Effect of Hip Joint Movement on Elongation Rate of the Psoas Major in Three Dimensions

Analysis by Mathematical Model

Abstract

Purpose: The purpose of this study is to clarify the effect of hip joint movement on elongation rate of the psoas major in three dimensions.

Method: A musculoskeletal model was created using parameters reported by a previous study. The elongation rate of the psoas major when hip joint angles were changed was examined by a mathematical model. The muscle fiber length of the psoas major with the body in anatomical position was defined as 100%.

Result: The elongation rate of the psoas major was found to be 106.5% for 20° extension, 20° abduction, and 30° internal rotation of the hip joint, which is high compared with the elongation rate of 104.8% for 20° extension of the hip joint.

Conclusion: The elongation rate of the psoas major in the extension, abduction, and internal rotation of the hip joint compared with that in only extension of the hip joint could be high.