Clinical degradation and biocompatibility of different bioabsorbable interference screws: a report of six cases

The clinical biocompatibility and degradation of bioabsorbable interference screws of different polymer composition is described in this report for six patients who underwent repeat arthroscopy after anterior cruciate ligament (ACL) reconstruction. Bioabsorbable interference screws were used for bone plug fixation of bone--patellar tendon--bone (BPTB) autografts. Poly (L-lactide) (PLLA) interference screws were used in one case, poly (D,L-lactide-co-glycolide) (PDLLA-co-PGA) in two cases and poly (D,L-lactide) (PDLLA) in three cases. The patients either underwent removal of the femoral screw or had a biopsy taken from the screw site during re-arthroscopy. Large fragments of the PLLA screw were still present 20 months postoperatively. In one case, the PDLLA-co-PGA screw was extruded spontaneously from the tibial bone tunnel 3 weeks after the operation. In the second PDLLA-co-PGA screw case, there was no evidence left of the screw material on biopsy 12 months after implantation. The PDLLA screw in one patient was removed 6 weeks after implantation without any signs of degradation. No traces of the PDLLA screws were found in the two other patients, 10 or 14 months postoperatively. There were no clinical signs of foreign-body reactions in all cases.