FITMORE UNCEMENTED ACETABULAR CUP. A MINIMUM FOLLOW-UP OF 5 YEARS IN 108 HIPS.

Abstract

Introduction: Aseptic loosening is the major cause of implant failure. In cemented hip Arthroplasty it is well known that the acetabular side fails earlier due to lysis caused by wear particles. This is the rationale for Hybrid hip Arthroplasty. It might be advantageous to use a bearing which has a low wear rate. The purpose of this study is present the medium term results of this Uncemented cup with a metal-on-metal bearing.

Methods: We reviewed the results of 119 hips (101 patients) who had the Uncemented Fitmore® cup (Sulzer/Zimmer Orthopaedics, Inc). In 66 out of the 101 patients the femoral component used was CF-30® (Sulzer/Zimmer Orthopaedics, Inc) used with cement. In 35 patients Thrust plate prosthesis TPP® (Sulzer/Zimmer Orthopaedics, Inc) was used. This is a bolt type device which is fixed on to the neck; the femoral canal is not violated. Of the 101 patients, 90(108 hips) were available for study. All had minimum of 5 years follow-up.

Results: Mean follow-up of the 90 patients is 87.4 months (range 60 – 129 months). The mean pre-op Harris hip score is 38.2. The mean post-op Harris hip score is 89.6 at the last follow up. Taking aseptic loosening as the end point the survival rate of the Fitmore cup is 100% at 11 years. Four cups were revised for other causes.

Discussion: Histological studies of retrieved metal-on-metal implants have always shown low volume of inflammatory tissue. Wear rate of metal-on-metal hips is 60–100 times lower than metal-on-polyethylene hips. In the medium to long term Uncemented cups fare better than cemented cups. It might be advantageous to use an Uncemented cup with a metal-on-metal bearing. This follow-up study which has a 100% survival rate at 11 years proves that.