CLINICAL DEGRADATION AND BIOCOMPATIBILITY OF DIFFERENT BIOABSORBABLE INTERFERENCE SCREWS - A REPORT OF 6 CASES

The clinical biocompatibility and degradation of bioabsorbable interfe rence screws of different polymer composition is described in this rep ort for six patients who underwent repeat arthroscopy after anterior c ruciate ligament (ACL) reconstruction. Bioabsorbable interference scre ws 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 un derwent removal of the femoral screw or had a biopsy taken from the sc rew site during re-arthroscopy. Large fragments of the PLLA screw were still present 20 months postoperatively. In one case, the PDLLA-co-PG A 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 impl antation. The PDLLA screw in one patient was removed 6 weeks after imp lantation without any signs of degradation. No traces of the PDLLA scr ews were found in the two other patients, 10 or 14 months postoperativ ely. There were no clinical signs of foreign-body reactions in all cas es.