The Müller acetabular support ring. A preliminary review of indications and clinical results.

A series of 41 total hip arthroplasties with acetabular reinforcement by a Müller support ring is reviewed. The postoperative management was the same as that used in conventional cemented total hip arthroplasty. The overall clinical results and the radiological findings were most satisfactory after one to six years. Of the 30 hips available for functional assessment using the Merle d'Aubigné scale, 16 were excellent, 10 good, 2 fair, 1 poor and 1 bad. These results indicate that, regardless of the primary disorder, the Müller support ring has been helpful when dealing with severe osteoporosis, an acetabular floor lined by bone which does not allow adequate penetration of methyl methacrylate, a small acetabulum needing a small polyethylene socket and localised destruction of the acetabular roof or of the anterior or posterior acetabular pillar. A good result can only be guaranteed if the ring makes a perfect fit with the reamed acetabular cavity.