Movement coordination of the lumbar spine and hip during a picking up activity in low back pain subjects.

The effect of low back pain, with or without nerve root signs, on the joint coordination and kinematics of the lumbar spine and hips during everyday activities, such as picking up an object from the floor, are largely unknown. An experimental study was designed to compare lumbar spine and hip joint kinematics and coordination in subjects with and without sub-acute low back pain, while picking up an object in a sitting position. A three-dimensional real-time electromagnetic tracking device was used to measure movements of the lumbar spine and hips. Sixty participants with subacute low back pain, with or without straight leg raise signs, and twenty healthy asymptomatic participants were recruited. The ranges of motions of lumbar spine and hips were determined. Movement coordination between the two regions was examined by cross-correlation. Results showed that mobility was significantly reduced in subjects with back pain, who compensated for limited motion through various strategies. The contribution of the lumbar spine relative to that of the hip was, however, found to be similar in all groups. The lumbar spine-hip joint coordination was substantially altered in subjects with back pain, in particular, those with a positive straight leg raise sign. We conclude that changes in the lumbar and hip kinematics were related to back pain and limitation in straight leg raise. Lumbar-hip coordination was mainly affected by the presence of positive straight leg raise sign when picking up an object in a sitting position.