Effect of PEEK polymer on tunnel widening after hamstring ACL reconstruction

The purpose of this study was to evaluate the effect of the AperFix device (Cayenne Medical, Inc, Scottsdale, Arizona), composed of polyetheretherketone (PEEK) polymer, on tunnel widening after hamstring anterior cruciate ligament (ACL) reconstruction as compared with 2 other fixation devices: the TransFix (Arthrex, Inc, Naples, Florida) and the EndoButton (Smith & Nephew Endoscopy, Mansfield, Massachusetts). Sixty-seven patients with isolated total ACL ruptures who underwent arthroscopically assisted reconstruction using hamstring autografts at the authors' institution were included in the study. Patients were assigned into 1 of 3 groups in a nonrandomized fashion: AperFix (n=18), TransFix (n=29), and EndoButton (n=20). Mean follow-up was 30 months. Tunnel widening measurements were performed on anteroposterior and lateral digital plain radiographs taken in postoperative week 1 and at final follow-up. Laxity testing, Lysholm scoring, and arthrometric evaluation were performed.All 3 graft fixation devices resulted in significant tunnel widening in both tibial and femoral tunnels at final follow-up when compared with the immediate postoperative period. Tunnel widening between groups was not significantly different in terms of coronal and sagittal femoral tunnel diameters. Tibial tunnel diameter increase in the sagittal plane in the EndoButton group was significantly smaller than that in the TransFix and AperFix groups. No correlation was found between the amount of tunnel enlargement and clinical outcomes of ACL surgery. This study's findings suggest that tunnel enlargement after ACL reconstruction is influenced by the type of graft fixation on the tibial side irrespective of clinical outcome, and PEEK polymer does not have an effect on tunnel widening after hamstring ACL reconstruction.