Hybrid fixation: evaluation of a novel technique in adult osteochondritis dissecans of the knee.

Purpose: Treatment of osteochondritis dissecans of the adult knee requires bone and cartilage integration of the loose fragment. Screw fixation provides primary stability but does not guarantee bony consolidation. Additional biological fixation using osteochondral grafts-hybrid fixation-could improve fragment integration.

Methods: The study included seven patients [median age 21 years (15-29)] who underwent surgery for Bedouelle IIB or III osteochondritis dissecans of the medial femoral condyle. The technique involved metal screw fixation of the fragment. Mosaicplasty grafts were then press-fitted through the fragment. Cancellous autograft was utilized in the cases of subchondral bone loss. Patients were followed up clinically and radiologically (Hughston score). Screws were removed arthroscopically at 3 months and the cartilage graded using the International Cartilage Repair Society score. Fragment integration was evaluated by MRI Arthrogram (4 patients).

Results: Median follow-up was 27 months (7-35). Median clinical Hughston score was 2 (0-3) preoperatively and 4 (2-4) postoperatively. Median radiological Hughston score was 3 (2-4) and 4 (3-4). During arthroscopic removal of metalwork, osteochondritis fragments were well integrated in all cases. The International Cartilage Repair Society score was I in one patients, II in five, and III in one. Postoperative MRI arthrograms confirmed that cartilage and bone integration was complete.

Conclusions: Isolated screw fixation of osteochondritis dissecans in adults provides poor bony integration. Mosaicplasty is an alternative but does not retain normal condylar anatomy. The hybrid fixation technique adds a biological "booster" to osteochondritis fixation, with excellent short-term outcome. Further studies are required to investigate the long-term results.