title: Acetabular Abduction and Dislocations in Direct Anterior vs Posterior Total Hip Arthroplasty: A Retrospective, Matched Cohort Study.
abstract: There is purported improvement in component positioning and hip stability with the use of direct anterior approach (DAA) total hip arthroplasty (THA). We sought to determine if there is a difference in acetabular component position or dislocation frequency between DAA and posterior THA.
  
  
  
  One arthroplasty fellowship-trained surgeon introduced DAA THA into his practice. From the initiation of DAA in 4/2012-8/2015, this comparative series resulted in 66 DAA THAs. A matched cohort (age, gender, body mass index [BMI], and comorbidities) was then created for posterior THA, 66 hips. DAA THA used fluoroscopy with anterior capsular excision; posterior group used no image guidance and had capsular repair. Posterior group BMI was 27.8 and DAA group BMI was 27.6 (P = .36). Minimum 3-month follow-up occurred in both groups.
  
  
  
  Average acetabular abduction angle in the posterior group was 41.9° (range, 32°-60°; standard deviation [sdev], 6.24) and DAA group 43.8° (range, 30°-62°; sdev 6.9), P = .12. The percentage of outliers (outside Lewinnek safe zone, 30°-50°) was 9.1% (6 of 66) in posterior group and 13.6% (9 of 66) in DAA group. There were 2 anterior dislocations in the DAA THA group and 1 anterior dislocation in the posterior THA group, resulting in P = .56. The DAA dislocation frequency in this group was overall higher at 3.0% (2 of 66) compared with the matched posterior (1.5%, 1 of 66) and unmatched posterior larger series (.8%, 3 of 360).
  
  
  
  We demonstrated no observable difference in hip stability or acetabular abduction. This study provides realistic outcomes for surgeons implementing DAA THA into their practice.
authors.affiliation: New Mexico Center for Joint Replacement, New Mexico Orthopaedic Associates, Albuquerque, New Mexico.
authors.forename: Krishna R
authors.initials: KR
authors.lastname: Tripuraneni
authors.affiliation: New Mexico Center for Joint Replacement, New Mexico Orthopaedic Associates, Albuquerque, New Mexico.
authors.forename: Natalie R
authors.initials: NR
authors.lastname: Munson
authors.affiliation: New Mexico Center for Joint Replacement, New Mexico Orthopaedic Associates, Albuquerque, New Mexico.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Archibeck
authors.affiliation: New Mexico Center for Joint Replacement, New Mexico Orthopaedic Associates, Albuquerque, New Mexico.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Carothers
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D005471:Fluoroscopy / Q000379:methods; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D012189:Retrospective Studies
keywords: arthroplasty; direct anterior approach; hip; hip dislocation; retrospective studies; supine position