Interaction between anterior cruciate ligament and tibial slope: what is the role for tibial deflexion osteotomy

Background: Anterior cruciate ligament (ACL) reconstruction failure remains a clinical challenge, with graft rupture rates reaching 25% in revision settings. While technical errors such as tunnel malposition were historically primary causes of failure, recent evidence identifies excessive posterior tibial slope (PTS) as a critical anatomical risk factor. Increased PTS correlates linearly with elevated graft tension and static anterior tibial translation (SATT), potentially leading to fatigue failure and residual laxity.

Objective: This article evaluates the biomechanical influence of PTS on ACL graft stability and details the radiographic assessment and surgical management of sagittal tibial malalignment through tibial deflexion osteotomy (TDO).

Key Points: Biomechanical data indicate that each degree of medial PTS increases anterior translation by 0.46 mm. Radiographic assessment requires true lateral views in single-leg weight-bearing to measure PTS and SATT. Surgical intervention via supra-tubercular, trans-tubercle, or infra-tubercle TDO is indicated for revision cases with PTS ≥ 12° and SATT ≥ 5 mm. The supra-tubercular technique involves a biplanar anterior closing wedge osteotomy to achieve a target PTS of 4–6°. Clinical outcomes demonstrate graft rupture rates as low as 2% following TDO, though risks include iatrogenic genu recurvatum and minor increases in patellar height.

Conclusion: Addressing sagittal plane tibial morphology is essential in managing recurrent ACL deficiency. Tibial deflexion osteotomy effectively reduces graft strain by correcting excessive PTS and SATT, providing a stable environment for ligament reconstruction and improving long-term functional outcomes in high-risk patients.