A preliminary review of the Müller acetabular and Burch-Schneider antiprotrusio support rings.

A high incidence of acetabular loosening following total hip arthroplasty is emerging as long term follow-up studies become available. The Müller and Burch-Schneider acetabular supports are indicated for acetabular deficiencies which are frequently present during revision hip arthroplasty. The Burch-Schneider support is indicated where the deficiencies are of such magnitude that the Müller ring does not have stable seating prior to screw fixation. These devices bring the resultant of forces across the hip joint under the acetabular roof and provide metal backing for the acetabular cup. They have the additional advantage of screw fixation which in the Müller ring is in line with the resultant of forces across the hip joint. In a one to three year follow-up of twenty-five hip replacements in twenty-four patients, the Müller support ring was used in twenty hips and the Burch-Schneider in five hips. The results were satisfactory and indicate that these supports are valuable in the treatment of patients with acetabular deficiencies.