| The purpose of this study was to examine the radiographic and histologic response. to corundum blasted implant surfaces of varying roughness in a canine total hip arthroplasty model. Three types of tapered femoral implants were made from titanium alloy and were identical in every respect except surface finish. The entire surface of the femoral implant possessed either a 2.9, 4.2 or 6.7 micrometer average surface roughness (Ra) from blasting with 60, 24, or 16 grit corundum particles, respectively. Staged bilateral total hip arthroplasties were performed such that each dog received a 60 grit on one side and a 24 grit or 16 grit implant on the contralateral side. Twenty-two stems in 11 dogs were evaluated at 6 months. The appearance of the bone implant interface was qualitatively characterized. Bone apposition and average bone-implant contact length were determined. Twenty-one of the stems demonstrated osseointegration while one stem developed a stable fibrous interface. All three types of corundum blasted implants demonstrated consistently high amounts of bone apposition, averaging 30.5%. Abundant new peri-implant bone consistently formed, particularly within the intramedullary canal where trabeculae spanned implant-cortical gaps up to 5 mm and established osseointegration ration. There was no statistical difference amongst bone apposition with the 60, 24, and 16 grit stems which averaged 31.7%, 32.0% and 27.9% respectively. However, the pattern of new bone formation was different in that the average length of each region of bone apposition for the 60 and 24 grit surfaces was 50% greater than that for the coarser 16 grit surface (p < 0.02). Through detailed qualitative and quantitative radiographic and histologic elucidation of the osseous response to corundum blasted hip implant surfaces, this study provided new understanding of their potential for biologic fixation. Corundum blasted surfaces represent an important and valuable technology for the design of noncemented implants. (Abstract shortened by UMI.). |
