Sterile pretibial abscess after anterior cruciate reconstruction from bioabsorbable interference screws: a report of 2 cases.

We report 2 cases of extra-articular pretibial sterile abscesses with minimal osteolysis after anterior cruciate ligament reconstruction with poly-L-lactic acid bioabsorbable interference screw fixation. No joint involvement was evident in either case. Both patients underwent surgical exploration for incision, drainage, and excision with debridement of the biodegradable screw debris from the tibial bone tunnel. The cystic area in case 1 contained 8 mL of chalky white fluid with fragments of particulate matter. Microscopic evaluation revealed birefringent foreign material in a benign histiocyte-lined cyst. We encountered 20 mL of chalky white material during surgical debridement in case 2. Intraoperative cultures and Gram's stain were negative. Both patients had an uneventful recovery after surgical debridement and were able to return to their athletic activities. To our knowledge, this is the first case report of a local reaction to poly-L-lactic acid bioabsorbable interference screws after anterior cruciate ligament reconstruction.