[10 years results with the corund-blasted Zweymüller titanium alloy threaded acetabular cup]

The Zweymüller threaded acetabular cup is cone-shaped with a corundblasted surface to allow bony ingrowth. We do not know any report of a ten-years follow-up of this cup. 90 consecutive patients with 92 primary THR of this system are investigated on average of 10.25 years of implantation. 6 patients were lost of follow-up. 36 patients had died without any signs or symptoms of aseptic loosening. 48 patients with 50 hips were accepted in the retrospective study. We observed 5 aseptic loosenings of the cup and 4 aseptic loosenings of the stem. A total of 11 additional operations was necessary in these 90 patients including two explantations due to acute deep infection. The Harris hip score was 76.5 points on average. Patients with disabling diseases reached only 62.3 points. Compared to the remaining patients with 88.3 points the difference was highly significant. Revision surgery of the acetabular component was not hampered by the conical reamed acetabular bone stock. No massive polyethylen wear occurred in this period. After ten years the survival rate was 92.6% for the cup and 90.6% for the stem respectively. This survival rate is superior to similar threaded cups. We conclude that the roughened surface of the titanium cup leads to a significant improvement of long-term stability.