Utilizing the ICRS classification system, for all three readers combined, the respective sensitivity, specificity, and accuracy of MR imaging to determine lesion stability were 70%, 81%, and 76%. When compared to the original MRI report, the overall accuracy increased from 53% to 76% when readers were given the specific criteria of the OCD ICRS classification. However, inter-reader variability remained high, with Krippendorf's alpha ranging from 0.48 to 0.57. Conclusions In this paper, we utilize arthroscopy as the gold standard to determine if MRI can predict OCD lesion stability, the most important information to guide patient treatment decisions. To our surprise, the analysis of the existing radiology reports that addressed stability revealed an overall accuracy in defining OCD lesion stability of about 53%. The classification system of the ICRS, created by an international multidisciplinary, multi-expert consortium, did markedly improve the accuracy, but consistency among different readers was lacking. This retrospective study on OCD reporting and classification highlights the inadequacy of existing classification schemes, and emphasizes the critical need for improved diagnostic MRI protocols in musculoskeletal radiology in order to propel it toward evidence-based medicine.

Objectives: Annually, an estimated 250,000 anterior cruciate ligament (ACL) reconstructions are performed. Operative management of ACL injuries has increased 22% between 2002 and 2014. With national healthcare expenditures rising at unsustainable rates, an improved understanding of healthcare costs is essential to identifying avenues of inefficiency and implement innovative solutions. This study is purposed to utilize time-driven activity-based costing (TDABC) to estimate the costs for the two-year care episode in the surgical reconstruction of ACL tears. Provided its high incidence, the operative reconstruction of ACL injuries serves as a prime setting for this study. Methods: This study follows 611 patients that underwent an ACL reconstruction for an acute ACL tear between 2009-2016 within a single outpatient orthopaedic surgery center (Figure 1). Patient demographics were collected via the electronic medical record (EMR) (Table 1). The total cost-of-care was determined using time-driven activity-based-costing (TDABC). This formula derives the cost of care as a function of the time spent for each activity and personnel cost contributions for all involved. This process was performed at all phases: surgical intervention, all clinical follow-ups, and physical therapy (PT) sessions. Results: A total of 611 patients were included for this investigation. The patient sample was primarily female (n=355, 58.1%) with an average age of 28.9 + 12.9 [27.9, 30.0], and average BMI of 25.5 + 4.5 [25.2, 25.9]. The majority of the patients identified with an Anesthesiologist Society of America (ASA) score of 1 (n=505, 83.9%). The average operative time was 107.1 + 31.5 minutes [104.6, 109.6]. The average TDABC cost-of-care was derived at $3364.95 + $958.99 [$3288.75, $3441.14]. Surgical costs occupied the greatest proportion of the overall cost-of-care, $1836.11 (53.2%), followed by costs relating to surgical implants, $911.61 (27.1%), physical therapy appointments, $342.00 (10.2%), and clinical follow-up appointments, $318.77 (9.5%) (Figure 1). A total of 459 (75.1%) patients were treated with an autograft, averaging a total cost-of-care of $2882.19, with the 90th percentile costing $3427.23 and 10th percentile costing $2343.08, reporting a 16.0% variability in costing. Of the 152 (24.9%) allografts, the average cost of care was $4884.10, with the 90th percentile costing $5321.50 and 10th percentile costing $4411.25, reporting a 9.0% variability. Hamstring autografts reported a significantly higher cost-of-care when compared to bone-patellar-bone (BTB) autografts (Hamstring: $3120.10 vs BTB: $2718.60; p

Objectives: Value-based payment models attempt to incentivize healthcare practices that reduce costs while improving patient outcomes. In order to optimize value, orthopaedic practices need a mechanism to quantify the value of the care that is provided to each individual patient. While this concept has been applied to total joint arthroplasty, sports has been largely excluded. Patient-level value-analysis (PLVA) defines value as a patient’s outcome achieved divided by the total cost of their episode of care. Measuring value on the patient-level allows a single number to describe value of the care received. The purpose of this study is to report PLVA and measure factors that influences the value of care delivered. Methods: All patients that underwent an ACL reconstruction for an acute ACL tear between the years of 2009 and 2016 at a single outpatient orthopaedic surgery center were identified via retrospective review of a prospectively collected patient-reported outcomes (PROs) registry. Patient demographics were collected via the electronic medical record (EMR) (Figure 2). The episode of care was defined as 2 years after surgery. The knee osteoarthritis outcomes score (KOOS) system was collected at initial preoperative baseline and two-years following surgery. The total cost-of-care was determined using time-driven activity-based-costing (TDABC). This formula derives the cost of care as a function of the time spent for each activity and personnel cost contributions for all involved. This process was performed at all phases: surgical intervention, all clinical follow-ups, and physical therapy (PT) sessions. Results: A total of 611 patients were included for this investigation. The patient sample was primarily female (n=355, 58.1%), average age of 28.9 + 12.9 [27.9, 30.0], and average BMI of 25.5 + 4.5 [25.2, 25.9]. A total of 151 (24.7%) patients were treated with an allograft with 128 (84.8%) utilizing a bone-patellar-bone (BTB) graft source. A total of 460 (75.3%) patients were treated with autograft with 272 (59.1%) utilizing a BTB graft source. The KOOS score was 65.3 + 15.9 [63.6, 66.9] at baseline and 83.2 + 13.5 [81.8, 84.6] at two-years, representing an improvement of 17.9 + 16.8 [16.2, 19.7]. There was a poor correlation between the change in two-year KOOS score and the TDABC cost-of-care (r=0.11). Autograft BTB demonstrated the highest overall value at two-years, 0.74 (ANOVA F: pConclusion: This is the first study to apply PLVA methodology over the entire episode of care for ACL reconstructions. In our study, there was no correlation between an increased cost-of-care and an improvement in patient-reported outcomes. The autograft BTB demonstrated the greatest patient-level value within this cohort. With the growing focus of healthcare transitioning towards value-based delivery, PLVA offers orthopaedic practices and healthcare institutions a quantitative framework to evaluate the value of individual patient care delivery over the entire episode of care. This data can be utilized to drive physician behavior change, develop better care pathways, and optimize care delivery. [Figure: see text][Figure: see text]

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: Fear of reinjury is common after anterior cruciate ligament reconstruction (ACLR) and often deters a return to preinjury sport participation. A better understanding of injury-related fear is needed to inform rehabilitation strategies. Purpose/Hypothesis: The purpose of this study was to (1) identify individual fear-evoking tasks or situations, (2) compare the intensity and amount of change relative to other injury-related fears (reinjury, knee giving way, and knee pain) after completion of a return-to-sport training program, and (3) determine whether standardized questionnaires can identify the intensity of fear for the individual fear-evoking task or situation and for fear of reinjury. The hypothesis was that the task or situation that evokes fear would vary across patients and the intensity of that fear would be higher and show less change after return-to-sport training compared with other injury-related fears. Study Design: Case series; Level of evidence, 4. Methods: Participants included 33 patients (15 males; mean age, 18 years) with ACLR who enrolled in a group-format return-to-sport training program. Questionnaires completed before and after return-to-sport training included items to specify fear-evoking tasks or situations, items to rate the intensity of various injury-related fears, the Anterior Cruciate Ligament Return to Sport after Injury scale (ACL-RSI), and the Tampa Scale for Kinesiophobia (TSK-11). Results: The most common fear-evoking task or situation was cutting, followed by contact, jumping, and other. Intensity of fear-evoking task or situation was higher than other injury-related fears, but all fears decreased in intensity after training. The ACL-RSI score better identified the intensity of fear for the individual fear-evoking task or situation and for fear of reinjury than did the TSK-11 score. Conclusion: Activities that evoke fear vary across patients, but fear of cutting is common. The intensity of common fears after ACLR decreased after advanced group training, and large effect sizes were seen for nearly all examined fears. Fear of reinjury and intensity of individually feared tasks may be better reflected in the ACL-RSI score than the TSK-11 score.

Performing exercises, especially cutting and pivoting activities, with poor lower extremity mechanics can lead to severe damage of the knee, such as anterior cruciate ligament (ACL) tears [1]. A common movement pattern observed in at-risk athletes is knee valgus. This term refers to the medial collapse of the knee (when the knees falls inward towards the center of the body). Intervention to prevent knee valgus could reduce the chance of injury for at-risk athletes, or re-injury for those recovering from a knee injury. Currently, in patients with knee injuries, knee valgus is monitored by physical therapists, who observe a patient’s movements visually during exercise. The therapists instruct patients on how to identify valgus and how they might correct it. Visual diagnosis of valgus can be difficult and subjective, thereby allowing the unavoidable presence of human error. In addition, monitoring in real time is only possible when the patient is with a therapist. Several studies have focused on the issue of accurate detection of knee valgus by using a variety of systems such as 2D and 3D motion capture systems to track knee and hip movements, dynamometers, and electromyography [2][3][4]. Although these systems are able to determine knee valgus, they are difficult to use, require expensive equipment, and do not provide real-time feedback outside of the clinic setting. The purpose of this study was to inform the design of a valgus-sensing legging by exploring sensor placement options to maximize the magnitude of the sensor response difference between valgus and non-valgus knee bends.

There are many ways to perform stabilization of unstable acromioclavicular injuries, and there are generally good results with all surgical techniques. Unfortunately, the literature is weak on comparing surgical results with nonsurgical management, so we still have not defined which patients need surgery and which patients do not.

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: To describe the results and extra-physeal position of a pediatric distal femoral trochleoplasty in a pediatric cadaveric model. Methods: Eight pediatric cadaveric specimens (mean maturity: 7.75 years, range 4-11) were used to model a distal femoral anterolateral metaphyseal osteotomy immediately proximal to the physis. A standardized 4 mm wedge was placed at the distal end of an anterior cortical shingle; created by an osteotomy 3.25 mm below the anterior cortex (range 2.5 – 4.4), with a transverse corticotomy just proximal to the physis, and hinged 25.5 mm proximally (range 21.9-28.1). The specimens were evaluated with multi-planar micro-CT scans (0.67 mm) pre and post-osteotomy. Lateral cortical elevation, the pre and post sulcus angle of the anterior supra-trochlear metaphysis, distance from distal elevated margin of the osteotomy to the superior edge of the trochlear cartilage, and distance from the distal margin of the osteotomy to the superior edge of the physis were evaluated. Results: The supra-physeal trochleoplasty elevated the lateral cortex an average of 3.26 mm (range 2.8-3.9). The resultant mean angle of the supra-trochlear metaphyseal sulcus was changed by 15.25° (range 8° -21°) (pConclusion: A technique for an extra-physeal, metaphyseal, distal femoral trochleoplasty resulted in alterations to the anterior femoral cortex that may serve as deterrents to lateral patellar translation. Lateral cortical elevation immediately superior to the trochlea may serve as a guide for centralizing patellar motion during early flexion in the setting of patella alta and trochlear dysplasia that is not uncommon in pediatric lateral patellar instability. A pediatric cadaveric model demonstrated changes in close proximity to the superior entrance of the femoral trochlea, while avoiding injury to the distal femoral physis. Significance: A supra-trochlear, lateral metaphyseal elevating osteotomy may be feasible and merit further study as an option for the treatment of lateral patellar instability in the skeletally immature.

Background: Tibial torsion is a lower extremity disorder of children and adolescents that may be idiopathic in nature. While spontaneous correction of the torsion occurs in the majority of patients during childhood, a small percentage of cases will persist into adulthood and can be associated with significant functional compromise due to patellofemoral instability, osteoarthritis, and anterior knee pain. Furthermore, late detection of tibial torsion may lead to compromise of other therapeutic efforts to alleviate symptoms. Idiopathic tibial torsion is best corrected by a tibial derotational osteotomy. However, determining which patients may benefit most from surgical correction is not well-understood, given the wide range of accepted values for normal tibial torsion depending on various measurement techniques. This review seeks to establish surgical indications for the procedure in a pediatric population with no underlying neurological, muscular, or osseous abnormalities. Methods: Systematic literature searches of 10 major databases and grey literature resources were conducted (Medline and Embase (via OVID), Cochrane Library, SPORTDiscus, Web of Science, Scopus, ClinicalTrials.gov, WHO ICTRP, and Global Index). Studies were screened by two independent reviewers based on previously established inclusion and exclusion criteria. Articles that focused on non-idiopathic torsion, such as torsion associated with neuromuscular causes, or that did not involve derotational osteotomy were excluded. Included studies were assessed for bias by two independent reviewers using GRADE and the Newcastle Ottawa Scale. Results: 911 articles were retrieved through the searches, 16 of which were ultimately included in the study. Due to the rarity of the condition, most authors studied a mixed population of skeletally mature and immature patients, except for one study. The most common surgical indications described were functional gait or cosmetic disability (70%), followed by patellofemoral instability and anterior knee pain (30%). Only a few articles cited numerical limits of abnormal torsion, and these depended on the method of measurement. Thigh-foot angle (TFA) was most often used (external torsion > 30°, internal torsion > 15°, and TFA > 2 or 3 standard deviations from the mean for the patient’s age). A bimalleolar axis with Conclusion/Significance: The diversity of measurement techniques and different anatomic references axes for describing tibial torsion has translated into a heterogenous set of surgical indications for tibial derotational osteotomies. At this time, the literature suggests that most correction procedures are decided by a patient’s functional and/or cosmetic disability. Further research is warranted to define clear standards and numerical values of tibial torsion that would benefit from surgical correction.

Durability of plate fixation is important in delayed union. Although locking plates result in stronger constructs, it is not known if locking affects the fatigue life of a plate. Two locking screws on either side of the nonunion could decrease working length and increase strain in the plate. However, the reinforcing effect of the locking head on the plate may compensate, so that it is unclear whether locking reduces fatigue life.We determined whether locking screws, compression screws, and locking buttons reduce or increase the fatigue life of a plate.We tested fatigue life of four constructs using an eight-hole locking plate in a segmental defect model: (1) all locking screws (Locked; n = 5); (2) all compression screws (Unlocked; n = 5); (3) six compression screws with two locking buttons in the central holes (Button; n = 6); and (4) six compression screws with two open central holes (Open; n = 6).The Button group had the longest fatigue life (1.3 million cycles). There was no difference between the Locked and Unlocked groups. All of the constructs failed by fracture of the plates through a screw hole adjacent to the defect.Locking screws did not improve fatigue life, however a locking button increased the fatigue life of a locking plate in a segmental bone defect model.Locking buttons in holes adjacent to a defect may improve durability, which is important when delayed union is a possibility.

BACKGROUND: Anterior cruciate ligament (ACL) tears are thought to occur with increasing frequency in young patients. No study has shown increased incidence over time. We hypothesized the incidence of ACL tears in young patients has increased over the past 20 years. METHODS: This descriptive epidemiology study is a retrospective review of insurance billing data of all patients aged 6 to 18 years with Current Procedural Terminology, Fourth Revision codes for ACL tear and reconstruction or International Classification of Diseases, Ninth Revision, Clinical Modification codes from 1994 to 2013. Injuries were normalized to persons per year enrolled in the insurance database based on age and sex. Analysis was performed based on sex and age (6–14, 15–16, and 17–18 years). RESULTS: The rate of ACL tears per 100 000 person-years averaged 121 ± 19 (range 92–151). All trends increased significantly except for the male 6- to 14-year-old and 17- to 18-year-old age groups. Overall there was an annual increase of 2.3%. Females had significantly higher incidence except in the 17- to 18-year-olds. Females peaked at age 16 years and males at age 17 years, with rates of 392 ACL tears and 422 ACL tears per 100 000 person-years, respectively. CONCLUSIONS: The incidence of ACL tears in pediatric patients increased over the last 20 years. Females were at higher risk except in the 17- to 18-year -old group. Peak incidence is noted during high school years. These data help target the most at-risk patients for ACL prevention programs.

Objectives: There is not a formula that is regularly used to help predict the risk of redislocation for an individual patient following first time lateral patellar dislocation (LPD). Our objective was to develop a model to help predict the risk of redislocation that can be easily applied in a clinic visit following first time LPD. Methods: Between 2008-2012, patients were prospectively identified at 2 musculoskeletal outpatient clinics. Patients were included if they had a history, physical exam, & magnetic resonance imaging (MRI) consistent with LPD without other significant ligamentous injury. Multiple anatomic & injury variables were obtained from the MRI including tibial tubercle - trochlear groove distance, patellar tilt, trochlear depth, trochlear facet asymmetry, trochlear condyle asymmetry, lateral trochlear inclination angle, trochlear sulcus angle (SA), Insall-Salvati ratio (ISR), Caton-Deschamps index, patellotrochlear index, location & severity of chondral injury, location & severity of MPFL injury, location of bone bruising, & whether the patient had open or closed physes (GP). Demographic patient information was also collected to include age, sex, & whether the injury was contact or non-contact. Patients were contacted at a minimum of 2 years post injury to determine if they had experienced a redislocation injury. Demographic and MRI variables were compared between patients with and without patellar redislocation using two group t-tests for continuous variables and Fisher’s exact tests for categorical variables; the statistical analysis was completed by an independent professional statistician at our institution. Stepwise logistic regression models were used to identify potential predictors of redislocation. Initially, MRI variables that had continuous data were treated as continuous variables and then a second stepwise logistic regression model was run using binary indicator variables. A cutpoint for each variable was determined using an outcome-oriented approach; the cutpoint yielding the most significant association with the redislocation outcome in a simple logistic regression model was chosen. P-values less than 0.05 were considered statistically significant. A prediction model was then created using the statistically significant variables, and a receiver operating characteristic (ROC) curve was applied to the model to evaluate for diagnostic performance. Results: Inclusion criteria were met by 108 patients. Of all of the variables, the statistically significant variables were sex, GP, SA, and ISR. The cutpoints were SA ≥ 154 degrees and ISR ≥ 1.3. The predicted probability of redislocation (percent) was 6.4 for males and 2.3 for females if the patient had closed growth plates and normal SA and ISR. The predicted probability of redislocation (percent) was 89.9 for males and 75.7 for females if the patient had open growth plates and abnormal SA and ISR. If two of three variables (GP, SA, ISR) were positive, the risk was M70.4/F45.4 (GP, SA), M46.5/F23.3 (GP, ISR), and M72.5/F47.9 (SA, ISR). The area under the curve for the ROC curve was 0.81 indicating good diagnostic performance. Conclusion: Our model demonstrates high risk of redislocation with open growth plates and SA & ISR values above the cutpoints, whereas there are low rates of redislocation with the inverse findings. This model may serve as a clinically applicable means of predicting redislocation following first time LPD.