Background: Obesity is routinely cited as a negative predictive factor for outcomes after total knee arthroplasty (TKA), but the direct mechanism responsible for this relationship has not been described. One possible explanation is a propensity for component malalignment in obese patients that is attributable to difficulty with surgical exposure.
Methods: This study evaluated the effect of obesity on TKA component alignment in 251 primary TKAs during a 12-month period at a single center in 2009. Postoperative component alignment was retrospectively measured and compared between patients defined as obese (body mass index [BMI] ≥30 kg/m2) and patients defined as nonobese (BMI <30 kg/m2). Alignment was determined by measuring the coronal tibiofemoral angle, coronal femoral component angle, coronal tibial component angle, sagittal femoral component angle, and sagittal tibial component angle in all of the study patients.
Results: Statistical analysis failed to demonstrate a statistically significant relationship between obesity and component alignment in any of the measured parameters.
Conclusion: The results of this study support that obesity does not negatively affect TKA component alignment; another factor must be associated with the worse outcomes in obese patients undergoing TKA.
Keywords: Body mass index; obesity; total knee arthroplasty.