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Tue. Dec 20  

Speaker: David B. Lipps, MSE (University of Michigan, Ann Arbor)

Title: Effect of Gender-related Differences in Knee Morphology and Quadriceps Stiffness on Peak Anterior Cruciate Ligament Strain during Pivot Landings

Abstract: Anterior cruciate ligament (ACL) injuries are associated with considerable morbidity.  For example, individuals who suffer an ACL rupture have a 50% chance of developing knee osteoarthritis with 10-20 years.  A knowledge gap exists as to why adolescent female athletes have a 2- to 8-fold increase of rupturing their ACL when compared to sport-matched males. Individuals with a smaller ACL cross-sectional area and greater lateral tibial slope have been shown to have an increased ACL injury risk.  Using a custom in vitro testing apparatus, we tested the hypothesis that a gender difference in peak ACL strain in size-matched male and female cadaver lower extremities during a standardized two-times body weight (2*BW) pivot landing is due to females having a smaller ACL cross-sectional area and a greater lateral tibial slope than males.  The results showed that females had 95% greater ACL strain than size-matched male knees during the pivot landing.  A multiple regression analysis showed why: ACL cross-sectional area and lateral tibial slope explained 59% of the variance in ACL strain.  A follow-up study using similar testing methods in female knees demonstrated that increasing quadriceps tensile stiffness by 30% to male values decreases female ACL strain by 20%, thereby reducing their risk for injury.  This could be achieved in vivo by increasing muscle activation or by muscle hypertrophy.  Overall, these results suggest the importance of knee morphology and quadriceps stiffness in future interventions for reducing the risk of ACL injuries in female athletes.
Host: Dr. Perreault