title: Similar clinical outcomes for THAs with and without prior periacetabular osteotomy.
abstract: BACKGROUND
  Some patients opt to undergo conversion to a THA for continued pain or progression of hip arthritis after periacetabular osteotomy. Whether patients are at greater risk for postoperative complications, revision THA, poor clinical outcomes, or compromised radiographic results after periacetabular osteotomy is debatable.
  
  
  OBJECTIVE
  When compared with a matched cohort of patients who underwent THAs for developmental dysplasia of the hip (DDH) without previous periacetabular osteotomy, we asked whether a THA after a periacetabular osteotomy has (1) a higher complication rate, (2) a higher likelihood of resulting in revision THA, (3) comparable improvements in Harris hip score, and (4) comparable radiographic results.
  
  
  METHODS
  A multicenter retrospective review of 562 patients undergoing 645 periacetabular osteotomies was performed. Twenty-three hips in 22 patients underwent a THA after periacetabular osteotomy. The patients were matched for age, sex, and BMI with 23 hips in 23 patients with DDH undergoing THA without a history of periacetabular osteotomy. Minimum followup for both groups of patients was 2 years (mean, 10±4 years and 6±4 years, respectively). Comparisons were made to answer the study questions based on a retrospective review from prospectively maintained registries of clinical and radiographic information at two participating centers.
  
  
  RESULTS
  With the numbers available, there was no difference in complication or revision rates between the two groups (p=0.489 and 1.000, respectively); however, a post hoc power analysis showed our study was underpowered to detect a difference in the rate of postoperative complications or revision THA. There was marked improvement in Harris hip score with THA after periacetabular osteotomy (p<0.001) and THA for DDH (p<0.001), but there was no difference (p=0.265) in the Harris hip score at final followup between either group. The acetabular component was placed at a mean of 17° more retroversion during THA after periacetabular osteotomy compared with THA for DDH (p=0.002).
  
  
  CONCLUSIONS
  This study did not detect any differences in the clinical outcomes in patients undergoing THA after periacetabular osteotomy done with a modern abductor-sparing approach when compared with a matched cohort undergoing THA for DDH. However, even with patients tallied across two high-volume centers during nearly 15 years, our study was underpowered to detect potentially important differences between the THA after periacetabular osteotomy group and the THA for DDH group. The data in this report are suitable as pilot data for future studies and for systematic reviews. Larger multicenter studies are needed to understand how the technical challenges of THA after periacetabular osteotomy affect postoperative complications and revision THA.
  
  
  METHODS
  Level III, therapeutic study.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, Redwood City, CA, USA.
authors.forename: Derek F
authors.initials: DF
authors.lastname: Amanatullah
authors.forename: Louis
authors.initials: L
authors.lastname: Stryker
authors.forename: Perry
authors.initials: P
authors.lastname: Schoenecker
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Taunton
authors.forename: John C
authors.initials: JC
authors.lastname: Clohisy
authors.forename: Robert T
authors.initials: RT
authors.lastname: Trousdale
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Sierra
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip; D005270:Femur Head / Q000473:pathology; D006617:Hip Dislocation / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D010027:Osteotomy / Q000379:methods; D011859:Radiography; D012189:Retrospective Studies; D016896:Treatment Outcome