AANA Lab Course 913 - Advanced Knee Course-What You Need to Know About Tibial Slope and its Effect on Cruciate Ligament Reconstructions Faculty Lecture

What You Need to Know About Tibial Slope and its Effect on Cruciate Ligament Reconstructions Faculty Lecture_ Andrew S. Bernhardson, MD

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This presentation by Dr. Andrew S. Bernhardson discusses the critical role of posterior tibial slope (PTS) in anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) reconstruction failures. Key factors influencing ACL or PCL failure include coronal alignment, missed injuries to secondary stabilizers like the posterolateral corner, and crucially, the posterior tibial slope.<br /><br />The PTS varies from 0 to 18 degrees. A flat slope (closer to 0°) tends to protect the ACL but increases PCL injury risk, whereas an increased slope raises ACL injury risk but can be protective for the PCL. Measuring tibial slope can vary based on reference points and imaging methods.<br /><br />For ACL reconstruction (ACLR), increased PTS is linked to greater anterior tibial translation, pivot shift, and higher graft forces, correlating with higher failure rates: studies show up to 5 times higher failure with steep slopes (>12°). Increased slope also contributes to tunnel dilation post-quad tendon ACLR, important for revision surgery planning. Slope-modifying osteotomies performed with ACL revision have shown improved outcomes, with an optimal PTS target around 6° to reduce graft strain.<br /><br />In PCL reconstruction (PCLR), a flat PTS results in higher graft forces and a higher failure rate, especially with single-bundle reconstructions. Double-bundle PCL reconstructions better resist the negative effects of a flat slope, supporting recommendation of double-bundle techniques when slope is low. Increasing slope reduces PCL graft forces and posterior tibial sag, aiding in knee stability.<br /><br />A clinical case illustrated addressing failed ACLR by correcting varus alignment, posterior tibial slope, and repairing secondary injuries to improve stability.<br /><br />In summary, evaluating tibial slope is essential in failed cruciate ligament reconstructions. High slopes (>12°) predispose to ACL graft failure, warranting slope-reducing osteotomy. Conversely, flat slopes increase PCL graft forces and failure risk, suggesting double-bundle reconstruction. Addressing sagittal and coronal alignment alongside slope optimization enhances reconstructive success and stability.

Keywords

posterior tibial slope

anterior cruciate ligament reconstruction

posterior cruciate ligament reconstruction

ACL failure factors

PCL failure factors

slope-modifying osteotomy

double-bundle PCL reconstruction

tibial slope measurement

graft failure rates

knee stability