The human spine is an extremely complex biomechanical structure with multiple joints, bones, muscles, and nerves. Functional and structural disorders of the spine often produce symptoms affecting more than one region of the spine and these problems are not captured within the diagnostic groups previously discussed. They include patients with pelvic symptoms, headaches related to the cervical region, and fibromyalgia. While disabling too many patients, the true estimate of health care utilization in these patients is difficult to estimate.