title: High complication rate after revision of large-head metal-on-metal total hip arthroplasty.
abstract: BACKGROUND
  Previous studies have indicated poor outcomes in patients having revision of hip resurfacing resulting from adverse local tissue reaction and pseudotumor.
  
  
  OBJECTIVE
  We reviewed all patients at our institution who had revision of failed large-head metal-on-metal total hip arthroplasty to determine (1) complications including reoperations; (2) radiologic outcomes; and (3) changes in serum ions after removal of the metal bearing.
  
  
  METHODS
  From our research database, we identified 32 hips in 30 patients. Revisions were performed through a posterior approach; 17 were performed with a titanium fiber-metal shell and 15 with a porous tantalum shell, and 29 of the 32 revisions were performed with large (36- or 40-mm) femoral heads. Clinical records were reviewed and interviews conducted in the clinic or by telephone. Nineteen hips had a pre- or intraoperative diagnosis of adverse local tissue reaction, three had deep infection, and 10 had loosening of the acetabular component.
  
  
  RESULTS
  Major complications occurred in 12 (38%) of the 32 revisions. Nine of 32 hips (28%) sustained dislocations. Four of 17 fiber-metal acetabular components failed to ingrow; none of the porous tantalum cups failed to ingrow. Seven repeat revisions were performed in six patients: three for acetabular loosening, three for recurrent dislocation, and one for recurrent adverse local tissue reaction. The mean WOMAC pain score was 78 of 100 and the function score was 83 of 100. Metal ion levels decreased after revision in most patients.
  
  
  CONCLUSIONS
  As a result of the high rate of failure of the fiber metal cups, we have elected to use an enhanced fixation surface with a high-porosity cup for revision of these cases. We observed a high rate of dislocation despite the use of 36-mm and 40-mm heads.
authors.affiliation: Department of Orthopaedics, University of British Columbia, Room 3114, 910 West 10th Avenue, Vancouver, British Columbia, V5Z 4E3, Canada.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Munro
authors.forename: Bassam A
authors.initials: BA
authors.lastname: Masri
authors.forename: Clive P
authors.initials: CP
authors.lastname: Duncan
authors.forename: Donald S
authors.initials: DS
authors.lastname: Garbuz
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation*; D015415:Biomarkers / Q000097:blood; D020878:Device Removal / Q000009:adverse effects*; D005260:Female; D005549:Foreign-Body Reaction / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008670:Metals / Q000097:blood; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood / Q000000981:diagnostic imaging / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D017211:Treatment Failure
chemical_list: D015415:Biomarkers; D008670:Metals