Effect of Systemic Teriparatide (PTH1-34) versus Placebo on Bone MineralDensity (BMD) after Lumbar Spinal Arthrodesis: A Secondary Analysis of aRandomized Clinical Trial

Background: The present study is a secondary analysis of data from a randomized, double-blind, placebo controlled clinical trial. Patients undergoing decompression and non-instrumented lumbar arthrodesis may have initial bone loss after surgery, increasing their fracture risk. The aim of this analysis is to determine whether short term systemic Teriparatide has a beneficial effect on Bone Mineral Density (BMD) in patients 60 years and older undergoing non-instrumented lumbar arthrodesis. Method: Patients were 87 Danish patients eligible for spinal decompression and non-instrumented arthrodesis, who received either 20 micrograms Teriparatide (N=43) or placebo (N=44) daily for 3 months starting prior to surgery. Randomization and allocation were computer-generated. Outcome measures were BMD and Patient reported Outcome measures (PROs) containing Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for leg pain. DXA scans were performed preoperatively and at 1,3,6 and 12 months after surgery. PROs were collected at the same time points aside at 1 month after surgery. ANCOVA comparing Lumbar Spine BMD and Hip BMD in Teriparatide vs Placebo with gender, weight, age and baseline BMD as covariates were performed. Results: There was some improvement in BMD in the Teriparatide group compared to placebo at 3 months after surgery, but not sustained at 6 and 12 months. There was a loss of Lumbar Spine BMD at 1 month after surgery in both groups. Conclusion: Systemic Teriparatide provided a short term beneficial effect on BMD compared to placebo in patients undergoing decompression and non instrumented lumbar arthrodesis. There was an initial rapid bone loss 1 month after surgery in both groups.