Skeletal measures dictating hip abductor force production during locomotion

Abstract

This study evaluated the relationship between skeletal dimensions of the hip and pelvis and biomechanical parameters dictating force production of the hip abductors during locomotion. Twenty‐eight subjects participated in this study (IRB, Washington University in St. Louis). Lower limb and trunk kinematics were determined during walking and running trials using high‐speed motion capture (Vicon, 200Hz) while ground reaction forces were simultaneously recorded (AMTI, model‐OR force‐plate, 1000Hz). Anatomical data for each subject was obtained from full lower body MRI (Avanto 1.5T, isotropic 1.7mm resolution). Results indicate that femoral neck length and biiliac breadth are both good predictors of the length of the hip abductor moment arm, but biacetabular width, generally considered a reliable proxy for the body weight moment arm, is not predictive of the true external moment arm about the hip during the course of stance phase. Sex differences were observed in the length of the hip abductor moment arm, with women having muscle moment arms an average of 1cm shorter than men. There were no sex differences in the length of the external moment arm at the hip in the coronal plane, although mass‐specific hip abductor force production was slightly higher in women because of shorter abductor moment arms. Research funded by: NSF #0850841, The Leakey Foundation, and The Wenner‐Gren Foundation.