John C. Jacobs

The Demographics and Epidemiology of Osteochondritis Dissecans of the Knee in Children and Adolescents

Background: Osteochondritis dissecans (OCD) is a disorder of subchondral bone and articular cartilage whose incidence in children is not clearly known. Purpose: The purpose of this study was to assess the demographics and epidemiology of OCD of the knee in children. Study Design: Descriptive epidemiology study. Methods: A retrospective chart review of an integrated health system was performed on patients with OCD of the knee aged 2 to 19 years from 2007 to 2011, with over 1 million patients in this cohort. Lesion location, laterality, and all patient demographics were recorded. The incidence of OCD was determined for the group as a whole and by sex and age group (2-5 years, 6-11 years, and 12-19 years). Patient differences based on age, sex, and ethnicity were analyzed, and using multivariable logistic regression models, associations between age, sex, ethnicity, and diagnosis of OCD of the knee were evaluated. Results: One hundred ninety-two patients with 206 OCD lesions of the knee fit the inclusion criteria. No OCD lesion of the knee was found in 2- to 5-year-old children. One hundred thirty-one (63.6%) lesions were in the medial femoral condyle, 67 (32.5%) were in the lateral femoral condyle, 96 (50.0%) lesions were right sided, 82 (42.7%) were left sided, and 14 (7.3%) were bilateral. The incidence of patients with OCD of the knee aged 6 to 19 years was 9.5 per 100,000 overall and 15.4 and 3.3 per 100,000 for male and female patients, respectively. Those aged 12 to 19 years represented the vast majority of OCD, with an incidence of 11.2 per 100,000 versus 6.8 per 100,000 for those aged 6 to 11 years. For those aged 6 to 11 and 12 to 19 years, female patients had an incidence of 2.3 and 3.9 per 100,000, respectively, while male patients had an incidence of 11.1 and 18.1 per 100,000, respectively. Multivariable logistic regression analysis revealed a 3.3-fold increased risk of OCD of the knee in patients aged 12 to 19 years compared with those aged 6 to 11 years (P < .001; 95% confidence interval [CI], 2.37-4.48), and male patients had 3.8 times a greater risk of OCD of the knee than female patients (P < .001; 95% CI, 2.71-5.41). Based on race and ethnicity, blacks had the highest odds ratio of OCD of the knee compared with all other ethnic groups. Conclusion: In this population-based cohort study of pediatric OCD of the knee, male patients had a much greater incidence of OCD and almost 4 times the risk of OCD compared with female patients. Also, patients aged 12 to 19 years had 3 times the risk of OCD of the knee as compared with 6- to 11-year-old children.

Anterior Cruciate Ligament and Knee Injury Prevention Programs for Soccer Players A Systematic Review and Meta-analysis

Background: Soccer has one of the highest incidences of anterior cruciate ligament (ACL) injuries for both males and females. Several injury prevention programs have been developed to address this concern. However, an analysis of the pooled effect has yet to be elicited. Purpose: To conduct a systematic review and meta-analysis of ACL and knee injury prevention programs for soccer players, assess the heterogeneity among the studies, and evaluate the reported effectiveness of the prevention programs. Study Design: Systematic review and meta-analysis. Methods: A systematic search of the literature was conducted on PubMed (Medline), Embase, CINAHL, and Central-Cochrane Database. Studies were limited to randomized controlled trials (RCTs) of injury prevention programs specific to the knee and/or ACL in soccer players. The Cochrane Q test and I 2 index were independently used to assess heterogeneity among the studies. The pooled risk difference, assessing knee and/or ACL injury rates between intervention and control groups, was calculated by random-effects models with use of the DerSimonian-Laird method. Publication bias was assessed with a funnel plot and Egger weighted regression technique. Results: Nine studies met the inclusion criteria as RCTs. A total of 11,562 athletes were included, of whom 7889 were analyzed for ACL-specific injuries. Moderate heterogeneity was found among studies of knee injury prevention (P = .041); however, there was insignificant variation found among studies of ACL injury prevention programs (P = .222). For studies of knee injury prevention programs, the risk ratio was 0.74 (95% CI, 0.55-0.89), and a significant reduction in risk of knee injury was found in the prevention group (P = .039). For studies of ACL injury prevention programs, the risk ratio was 0.66 (95% CI, 0.33-1.32), and a nonsignificant reduction in risk of ACL injury was found in the prevention group (P = .238). No evidence of publication bias was found among studies of either knee or ACL injury prevention programs. Conclusion: This systematic review and meta-analysis of ACL and knee injury prevention program studies found a statistically significant reduction in injury risk for knee injuries but did not find a statistically significant reduction of ACL injuries.

Osteochondritis Dissecans Knee Histology Studies Have Variable Findings and Theories of Etiology

BackgroundAlthough many etiological theories have been proposed for osteochondritis dissecans (OCD), its etiology remains unclear. Histological analysis of the articular cartilage and subchondral bone tissues of OCD lesions can provide useful information about the cellular changes and progression of OCD. Previous research is predominantly comprised of retrospective clinical studies from which limited conclusions can be drawn.Questions/purposesThe purposes of this study were threefold: (1) Is osteonecrosis a consistent finding in OCD biopsy specimens? (2) Is normal articular cartilage a consistent finding in OCD biopsy specimens? (3) Do histological studies propose an etiology for OCD based on the tissue findings?MethodsWe searched the PubMed, Embase, and CINAHL databases for studies that conducted histological analyses of OCD lesions of the knee and identified 1560 articles. Of these, 11 met our inclusion criteria: a study of OCD lesions about the knee, published in the English language, and performed a histological analysis of subchondral bone and articular cartilage. These 11 studies were assessed for an etiology proposed in the study based on the study findings.ResultsSeven of 11 studies reported subchondral bone necrosis. Four studies reported normal articular cartilage, two studies reported degenerated or irregular articular cartilage, and five studies found a combination of normal and degenerated or irregular articular cartilage. Five studies proposed trauma or repetitive stress and two studies proposed poor blood supply as possible etiologies.ConclusionsWe found limited research on histological analysis of OCD lesions of the knee. Future studies with consistent methodology are necessary to draw major conclusions about the histology and progression of OCD lesions. Inconsistent histologic findings have resulted in a lack of consensus regarding the presence of osteonecrosis, whether the necrosis is primary or secondary, the association of cartilage degeneration, and the etiology of OCD. Such studies could use a standardized grading system to allow better comparison of findings.

The Anterolateral Ligament of the Knee: An Inconsistent Finding in Pediatric Cadaveric Specimens.

Background: The anterolateral ligament (ALL) of the knee has been identified as a structure that limits internal rotation, and thus, affects the pivot shift mechanism. It has previously been reported in a high percentage of adult subjects. The purpose of the current study was to evaluate whether the ALL could be identified on pediatric cadaveric knee specimens and compare these findings to previously published reports. Methods: Eight skeletally immature cadaver knee specimens were examined through gross dissection: ages 3 months, 4 months, 1 year, 2 years, 3 years, 3 years, 8 years, and 10 years. There were 3 male and 5 female (7 right, 1 left) specimens. The presence or absence of the ALL was documented in each specimen, through dissection, intermittent internal and external rotation of the tibia, and anterior translation of the tibia, to produce tension of the lateral collateral tissues and joint capsule. These dissections were performed by a group of fellowship-trained orthopaedic surgeons. Results: The iliotibial band, entire lateral joint capsule, lateral collateral ligament, and popliteus were readily identified in each specimen. In 7 specimens, a distinct ALL structure was not identified during dissection. The ALL was identified in 1 of 8 specimens (1-year-old female, right knee). The ALL was further delineated under applied internal rotational stress. Conclusions: Previous research has suggested that this ligament is present in the majority of adult specimens. This finding was not reproduced in the current study of pediatric cadaveric specimens, where only one of 8 specimens had an identifiable ALL. This suggests that this ligament may develop later in life, after physiological loads are applied to the joint capsule. Further research in both adult and pediatric knees needs to be conducted to further elucidate the development of this ligament, and the role of this structure in knee stability. Clinical Relevance: The ALL is a knee ligament that has been described in adults. However, it is unclear whether this structure is present or fully developed in younger populations. The current study sought to identify the ALL in pediatric cadaver knee specimens, identifying this structure in only one of 8 specimens. The findings of this study suggest that the ALL may be an inconsistent structure in the pediatric population.

Novel Radiographic Feature Classification of Knee Osteochondritis Dissecans A Multicenter Reliability Study

Background: Osteochondritis dissecans (OCD) is a vexing condition for patients, parents, and physicians because of the frequent slow healing and nonhealing that leads to prolonged treatment. Several features on plain radiographs have been identified as predictors of healing, but the reliability of their measurement has not been established. Purpose: To determine the inter- and intrarater reliability of several radiographic features used in the diagnosis, treatment, and prognosis of OCD femoral condyle lesions. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Pretreatment anteroposterior, lateral, and notch radiographs of 45 knees containing OCD lesions of the medial or lateral femoral condyle were reviewed in blinded fashion by 7 orthopaedic physician raters from different institutions over a secure web portal at 2 time points over a month apart. Classification variables included lesion location, growth plate maturity, parent bone radiodensity, progeny bone fragmentation, progeny bone displacement, progeny bone contour, lesion boundary, and radiodensity of the lesion center and rim. Condylar width and lesion size were measured on all views. Interrater reliability was assessed using free-marginal kappa and intraclass correlations. Intrarater reliability was assessed using the Cohen kappa, linear-weighted kappa, and intraclass correlations based on measurement type. Results: Raters had excellent reliability for differentiating medial and lateral lesions and growth plate maturity and for measuring condylar width and lesion size. In the subset of knees with visible bone in the lesion, the fragmentation, displacement, boundary, central radiodensity, and contour (concave/nonconcave) of the lesion bone were classified with moderate to substantial reliability. The radiodensity of the lesion rim and surrounding epiphyseal bone were classified with poor to fair reliability. Conclusion: Many diagnostic features of femoral condyle OCD lesions can be reliably classified on plain radiographs, supporting their future testing in multifactorial classification systems and multicenter research to develop prognostic algorithms. Other radiographic features should be excluded, however, because of poor reliability.

Emerging genetic basis of osteochondritis dissecans

Genome-wide association studies (GWAS) provide an unbiased approach in the identification of genes that increase the risk for osteochondritis dissecans (OCD). Recent GWAS in humans, horses, and pigs are reviewed and genes identified. The identified genes tended to cluster with respect to function and biologic processes. GWAS in humans are a critical next step in the effort to provide a better understanding of the causes of OCD, which will, in turn, allow preventive strategies for treatment of adolescents and young adults who are at risk for the development of degenerative joint disease due to the effects of OCD.

The relationship of the femoral physis and the medial patellofemoral ligament in children: a cadaveric study.

Background: Patellar dislocations are common in skeletally immature athletes, and the medial patellofemoral ligament (MPFL) is an important primary restraint to lateral patellar translation. The relationship between the MPFL femoral origin footprint and femoral physis is unclear. The purpose of this study was to evaluate the MPFL femoral origin footprint and its relationship to the femoral physis in skeletally immature anatomic specimens. Methods: Six skeletally immature cadaver knee specimens were examined through gross dissection (group A: 1, 11, and 11 mo; and group B: 8, 10, and 11 y). Metallic markers were placed at the center of the MPFL femoral origin footprint. Computed tomography scans for each specimen were analyzed. The MPFL footprint width, and the vertical distances from the center and proximal extent of the MPFL footprint to the medial aspect of the physis were measured. Results: The mean width of the MPFL femoral origin footprint was 0.70 cm (0.48 to 1.09 cm) and 1.12 cm (1.03 to 1.29 cm) for groups A and B, respectively. The mean distance from the center of the MPFL origin footprint to medial aspect of the distal femoral physis was 0.90 cm (0.52 to 1.30 cm) and 0.40 cm (0.00 to 0.86 cm) distal to the physis for groups A and B, respectively. The mean distance from the proximal extent of the MPFL origin footprint to the medial aspect of the femoral physis was −0.55 cm (−0.28 to −1.03 cm) and 0.16 cm (−0.34 to 0.64 cm) for groups A and B, respectively. Conclusions: All subjects were found to have a center of the MPFL origin footprint at or below the physis. The proximal extent of the MPFL origin footprint was found to extend above the physis in the 2 older specimens. Clinical Relevance: The relationship of the MPFL origin footprint to the femoral physis in the skeletally immature is not well understood. These dissections may be useful to surgeons performing MPFL reconstructions in skeletally immature patients.

Osteochondritis Dissecans of the Ankle in Children and Adolescents Demographics and Epidemiology

Background: Osteochondritis dissecans (OCD) of the ankle is a disorder of the talar or distal tibial subchondral bone and articular cartilage whose incidence in children is not clearly known. Purpose: To assess the demographics and epidemiology of OCD of the ankle in children. Study Design: Descriptive epidemiologic study. Methods: A retrospective chart review of an integrated health system was conducted on patients with ankle OCD aged 2 to 19 years from 2007 to 2011, with >1 million patients in this cohort. Lesion location, laterality, and all patient demographics were recorded. Ankle OCD incidence was determined for the group as a whole and by both sex and age group (divided into age groups of 2-5, 6-11, and 12-19 years). The risk for ankle OCD for age group, sex, and ethnicity was assessed using multivariate logistic regression models. Results: A total of 85 patients fit the inclusion criteria, and 71.8% of lesions found were in the medial talus, 56.5% of lesions were right sided, and none were bilateral. No ankle OCD lesions were found in 2- to 5-year-olds. The incidence of ankle OCD in patients aged 6 to 19 years was 4.6 per 100,000 overall and 3.2 and 6.0 per 100,000 for male and female patients, respectively. Patients aged 12 to 19 years represented the vast majority of those with OCD, with an incidence of 6.8 per 100,000 compared with 1.1 per 100,000 in those 6 to 11 years of age. In those aged 6 to 11 and 12 to 19 years, female patients had a respective incidence of 1.5 and 8.9 per 100,000, whereas male patients had a respective incidence of 0.7 and 4.8 per 100,000. The overall female/male ratio of ankle OCD was 1.6:1. Multivariate logistic regression analysis revealed a 6.9 times increased risk for ankle OCD in patients aged 12 to 19 years compared with those aged 6 to 11 years (95% CI, 3.8-12.5; P < .0001), and female patients had a 1.5 times greater risk for ankle OCD than male patients (95% CI, 1.0-2.3; P = .06). On the basis of race and ethnicity, non-Hispanic whites had the highest relative risk for disease and African Americans the lowest risk. Conclusion: In this population‐based cohort study of pediatric ankle OCD, female patients had a greater incidence of OCD and a 1.5 times greater risk for ankle OCD compared with male patients. Teenagers had nearly 7 times the risk for ankle OCD compared with children 6 to 11 years of age.

The Incidence of Surgery in Osteochondritis Dissecans in Children and Adolescents.

Background: The frequency of osteochondritis dissecans (OCD), a disorder of the subchondral bone and articular cartilage, is not well described. Purpose: To assess the frequency of pediatric OCD lesions that progress to surgery based on sex, joint involvement, and age. Study Design: Descriptive epidemiology study. Methods: A retrospective chart review (2007-2011) was performed on OCD. Inclusion criteria included OCD of any joint and patients aged 2 to 19 years. Exclusion criteria included traumatic osteochondral fractures or coexistence of non-OCD intra-articular lesions. Differences in progression toward surgery were compared between age groups, sex, and joint location. Logistical regression analysis was performed by sex, age, and ethnicity. Results: Overall, 317 patients with a total of 334 OCD lesions were found. The majority of lesions (61.7%) were in the knee, with ankle, elbow, shoulder, and foot lesions representing 25.4%, 12.0%, 0.6%, and 0.3% of all lesions, respectively. The majority of joints needing surgery were in the knee (58.5%), with ankle and elbow lesions representing 22.9% and 18.6% of surgeries performed, respectively. The percentage of all OCD lesions progressing to surgery was 35.3%; surgical progression for knee, ankle, and elbow joints was 33.5%, 31.8%, and 55.0%, respectively. Logistic regression analysis found no statistically significant different risk of progressing to surgery for OCD of the knee, elbow, and ankle between sexes. Patients aged 12 to 19 years had a 7.4-times greater risk of progression to surgery for knee OCD lesions than 6- to 11-year-olds. Patients aged 12 to 19 years were 8.2 times more likely to progress to surgery for all OCD lesions than patients aged 6 to 11 years. Progression to surgery of ankle OCD did not significantly differ based on location. Three of 4 trochlear lesions progressed to surgery, along with 1 of 1 tibial, 1 of 3 patellar, 40.3% of lateral femoral condylar, and 28.2% of medial femoral condylar lesions. Conclusion: In this large cohort study of pediatric OCD patients, 35% progressed to surgery. Progression to surgery did not differ significantly between sexes with OCD of any joint. Progression to surgery for OCD of the knee, elbow, and ankle strongly correlated with patient age at the time of diagnosis. Clinical Relevance: The knowledge of likelihood of progression to surgery of OCD by location, sex, and age is useful in counseling patients and in planning treatment. This study confirms a worse prognosis in the nonoperative treatment of older patients with OCD.

The Relationship of the Femoral Physis and the Medial Patellofemoral Ligament in Children A Cadaveric Study

Background: Young athletes sustain patellar dislocations in a variety of sports. The medial patellofemoral ligament (MPFL) is a critical structure that functions as an anatomic checkrein to help prevent lateral patellar dislocation. Reconstruction of this ligament is challenging in patients with open physes because of concerns about iatrogenic damage to the femoral physis. Purpose: To evaluate the relationship of the distal femoral physis and the MPFL. Study Design: Descriptive laboratory study. Methods: In 15 cadaveric, pediatric knees (age, 7-11 years), markers were placed at the proximal/distal limits of the MPFL femoral attachment and were evaluated with computed tomography. The distance from the MPFL attachment midpoint to the most medial aspect of the distal femoral physis was measured. Results: The mean femoral width of the MPFL was 8.1 mm (range, 4.3-13.8 mm). The femoral MPFL midpoint was distal to the femoral physis in 11 specimens and proximal to the physis in 4 specimens. The most proximal portion of the MPFL femoral attachment extended above the medial physis in 7, was at the physis in 5, and was below the physis in 3 specimens. One specimen had the entire MPFL femoral attachment above the physis. For knees with the MPFL midpoint above the medial physis, the distance between the center of the MPFL and physis was 3.3 mm (range, 0.3-7.1 mm). For knees with the MPFL below the medial physis, the distance between the center of the MPFL and physis was −6.8 mm (range, −0.7 to −22.0 mm). Conclusion: The relationship of the femoral attachment of the MPFL and the medial femoral physis shows some anatomic variation. In all cases, the MPFL is close to the medial femoral physis, but the midpoint of the MPFL is at, slightly above, or slightly below the physis. Clinical Relevance: The relationship of the MPFL femoral attachment footprint to the femoral physis in the skeletally immature patient is not well understood, and access to pediatric cadaveric tissue is very limited. This small series demonstrates that there is considerable variation in the relationship between the MPFL and distal femoral physis. This anatomic information may guide MPFL reconstruction technique in young patients and reduce the risk of iatrogenic physeal arrest on the femur.