title: Redefining the Acetabular Component Safe Zone for Posterior Approach Total Hip Arthroplasty.
abstract: BACKGROUND
  Acetabular component orientation influences joint stability in total hip arthroplasty (THA). The purpose of this study was to evaluate the effect of cup orientation and other variables on hip dislocation risk and to define a posterior approach specific safe zone.
  
  
  METHODS
  A cohort of 1289 posterior approach primary THA cases was prospectively followed and component position measured radiographically.
  
  
  RESULTS
  Cup malposition, with respect to the Lewinnek safe zone, was an independent risk factor for dislocation (OR1.88). Modifying the anteversion safe zone limits to 10-25° strongly predicted increased dislocation risk (OR2.69). No dislocations occurred within a zone defined by a circle centered at 41.4° abduction and 17.1° anteversion, radius 4.3°.
  
  
  CONCLUSIONS
  Utilizing a posterior approach specific safe zone of 10-25° anteversion and 30-50° abduction may minimize THA dislocations.
  
  
  METHODS
  Level III.
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Danoff
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Bobman
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Gregory
authors.initials: G
authors.lastname: Cunn
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Taylor
authors.initials: T
authors.lastname: Murtaugh
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Prakash
authors.initials: P
authors.lastname: Gorroochurn
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Geller
authors.affiliation: Center for Hip & Knee Replacement, Department of Orthopaedic Surgery, New York Presbyterian Hospital/Columbia University Medical Center, New York, New York.
authors.forename: William
authors.initials: W
authors.lastname: Macaulay
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D006617:Hip Dislocation / Q000209:etiology*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
keywords: acetabulum; cup orientation; dislocation; safe zone; total hip arthroplasty