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Body mass index as a risk factor for mis-seating of ceramic liners in total hip arthroplasty

Winemaker, Mitchella,b,c; Burton, Kirsteena,d; Finlay, Karena,c,e; Petruccelli, Danielleb,c; de Beer, Justina,b,c

doi: 10.1097/BCO.0b013e3182125b3c

Background A retrospective radiographic review was undertaken to determine the prevalence of mis-seated ceramic liners in primary total hip arthroplasty and the association between body mass index and mis-seating risk.

Methods Patients with primary implantation of the Trident (Stryker, Mahwah, NJ) uncemented ceramic acetabular component were identified from a prospective database of 2227 primary total hip arthroplasties and radiographically reviewed. All procedures were performed at one center between 1999–2006. The mis-seating angle and location were determined. The risk of mis-seating by body mass index was calculated using logistic regression models.

Results A total of 411 primary total hip arthroplasties were identified. Mis-seating occurred in 81 patients (19.7%). Of the 411 total hip arthroplasties, 83 (20.2%) were performed in patients with a body mass index of less than 25.0 defined as underweight to normal, 133 (32.4%) in patients who were overweight with a body mass index between 25.0–29.9, and 195 (47.4%) in patients who were obese with a body mass index of over 30.0. Adjustment for case mix revealed a significant association between body mass index and risk of mis-seating of ceramic components. Patients who were overweight at the time of total hip arthroplasty (body mass index 25.0–29.9) were at increased risk of mis-seating (adjusted odds ratio 2.52, 95% confidence interval (1.24-5.12, P=0.01).

Conclusions Mis-seating of ceramic acetabular systems in total hip arthroplasty was a frequent occurrence. Patients who were overweight were more than two times more likely to suffer mis-seating than those who were underweight, of normal weight, or obese.

aMcMaster University, Hamilton, Ontario, Canada

bHamilton Arthroplasty Group, Hamilton, Ontario, Canada

cHamilton Health Sciences Henderson Hospital, Hamilton, Ontario, Canada

dRadiologist-Scientist Training Program, University of Toronto, Department of Medical Imaging, Toronto, Ontario, Canada

eDiagnostic Radiology, McMaster University, Hamilton, Ontario, Canada

None of the authors (or members of their immediate families) have a financial interest or other relationship with a commercial company related directly or indirectly with the scientific material presented in this manuscript.

Correspondence to Danielle Petruccelli, MLIS, MSc, Hamilton Arthroplasty Group, Hamilton Health Sciences Henderson Hospital, 711 Concession St., Hamilton, Ontario, Canada L8 V 1C3 Tel: +905 527 4322, ext. 42296; fax: +905 389 5617; e-mail:

© 2011 Lippincott Williams & Wilkins, Inc.