著明なメタローシスを生じたＢｉｐｏｌａｒ ＴＨＡの小経験

Abstract

We report two cases of metallosis following total hip arthroplasty (THA). Case 1 was a 57-year-old female, operated for left coxarthrosis by THA with bone-grafting acetabuloplasty with a bipolar endoprosthesis. Sapphire screws were used for grafted bone fixation. Three years after the operation, gradual migration of the outer head occurred and fracture of the screws was observed. Eight years later, radiographs showed severe metallosis of the surrounding tissue. As she had many general disorders, she was observed conservatively.Case 2 was a 57-year-old female with severe right coxarthrosis, operated in the same way as the case 1.4 years after the operation, a big mass was found in the inguinal resion. Radiographs showed migration of the outer head and severe metallosis. In the revision, the mass was found to be black granulaion tissue enveloped by thin membrane. The inner head had warned out severely. Detailed examination, including scanning electron micrograph and energy-dispersive x-ray analysis, revealed that, many rough edged ceramic particles originating from the fractured ceramic screws had become embedded in the inner surface of the polyethylene bearing insert. These ceramic fragments had entered the prosthetic joint space during joint movement, thereafter causing continuous abrasion of the metal head.