Adverse Reaction to Metal Debrisの診断に股関節鏡が有用であった1例

抄録

 Recently, concerns have been raised about adverse reactions to metal debris (ARMD) after receiving metal-on-metal (MOM) total hip arthroplasty (THA). The diagnosis of ARMD is often difficult. This case report describes the usefulness of hip arthroscopy in diagnosing ARMD after a MOM THA.

 A 63-year-old woman underwent a primary right THA for osteoarthritis with a M2a-taper MOM articulation [Biomet^®, Inc., Warsaw, IN]. Her postoperative course was uneventful. One year and eight months later, however, she developed right groin pain and became unable to mobilise. A plain radiograph of her left hip showed radiolucencies around the acetabular cup, suggesting loosening of the acetabular components. A computed tomography scan demonstrated a large mass anterior to the hip joint. Serologic tests showed no elevation of leukocytes or C-reactive protein. These findings suggested the possibility of ARMD and/or occult infection. A hip arthroscopy was then performed, which revealed necrotic soft tissue debris within the joint. The lesion was arthroscopically biopsied and samples were analysed through bacterial culture and histology. The bacterial culture was negative, and histological analysis showed multiple macrophages that were phagocytizing metal debris. These results established a definitive diagnosis of ARMD. During the following month, a revision surgery with debridement of the pseudotumor was performed. The femoral stem was well-fixed. The acetabular components and the head were replaced. The metal liner was replaced with a polyethylene liner and the head was changed to a zirconia type. Intraoperative cultures were later found to be negative and the surgical specimen revealed the same findings with those obtained by the previous arthroscopy. Recovery from the surgery was uneventful.