2025 ISAKOS Biennial Congress Paper
Lateral Tibial Slope and Medial Tibial Spine Geometries Have Similar Effects on Anterior Cruciate Ligament Force in Response Pivoting Loads: A Sex-Specific Computational Modeling Study in 168 Young High-Risk Athletes
Andrew Pechstein, PhD, New York UNITED STATES
Mitchell Wheatley, PhD, Long Island City, New York UNITED STATES
David Shamritsky, MEng, New York, NY UNITED STATES
Mark Amirtharaj, MD, New York, NY UNITED STATES
Michael Parides, PhD, New York, NY UNITED STATES
Carl W Imhauser, PhD, New York, NY UNITED STATES
Thomas L. Wickiewicz, MD, New York, NY UNITED STATES
Andrew D. Pearle, MD, New York, NY UNITED STATES
Bruce D. Beynnon, PhD, Burlington, VT UNITED STATES
Danyal H. Nawabi, MD, FRCS(Orth), New York, NY UNITED STATES
Hospital for Special Surgery, New York, New York, UNITED STATES
FDA Status Not Applicable
Summary
In geometry-driven computational knee models of 168 young, male and female athletes, lateral tibial slope, medial tibial spine volume, and medial tibial spine position had similar, but sex-specific effects on ACL force under pivoting loads.
Abstract
Background
Both increased lateral tibial plateau cartilage slope (Lateral-Slope) and medial tibial spine volume (Spine-Volume) predispose non-contact ACL injury and a more anteriorly positioned medial tibial spine (Spine-Position) is related to reduced ACL loads. Geometric risk factors for ACL injury may be sex-specific but it is unknown how tibial geometries relate to ACL loading in young, male and female athletes.
Aim
Under pivoting loads in computational knee models, determine if Lateral-Slope, Spine-Volume, and Spine-Position are related to ACL force, and compare the relative effects these features on ACL force in males and females.
Methods
With IRB approval we used MRI data from the uninjured knee of 168 high-school and college-athletes (120 females, 48 males), including cases (first-time-noncontact ACL injury) and uninjured controls matched 1:1 by sex, age, and sports team. Computational knee models were built with individualized 3D renderings of tibiofemoral bone, cartilage, meniscal geometries, and ligament attachments. Tissue stiffnesses and ligament slack lengths were standardized. A pivoting load, including axial compression (100N), a valgus moment (8Nm), and an anterior force (30N) was applied sequentially to the tibia with the femur fixed at 15° flexion and the tibia free to move in all remaining directions. The model output was ACL force (N) at peak applied loads. Lateral-Slope (°), Spine-Volume (mm3), and Spine-Position (mm) were measured using published methods. Relationships between geometries and ACL force were estimated with linear regressions and were also expressed as a 2-standard deviation change (from -1SD to +1SD) in the tibial geometries within our cohort.
Results
Mean ACL force was 110.5±41.9N in females and 82.1±35.6N in males. Steeper Lateral-Slope related to greater ACL force in females (β=+2.9N per 1° increase, p<0.001) and in males (β=+3.6N per 1° increase, p=0.012). A more anterior Spine-Position related to lower ACL force in females (β=-5.4N per 1mm anterior, p=0.002), not males (p=0.63). A larger Spine-Volume related to lower ACL force in males (β=-5.9N per 100mm3 increase, p=0.031), not females (p=0.2). In females, a 2-SD change in Spine-Position had a similar effect on ACL force (Δ23.4N) compared to a 2-SD change in Lateral-Slope (Δ26.8N). In males, a 2-SD change in Spine-Volume had a similar effect on ACL force (Δ22.2N) compared to a 2-SD change in Lateral-Slope (Δ25.7N).
Conclusions
Steeper Lateral-Slope was related to higher ACL force under pivoting loads in both sexes. Spine-Volume and Spine-Position had similar effects on ACL force compared to Lateral-Slope. In females, a more anterior Spine-Position related to lower ACL force, which was 87% of the effect that Lateral-Slope had on ACL force. In males, increased Spine-Volume related to lower ACL force, which was 86% of the effect that Lateral-Slope had on ACL force. Multiple linear regression showed that the effects of Spine-Volume, Spine-Position, and Lateral-Slope on ACL force were independent of each other. Our data indicate that clinicians may consider both medial tibial spine geometries and lateral slope for injury-risk stratification and surgical indications. We speculate that slope-leveling-osteotomy may not provide predictable benefit if a knee has variants of spine geometry that predispose high ACL loads.