Low back pain: current physiologic concepts.

It is clear that low back pain is not a simple process that can be explained on purely anatomic, biomechanical, or neurophysiologic theories. The intimate relationship of these processes have to be considered. Each of the potential biomechanical stresses influence the different spinal structures in different ways, depending on the forces applied and the structure being affected. The biomechanical response to the trauma caused by these forces may be immunologic, inflammatory, or neurochemical, depending on the structures being traumatized. Once a nociceptive process is underway, it is greatly influenced by the spinal cord and the brain. Only by following this process through its various steps can a clinician begin to formulate an understanding of the mechanisms involved in the genesis of low back pain.