Effect of lumbar spinal stenosis on bone mineral density in osteoporosis patients treated with ibandronate.

Background: Lumbar spinal stenosis (LSS) can cause various neurological symptoms and reduce the daily activity of patients. Many studies have shown that free physical activities and exercise can improve bone mineral density (BMD) in patients with osteoporosis. However, the effect of LSS on BMD has not been reported. The purpose of this study was to investigate the effects of LSS on BMD in patients treated with ibandronate for newly diagnosed osteoporosis.
Methods: Group 1 included 83 patients treated for osteoporosis alone, and group 2 included 76 patients treated for both osteoporosis and symptomatic LSS. We confirmed four BMD values presented as T-score at initial, and 1-, 2-, and 3-year follow-ups. Mean BMD and annual changes of BMD for three years were compared between the two groups. Correlations between initial BMD and total change of BMD, and related factors for continuous BMD improvement for three years were also evaluated.
Results: Mean annual BMDs were significantly higher in group 1 compared than in group 2 (-3.39 vs. -3.58 at 1-year; -3.27 vs. -3.49 at 2-year; -3.13 vs. -3.45 at 3-year; all p < 0.05). Annual change of BMD at 1-year follow-up (0.32 vs. 0.21, p = 0.036) and total change of BMD for three years (0.57 vs. 0.35, p = 0.002) were significantly higher in group 1. Group 1 had a strong negative correlation (r = -0.511, P = 0.000) between initial BMD and total change of BMD, whereas group 2 showed a weak negative correlation (r = -0.247, p = 0.032). In multivariate analysis, symptomatic LSS was the only independent risk factor for continuous BMD improvement (Odds ratio = 0.316, p = 0.001).
Conclusions: Symptomatic LSS may interfere with BMD improvement in the treatment of osteoporosis with ibandronate. Active treatment for LSS with more potent treatment for osteoporosis should be taken to increase BMD for patients with osteoporosis and LSS.