title: Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty.
abstract: BACKGROUND
  The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.
  
  
  METHODS
  Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4-11 years).
  
  
  RESULTS
  There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.
  
  
  CONCLUSIONS
  Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.
authors.affiliation: Department Orthopaedics-IDi Paz, Hospital La Paz, P° Castellana 261, 28046 Madrid, Spain. edugrey@yahoo.es
authors.forename: Eduardo
authors.initials: E
authors.lastname: García-Rey
authors.forename: Ricardo
authors.initials: R
authors.lastname: Fernández-Fernández
authors.forename: David
authors.initials: D
authors.lastname: Durán
authors.forename: Rosario
authors.initials: R
authors.lastname: Madero
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D019651:Plastic Surgery Procedures / Q000295:instrumentation / Q000379:methods; D012086:Reoperation; D012307:Risk Factors