The Demographics, Epidemiology, and Incidence of Progression to Surgery of Osteochondritis Dissecans of the Knee in Children and Adolescents

OBJECTIVES: To assess the demographics and epidemiology of osteochondritis dissecans (OCD) of the knee in patients age 2-19 and the frequency with which these lesions progress to surgery. METHODS: A retrospective EMR chart review of an integrated health system was done on OCD between 2007 and 2011. Inclusion criteria included OCD of the knee and patients aged 2-19, with approximately 1 million patients in this cohort. Lesion location, laterality, and all patient demographics were recorded. OCD incidence was determined for the group as a whole and by age group (divided into age 2-5, group A=6-11, group B=12-19). Differences in progression toward surgery were compared between age groups, gender, and joint location. RESULTS: 192 patients with a total of 206 OCD lesions fit the inclusion criteria. No OCD lesions were found in 2-5 year olds. 53.4% of lesions were right-sided, 46.6% left-sided. The medial femoral condyle was the most commonly affected location with 63.6% of the knee OCD lesions, followed by the lateral femoral condyle with 32.5%. Lesions of the femoral trochlea, patella, and lateral tibial plateau represented less than 4% of the total combined. No OCD lesions were found in the 2-5 year-olds. The incidence of knee OCD for patients aged 6-19 was 9.6 per 100,000 for all patients, and 15.7 and 3.3 per 100,000 for males and females, respectively. Group B represented the vast majority of OCD, with an incidence of 21.8 per 100,000 in 12-19 year olds versus 8.7 in group A. Females in group A and B had an incidence of 4.6 and 13.3 per 100,00, respectively, while males had an incidence of 12.5 and 30.1 per 100,00 for group A and B, respectively. The overall male/female ratio for knee OCD was 3.7/1. 33.8% of all lesions progressed to surgery. Lesion location did correlate with progression to surgery, with rare trochlear lesions and tibial lesions more likely to undergo surgery (100%, 100%) than lateral and medial femoral condyle lesions (40.3% and 28.7%) and patellar lesions (33.3%). CONCLUSION: In this population-based cohort study of pediatric OCD in nearly 1 million children, males had a much greater incidence of OCD and the majority were right sided lesions. Teenagers had nearly 3 times the incidence of OCD as compared to the 6-11 year old group. Although most OCD lesions were located on the medial femoral condyle, lateral femoral condyle lesions were also common. The incidence of OCD in this study was similar to a smaller Swedish study by Linden et al 40 years previously. The knowledge of likelihood of progression to surgery of OCD by location, sex, and age is useful in counseling patients and in planning treatment. To our knowledge, this is the largest study of the demographics, epidemiology, and incidence of progression to surgery of OCD of the knee in children ever reported.