Untreated osteochondritis dissecans of the femoral condyles: prediction of patient outcome using radiographic and MR findings.

OBJECTIVE: We investigated the usefulness of plain film and MR findings in predicting the outcome of conservatively treated patients with femoral osteochondritis dissecans.
DESIGN: Without knowledge of the clinical outcome, we retrospectively reviewed the initial plain films and MR examinations. Each MR examination was evaluated for the four MR findings of instability. PATIENTS: Fourteen patients were studied in whom osteochondritis dissecans of a femoral condyle had been treated conservatively for periods ranging from 1.2 to 8.5 years. RESULTS AND
CONCLUSION: Three of five patients with an open femoral growth plate and one of nine patients with a closed growth plate had a good clinical outcome. Both patients with lesions smaller than 160 mm2 in area had a good outcome and ten of 12 patients with larger lesions had a poor outcome. Both patients with stable lesions by MR imaging had a good outcome while ten of 12 patients with a lesion unstable by MR imaging had poor outcomes. All six patients with a cartilage fracture or articular defect had poor outcomes. The results of this study should be considered preliminary since only 14 patients were followed. However, it appears that a good clinical outcome is likely when the femoral growth plate is open, when the osteochondritis dissecans is small, and when the lesion is stable by MR imaging. When a cartilage fracture or articular defect is found on MR imaging, the patient is likely to have a poor outcome.