Abstract

SUMMARY. A clinical, anatomical and biomechanical model is introduced based on the concept that under postural load specific ligament and muscle forces are necessary to intrinsically stabilize the pelvis. Since load transfer from spine to pelvis passes through the sacroiliac (SI) joints, effective stabilization of these joints is essential. The stabilization of the SI joint can be increased in two ways. Firstly, by interlocking of the ridges and grooves on the joint surfaces (form closure); secondly, by compressive forces of structures like muscles, ligaments and fascia (force closure). Muscle weakness and insufficient tension of ligaments can lead to diminished compression, influencing load transfer negatively. Continuous strain of pelvic ligaments can be a consequence leading to pain. For treatment purposes stabilization techniques followed by specific muscle strengthening procedures are indicated. When there is a loss of force closure, for instance in peripartum pelvic instability, application of a pelvic belt can be advised. Copyright 1998 Harcourt Publishers Ltd.