FAILURE OF THE MECRING SCREW-RING ACETABULAR COMPONENT IN TOTAL HIP-ARTHROPLASTY - A 3-YEAR TO 7-YEAR FOLLOW-UP-STUDY

We prospectively studied the results of 411 consecutive total hip arthroplasties with a Mecring screw-ring acetabular component inserted without cement combined with a Stanmore femoral stem inserted with cement. The duration of follow-up ranged from three to seven gears (mean, four years and six months). Three hundred and thirty-one patients (378 hips) were available for physical examination and had a complete set of radiographs. The clinical result was good or excellent for 82 per cent (309) of the 378 hips. However, the rate of radiographic loosening of the acetabular component, as evidenced by migration at the most recent follow-up examination, was alarmingly high: 25 per cent (ninety-five) of the 378 hips. In general, these patients did not have serious clinical symptoms. The cups in women migrated significantly more often (p = 0.003) than those in men. Migration was also more frequent in patients who were less than fifty-one years old and in patients in whom the index procedure was a revision arthroplasty, but these differences were not significant. Twenty-one (6 per cent) of the acetabular cups were revised for aseptic loosening. T he high rate of radiographic loosening has led us to abandon the use of the Mecring screw-ring acetabular component.