Intervertebral disc height changes after weight reduction in morbidly obese patients and its effect on quality of life and radicular and low back pain.

STUDY DESIGN: Prospective study in a morbidly obese population after bariatric surgery.

OBJECTIVE: To document the effect of significant weight reduction on intervertebral disc space height, axial back pain, radicular leg pain, and quality of life.

SUMMARY OF BACKGROUND DATA: Low back pain is a common complaint in obese patients, and weight loss is found to improve low back pain and quality of life. The mechanism by which obesity causes low back pain is not fully understood. On acute axial loading and offloading, intervertebral disc changes its height; there are no data on intervertebral disc height changes after significant weight reduction.

METHODS: Thirty morbidly obese adults who underwent bariatric surgery for weight reduction were enrolled in the study. Disc space height was measured before and 1 year after surgery. Visual analogue scale was used to evaluate axial and radicular pain. The 36-Item Short Form Health Survey and Moorehead-Ardelt questionnaires were used to evaluate changes in quality of life.

RESULTS: Body weight decreased at 1 year after surgery from an average of 119.6 ± 20.7 kg to 82.9 ± 14.0 kg corresponding to an average reduction in body mass index of 42.8 ± 4.8 kg/m(2) to 29.7 ± 3.4 kg/m(2) (P < 0.001). The L4-L5 disc space height increased from 6 ± 1.3 mm, presurgery to 8 ± 1.5 mm 1 year postsurgery (P < 0.001). Both axial and radicular back pain decreased markedly after surgery (P < 0.001). Patients' Moorehead-Ardelt score significantly improved after surgery (P < 0.001). Although the 36-Item Short Form Health Survey score did not show any statistically significant improvement after surgery, the physical component of the questionnaire showed a positive trend for improvement. No correlation was noted between the amount of weight reduction and the increment in disc space height or back pain improvement.

CONCLUSION: Bariatric surgery, resulting in significant weight reduction, was associated with a significant decrease in low back and radicular pain as well as a marked increase in the L4-L5 intervertebral disc height. Reduction in body weight after bariatric surgery in morbidly obese patients is associated with a significant radiographical increase in the L4-L5 disc space height as well as a significant clinical improvement in axial back and radicular leg pain.