Bioabsorbable interference screws for bone-patellar tendon-bone anterior cruciate ligament reconstruction: Clinical and computerized tomography results of four different models. A prospective study

We investigated the effectiveness of four bioabsorbable interference screws for bone block fixation in ACL reconstruction, and assessed their complete absorption and graft integration. We performed a prospective clinical evaluation with the IKDC form and computed tomography (CT) scans 3, 6, 9, 12, 18 and 24 months after arthroscopic ACL reconstruction with the bonepatellar tendon-bone (BPTB) technique. A total of 20 patients was divided into five groups according to the type of screw used for the femoral fixation (half-tunnel technique): group A, poly L-lactic acid; group B, polyglyconate copolymer; group C, lactic acid and glycolic acid copolymer; group D, polylactic acid; and group E (control), titanium. Proximal bone graft integration was always achieved within 6 and 12 months. Cystic bone absorption was observed in two group A patients. Ten screws were absorbed (9 completely; 1 partially): 1 completely and 1 partially in group A at 9 and 24 months; 4 in Group B between 12 and 18 months; 4 in Group C (2 each at 12 and 24 months); and none in Group D. The IKDC ratings were: group A, four patients with A; group B, 2 with A, 1 with B and 1 with C; group C, 2 with A, 2 with B; group D, 4 with A. Effusion that resolved within 6 months was noted in 2 group A and 2 group C patients. One patient in group B had a traumatic re-rupture of the graft; the screw was not found when he was re-operated at 18 months. The four bioabsorbable interference screws provided safe and effective bone block fixation during ACL reconstruction. Their 93.75% excellent and good overall IKDC results were in line with those achieved with metal interference screws. The fact that none of the group D screws (polylactic acid) were absorbed at 2 years indicates that absorption of polylactic acid is a slow biological process. This is also suggested by the absence of effusion in this group.