Relationship between the movements of the lumbar spine and hip.

Movements of the lumbar spine and hips were measured in 20 healthy subjects using an electromagnetic tracking device. Movement sensors were attached to the L1 spinous process, the sacrum and the thighs. Each subject was requested to perform the following movements of the trunk: forward and backward bending, lateral bending and twisting. The ratio of the maximum magnitude of spine movement to that of the hip was determined. Angle-angle plot and cross-correlation were used to examine the relationship between the movements of the spine and hip. It was shown that during forward and backward bending of the trunk, the overall contributions of the lumbar spine and hip were similar, but the spine had a greater contribution to the early stage of the movement. Lateral bending of the trunk was found to be primarily accomplished by movement of the spine, whereas the hips were the predominate sources of movement for twisting. Moreover, it was shown that in the sagittal and horizontal planes, the movement patterns of the spine and hip were in phase, whereas in the coronal plane, the spine generally moved earlier than the hips. It is concluded that clinical examination of the back should include kinematic measures of both the lumbar spine and hips.