Low-back disability with sciatic radiation may arise from an infinite number of causes. The most frequent cause is injury to the ligaments, muscles, and fascia supporting or investing the low back or pelvis. The cutaneous radiation is most commonly a reflex phenomenon, a referring of pain from deep structures to the cutaneous distribution of the same nerve root. The lumbosacral region of the spine is the weakest portion of the vertebral column. Contributing factors to sprains at this area are anomalies and diseases of the vertebrae and faulty habits of use of the body. Faulty body mechanics leads to impaired functioning of the muscle supports, defects in balance against gravity, and the tendency of the low spinal joints to be used at the limit of their extension.
Adequate conservative treatment should include rest of the entire spine in a good mechanical position on a firm surface, heat applied to the injured portion of the spine, and, when movements can be performed with relative comfort, exercises to teach the patient how to use the body habitually in good body mechanics. Later when the patient is first ambulatory, a support should be fitted with the patient's body in the best corrected posture possible, so that strain will not come upon the healing structures.
Pain referred along the sciatic nerve is relieved by such treatment in approximately 79 per cent. of all patients who present this symptom. When we group patients according to the cause of the disability we find that low-back disability caused by ligamentous and muscular strains responds most frequently to conservative treatment.