Study design: An experimental study, in which spinal fusion in rats was conducted using a hydroxyapatite fiber mesh (HAM) as a carrier for recombinant human bone morphogenetic protein (rhBMP)-2.
Objectives: To study the usefulness of the HAM as a carrier and seek the possibility of clinical application in spinal fusion.
Summary of background data: Several biomaterials have been used as a carrier for BMP to achieve spine fusion, however, to our knowledge, the most effective carrier has not been established.
Methods: In experiment No. 1, HAMs and the controls (commercially available hydroxyapatite ceramic body), loaded with rhBMP-2, were immersed in phosphate-buffered saline to evaluate the time course of the release of rhBMP-2. In experiment No. 2, posterolateral fusion was conducted in rats using HAM and the control loaded with rhBMP-2. The fusion status was evaluated radiologically and histologically after surgery.
Results: In experiment No. 1, HAMs released a larger amount of rhBMP-2 for up to 28 days than the controls (49.5% vs 7.8%). In experiment No. 2, the fusion rate was significantly higher in the HAM group (>80%) than in the control group (20%). Dense new bone formed close to the spine, and the HAMs were markedly absorbed compared with the controls.
Conclusion: HAM provided more solid fusion mass than the control, suggesting that HAM is an efficient carrier for BMP.