Towards a theory of lumbar mobilisation–the relationship between applied manual force and movements of the spine

SUMMARY. Optimal use of lumbar mobilisation requires a theoretical knowledge of the mechanical effects that occur. When a mobilisation force is applied the target vertebra will move with accompanying intervertebral displacements at many intervertebral joints. In addition, displacements and deformations of other tissues will contribute to the movement of the skin surface under the therapist's hands. The responses can be quantified in terms of the movements of the skin surface (described by the force-displacement relation), the absolute movement of the target vertebra, or the relative intervertebral movements. There are at least seven variables related to the manner of application of the mobilisation force that can be controlled by the therapist to alter the nature of the response. The patient's response is also determined by a number of variables related to the mechanical properties of the tissues of the spine, extra-spinal structures and the interaction between the patient and the treatment couch. Currently there is a moderate amount of information available about the effects of technique variations but there is very little data to directly link variations in the properties of specific anatomical structures with variations in either absolute or relative spinal movements or tissue loads. Copyright 1996 Harcourt Publishers Ltd