Femoral offset aimer use is not associated with improved anatomic accuracy in hamstring ACL reconstruction: A 3D-CT study.

Abstract

To assess femoral and tibial tunnel positioning after primary hamstring autograft anterior cruciate ligament (ACL) reconstruction using postoperative three-dimensional computed tomography (3D-CT), and to evaluate whether tunnel placement differs with the use of a 7-mm femoral offset aimer and surgeon experience. This retrospective cross-sectional study included patients aged 18-50 years who underwent Primary single-bundle hamstring ACL reconstruction between 2022 and 2025 and had postoperative 3D-CT imaging available. The femoral and tibial tunnel positions were assessed using validated 3D-CT measurement methods and then classified according to the published anatomic reference ranges. The association of tunnel accuracy with 7-mm femoral offset aimer use and surgeon experience was analysed. Interobserver reliability was assessed using the intraclass correlation coefficient. Eighty-six patients were included (37.2% female; median age 25.5 years). High-experience surgeons performed the procedures in 39.5% of cases, and a 7-mm offset aimer was used in 81.4% (<i>n</i> = 70). Interobserver reliability was good-to-excellent. Mean femoral depth and height were 31.3 ± 4.3% and 29.0 ± 4.5%, respectively, while the mean tibial anteroposterior and mediolateral positions were 40.7 ± 4.3% and 47.0 ± 1.9%. The femoral and tibial tunnels were anatomic in 76.7% and 67.4% of the cases, respectively. Offset aimer use was not associated with femoral anatomic accuracy (<i>p</i> = 0.75) but was associated with a more posterior femoral tunnel position (depth 30.7 ± 3.9% vs. 34.5 ± 4.9%; <i>p</i> = 0.002). There was no difference in femoral height (<i>p</i> = 0.90). Surgeon experience was not associated with anatomic femoral (<i>p</i> = 0.46) or tibial (<i>p</i> = 0.99) tunnel placement accuracy. In this retrospective 3D-CT study, 7-mm femoral offset aimer use was associated with a more posterior femoral tunnel position but not with improved overall anatomic accuracy. Surgeon experience was not associated with femoral or tibial tunnel accuracy. The clinical relevance of these radiological findings remains uncertain. Level III.