The effect of alendronate on progression of spinal osteophytes and disc-space narrowing

Background: Bisphosphonates may have chondroprotective effects that could be of relevance in osteoarthritis. Using data from a large fracture prevention trial, we evaluated the effect of alendronate on the progression of radiographic spinal osteophytes (OST) and disc-space narrowing (DSN). Methods: The Fracture Intervention Trial (FIT) evaluated the effectiveness of alendronate at 5 mg/day (first 2 years) followed by 10 mg/day (third year) vs placebo over 3-4 years in preventing osteoporotic fractures. In 200 randomly selected subjects from FIT, we read baseline and follow-up lateral x rays for anterior OST and DSN (both scored 0-3 at each vertebral level) in the thoracic and lumbar spine. We calculated the mean difference in change in the sum of OST and DSN scores at T4 to L5 from baseline to follow-up, respectively, in each treatment arm using linear regression. Results: The participants' baseline characteristics were similar in the alendronate and placebo arms. The adjusted mean change in summary OST score was less in the alendronate group compared to placebo (3.2 vs 4.7, p = 0.04), indicating that OST progression was less in the alendronate group. The adjusted mean change in summary DSN score was less in the alendronate group vs placebo for the whole spine (0.4 vs 0.7, p = 0.2), particularly when limited to the lumbar spine (0.3 vs 0.6, p = 0.04). Conclusions: In this secondary analysis of data from a randomised controlled trial, alendronate was associated with less spinal OST and DSN progression than placebo. This suggests a role for bisphosphonates in altering the pathological processes seen in osteoarthritis.