Abstract
The negative effects of obesity following total joint arthroplasty, such as increased
morbidity and mortality, have been well documented in literature. However, little
is known about whether specific body mass indices can be used as cutoffs to determine
which patients are most at risk for having a poor postoperative outcome. We evaluated
the effects of differing levels of obesity as measured by body mass index (BMI) on
implant survivorship, Knee Society scores, complications, and radiographic outcomes.
A systematic review of the literature was performed to identify all studies reporting
outcomes of total knee arthroplasty in obese (30 ≤ BMI < 40 kg/m2) and morbidly obese patients (40 ≤ BMI < 50 kg/m2). Twenty-four studies were identified in our literature search. At a mean 5-year
follow-up, morbidly obese patients (88%) had significantly lower implant survivorship
than obese patients (95%) and nonobese patients (97%). Significantly, lower postoperative
mean Knee Society objective and function scores (71 and 60 points) were observed for
morbidly obese patients than for nonobese patients (75 and 90 points), but obese patients
did not have significantly lower Knee Society objective and function scores than nonobese
patients (78 and 84 points). Complication rates for nonobese, obese, and morbidly
obese patients were 9, 15, and 22%, respectively, all of which were significantly
different. However, no significant difference was observed in the incidence of radiolucent
lines that were 12, 19, and 14%, respectively. Thus, we conclude that a BMI greater
than 40 kg/m2 may be used as a cutoff to help guide patient education and treatment options for
primary total knee arthroplasty.
Keywords
total knee arthroplasty - obesity
