The Effect of Dual Acid Texturing Implants on Bone Ongrowth - an Unloaded Implant Model in an Experimental Canine Study

INTRODUCTION: Treatment of osteoarthritis and rheumatoid arthritis by total joint replacement generally shows a high success rate; however challenges remain, particularly in improving revision implant fixation. Prostheses with a roughened surface inserted without cement are popular worldwide, especially for younger more active patients. Early bone ongrowth is known to be critical to long-term fixation of implants, and it is known that new bone forms better on a textured surface than on a smooth surface. Acid etching is a method of surface roughening whereby material is removed without applying stress on the adjacent metal and without leaving embedded particles. Experimentally, surface texturing by acid etching appears to induce bone formation in vitro and enhance the potential for implant integration in vivo (Keller). The resulting topography of an etched implant relies on the acid mixture, etching time, temperature and roughening prior to etching. Depending on the etching conditions, the process can create pits of depth and roughness on the micrometer scale. In this study we compare titanium alloy implants with a surface that has a primary coarser texture made by a chemical milling process, to implants with a secondary dual acid etched texture surface. We hypothesize that a dual-acid-etched textured surface superimposed on a non-particulate roughened implant surface will improve the bone ongrowth at the bone-implant interface.