title: Morbidly Obese Patients Undergoing Reduced Cup Anteversion Through a Direct Lateral Approach.
abstract: BACKGROUND
  The presence of obesity negatively affects the results after total hip arthroplasty. The influence of morbid obesity on cup positioning is investigated.
  
  
  METHODS
  A retrospective analysis of radiographs from 790 patients in 2013 and 2014 was performed. The correlation of cup inclination and anteversion with body mass index (BMI) was analyzed. Three groups were formed: 139 patients with normal weight (BMI of <25 kg/m(2)), 566 patients with moderate obesity (BMI between 25 and 34 kg/m(2)), and 85 patients with morbid obesity (BMI of ≥35 kg/m(2)).
  
  
  RESULTS
  Cup anteversion significantly correlated with BMI (R = -0.127, p < 0.001) and patient age (R = 0.115, p = 0.001). This corresponded with a reduction of anteversion by 3.4° (p < 0.001) in the morbidly obese group compared with the normal-weight group. Cup inclination was not influenced by BMI or patient age.
  
  
  CONCLUSIONS
  The precision of cup positioning declines with increasing obesity. In addition, significantly reduced anteversion is found in younger patients. We assume that this is due to iatrogenically changed pelvic tilt resulting from increased pressure exerted on the dorsal and ventral acetabular rim retractors.
  
  
  METHODS
  Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Orthopedic Department, Campus Eisenberg, University Hospital, Jena, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Brodt
authors.affiliation: Orthopedic Department, Campus Eisenberg, University Hospital, Jena, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Jacob
authors.affiliation: Orthopedic Department, Campus Eisenberg, University Hospital, Jena, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Windisch
authors.affiliation: Department of Orthopaedics and Orthopaedic Surgery, University Hospital of Giessen and Marburg, Giessen, Germany.
authors.forename: Joern
authors.initials: J
authors.lastname: Seeger
authors.affiliation: Orthopedic Department, Campus Eisenberg, University Hospital, Jena, Germany g.matziolis@krankenhaus-eisenberg.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Matziolis
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000000981:diagnostic imaging / Q000601:surgery*; D056888:Patient Positioning; D011474:Prosthesis Design; D011859:Radiography; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods; D016896:Treatment Outcome