Association of Body Mass Index With Severity and Lesion Location in Adolescents With Osteochondritis Dissecans of the Knee

Background: The association between body mass index (BMI) and severity of osteochondritis dissecans (OCD) of the knee at presentation is poorly understood.

Hypothesis: We hypothesized that adolescents in higher BMI percentiles for age and sex would have OCD lesions that were more severe at their initial presentation and located more posteriorly on the condyle as compared with adolescents in lower BMI percentiles.

Study design: Cohort study; Level of evidence, 3.

Methods: This study included patients aged 10 to 18 years who were treated for knee OCD at a tertiary care hospital from 2006 to 2017. Patients with noncondylar OCD or missing BMI data within 3 months of presentation were excluded. Patients were stratified per the Centers for Disease Control and Prevention guidelines as underweight, normal weight, overweight, or obese, and the groups were compared according to age, side of lesion, 4 markers of lesion severity (cystic changes, loose fragments, subchondral fluid, and subchondral edema), and surgical treatment. Lesion angle was measured in reference to a line parallel to the femoral axis drawn through the center of a best-fit circle covering the distal condyle. Data were analyzed using chi-square tests, relative risk, Student t tests, analysis of variance, and linear regression of cumulative running percentages. Bonferroni correction was performed when applicable.

Results: A total of 77 patients met our inclusion criteria (mean age, 14.2 years; range, 10.1-18.8): 2 were underweight, 50 had normal BMI, 13 were overweight, and 12 were obese. We found correlations between BMI percentile and surgical treatment (R ² = .732), subchondral fluid (R ² = .716), subchondral edema (R ² = .63), loose fragments (R ² = .835), and the presence of at least 1 marker of lesion severity (R ² = .857) (P < .0001 for all). No correlation was observed for cystic changes (R ² = .026). There were significant associations between BMI ≥80th percentile and subchondral edema (risk ratio, 2.5; 95% CI, 1.3-4.8), medial condylar lesions (risk ratio, 1.3; 95% CI, 1.01-1.7), and lesions more anterior on the condyle (P < .05).

Conclusion: Higher BMI in adolescents was strongly correlated with multiple markers of severity of knee OCD at initial presentation as well as with more anterior lesions.