2025 ISAKOS Biennial Congress Paper
A Prospective Study of In-Silico Knee Mechanics in Response to Pivoting Loads in Female Athletes With a Single ACL Tear and Female Athletes With a Subsequent Contralateral ACL Tear
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
Aaron Dees, MS, Burlington 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 41 young, female athletes, under pivoting loads, ACL force, internal tibial rotation, valgus angulation, and anterior tibial translation did not differ between female athletes with a single ACL tear and female athletes with a further contralateral ACL tear, but both groups had aberrant knee mechanics compared to uninjured female athletes.
Abstract
Background
Young, female, cutting-and-pivoting-sport-athletes have high risk of noncontact ACL injury and subsequent contralateral ACL (CACL) injury. Anatomic risk-factors include geometries of the tibiofemoral bone, articular cartilage, and menisci, which collectively impact knee mechanics. However, it is unknown if knee mechanics differ between females who sustain ACL injury without subsequent injury and females who sustain CACL injury. We developed a computational modeling workflow and leveraged a unique clinical data set to assess if under pivoting loads, ACL force, internal tibial rotation (ITR), valgus angulation, and anterior tibial translation (ATT) differ between females with one-time-ACL-injury and females who sustained CACL injury.
Methods
With IRB approval, we enrolled 200 participants who sustained an ACL injury and underwent ACLR. Of these, we identified seven females (age: 18.0±3.5, 14–24 years) who sustained CACL injury after returning to pre-injury-activities and 34 females with similar age (age: 18.9±2.7, 14-26 years) but without subsequent injury after return to pre-injury activities at a minimum of 2.5 years after ACLR. All ACL injuries involved noncontact-injury-mechanism during cutting-and-pivoting-sports. We built computational knee models for each participant using MRI data from their uninjured knee taken during return-to-sports-testing. This involved using 3D renderings of individuals’ tibiofemoral bone, articular 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 to the tibia with the femur fixed at 15° flexion and the tibia free to move in all remaining directions. ACL force (N) at the peak applied loads, ITR (°), valgus angulation (°), and ATT (mm), were measured. Kinematics were calculated as the difference in knee position between the unloaded state and at peak applied loads. Differences between groups were assessed using two-sample t-tests or Wilcoxon-rank-sum-tests (α = 0.05).
Results
ACL force [one-time-ACL=169±19N vs CACL=160±10N, p=0.30], ITR [one-time-ACL=19°(14-25°) vs CACL=20°(12-23°), p=0.80], valgus angulation [one-time-ACL=8.6±1.5° vs CACL=7.5±2.0°, p=0.08], and ATT [one-time-ACL=2.9mm(1.0-5.1mm) vs CACL=2.7mm(1.7-4.1mm), p=0.91] did not differ between females with one-time-ACL-injury and females with CACL injury.
Conclusions
ACL force and knee kinematics under pivoting loads are similar between females with one-time-ACL-injury and CACL injury, suggesting that the knee mechanics associated with first-time ACL injury may contribute to the high risk of CACL injury. Interestingly, ACL force in both the one-time-ACL-injured and CACL-injured groups was at least 60% greater than a previously modeled cohort of uninjured, young, female athletes (98±42N). We controlled for soft tissue properties in our model, which suggests certain knee geometries in young, ACL-injured females cause higher ACL force compared to similarly active uninjured females. A larger sample with longer follow-up that accounts for physical activity intensity may reveal potential mechanical differences that were not detected in the current analysis. Additional investigation of knee laxity, ACL properties, and movement mechanics is needed to determine CACL-risk-factor-combinations in young female athletes. Our findings suggest that knee mechanics are similar in one-time-ACL-injured and CACL-injured female athletes, but both groups have aberrant knee mechanics compared to uninjured female athletes.