Methods: A prospective and controlled study investigated the relation of muscle dysfunction to residual pain and disability in patients with lumbar disc herniation. Objective: To determine the incidence of lower limb muscle dysfunction in lumbar disc herniation and its evolution over time after surgery, and to ascertain whether neuromuscular dysfunction has a prognostic value regarding pain and disability.

Background: Residual sciatica, low back pain, and disability are common after lumbar discectomy. Preoperative motor dysfunction corresponding to the afflicted nerve root is often seen.

Methods: The participants in this study were 71 patients, ages 15 to 50 years, with disc prolapse at L4-L5 or L5-S1. Before surgery, then 6 weeks, 4 months, and 12 months after surgery, low back pain and leg pain were estimated on a visual analog scale, and disability was determined according to the Roland-Morris Questionnaire and a designed functional muscle test.

Results: Motor function of the sciatic leg frequently was impaired. Inferior outcome of proximal motor tests 6 weeks after surgery predicted pain and disability 1 year after surgery. The mean leg pain was 59 mm before surgery and 15 mm at 6 weeks, remaining at that level during the follow-up period. The mean disability score was 14.4 before surgery, 8.8 at 6 weeks, and 4.7 at 4 and 12 months, whereas muscle function improved gradually through 1 year of follow-up evaluation.

Conclusions: Neuromuscular dysfunction frequently is present in patients with lumbar disc herniation. Sciatica resolves quickly after surgery, whereas disability improves gradually up to 4 months and muscular performance improves throughout the first year. Proximal muscular dysfunction in lumbar disc herniation has a prognostic value concerning residual pain and disability.