SURFACE FINISH AFFECTS THE CLINICAL AND RADIOGRAPHIC PERFORMANCE OF A MODERN CEMENTED FEMORAL STEM. A PROSPECTIVE STUDY AFTER A FOLLOW UP OF 4 TO 7 YEARS.

Abstract

The role of surface finish on the survivorship of cemented stems is controversial. The purpose of this study is to prospectively evaluate the mid-term clinical and radiographic performance of a cohort of patients who underwent total hip replacement with two identical cemented femoral stems differing only in surface finish (VerSys, Zimmer, Warsaw, IN). 64 total hip replacements with a rough stem and 138 total hip replacements with a satin finish stem were followed clinically and radiographically for 4 to 7 years. All surgeries were performed by one surgeon. The groups had similar demographics, diagnosis, length of follow up, cement mantle quality and alignment. The preoperative and postoperative Hospital for Special Surgery Hip Score at last follow up was not significantly different among the two groups. Five hips in the rough group and none in the satin group developed aseptic loosening (p=0.0009). The femoral bone-cement interface revealed progressive radiolucent lines or osteolysis in 8 out of 64 rough stems and in 3 out of 138 satin stems (p=0.01). There were progressive radiolucencies or osteolysis in 44 out of possible 448 Gruen zones in the rough surface group and in 8 out of possible 966 Gruen zones in the satin finish group (p< 0.001). A rough, textured stem is more likely to fail at intermediate follow-up than a satin surface stem. We recommend that the surface of cemented stems should be satin or polished, with a Ra of less than 20 microinches.