Lateral femoral condyle OCD lesions in children on knee MRI

To systematically investigate the various MRI findings that can associate with unstable lateral femoral condyle (LFC) osteochondritis dissecans (OCD) lesions in the pediatric knee.

This retrospective study included patients < 18 years who underwent knee MRI and treatment for LFC OCD lesions, between 2018 and 2025. Blinded to outcome, 2 radiologists independently and retrospectively reviewed all examinations to determine the presence of effusion, skeletal maturity, and various direct and indirect findings that can associate with lesion instability. Demographic characteristics and lesion volume were also collected. The reference standard for lesion stability included arthroscopy (n = 16) and in those managed conservatively, follow-up clinical and imaging evaluations (n = 21). Findings between stable and unstable lesions were compared.

Thirty-two patients (21 males, 11 females, mean age = 12.0 ± 2.0 years, range = 8.1-17.2) had a total of 37 (26 stable, 11 unstable) lesions. Older age (14.4 ± 1.9 vs. 11.9 ± 1.5 years, P < .01), skeletal maturity (36.4% vs. 3.8%, P = .02), larger lesion volume (436.4 mm³ vs. 230.8 mm³, P < .01), presence of overlying cartilage alteration (90.9% vs. 7.7%, P < .01), progeny-parent bone interface (81.2% vs. 23.1%, P < .01), altered surface curvature (72.7% vs. 23.1%, P < .01), parent bone low-signal-intensity marginal rim (81.8% vs. 11.5%, P < .01), and extensive perilesional marrow edema (72.7% vs. 11.5%, P < .01) were more common among unstable than stable lesions. Cartilage alteration had the highest discriminative performance for identifying lesion instability with sensitivity of 91% and specificity of 92% (area under the curve, AUC = .92, 95% CI = 0.81-1.00).

Various MRI findings can associate with unstable LFC OCD lesions, but the presence of overlying cartilage alteration had the highest discriminative performance.