A Radiographic Healing Classification for Osteochondritis Dissecans of the Knee Provides Good Interobserver Reliability

BACKGROUND: Recent studies have examined radiographic factors associated with healing of osteochondritis dissecans (OCD) lesions of the knee. However, there is still no gold standard in determining the healing status of an OCD lesion. PURPOSE: We examined temporally associated patterns of healing to (1) evaluate the practicality of a classification system and (2) elucidate any associations between healing pattern and patient age, sex, lesion location, treatment type, and physeal patency. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: We retrospectively screened 489 patients from 2006 to 2010 for a total of 41 consecutive knee OCD lesions that met inclusion criteria, including at least 3 consecutive radiographic series (mean patient age, 12.8 years; range, 7.8-17.1 years; mean follow-up, 75.1 weeks). Radiographs were arranged in sequential order for ratings by 2 orthopaedic sports medicine specialists. Healing patterns were rated as boundary resolution, increasing radiodensity of progeny fragment, combined, or not applicable. Repeat ratings were conducted 3 weeks later. RESULTS: Patients were most commonly adolescent males aged 13 to 17 years, with a medial femoral condyle lesion that was treated operatively. Interobserver reliability of the healing classification was good (intraclass correlation coefficient, 0.67; 95% CI, 0.55-0.79). Boundary and radiodensity healing was observed for all ages, sexes, lesion locations, treatment types, and physeal patency states. CONCLUSION: This study evaluated a valuable radiographic paradigm—boundary resolution, increasing radiodensity of progeny fragment, or combined—for assessment of OCD lesion healing. The proposed system of healing classification demonstrated good inter- and intraobserver reliability. Healing patterns were not significantly associated with any particular age, sex, lesion location, treatment type, or physeal patency status. The development of a classification system for knee OCD may eventually improve clinical assessment and management of OCD lesions.