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Word of the Day

Complications after knee replacement higher in obese patients, but still low

Clinical Question:
Are obese patients more likely than nonobese patients to have complications after knee replacement?

Bottom Line:
Obese patients undergoing knee replacement surgery have a higher rate of postoperative infections and are more likely to undergo revisions. However, more than 90% will still do well. (LOE = 1a)

Kerkhoffs GM, Servien E, Dunn W, Dahm D, Bramer JA, Haverkamp D. The influence of obesity on the complication rate and outcome of total knee arthroplasty: a meta-analysis and systematic literature review. J Bone Joint Surg Am 2012;94(20):1839-1844.  [PMID:23079875]

Study Design:
Meta-analysis (other)


Various (meta-analysis)

These authors systematically reviewed several databases to identify trials evaluating outcomes of knee replacement in obese and nonobese patients. Two authors independently determined which studies to include. They also hand-searched the reference lists of included studies, but do not describe efforts to identify unpublished studies, nor do they describe formally assessing the potential for publication bias. They resolved discrepancies by consensus and with third-party adjudication when consensus could not be reached. Similarly, 2 authors independently evaluated the quality of the included studies and extracted the data. Ultimately, the authors included 20 studies with more than 15,200 patients. They used a body mass index cutoff of 30 kg/m2 to stratify obese and nonobese patients. The most commonly reported postoperative complications were infections, revisions, and venous thromboembolism. The good news: The rate of thromboembolism was similar in each group. However, obese patients had a higher rate of infections (2.8% vs 1.1%; odds ratio [OR] = 1.9; 95% CI, 1.5 - 2.5). Obese patients were also more likely to undergo revisions (5.2% vs 2.7%; OR = 1.8; 95% CI, 1.2 - 2.8). Although the authors found no significant heterogeneity, a handful of studies suggest that the complication rate is mainly among extremely obese patients. The authors did not assess this.


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