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

Document Type

Article

Abstract

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.

Medical Subject Headings

Animals; Bone Morphogenetic Protein 2 (therapeutic use); Bone Transplantation (methods); Combined Modality Therapy; Dose-Response Relationship, Drug; Drug Therapy, Combination; Follow-Up Studies; Humans; Lumbar Vertebrae (surgery); Male; Parathyroid Hormone (therapeutic use); Rabbits; Recombinant Proteins (therapeutic use); Spinal Fusion (methods); Transforming Growth Factor beta (therapeutic use); Transplantation, Autologous; Treatment Outcome

Publication Date

3-1-2014

Publication Title

Spine

E-ISSN

1528-1159

Volume

39

Issue

5

First Page

347

Last Page

55

PubMed ID

24365898

Digital Object Identifier (DOI)

10.1097/BRS.0000000000000169

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