Interference screw divergence in endoscopic anterior cruciate ligament reconstruction

Interference screws are commonly used for graft fixation in bone-tendon-bone patellar tendon anterior cruciate ligament (ACL) reconstruction. The clinical significance of graft screw divergence has not been well studied. This report retrospectively reviews our initial experience in 73 consecutive endoscopic (single-incision) ACL reconstructions using interference screw fixation. Femoral divergence occurred more frequently in the lateral plane (29%) than the anteroposterior (AP) plane (15%). No early graft failures were noted clinically or by KT-1000 arthrometer testing. If properly tested at the time of operation, it does not appear that divergence of femoral screws < 30 degrees leads to early clinical failure in endoscopic ACL reconstruction. We propose that stresses on the graft-screw-tunnel constrict will concentrate distally when placed in a divergent fashion, resulting in a wedge effect. No changes in early range of motion protocols or rehabilitation are recommended if screw divergence is noted and provided intraoperative stability is noted.