Secondary intra-articular dislocation of a broken bioabsorbable interference screw after anterior cruciate ligament reconstruction.

We report a case of intra-articular migration of the proximal part of a broken polylactic acid screw from the tibial site of anterior cruciate ligament-reconstruction with quadrupled semi-tendinosus tendon. Five months after initially successful ACL surgery the patient felt a sudden locking of the knee without another injury. MRI showed intra-articular migration of one-half of the polylactic acid screw, and standard radiographs a widening of the proximal tibial tunnel. At revision arthroscopy the broken part was easily removed. The patient had full recovery. This case demonstrates the problem of "bioscrew" breakage in ACL surgery.