Potential complication of bioabsorbable screw fixation for osteochondritis dissecans of the knee.

The 3 cases presented describe loosening or failure of bioabsorbable screws in the treatment of osteochondritis dissecans (OCD). In case 1, a 17-year-old boy with OCD of the medial femoral condyle was treated with bioabsorbable screw fixation. Six months after surgery, the patient had an acute episode of pain with effusion. Arthroscopic examination revealed 2 of the 4 screws backed out, causing cartilage damage to the corresponding tibial plateau. The shafts of the remaining 2 screws had completely absorbed, leaving the unabsorbed screw heads as intra-articular loose bodies in the knee. Unpredictable and inconsistent degradation of the screws is believed to be the mechanism for screw back-out and cartilage damage.