Geometrical constraints on the rotational function of the femoral adductors in man.

Various authors have ascribed differing roles to the adductor muscles of the thigh in producing rotation of the femur. In the present study, measurements have been made on the changes in distance between origin and insertion of the adductor muscles which occur with rotation of the femur. Increases in distance indicate the muscle cannot produce a particular movement, while a decrease in length supports an argument that the muscle has a particular function. Measurements were made for positions of flexion-extension and adduction-abduction as well as anatomical rest. The adductor magnus was found to decrease in length during internal rotation while the adductor longus decreased in length during external rotation in most of the positions studied.