Pretibial cyst formation after anterior cruciate ligament reconstruction with poly-L acid screw fixation: a case report presentation and review of the literature.

A pretibial cyst after anterior cruciate ligament (ACL) reconstruction is a rare complication. This report presents a case of a subcutaneous pretibial ganglion with direct communication to the tibial tunnel, after ACL reconstruction with a quadrupled hamstrings tendon autograft, in a 26-year-old Caucasian male. The hamstrings tendon graft was fixed to the tibia using a 9-mm poly-L-lactide interference screw, 4 years earlier. There were no clinical signs of inflammation at the time the cyst appeared. The patient underwent excision of the cyst and curettage of the tibial tunnel. Fibrous tissue and gelatinous material exuded, whereas the screw had completely bioabsorbed. The cyst wall and the content were sent for histological examination (HE). Arthroscopically the graft was probed and found to be intact. HE showed a few giant cells and macrophages. This complication is believed to occur because of a diversion of the biodegrading-bioabsorbing process of the poly-L-lactic acid fixation screw, which led to direct communication between the joint and the pretibial subcutaneous tissue through a fibrous tibial tunnel.