β-Tricalcium Phosphate Combined with Recombinant Human Bone Morphogenetic Protein-2: A Substitute for Autograft, Used for Packing Interbody Fusion Cages in the Canine Lumbar Spine

Abstract

The use of -tricalcium phosphate (-TCP) as osteoconductive and bone morphogenetic protein-2 (BMP-2) as osteoinductive bone graft substitutes has recently gained considerable research interest in spine surgery. However, whether the combination can be extrapolated to a successful interbody spinal arthrodesis remains uncertain. In this study, -TCP combined with recombinant human BMP-2 was examined in the canine lumbar spine model as a substitute for autograft used for packing interbody fusion cages. The discectomy and interbody cage fusion were performed at three disc spaces in 8 dogs. The examination of microradiographs and histological sections of the lumbar spine at 16 weeks postsurgery revealed three fusions in autograft group (A), three -TCP group (B), and five in -TCP-BMP-2 (C). The mean percentage of trabecular bone area in the cages was 51.9% in group A, 48.8% in group B and 65.6% in group C. Statistical analyses of the results could not give significance. The young animal model used in this study might suppress difference between the groups. As mentioned, however, actual data of mean percentage of trabecular bone formation and of mechanical stiffness were largest in the cages filled with -TCP and BMP-2. In clinical settings, we expect that a cage filled with -TCP and BMP gives beneficial effects especially for patients with poor fusion statuses.

Current Application of β‐tricalcium Phosphate Composites in Orthopaedics

“…In other words, BMP can accelerate the degradation of β‐TCP scaffold, which provide sufficient space for new bone formation and remodeling. Ohyama et al . reported that the β‐TCP + BMP composite produced better interbody fusion rate and mechanical strength, and more bone trabecula in posterior lumbar fusion of dogs, compared with β‐TCP alone, autograft, and untreated groups.…”

BMP-2 Incorporated in a Tricalcium Phosphate Bone Substitute Enhances Bone Remodeling in Sheep

“…Before use, the stock solution was diluted in PBS. We choose a concentration of 200 mg rhBMP-2 on the basis of our in vitro assays with human osteoblast-like cells, our results from experiments in rats [26] and the known literature [30].…”

Ectopic osteoinduction and early degradation of recombinant human bone morphogenetic protein-2-loaded porous β-tricalcium phosphate in mice

“…Despite the seminal work of Marshall Urist reported nearly four decades ago, showing a 12 times much greater de novo ectopic bone formation using the BMP-loaded b-TCP as compared to the BMP alone [3], there is still no routine use of BMPloaded b-TCP in the clinics. One of the most critical issues surrounding its potential clinical use is to understand the optimum three-dimensional structure of b-TCP and loading dose of BMP required for optimum bone regeneration and healing [24][25][26]. The effect of the three-dimensional structure of HA scaffolds on BMPinduced osteogenesis has been intensively investigated [27][28][29], but few studies have been conducted with b-TCP scaffolds.…”