Radiographic and functional outcomes of bisphosphonate use in lumbar fusion: a systematic review and meta-analysis of comparative studies

Purpose To date, there are conflicting reports with no consensus on the influence of bisphosphonates on lumbar fusion. The goal of this study was to compare the radiographic and functional outcomes of patients that had lumbar fusion with and without bisphosphonates. Methods A systematic search of multiple medical reference databases was conducted for studies comparing bisphosphonate use to controls following spinal fusion. Meta-analysis was performed using the random-effects model for heterogeneity. Radiographic outcome measures included fusion rates and risk of screw loosening, cage subsidence and vertebral fracture. Functional outcomes measures included Oswestry Disability Index and visual analog scale score for back and leg pain. Results Bisphosphonate use was statistically suggestive of a higher fusion rate compared to controls (OR 2.2, 95% CI 0.87-5.56, p = 0.09). There was no difference in screw loosening rates between the bisphosphonate group and controls (OR 0.45, 95% CI 0.14-1.48, p = 0.19). However, bisphosphonate use was associated with decreased odds of cage subsidence and vertebral fractures compared to controls (cage subsidence: OR 0.29, 95% CI 0.11-0.75, p = 0.01; vertebral fracture: OR 0.18, 95% CI 0.07-0.48, p = 0.0007). Conclusion Bisphosphonate use does not appear to impair successful lumbar fusion compared to controls. Additionally, bisphosphonate use was associated with decreased odds of cage subsidence and vertebral fractures compared to controls that had lumbar fusion. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.