title: Does a cemented cage improve revision THA for severe acetabular defects?
abstract: BACKGROUND
  Evidence suggests a growing incidence of revision total hip arthroplasty (THA) including a subset with large acetabular defects. Revision THA for severe acetabular bone loss is associated with a relatively high rate of mechanical failure.
  
  
  OBJECTIVE
  We questioned whether cementing a cage to the reconstructed acetabular defect and pelvis would improve the rate of mechanical failure for patients with Type 3 defects (Paprosky et al.) with and without pelvic discontinuity in comparison to historical controls.
  
  
  METHODS
  We retrospectively collected data on 33 patients who underwent 35 revision THAs using an acetabular reconstruction cage cemented to morselized allograft and either structural allograft or trabecular metal augmentation for Type 3 defects in the presence (n = 13) and absence (n = 22) of pelvic discontinuity at a mean followup of 59 months (range, 24-92 months). The primary outcome was mechanical failure, defined as revision of the acetabular reconstruction for aseptic loosening.
  
  
  RESULTS
  Revision surgery for mechanical failure occurred in four of the 13 patients with pelvic discontinuity and two of the 22 patients without discontinuity. Radiographic loosening occurred in one patient with and one patient without pelvic discontinuity. Seven of the 35 revisions were subsequently revised for deep infection all in patients who were immunocompromised.
  
  
  CONCLUSIONS
  Cementing the cage to the pelvis can offer an advantage for treating severe acetabular defects. Trabecular metal augmentation appears to provide better initial mechanical stability than a structural allograft, but successful allograft reconstruction may restore bone stock.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, 500 Parnassus Avenue, MU 320-W, San Francisco, CA 94143, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Hansen
authors.forename: David
authors.initials: D
authors.lastname: Shearer
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ries
mesh_terms: D000077:Acetabulum / Q000473:pathology / Q000601:surgery*; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D001843:Bone Cements; D002484:Cementation / Q000379:methods; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D011475:Prosthesis Failure / Q000209:etiology; D012086:Reoperation; D012189:Retrospective Studies
chemical_list: D001843:Bone Cements