Abstract
Objectives:
Osteochondritis dissecans (OCD) lesions are focal, idiopathic lesions of bone and/or its precursor that involves subchondral bone and can disrupt the overlying cartilage. These lesions most commonly occur in young adolescents at a rate of 9.5 per 10,000 patients. They are most commonly located on the femoral condyles, but can be found elsewhere in the knee, as well as other joints. OCD lesions cause pain that is worse with higher levels of activity. In unstable lesions, with separation of the articular cartilage from the underlying subchondral bone, mechanical symptoms, such as locking or clicking, can be experienced. Ultimately, if left untreated OCD lesions can lead to the development of early osteoarthritis, severely impairing joint function.
The Research in Osteochondritis of the Knee (ROCK) group is a multicenter group that formed for the purpose of investigating all aspects of OCD lesions. The purpose of this study is to evaluate age-related changes of OCD lesions through magnetic resonance imaging using the ROCK prospective database of patients with OCD. We hypothesize that OCD lesion size and morphology correlate with age.
Methods:
Patients with radiographic or magnetic resonance imaging evidence of OCD lesion seen at one of the study group institutions between 2013 and 2024 were eligible for inclusion in this study. Exclusion criteria included age of 26 years or greater at the time of enrollment, incomplete screening forms, missing magnetic resonance imaging (MRI) readings, and missing data regarding OCD lesion location. Patient history, including personal or family history of OCD lesion, information was collected at baseline from each patient. Physical examination, including ligamentous laxity, was documented at initial evaluation. MRI was reviewed independently by each surgeon for information regarding lesion size and location, adjacent bone edema, instability characteristics such as the omen sign, and physeal patency.
Statistical analysis was performed using Intellectus Statistics. Descriptive statistics included mean ± standard deviation for scale variables and counts and percentages for categorical variables. Pearson and Spearman correlations were performed for analysis of relationships between lesion size and age. Statistical significance was set to an alpha value of p ≤ 0.05.
Results:
A total of 1599 patients were included in this study. The average patient age was 13.5 ± 2.8 years, and the average BMI was 21.7 ± 5.1. Most patients were male (n = 1092, 68.3%). Thirty-three patients (2.1%) had documented ligamentous laxity at the time of fist visit. Six percent of patients (n = 93) had a family history of OCD lesion, most commonly in their biologic father (n = 26, 1.6%) or brother (n = 23, 1.4%).
Most patients had only one OCD lesion (n = 1,531, 95.7%), with 63 patients (3.9%) having 2 lesions and only 5 patients (0.3%) having 3 OCD lesions. Most patients had lesions of the medial femoral condyle(MFC) (n = 891, 55.7%), with the second most common site being the lateral femoral condyle(LFC) (n = 279, 17.5%). Sixty-five percent of patients (n = 1,042) had an open physis on sagittal MRI, while 147 (9.2%) had a closed physis and 195 (12.2%) had a closing physis.
Characteristics of MFC Lesions
There is a moderate correlation between age and coronal width of lesions for medial MFC lesions (r = 0.39, 95%CI = [0.33, 0.45]; p < 0.001) and small correlation between sagittal length of lesion and age for MFC lesions (r = 0.24, 95%CI = [0.18, 0.31]; p < 0.001). MFC lesions with omen signs had larger average coronal (16.2 ± 4.6mm vs 13.8 ± 4.7mm; p < 0.001) and sagittal size (22.4 ± 7.4mm vs 20.0 ± 7.1mm; p < 0.001). Patients with MFC lesions that had extensive edema of the epiphysis had larger average coronal (15.6 ± 4.6mm vs 13.8 ± 4.8mm; p < 0.001)and sagittal (22.4 ± 7.2mm vs 19.6 ± 7.1mm; p < 0.001) lesion sizes than their counterparts with no to minimal edema.
Characteristics of LFC Lesions
In lesions of the LFC, there was a moderate correlation between sagittal length of lesion and age (r = 0.33, 95%CI = [0.21, 0.43]; p < 0.001) and a moderate correlation between coronal width of lesion and age (r = 0.34, 95%CI = [0.23, 0.44]; p < 0.001). ). LFC lesions with omen signs had larger average coronal (18.3 ± 5.8mm vs 15.8 ± 6.1mm; p = 0.011) and sagittal size (22.5 ± 7.8mm vs 18.8 ± 7.0mm; p = 0.002). Marrow edema with involvement of greater than 25% of the epiphysis was associated with higher average coronal lesion size (18.6 ±6.6mm vs 15.2 ± 5.6; p < 0.001) and sagittal lesion size (22.4 ± 6.6 vs 18.6 ± 7.6; p < 0.001) than their counterparts with minimal or no edema.
Conclusions:
The present findings demonstrate correlations between OCD lesion size and patient age for MFC and LFC lesions. In addition, there is a correlation of increased adjacent bony edema for larger OCD lesions. This data may suggest that OCD lesions are generally sustained during a certain age range and progress, in terms of developing more symptomatic MRI findings, as patients age. Further research can explore the relationship between time from symptom onset and size/morphology of OCD lesions.
