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Patients with anterior cruciate ligament reconstruction (ACLR) areoften psychologically and physically under-prepared for sport participation. This study compared readinessto return to sport based oncompletion ofadvanced training after ACLR. Patients with ACLR who self-selectedparticipation in a 6-week group-format advanced training program (TRAINING)were compared to age- and sex-matched patients who did not participate (NoTRAINING). Each group had 23 participants (14 females). Advanced training consisted of plyometric, strengthening and agility exercises. Baseline and follow-up testing includedpsychologicalmeasures (Anterior Cruciate Ligament Return to Sport after Injury, ACL-RSI; Tampa Scale for Kinesiophobia, TSK-11; Knee Activity Self-Efficacy, KASE; and fear intensity for the primary fear-evoking task or situation) and a hop test battery.Return to sport criteria were ACL-RSI score ≥70 points and limb symmetry index ≥90% on all hop tests. At follow-up, KASE score was higher in TRAINING than NoTRAINING (92.7 vs 89.1 points; respectively), but ACL-RSI, TSK-11 and fear intensity scoreswere not significantly different between groups. Return to sport criteriapassing rate was not significantly differentbetween groups at baseline (TRAINING: 13%, NoTRAINING: 30%) or follow-up (TRAINING: 52%, NoTRAINING: 43%); however, thedistribution of criteria met at follow-up differed with more patients in TRAINING than NoTRAINING meeting hop test criteria (30% vs 4%; respectively) and more patients in NoTRAININGthan TRAINING failing to meet any criteria(25% vs 0%, respectively). Clinical significance:Advanced training after ACLR facilitated readiness for sport participation by improving confidence and hop performance, but may not have a preferential effect on fear. This article is protected by copyright. All rights reserved.

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.

Background Nonoperative treatment after first-time patellar dislocation is the standard of care. There is evidence that certain patients may be at high risk for recurrent instability. The aim of this study was to develop a multivariable model to guide management of patients based on their individual risk of recurrent dislocation. Methods A multivariable model was developed using 291 patients from 4 institutions to identify which patients were at higher risk for recurrent patellar dislocation within 2 years. This model was informed by a univariable logistic regression model developed to test factors based on the patient's history, physical examination, and imaging. The discriminatory ability of the model to classify who will or will not have a recurrent dislocation was measured using the area under the receiver operating characteristic curve (AUC). Results Age, a history of a contralateral patellar dislocation, skeletal immaturity, lateral patellar tilt, tibial tubercle-trochlear groove (TT-TG) distance, Insall-Salvati ratio, and trochlear dysplasia were the most important factors for recurrent patellar dislocation. Sex, mechanism of injury, Caton-Deschamps ratio, sulcus angle, inclination angle, and facet ratio were not factors for recurrent dislocation. The overall AUC for the multivariable model was 71% (95% confidence interval [CI]: 64.7% to 76.6%). Conclusions Optimizing the management of lateral patellar dislocation will improve short-term disability from the dislocation and reduce the long-term risk of patellofemoral arthritis from repeated chondral injury. This multivariable model can identify patients who are at high risk for recurrent dislocation and would be good candidates for early operative treatment. Further validation of this model in a prospective cohort of patients will inform whether it can be used to determine the optimal treatment plan for patients presenting with an initial patellar dislocation. Until validation of the model is done with new patients, it should not be used in clinical practice. Level of evidence Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

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

Background: Osteochondritis dissecans (OCD) occurs most commonly in the knees of young individuals. This condition is known to cause pain and discomfort in the knee and can lead to disability and early knee osteoarthritis. The cause is not well understood, and treatment plans are not well delineated. The Research in Osteochondritis Dissecans of the Knee (ROCK) group established a multicenter, prospective cohort to better understand this disease. Purpose: To provide a baseline report of the ROCK multicenter prospective cohort and present a descriptive analysis of baseline data for patient characteristics, lesion characteristics, and clinical findings of the first 1000 cases enrolled into the prospective cohort. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients were recruited from centers throughout the United States. Baseline data were obtained for patient characteristics, sports participation, patient-reported measures of functional capabilities and limitations, physical examination, diagnostic imaging results, and initial treatment plan. Descriptive statistics were completed for all outcomes of interest. Results: As of November 2020, a total of 27 orthopaedic surgeons from 17 institutions had enrolled 1004 knees with OCD, representing 903 patients (68.9% males; median age, 13.1 years; range, 6.3-25.4 years), into the prospective cohort. Lesions were located on the medial femoral condyle (66.2%), lateral femoral condyle (18.1%), trochlea (9.5%), patella (6.0%), and tibial plateau (0.2%). Most cases involved multisport athletes (68.1%), with the most common primary sport being basketball for males (27.3% of cases) and soccer for females (27.6% of cases). The median Pediatric International Knee Documentation Committee (Pedi-IKCD) score was 59.9 (IQR, 45.6-73.9), and the median Pediatric Functional Activity Brief Scale (Pedi-FABS) score was 21.0 (IQR, 5.0-28.0). Initial treatments were surgical intervention (55.4%) and activity restriction (44.0%). When surgery was performed, surgeons deemed the lesion to be stable at intraoperative assessment in 48.1% of cases. Conclusion: The multicenter ROCK group has been able to enroll the largest knee OCD cohort to date. This information is being used to further understand the pathology of OCD, including its cause, associated comorbidities, and initial presentation and symptoms. The cohort having been established is now being followed longitudinally to better define and elucidate the best treatment algorithms based on these presenting signs and symptoms.

Rotational deformity is a less common cause of patellar instability than trochlear dysplasia and patella alta. In some cases, rotational deformity is the primary bony factor producing the instability and should be corrected surgically. More research is needed on what are normal values for femoral version and tibial torsion, as well as when the axial plane alignment needs to be corrected. Many tools can be used to evaluate the axial plane and surgeons should be familiar with each of them. Understanding the advantages and disadvantages of each site for osteotomy will help the surgeon choose the most appropriate osteotomy.

Background: A discoid lateral meniscus (DLM) is a congenital anomaly of the knee in which the lateral meniscus has an “O” shape and contains irregular, abnormal collagenous tissue. A DLM can cause mechanical symptoms and pain. Treatment of a 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 to create instability. The residual width of the meniscus is crucial at the popliteus hiatus because here the peripheral rim is unattached at the capsule. Reports in the literature recommend a residual width of 6 to 8 mm. Purpose/Hypothesis: The purpose of this research was to determine the width of the lateral meniscus at the popliteal hiatus in normal specimens. Our null hypothesis was that a residual width of 6 to 8 mm will be sufficient to approximate normal anatomy. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We made direct measurements of the radial width of the lateral meniscus from the outer rim at the popliteal hiatus to the inner edge in 19 specimens (age, 2-120 months.) We measured one 4-year-old specimen with a bilateral complete DLM. We also measured 39 digital images of specimens (age, 1-132 months) using ImageJ. Finally, we made direct arthroscopic measurements of 8 skeletally mature specimens. Results: The average width of specimens Conclusion: We rejected our null hypothesis. Direct measurements suggest that a residual width of 6 to 8 mm is insufficient for children ≥8 years old. A width of at least a full centimeter approximates the normal for 8-year-olds and at least 15 mm for adolescents.

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]

Background:Treatment of meniscal tears is necessary to maintain the long-term health of the knee joint. Morphological elements, particularly vascularity, that play an important role in meniscal healing are known to change during skeletal development.Purpose:To quantitatively evaluate meniscal vascularity, cellularity, collagen, and proteoglycan content by age and location during skeletal development.Study Design:Descriptive laboratory study.Methods:Medial and lateral menisci from 14 male and 7 female cadavers aged 1 month to 11 years were collected and evaluated. For each meniscus, histologic and immunohistologic techniques were used to establish the ratio of the area of proteoglycan (safranin O) positivity to the total area (proteoglycan ratio), collagen type I and type II immunostaining positivity, number of blood vessels, and cell density. These features were evaluated over the entire meniscus and also separately in 5 circumferential segments: anterior root, anterior horn, body, posterior horn, and posterior root. Additionally, cell density and number of blood vessels were examined in 3 radial regions: inner, middle, and periphery.Results:Age was associated with a decrease in meniscal vessel count and cell density, while the proteoglycan ratio increased with skeletal maturity. Differences in vessel counts, cellular density, and proteoglycan ratio in different anatomic segments as well as in the inner, middle, and peripheral regions of the developing menisci were also observed. Collagen immunostaining results were inconsistent and not analyzed.Conclusion:The cellularity and vascularity of the developing meniscus decrease with age and the proteoglycan content increases with age. All of these parameters are influenced by location within the meniscus.Clinical Relevance:Age and location differences in meniscal morphology, particularly in the number of blood vessels, are expected to influence meniscal healing.

Background: Imaging characteristics of osteochondritis dissecans (OCD) lesions quantified by magnetic resonance imaging (MRI) are often used to inform treatment and prognosis. However, the interrater reliability of clinician-driven MRI-based assessment of OCD lesions is not well documented. Purpose: To determine the interrater reliability of several historical and novel MRI-derived characteristics of OCD of the knee in children. Study Design: Cohort study (diagnosis); Level of evidence, 3 Methods: A total of 42 OCD lesions were evaluated by 10 fellowship-trained orthopaedic surgeons using 31 different MRI characteristics, characterizing lesion size and location, condylar size, cartilage status, the interface between parent and progeny bone, and features of both the parent and the progeny bone. Interrater reliability was determined via intraclass correlation coefficients (ICCs) with 2-way random modeling, Fleiss kappa, or Krippendorff alpha as appropriate for each variable. Results: Raters were reliable when the lesion was measured in the coronal plane (ICC, 0.77). Almost perfect agreement was achieved for condylar size (ICC, 0.93), substantial agreement for physeal patency (ICC, 0.79), and moderate agreement for joint effusion (ICC, 0.56) and cartilage status (ICC, 0.50). Overall, raters showed significant variability regarding interface characteristics (ICC, 0.25), progeny (ICC range, 0.03 to 0.62), and parent bone measurements and qualities (ICC range, –0.02 to 0.65), with reliability being moderate at best for these measurements. Conclusion: This multicenter study determined the interrater reliability of MRI characteristics of OCD lesions in children. Although several measurements provided acceptable reliability, many MRI features of OCD that inform treatment decisions were unreliable. Further work will be needed to refine the unreliable characteristics and to assess the ability of those reliable characteristics to predict clinical lesion instability and prognosis.

Analytics are increasingly being used in sports medicine and throughout orthopaedics.Data collected by athletes and teams come in many forms, including wearable devices, smart apparel, and other modalities, and may include global positioning and accelerometry data, heart rate, and sleep data. There

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: First-time lateral patellar dislocations have historically been treated with a nonoperative approach; a clinical tool to predict patients who are most likely to redislocate may have clinical utility. Purpose: (1) To determine if there are discriminating factors present between patients who redislocated their patellas and those who did not after a first-time lateral patellar dislocation and (2) to use this information to develop a model that can predict the recurrence risk of lateral patellar dislocation in this population. Study Design: Case-control study; Level of evidence, 3. Methods: The study population included those with first-time lateral patellar dislocation, magnetic resonance imaging within 6 weeks, and 2-year minimum follow-up. Cohort A was from a prospective study with 2-year follow-up. Cohort B was a prospectively identified cohort with retrospective chart review. Follow-up was obtained clinically or via mail for patients without 2-year clinical follow-up. Results: Sixty-one patients (42%) out of 145 with primary lateral patellar dislocation had recurrent dislocation within 2 years. Stepwise logistic regression analysis demonstrated that skeletal immaturity (odds ratio, 4.05; 95% CI, 1.86-8.82; P = .0004), sulcus angle (odds ratio, 4.87; 95% CI, 2.01-11.80; P = .0005), and Insall-Salvati ratio (odds ratio, 3.0; 95% CI, 1.34-6.70; P = .0074) were significant predictors of redislocation. Receiver operator characteristic curves defined the cut points to be sulcus angle ≥154° and Insall-Salvati ratio ≥1.3. The probability of redislocation based on the presence of factors was 5.8% with no factors present and 22.7% with any 1 factor present, increasing to 78.5% if all 3 factors were present. Conclusion: This model demonstrates a high risk of lateral patellar redislocation when a patient presents with skeletal immaturity as well as magnetic resonance measurements of sulcus angle ≥154° and patellar height as measured by Insall-Salvati ratio ≥1.3. A patient will have a low risk of lateral patellar redislocation with the inverse findings.

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.

Sports injuries are common in pediatric and adolescent patients and the evaluation and treatment of these injuries continues to evolve. The purpose of this review is to provide a comprehensive appraisal of the literature, highlighting recent updates on sports-related knee injuries in the pediatric athlete. We specifically examined literature on tibial spine fractures, osteochondritis dissecans (OCD) of the knee, and patellar instability. Because of the volume of literature on the subject, pediatric, and adolescent anterior cruciate ligament injuries were not included in this review.An electronic search of the PubMed, EMBASE, and Google Scholar databases was performed for keywords related to pediatric: tibial spine fractures, patellar instability, and osteochondritis dissecans (OCD). Search results were filtered by publication date to yield articles published electronically or in print on or after January 1, 2013. Papers were selected based on expert opinion and consensus by the authors and included if deemed to have contributed important findings to the above topics.A total of 31 articles were deemed to have contributed significant findings to the literature: 5 tibial spine, 17 patellar instability, and 9 OCD. The level of evidence for most studies was either level III or IV.The optimal treatment for tibial spine fractures remains controversial. The evaluation of risk factors for recurrent patellar instability is important in determining the optimal treatment strategy following first-time patellar dislocation. Future multicenter studies on pediatric OCD have the potential to further understanding of this difficult problem. High-level, comparative outcomes research on a variety of pediatric sports related injuries is lacking and this review may help inform topics for future study.Level IV-literature review.

The patellofemoral joint is an articulation between the patella and the femoral trochlea, which serves to increase the lever arm of the extensor mechanism. The stability of the patella within the trochlear groove is supported statically by the bony confines of the groove itself, as well as the medial patellofemoral ligament, and dynamically by the vastus musculature. Pathologic changes seen on magnetic resonance imaging (MRI) are frequently well correlated with findings found by arthroscopy at the time of surgery. Degenerative changes to the articular cartilage, osteochondral lesions and loose bodies, tears in the retinaculum, and the medial patellofemoral ligament can be seen in MRI and are well correlated with arthroscopy. In addition, other findings that may predispose an individual to injury or degenerative changes over time, such as patella alta and trochlear dysplasia, can also be assessed by MRI and observed arthroscopically.