This study aims to evaluate patient reported and functional outcomes following hybrid versus cemented total knee arthroplasty (TKA) in patients, stratified by body mass index (BMI).
Registry data of patients undergoing primary TKA between January 2004 and January 2013 were collected. Baseline interviews were conducted preoperatively to assess sociodemographic characteristics, BMI, and knee arthritis severity, using the Knee Society Score which consists of the Knee Society Knee Score and the Knee Society Function Score (KSFS) and Oxford Knee Score (OKS). These scores were collected prospectively, preoperatively, and postoperatively up to 2 years. Two-year outcomes and 5-year revision rates were then compared between (1) hybrid and cemented TKA groups and (2) BMI subclasses within the hybrid and cemented TKA groups.
Patients who underwent cemented TKA had marginally better flexion range, KSFS, and OKS at 2 years postoperatively. In the overweight category, flexion range, KSFS, and OKS were marginally lower for hybrid TKAs. There were no differences in outcomes between the 2 groups in Class I and II obesity. Within the cemented TKA group, there were no differences in the outcomes between BMI subclasses. There were significant differences in the KSFS (0.023) and OKS (0.030) between the BMI subclasses within the hybrid TKA group, with patients in Class II obesity faring the worst. There was no statistically significant difference in the revision rates.
We conclude that obesity does not affect outcomes in hybrid versus cemented TKA.