The effect of a collar and surface finish on cemented femoral stems: a prospective randomised trial of four stem designs

This report has been verified by one or more authors of the original publication.

163 patients, between the ages of 60 and 80 years, who had been diagnosed with primary osteoarthritis, and who were scheduled to undergo THA were included in this randomized trial. Patients were randomly assigned into 1 of 4 groups to determine the effect of collared/collarless stems with various surface area alterations on implant survivorship rates and subsidence. Patients received cemented femoral implants with a matt collared stem, polished collared stem, matt collarless stem, or polished collarless stem. At the two year follow up, results from the study demonstrated a trend of increased subsidence in patients who received intervention with the matt collared stem, but the increase in subsidence was not significantly greater than that experienced by patients in other groups. At the eleven year follow up, survival curves indicated greatest survivorship in patients who received the polished collarless stem. Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores for patients with surviving implants were also comparable between the groups. Comparison of the collarless stem groups demonstrated a significant difference in survivorship, favouring polished finishes over matt finishes.