Comparison of Tibial Cortical Button Fixation and Bioabsorbable Interference Screw Plus U-Staple Fixation in Anterior...

Background and Objectives: This study aimed to compare the clinical, functional, and graft-related outcomes of two tibial fixation constructs used in primary hamstring autograft anterior cruciate ligament reconstruction (ACLR): tibial cortical button fixation and bioabsorbable interference screw fixation reinforced with a U-shaped staple. Materials and Methods: This retrospective two-center comparative cohort study included 58 patients with isolated anterior cruciate ligament injuries who underwent primary ACLR and had a minimum postoperative follow-up of 12 months. Patients were classified into the cortical button group (n = 26) or the U-staple group (n = 32) according to the initial graft diameter, which strictly dictated the tibial fixation construct documented in the operative report. Both the semitendinosus and gracilis tendons were used in each group. A shorter quadrupled graft construct was prepared in the cortical button group, whereas a longer doubled graft construct was used in the U-staple group. Donor-site pain measured using the visual analog scale (VAS), graft diameter, International Knee Documentation Committee (IKDC) score, Lysholm score, knee range of motion (ROM), Lachman and pivot-shift findings, and graft failure were compared between the groups. Graft failure was defined as magnetic resonance imaging (MRI) evidence of graft discontinuity or insufficiency accompanied by grade 2-3 Lachman laxity or a positive pivot-shift test. Numerical variables were analyzed using the Mann-Whitney U test, whereas categorical variables were compared using the Pearson chi-square or Fisher's exact test, as appropriate. Results: Donor-site pain was significantly higher in the cortical button group than in the U-staple group [median VAS score: 2.5 (2.0-4.0) vs. 2.0 (0-2.0), respectively; p = 0.007]. Graft diameter was also significantly greater in the cortical button group [10.0 mm (10.0-10.0) vs. 9.0 mm (8.0-9.0); p < 0.001]. In contrast, IKDC scores were significantly higher in the U-staple group [71.0 (51.5-78.0) vs. 60.0 (55.0-62.8); p = 0.017]. No significant differences were observed in Lysholm scores (p = 0.701), knee ROM (p = 0.508), positive pivot-shift findings (11.5% vs. 6.3%; p = 0.648), clinically relevant Lachman laxity (30.8% vs. 18.8%; p = 0.287), or graft failure rates (11.5% vs. 18.8%; p = 0.495). Conclusions: No significant between-group differences were observed in Lysholm scores, knee ROM, clinical stability, or graft failure rates after hamstring autograft ACLR. The U-staple group demonstrated lower donor-site pain and higher IKDC scores, whereas the cortical button group had larger graft diameters, likely reflecting the shorter quadrupled graft configuration. Overall, neither tibial fixation construct showed a consistent advantage across all clinical outcomes.