Abstract
As obesity becomes more prevalent, more patients are at risk of lower extremity osteoarthritis
and subsequent total knee arthroplasty (TKA). This study aimed to test (1) the association
of preoperative weight change with health care utilization and (2) the association
of pre- and postoperative weight changes with failure to achieve satisfaction and
minimal clinically important difference (MCID) in Knee injury and Osteoarthritis Outcome
Score for pain (KOOS-Pain) and function (KOOS-PS) 1 year after TKA. Prospectively
collected monocentric data on patients who underwent primary TKA were retrospectively
reviewed. Multivariable logistic regression assessed the influence of BMI and weight
change on outcomes while controlling for confounding variables. Outcomes included
prolonged length of stay (LOS >3 days), nonhome discharge, 90-day readmission rate,
satisfaction, and achievement of MCID for KOOS-Pain and KOOS-PS. Preoperative weight
change had no impact on prolonged LOS (gain, p = 0.173; loss, p = 0.599). Preoperative weight loss was associated with increased risk of nonhome
discharge (odds ratio [OR]: 1.47, p = 0.003). There was also increased risk of 90-day readmission with preoperative weight
gain (OR: 1.27, p = 0.047) and decreased risk with weight loss (OR: 0.73, p = 0.033). There was increased risk of nonhome discharge with obesity class II (OR:
1.6, p = 0.016) and III (OR: 2.21, p < 0.001). Weight change was not associated with failure to achieve satisfaction,
MCID in KOOS-Pain, or MCID in KOOS-PS. Obesity class III patients had decreased risk
of failure to reach MCID in KOOS-Pain (OR: 0.43, p = 0.005) and KOOS-PS (OR: 0.7, p = 0.007). Overall, pre- and postoperative weight change has little impact on the
achievement of satisfaction and clinically relevant differences in pain and function
at 1 year. However, preoperative weight gain was associated with a higher risk of
90-day readmissions after TKA. Furthermore, patients categorized in Class III obesity
were at increased risk of nonhome discharge but experienced a greater likelihood of
achieving MCID in KOOS-Pain and KOOS-PS. Our results raise awareness of the dangers
of using weight changes and BMI alone as a measure of TKA eligibility.
Keywords body mass index - total knee arthroplasty - weight loss - weight gain - patient-reported
outcome measures
