LONG TERM RESULTS OF ZWEYMULLER THR OVER 15 YEARS FOLLOW-UP

Abstract

Background: The long-term results for uncemented hip arthroplasty have not yet been sufficiently documented for a period of more than 15 years.

Methods: A clinical, phone, and radiological check-up with a mean follow-up of 15 (15–17) years analyzes the clinical results, the rate of aseptic loosening, the survival rate of the prosthesis, and the necessary re-interventions for a group of 320 consecutive total hip surgeries using Zweymüller screw cups and Zweymüller-SL stems in 303 patients from the years 1988 and 1989. The surgery was performed on 183 hips in women and 137 hips in men; 17 patients were operated on both sides. The mean age at the time of operation was 67 (29–99) years. All patients were permitted to put full stress on the leg immediately after the operation, and the prosthesis system was used as universal implant, no matter what the bone quality and the patient’s age. 164 (51.3%) of the hip patients had died at the time of the follow-up examination. Clinical and radiological examinations were available for 97 (30.3%) of the hips, phone interviews and radiological examinations for 4 (1.3%) of the hips, and phone follow-ups for only 49 (15.3%) of the hips. 6 (1.9%) of the hips were assessed as lost to follow-up.

Results: The Harris hip score results in a mean value of 88. The rate of aseptic loosening is 2% for the acetabular component and 1% for the femoral component. The stem and the cup had a survival rate of 98% in the surviving patients each. In 97.8% of the implanted prostheses, no exchange of a prosthesis component became necessary; in 95.2% of the patients, no operative revision of any kind was required.

Conclusions: With the Zweymüller hip endoprosthesis, excellent long-term results can be achieved both from a clinical perspective and regarding the rate of aseptic loosening and the survival rate. The system can be fully stressed immediately after the operation; age and poor bone quality are not contraindications for an implantation.