What happens to muscle strength and size after back fusion? How do the results compare with the muscles of back pain patients going through an exercise program? Scientists in Norway are sorting this all out. In this study, back pain patients were divided into two treatment groups. One group received a lumbar fusion; the other was prescribed exercise and education.

The researchers used tests of muscle strength and CT scans of the muscle size and density as the main measures of outcome. They found the exercise group did better than the fusion group in all areas, including muscle strength, density, and endurance.

The authors suggest that weakness and atrophy of back muscles in patients with spinal fusion comes from the operation itself. Nerves are cut and muscles may be injured during the operation. Muscle tissues can generally recover with activity and exercise. Exercise has been shown to make muscle fibers larger.

The scientists aren't sure why that didn't happen in the fusion group. They had more Physical Therapy than the exercise group. And the exercise group didn't exercise intensely. Patients were followed for one year and results were the same at the one-year checkup. Muscle strength was still greater in the exercise group. There was a significant decrease in the muscle strength of the patients with a lumbar fusion. Exercise therapy for chronic low back pain still seems to be the best treatment.

Anne Keller MD, et al. Trunk Muscle Strength, Cross-sectional Area, and Density in Patients with Chronic Low Back Pain Randomized to Lumbar Fusion or Cognitive Intervention and Exercises. In Spine. January 1, 2004. Vol. 9. No. 1. Pp. 3-8.