Effect of daily parathyroid hormone (1–34) on lumbar fusion in a rat model

Abstract: Background context: Despite numerous studies evaluating the anabolic effects of intermittent administration of parathyroid hormone (PTH) on bone, there are no published studies examining its effect on spinal fusion outcomes. Purpose: To determine the effect of daily injection of human recombinant PTH(1–34) on posterolateral lumbar fusions in a rat model. Study design: Prospective, case-controlled, preclinical animal study. Outcome measures: Manual palpation and serum osteocalcin. Methods: Single-level, intertransverse process spinal fusions were performed with iliac crest autograft in 56 Sprague-Dawley rats. Animals received daily injections of placebo or PTH(1–34). At 6 weeks, fusion masses were assessed by manual palpation. Serum osteocalcin levels were assessed in a subset of the animals. Results: Manual palpation revealed the control group to have a fusion rate of 37% (10/27) and the PTH(1–34)-treated group to have a fusion rate of 52% (15/29). Mean serum osteocalcin levels were 59.8 and 88.6 ng/L for the control and PTH(1–34) groups, respectively. Conclusions: There was a trend towards greater fusion rate in the PTH(1–34) group as compared with the placebo group. Further, PTH(1–34) administration was associated with a significant increase in osteocalcin levels. Certainly, further investigations are warranted, as an injectable agent capable of increasing fusion rates would be of great clinical value. [Copyright &y& Elsevier]