The effect of leg length discrepancy on spinal motion during gait: three-dimensional analysis in healthy volunteers.

STUDY
DESIGN: This study focused on the effects of leg length discrepancy on the motion of the normal spine during gait in healthy male volunteers who wore a heel-raising orthotic device on the right foot.
OBJECTIVE: To evaluate the effect of leg length discrepancy on the changes in curvature of the normal spine during gait. SUMMARY OF BACKGROUND DATA: There are few published data on the effects of leg length discrepancy on the motion of the normal spine during gait.
METHODS: An orthotic device that raised the heel by 3 cm was used to simulate leg length discrepancy. Twenty-two healthy male volunteers participated (age: 28.2 +/- 6.1 years, average +/- SD). The dynamic curvatures of the spine under two conditions (without and with a heel-raising orthotic device; normal gait and heel-raising gait) were evaluated during gait. The leg length discrepancy values without and with the device were measured and analyzed using a VICON system (Oxford Metrics, United Kingdom).
RESULTS: The spine showed an asymmetrical lateral-bending motion during heel-raising gait as compensation for the leg length discrepancy. Maximum lateral bending angle of the thoracic spine was 4.2 +/- 1.4 degrees in heel-raising gait, whereas it was 3.0 +/- 1.0 degrees in normal gait. Maximum lateral bending angle of the lumbar spine was 8.1 +/- 2.8 degrees in heel-raising gait, whereas it was 6.1 +/- 2.1 degrees in normal gait. The maximum bending angle and bending velocity were significantly larger in the heel-raising gait than in normal gait.
CONCLUSION: Patients who have leg length discrepancy due to disorders in the lower extremities are at greater risk of developing disabling spinal disorders due to exaggerated degenerative change. Therefore, treatment for leg length discrepancy may be helpful in preventing degenerative spinal changes.