Early Results of Total Cementless Hip Joint Arthroplasty with a Conical Screw Cup

Abstract

Background: With the development of hip arthroplasty, there are increasingly more indications for effective use of this surgical method. Endoprostheses are now being more and more commonly used in difficult cases of secondary coxarthrosis and in increasingly younger patients. The aim of this study is to present the early results of hip joint arthroplasty with the Zweymüller conical screw cup.

Materials and methods: The study enrolled 117 patients (64 women and 53 men) who underwent a total of 123 hip joint arthroplasties with the Zweymüller conical screw cup. The mean age of the patients at surgery was 60.8 years (range: 26-81 years). The mean follow-up period was 7.7 years (range: 5-12.6 years).

Results: Pre-operative Merle d'Aubigne-Postel scores (modified by Charnley) of the study group were poor in all patients. Mean post-operative improvement was 6.3 points. The outcomes were classified as excellent in 42 cases (34.15%), good in 56 cases (45.53%), satisfactory in 14 (11.38%) and poor in 11 cases. Poor results were always associated with implant loosening. Heterotopic ossification was noted in 8 cases (6.5%). According to the Kaplan-Meier estimator, 5-year survival probability was 91.1% for the whole implant and 94.3% for the stem alone.

Conclusions: 1. Our follow-up data (from a mean follow-up period of more than 7 years) indicate that the Zwey-müller conical screw cup affords excellent clinical and functional results in patients operated on for advanced hip osteoarthritis. 2. In patients correctly qualified for this procedure, with good surgical technique and in the absence of complications, the risk of aseptic loosening is minimal. 3. As only medium-term follow-up data are available, there may be more cases of loosening over time, indicating a need of regular long-term follow-up.

Keywords: Zweymüller endoprosthesis; arthroplasty outcomes; conical screw cup; hip joint arthroplasty.