Cervical and lumbar spine fusion procedures are increasing every year. Nonetheless, these procedures are associated with high infection rates, resulting in additional cost burden. The conundrum of achieving efficient spinal fusions with minimum complications requires an ideal bone graft with osteoconductive, osteoinductive, osteogenic and structural characteristics. Synthetic bone graft substitutes with or without autograft, allograft or synthetic bone substitutes have been commonly used for fusion procedures. We carried out a meta-analysis of comparative studies and prospective case series (n = 29) with cervical and lumbar fusion procedures using synthetic bone graft substitutes, autograft or allograft and other biologics. Synthetic bone graft substitutes analysed included HA (Hydroxyapatite), β-TPC (Tri Calcium Phosphate), β-TSC (Tri Calcium Sulfate), PMMA (Polymethylmetacrylate), Surgibone, BOP (Biocompatible Osteoconductive Polymer). The analysis revealed suboptimal evidence for the efficacy and safety of synthetic products used in spinal fusion procedures. Further studies are needed to determine beneficial effects of synthetic substitutes. However, the infection rate could be highly decreased with surface and composition modification of widely used polyether ether ketone (PEEK) implants. Laser modification of surface characteristics and collagen fleeces with micro and nano pore structures can prove to be excellent surface for increased osteoblasts cell proliferation and vitality.

Introduction

The objective of this study was to investigate the effects of different doses rhBMP-2 on bone healing in an ovine lumbar interbody fusion model.

Study Design: Experimental study in dogs:

Objective: To assess the efficiency of disc chondrocyte transplantation in a canine model.

Summary of Background Data: Conventional clinical treatments of intervertebral disc herniation and degeneration are focused on excision of damaged tissue, stabilization, and spinal fusion. The development and refinement of cell-based therapeutics for tissue regeneration and repair have spawned a multitude of applications including autologous disc chondrocyte transplantation. For clinical application the efficiency of disc chondrocyte transplantation was assessed using a pre-clinical canine model to show the technical feasibility and biological relevance for disc repair and retardation of disc degeneration. This report examined the protein expression of transplanted disc chondrocytes and their role in the clinically observed disc repair following autologous disc chondrocyte transplantation.

Methods: The nucleus and inner annulus were sampled from four skeletally-mature dogs by micro-discectomy. Disc chondrocytes were isolated and propagated under GMP validated conditions including completely autologous serum conditions. Two months later, the cultured cells were transplanted through the contralateral side of experimental discs after testing complete healing of the annulus by measuring intradiscal pressure stability. After seven months the animals were humanely killed. One half of the vertically halved lumbar spines were embedded in paraffin and sections were analysed histologically and immunohistochemically.

Results: Histological examinations revealed large clusters of cells within the nucleus area of the treated discs. Cells within these cell clones were found to be viable and surrounded by de novo synthesized matrix as evidenced by a distinct histological staining and immunohistochemical expression pattern. A disc-specific expression of collagen type I and II and hyaline-specific proteoglycans was observed indicating the regenerative and reconstructive capacity of the transplanted disc chondrocytes.

Conclusions: These results indicate the contribution of transplanted disc chondrocytes to the observed clinical success of this cell-based therapy.