Lumbar paraspinal muscle function, perception of lumbar position, and postural control in disc herniation-related back pain

Study Design. A follow-up study evaluating postural control, lumbar movement perception, and paraspinal muscle reflexes in disc herniation-related chronic low back pain (LBP) before and after discectomy. Objectives. To assess the effect of discectomy on postural control, lumbar perception, and reflex activation of paraspinal muscles during sudden upper limb loading. Summary of Background Data. Impaired muscle function, postural control, and lumbar proprioception have been observed in LBP. However, they have not been studied in sciatica patients after surgery. Methods. The study included 20 patients selected for an operation for chronic LBP caused by disc herniation and 15 controls without chronic LBP. The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface electromyography. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The postural control was measured with a vertical force platform. Pain, disability, and depression scores were recorded. Results. Patients had poorer lumbar perception ( P = 0.012) and postural control ( P < 0.05) than did healthy controls. The postural control remained unchanged, but lumbar perception ( P = 0.054) and the lumbar feed-forward control ( P = 0.043) improved after the surgery. Conclusions. The results demonstrate impaired lumbar proprioception and postural control in sciatica patients. During short-term follow-up after operative treatment, postural control does not seem to change, but impaired lumbar proprioception and feed-forward control of paraspinal muscles seem to recover.