Surface analysis on revised hip implants with stem taper for wear and failure incidence evaluation: a first investigation

Background: As revision surgeries of total hip arthroplasty are going to increase, success or failure of revised implants is a fundamental aspect in the orthopaedic field. Today, slight is known about the success rate of revised total hip arthroplasty when the femoral head is substituted on a retained stem. Question: We wanted to investigate if the interposition of a stem taper adapter between the paired elements can influence this rate of success. Methods: From a total of more than 1000 revised implants, recorded during their follow up in a regional registry, the study was limited to the ones subjected to a surgical revision, where the head has been revised but the stem taper has not. Investigations on wear, roughness, and corrosion on the available explants were conducted, with the aim of providing visual and empirical response on the topic and to furnish to other researches useful data for comparison. Results: Our results highlighted a higher incidence of second revisions when the femoral head is substituted without using an adapter. The topographic analysis refers that it is not evident a predominant roughness along any of the stems directions: no evidences were found that would define a recurrent rougher direction. This indicates a homogeneous worsening or corrosion of the stem taper along the circumference. Further, we found that the roughness values of the specimens analyzed not influence their surfaces and there is no a direct relation between the roughness of the bore heads and the stem tapers.