Predictors of Tunnel Widening After Anterior Cruciate Ligament Reconstruction

Background: Posterior tibial slope (PTS) has been implicated in tunnel widening after anterior cruciate ligament reconstruction (ACLR), yet its precise effect remains unclear. Additionally, the influence of lateral extra-articular tenodesis (LET) and meniscus root injuries on tunnel widening has not been well established. Purpose: To evaluate the effect of medial and lateral PTS, LET, and meniscus root injuries on tibial and femoral tunnel widening after ACL reconstruction using a hamstring tendon graft. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 307 patients who underwent primary ACLR with a hamstring tendon graft were included. Tibial and femoral tunnel diameters were measured immediately postoperatively and at 2-year follow-up. PTS was assessed by long lateral radiographs. Univariate and multivariate regression models were used to identify predictors of tunnel widening. Results: At 2 years, the mean ± Standard Deviation (SD) tibial tunnel diameter increased from 9.46 ± 1.00 mm postoperatively to 11.35 ± 1.55 mm ( P < .001), and the mean femoral tunnel diameter increased from 9.27 ± 0.83 mm to 11.52 ± 1.63 mm ( P < .001). Univariate analysis demonstrated that steeper medial and lateral PTS were significantly associated with tibial ( P < .0001) and femoral ( P < .0001) tunnel widening. Meniscus root injuries ( P = .0024) and higher body mass index ( P = .0127) were also associated with increased tunnel widening. In multivariate regression, medial PTS (β = −0.321; P < .0001), lateral PTS (β = −0.137; P = .0356), LET (β = 0.2207; P = .0257), and meniscus root injuries ( P = .0024) remained independent predictors of tunnel widening. Conclusion: Steeper medial and lateral PTSs, the addition of LET, and the presence of meniscus root injuries are significant independent predictors of tibial and femoral tunnel widening after ACLR with a hamstring graft. These findings highlight key anatomic and surgical factors influencing postoperative tunnel remodeling and emphasize the importance of considering these variables in ACLR planning.