Adolescents with Osteochondritis Dissecans of the Femoral Condyle Present with High Rates of Corresponding Coronal Malalignment.

Abstract

Background: Osteochondritis dissecans of the knee (KOCD) may be a source of pain in active, skeletally immature patients. An association between the condylar lesion location and lower-extremity coronal plane malalignment has been established, but clinical implications have been poorly understood. This study aimed to confirm the high rate of malalignment in KOCD and variation in demographic characteristics, presentation features, and disease severity between those with and without malalignment.

Methods: Prospectively collected clinical, demographic, and radiographic data were obtained, and standard standing alignment measurements were evaluated from an institutional KOCD cohort. Alignment was defined as whether the mechanical axis passed between the condyles (neutral), the lateral femoral condyle (valgus), or the medial femoral condyle (varus). Comparative analysis was performed between KOCD lesions in each condyle presenting with or without malalignment. The Fisher exact test or chi-square test was used to analyze categorical variables, and the t test or Mann-Whitney U test was used to analyze continuous variables.

Results: This study examined 187 knees (156 patients, with a mean age of 12.9 years, 36.4% female); 66.3% had medial femoral condyle (MFC) lesions. Malalignment was found in 47.6% of all KOCD cases and 45.9% of skeletally immature cases. Twenty-nine (23.4%) of 124 MFC KOCD cases were in varus knees, and 42 (66.7%) of 63 lateral femoral condyle (LFC) KOCD cases were in valgus knees. MFC KOCD cases that presented in varus knees were more likely in Black or African American patients (p = 0.008) and had a larger lesion size, with a coronal width of 16.6 mm compared with MFC KOCD cases not in varus knees at 14.1 mm (p = 0.008). Similar differences were found in LFC KOCD cases presenting in valgus knees, which represented nearly all LFC KOCD cases in Black or African American patients (91.7%; p = 0.05) and had a larger lesion size, with a sagittal width of 20.8 mm compared with 16.4 mm for LFC KOCD cases not in valgus knees (p = 0.006).

Conclusions: Nearly one-half of knees with KOCD in skeletally immature patients may be in coronal malalignment and, thus, candidates for guided growth. Malalignment corresponding to the involved compartment was common and was present in two-thirds of lateral lesions. When malalignment placed the weight-bearing axis within the involved compartment, lesions were larger and more advanced. Thus, consideration should be given to addressing malalignment found during evaluations.

Level of evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.