MODERN METAL ON METAL ARTICULATION FOR TOTAL HIP REPLACEMENTS

Between 1991 and 1994, 70 patients received total hip replacements wit h metal on metal articulation, The results of 51 of these patients wit h 54 hips who have a 2- to 4-year (2.7-year average) follow-up are rep orted. Patients were prospectively evaluated using the Harris hip scor e, a patient self assessment form, and radiographs, Hip aspiration was performed preoperatively and 6 to 24 months postoperatively in 24 hip s with metal on metal articulations. Implant retrieval was obtained fr om 2 patients, Harris hip score averages increased from 39 to 93. No p atient had revision surgery for loosening, but 1 had revision surgery for dislocation. Patient self assessment forms showed 51 of 51 patient s scored their results as good or excellent. Serial radiographs did no t show loosening or osteolysis. Wear could not be measured radiographi cally. Synovial fluid samples had metal particles of 1 to 10 mu m in 1 0 hips. Twenty patients had bilateral total hip replacements with 1 hi p metal on polyethylene articulation, and patients could not determine any difference between the hips. Compared with historic results of pr evious metal on metal prostheses, the modern metal on metal articulati on investigated in this study did not have early acetabular loosening or clinical symptoms of component impaction. Retrieval implants and sy novial fluid analysis suggest early wear was minimal.