Skip Navigation LinksHome > March 01, 2014 - Volume 39 - Issue 5 > Quantitative Study of Parathyroid Hormone (1-34) and Bone Mo...
doi: 10.1097/BRS.0000000000000169
Basic Science

Quantitative Study of Parathyroid Hormone (1-34) and Bone Morphogenetic Protein-2 on Spinal Fusion Outcomes in a Rabbit Model of Lumbar Dorsolateral Intertransverse Process Arthrodesis

Lina, Ioan A. BS; Puvanesarajah, Varun BS; Liauw, Jason A. MD; Lo, Sheng-fu L. MD; Santiago-Dieppa, David R. MD; Hwang, Lee MD; Mao, Annie; Bydon, Ali MD; Wolinsky, Jean-Paul MD; Sciubba, Daniel M. MD; Gokaslan, Ziya MD; Holmes, Christina PhD; Witham, Timothy F. MD

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Study Design. A posterolateral rabbit spinal fusion model was used to evaluate the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) and teriparatide (PTH [1–34]) used individually and in combination on spinal fusion outcomes.

Objective. To test the efficacy of parathyroid hormone on improving spinal fusion outcomes when used with BMP-2.

Summary of Background Data. Of the more than 250,000 spinal fusion surgical procedures performed each year, 5% to 35% of these will result in pseudarthrosis. Growing controversy on the efficacy and cost of rhBMP-2 for improving spinal fusion outcomes has presented a challenge for clinicians. Research into PTH as an adjunct therapy to rhBMP-2 for spinal fusion has not yet been investigated.

Methods. Forty-eight male New Zealand white rabbits underwent bilateral posterolateral intertransverse process arthrodesis surgery at the L5–L6 level. Animals were divided into 6 groups. Two groups were treated with autograft alone or autograft and PTH (1-34), whereas the other 4 groups were treated with low-dose rhBMP-2 alone, high-dose rhBMP-2 alone, or either dose combined with PTH (1-34). All animals were euthanized 6 weeks after surgery. The L4–L7 spinal segment was removed and assessed using manual palpation, computed tomography (CT), and biomechanical testing.

Results. CT assessments revealed fusion in 50% of autograft controls, 75% of autograft PTH (1-34) animals, 87.5% in the 2 groups treated with low-dose rhBMP-2, and 100% in the 2 groups treated with high-dose rhBMP-2. CT volumetric analysis demonstrated that all groups treated with biologics had fusion masses that were on average significantly larger than those observed in the control group (P < 0.0001). Biomechanical data demonstrated no statistical difference between controls, PTH (1-34), and low-dose rhBMP-2 in any testing orientation. PTH (1-34) did not increase bending stiffness when used adjunctively with either low-dose or high-dose rhBMP-2.

Conclusion. Although intermittent teriparatide administration results in increased fusion mass volume, it does not improve biomechnical stiffness over use of autograft alone. When delivered concurrently with high- and low-dose rhBMP-2, teriparatide provided no statistically significant improvement in biomechanical stiffness.

Level of Evidence: N/A

© 2014 by Lippincott Williams & Wilkins

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