The influence of obesity on clinical outcomes following primary total knee arthroplasty: A prospective cohort study.

Background: The aim of this study was to evaluate the influence of obesity on patients' function, pain, and complications following primary total knee arthroplasty (TKA) with an enhanced-recovery program.

Methods: A total of 157 patients were enrolled into a prospective study and assigned into one of three groups on the basis of their body mass index (BMI): normal (BMI 18.0-24.9 kg/m), overweight (BMI 25.0-29.9 kg/m), or obese (BMI ≥30.0 kg/m). The primary outcome was knee range of motion (ROM) on postoperative day (POD) 3, 15, 30, and 90, and secondary outcomes were visual analog scale (VAS) on POD 1, 2, 3, 15, 30, and 90, length of stay, and complications.

Results: The ROM of patients in the obese group on POD 3 was higher than in the normal (104.4 ± 8.5 vs. 98.9 ± 8.9, P = .010) and overweight (104.4 ± 8.5 vs. 97.7 ± 7.8, P = .001) groups. Similarly, the VAS in the obese group at rest on POD 1 was lower than in the normal (2.0 ± 0.7 vs. 2.2 ± 0.6, P = .043) and overweight (2.0 ± 0.7 vs. 2.3 ± 0.6, P = .010) groups. In addition, the incidence of complications did not differ significantly among the three groups, but the length of hospital stay in the obese group was longer (P = .027).

Conclusions: Obesity may not affect patients' function and pain, and may not increase the incidence of complications following primary TKA. Obese patients may obtain satisfactory functional rehabilitation outcomes, but with a longer duration of rehabilitation.