The Impact of Posterior Tibial Slope and Static Anterior Tibial Translation on ACL Graft Rupture Rates After Hamstring Autograft Reconstruction With Lateral Extra-articular Tenodesis

Background: The addition of a lateral extra-articular tenodesis (LET) to anterior cruciate ligament (ACL) reconstruction (ACLR) has been shown to reduce ACL graft rupture rates. Posterior tibial slope (PTS) and static anterior tibial translation (SATT) are also recognized as risk factors for ACL graft rupture. Purpose/Hypothesis: The purpose was to evaluate the effect of PTS and SATT on graft rupture rates after ACLR using hamstring tendon autografts combined with LET. It was hypothesized that increased PTS and SATT would result in increased ACL graft rupture rates despite the addition of an LET. Study Design: Case-control study; Level of evidence, 3. Methods: This retrospective, single-center, single-surgeon study included patients who underwent primary ACLR with hamstring tendon autografts combined with LET between January 2014 and December 2017. Demographic data were collected, and the association between PTS, SATT, and ACL graft rupture rates was assessed with a minimum follow-up of 6 years. Subgroup analyses were performed using PTS thresholds of 9° and 12°, as well as an SATT threshold of 5 mm. Univariate and multivariate analyses were conducted to identify significant risk factors for ACL graft rupture. Results: Of the 934 ACLR procedures performed, 207 patients met the inclusion criteria. With a 90% response rate, 186 patients who underwent primary ACLR with hamstring tendon autografts and LET were included for analysis. ACL graft rupture rate for patients with a PTS ≥12° (19.4%) was significantly ( P < .001) higher than that for patients with PTS <12° (2.7%). The highest ACL graft rupture rate (26%) was observed in patients with both a PTS ≥12° and an SATT ≥5 mm. Patients with a PTS <9° demonstrated no ACL graft ruptures (0/60). The risk of graft rupture was significantly associated with a PTS ≥12° (OR, 12; 95% CI, 0.1-0.4; P < .001), SATT ≥5 mm (OR, 1.4; 95% CI, 0.2-3; P = .045), and age <18 years (OR, 4.1; 95% CI, 0.8-22.1; P = .015). Conclusion: Despite the addition of an LET, almost 20% of patients undergoing ACLR with hamstring tendon autografts experienced graft rupture when PTS was ≥12°. When combined with an increased SATT (≥5 mm), the graft rupture rate rose to 26%. In contrast, no graft ruptures were observed in patients with a PTS <9°. These findings emphasize the importance of evaluating PTS and SATT individually rather than systematically performing LET.