title: Acetabular revision after failed total hip arthroplasty in patients with congenital hip dislocation and dysplasia. Results after a mean of 8.6 years.
abstract: BACKGROUND
  Revision of a total hip arthroplasty in a patient who has had congenital hip dysplasia or dislocation is often more difficult than a standard revision operation. The purpose of this study was to assess the efficacy and complications of use of a cementless hemispherical acetabular component for revision of an acetabular component of a failed total hip replacement in patients whose initial problem was arthritis secondary to congenital dislocation or dysplasia. The mean duration of follow-up was approximately eight years.
  
  
  METHODS
  We reviewed a consecutive series of sixty-one hips in fifty-three patients who underwent a cementless acetabular revision with use of a hemispherical acetabular component, with or without concurrent femoral revision. Data were collected prospectively. The mean age of the patients at the time of the index operation was fifty-six years. A mean of 1.9 ipsilateral hip operations had been performed previously. Thirty-nine hips (64 percent) had a so-called high hip center prior to the index revision. With one exception, the uncemented acetabular component was fixed with screws. Fifty-one acetabular components were placed with so-called line-to-line fit, and ten were oversized by one to three millimeters. In thirty-eight hips, the femoral component was revised as well. Twenty-nine femora were reconstructed with use of a cemented device, and nine were revised with an uncemented patch-porous-coated femoral stem (a stem on which the porous coating appears in patches).
  
  
  RESULTS
  Four patients (five hips) died prior to the five-year minimum follow-up interval. With the exception of one hip treated with resection arthroplasty because of deep infection, none of the hips in these deceased patients had been revised or had a loose component. One living patient (one hip) had a resection arthroplasty, and one additional patient (two hips) had both stable acetabular components rerevised at the time of femoral rerevision at another institution because of loosening and osteolysis. One patient refused to return for follow-up, but the components had not been revised. The remaining fifty-two hips in forty-six patients were followed for a mean of 8.6 years (range, 5.0 to 12.7 years). The mean Harris hip score was 80 points (range, 56 to 100 points) at the time of the latest follow-up. No acetabular component had been revised, although two had migrated. No other acetabular component was loose according to our radiographic criteria. Thus, the mechanical failure rate on the acetabular side was 3 percent (two of sixty-one) for the entire series and 4 percent (two of fifty-two) for the patients who had been followed for a mean of 8.6 years. On the femoral side, the mechanical failure rate was 3 percent (one of twenty-nine) for the cemented stems and six of nine for the uncemented patch-porous-coated stems.
  
  
  CONCLUSIONS
  Of the approaches used in this difficult series of patients requiring revision, the hybrid arthroplasty (a cementless acetabular component and a cemented femoral component) yielded overall good results after an intermediate duration of follow-up.
authors.affiliation: Fremont Orthopaedic Medical Group, California 94536, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Dearborn
authors.forename: W H
authors.initials: WH
authors.lastname: Harris
mesh_terms: D000077:Acetabulum; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012086:Reoperation; D017211:Treatment Failure