The biologic response to particles from a lumbar disc prosthesis

Abstract

Study Design: Particles of a proprietary polyolefin rubber compound used in a lumbar disc prosthesis were generated in vitro and tested for biocompatibility in two animal models. Objective: To characterize any tissue response to polyolefin rubber particles. Summary of Background Data: Intervertebral disc prostheses are emerging as alternatives to fusion techniques for the treatment of symptomatic disc degeneration. The biocompatibility of all novel components used in the construction of these devices must be verified before they can be considered for general use. Methods: Laboratory-generated polyolefin rubber particles were either injected into dorsal subcutaneous air pouches of 30 rats or placed directly onto the lumbosacral dura and nerve roots of 9 sheep. Histologic sections of tissues from, and remote from, the site of implantation were examined for evidence of inflammation and wound-healing responses. Results: Polyolefin rubber particle debris induced a tissue response that was consistent with a normal foreign body reaction to large particles. The response was not significantly greater than that seen with similar size particles of ultrahigh molecular weight polyethylene. There was no evidence of particle migration from the site of implantation, and there was no evidence of local or systemic toxic effects. Conclusion: Polyolefin rubber particles induce only localized tissue response that is consistent with a normal foreign body reaction to large nontoxic particles.