title: Are morbidly obese patients undergoing total hip arthroplasty at an increased risk for component malpositioning?
abstract: Acetabular cup positioning is a critical factor in determining adverse clinical outcomes in THA. This evaluation was performed to determine if morbid obesity (BMI ≥35kg/m(2)) is a contributing risk factor to cup malpositioning. Two groups of patients were obtained from a local arthroplasty registry and match-controlled for gender, age, and diagnosis (n=211 morbidly obese; n=211 normal). Intraoperative data and postoperative AP pelvis and cross-table lateral radiographs were obtained for each patient. The Martell Hip Analysis Suite was used to calculate cup positioning (successful positioning defined as 30°-45° of abduction, and 5°-25° of anteversion), as well as varus-valgus alignment of the femoral stem. There was a significant correlation between morbid obesity with respect to underanteversion; using multivariate analysis, there was a trend toward a combined underanteversion/overabduction of the acetabular cup. Of all variables considered, high BMI was the most significant risk factor leading to malpositioning.
authors.affiliation: Department of Orthopaedic Surgery, Harris Orthopaedic Laboratory, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Leah C
authors.initials: LC
authors.lastname: Elson
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Barr
authors.forename: Shaun E
authors.initials: SE
authors.lastname: Chandran
authors.forename: Viktor Johannes
authors.initials: VJ
authors.lastname: Hansen
authors.forename: Henrik
authors.initials: H
authors.lastname: Malchau
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kwon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D015992:Body Mass Index; D017760:Bone Malalignment / Q000000981:diagnostic imaging / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000601:surgery; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications*; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011859:Radiography; D012307:Risk Factors; D016896:Treatment Outcome
keywords: component malpositioning; obesity; total hip arthroplasty