We performed a systematic review and meta-analysis of the literature to quantify the impact of patients with severe obesity (body mass index [BMI] > 35 kg/m2), those with morbid obesity (BMI > 40 kg/m2), and those with super-obesity (BMI > 50 kg/m2) on revision rates and outcome scores after primary total hip arthroplasty compared with non-obese patients (BMI < 25 kg/m2).
Four electronic databases were reviewed (AMED, Embase, Ovid Healthstar, and MEDLINE) from their inception to August 2016. The search strategy used combined and/or truncated keywords, including hip replacement or arthroplasty and obesity, BMI, or any synonym of the latter in the title, abstract, or manuscript text. Abstracts and full text were reviewed by 3 pairs of reviewers to identify those assessing outcomes following primary total hip arthroplasty for different BMI categories. Outcomes evaluated were revisions (total, aseptic, and septic) and change in outcome scores (preoperative to postoperative).
The literature search identified 1,692 abstracts; 448 were included for the full-text review, and 33 were included in the meta-analysis. The morbidly obese and super-obese groups were at an increased risk for revision, especially for septic revisions, compared with the non-obese group. The severely obese group had risk ratios of 1.40 (95% confidence interval [CI], 0.97 to 2.02) for revision, 0.70 (95% CI, 0.45 to 1.10) for aseptic revision, and 3.17 (95% CI, 2.25 to 4.47) for septic revision. Morbidly obese patients had risk ratios of 2.01 (95% CI, 1.81 to 2.23) for revision, 1.40 (95% CI, 0.84 to 2.32) for aseptic revision, and 9.75 (95% CI, 3.58 to 26.59) for septic revision. Super-obese patients had risk ratios of 2.62 (95% CI, 1.68 to 4.07) for revision, 1.98 (95% CI, 0.80 to 4.94) for aseptic revision, and 7.22 (95% CI, 1.51 to 34.60) for septic revision. However, there was no significant difference (p > 0.05) in the standardized mean difference of functional outcome scores between the severely obese cohort (0.04 [95% CI, −0.02 to 0.10]), the morbidly obese cohort (0.19 [95% CI, −0.08 to 0.46]), and the super-obese cohort (−0.12 [95% CI, −0.57 to 0.33]).
Severely obese patients, morbidly obese patients, and super-obese patients undergoing total hip arthroplasty should be counseled that, although they have comparable outcome score improvements compared with non-obese patients, they have significantly higher risks of all-cause and septic revision.
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.
1Division of Orthopaedic Surgery, University of Western Ontario, London, Ontario, Canada
E-mail address for E.M. Vasarhelyi: Edward.Vasarhelyi@lhsc.on.ca
Investigation performed at the Division of Orthopaedic Surgery, University of Western Ontario, London, Ontario, Canada
Disclosure: There was no source of external funding for this study. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work (http://links.lww.com/JBJSREV/A440).