EFFECTS OF DESIGN CHANGES ON CEMENTED TAPERED FEMORAL STEM FIXATION

The effects of matte finish and modularity on loosening of tapered ste ms using the same cementing technique were studied prospectively. In 8 0 patients, 82 cemented Exeter primary stems were implanted at total h ip revision by one surgeon using the same surgical and cementing techn ique throughout the series. The polished stems behaved differently tha n the matte surfaced stems behaved. Polished stems subsided in the cem ent mantle an average of 1 mm at 2 years after implantation, but witho ut subsequent loosening of stems at as long as 12 years after implanta tion. Matte surfaced stems with metal centralizers had a higher loosen ing rate, and loss of fixation at the prosthesis to cement interface w as identified as an early sign of loosening of these stems. At a mean 6-year followup, there were no revisions nor was there radiographic ev idence of loosening of the polished modular stems. It is concluded tha t matte finish results in increased loosening of tapered stems but the introduction of modularity did not.