A functional-anatomical approach to the spine-pelvis mechanism: interaction between the biceps femoris muscle and the sacrotuberous ligament.

Summary. Sacroiliac joint dysfunction is often overlooked as a possible cause of low back pain. This is due to the use of reductionistic anatomical models. From a kinematic point of view, topographic anatomical models are generally inadequate since they categorize pelvis, lower vertebral column and legs as distinct entities. This functional-anatomical study focuses on the question whether anatomical connections between the biceps femoris muscle and the sacrotuberous ligament are kinematically useful. Forces applied to the tendon of the biceps femoris muscle, simulating biceps femoris muscle force, were shown to influence sacrotuberous ligament tension. Since sacrotuberous ligament tension influences sacroiliac joint kinematics, hamstring training could influence the sacroiliac joint and thus low back kinematics. The clinical implications with respect to 'short' hamstrings, pelvic instability and walking are discussed.