The purpose of this study was to ascertain whether aggressive surgical treatment of ankylosed knees, followed by immediate continuous passive motion (CPM), can restore acceptable function in children. A retrospective analysis was performed on five children operated on for severely contracted knees. In all cases, extensive intraarticular pathology was present, and lysis of adhesions, tendon lengthenings, and capsular releases were performed in each case. Cruciate ligament release, drilling of subchondral bone, and patellectomy or meniscectomy or both also were performed in certain cases. Surgery was followed by immediate CPM for 6 weeks. Knee motion improved significantly from a preoperative mean of 7° (range, 0-20°) to 63° (range, 15-90°) at final follow-up, and all patients were satisfied with the result. The mean follow-up interval was 4.6 years. The regenerative properties of articular cartilage as well as the physis in the skeletally immature may permit a radically different approach from that accepted in adults. Such an approach can spare the native joint and restore acceptable function.