Femoral and tibial attachment positions of the anterolateral ligament graft are associated with anterior instability after combined anterior cruciate ligament and anterolateral ligament reconstruction

BACKGROUND: While numerous studies have examined the benefits of combining anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction on clinical outcomes, detailed investigations into the relationship between reconstructed ALL femoral and tibial attachment positions and outcomes remain limited. The purpose of this study is to analyze the association between ALL graft attachment positions and clinical outcomes in patients undergoing combined ACL and ALL reconstruction. METHODS: Patients who underwent combined ACL and ALL reconstruction between 2019 and 2023 were retrospectively reviewed. Postoperative computed tomography was performed and reconstructed three-dimensionally to quantify the femoral and tibial graft attachment positions of the ALL. Clinical outcomes were assessed at 1- and 2-year follow-ups using objective and subjective measures, including anterior-posterior (AP) and rotational instability, range of motion, and several patient-reported outcomes. The associations between three-dimensionally measured graft attachment positions and clinical outcomes were analyzed. RESULTS: A total of 52 patients were included. At 1 year, a more proximal and posterior ALL femoral position correlated with reduced AP instability measures including KT-2000 and Lachman stress radiograph side-to-side difference (SSD) (r = -0.305 to -0.354) and lower likelihood of a positive Lachman test (r = -0.414 and -0.586). Posterior femoral position was associated with greater extension deficit (r = 0.281, P = 0.043). Regression analysis showed that femoral AP position was associated with KT-2000 SSD (B = -0.327, P = 0.011) and Lachman positivity (posterior OR 0.60, P = 0.005; proximal OR 0.77, P = 0.032). At 2 years, posterior femoral AP position remained associated with reduced anterior translation (B = -0.301, P = 0.012), while the tibial AP position was positively associated with Lachman SSD (B = 0.297, P < 0.001), indicating that a more anterior tibial position, represented by a lower AP ratio, was associated with lower Lachman SSD. ACL tunnel position showed no significant association with clinical outcomes. Significant range of motion (ROM) deficits occurred in 21.2% at 1 year but declined to 5.7% (extension) and 11.4% (flexion) at 2 years. Anatomical femoral positioning was associated with reduced anterior instability (Lachman SSD at 1 year, P = 0.032; at 2 years, P = 0.008) but was also associated with greater early ROM deficits, which resolved by 2 years. CONCLUSIONS: The femoral and tibial attachment positions of the ALL graft were associated with AP instability after combined ACL and ALL reconstruction. A more horizontal graft course was associated with reduced AP instability and mild, transient early ROM deficits.