Effects of low back pain on the relationship between the movements of the lumbar spine and hip.

Previous research had examined the effects of back pain on spinal movements, but information concerning movement coordination between the lumbar spine and hips was limited. The purpose of this study was to examine the effects of back pain and limitation in straight leg raise on the relationship between the movements of the lumbar spine and hip. An electromagnetic tracking system was employed to measure the movements of these joints in asymptomatic subjects (n = 20), and back pain subjects with (n = 24) and without (n = 17) limitation in straight leg raise. Subjects were requested to perform forward, backward and side bending, and twisting of the trunk. Back pain subjects were found to exhibit significant reductions in the magnitude of spine movements in all directions. Back pain was also associated with decrease in the magnitude of hip flexion but not hip movements in other directions. Cross-correlation analysis showed that there were changes in the strength of correlation and the time lag between lumbar spine and hip motions in normal and back pain subjects. In addition, back pain and limitation in straight leg raise were found to cause significant increases in the time required to complete the trunk movements. It was concluded that clinical assessment and treatment planning should take into account of the effects of back pain on the relationship between spine and hip movements.