Obesity is a Predictor of In-hospital Postoperative Complications in Patients Undergoing Elective Total Knee Arthroplasty

Malnutrition has long been linked to postoperative complications and adverse outcomes in a variety of surgical fields , such as increased susceptibility to infection, delayed wound healing, and increased frequency of decubitus ulcers. In particular, it is a modifiable risk factor, as evident by studies that have associated optimization of preoperative nutrition with improved surgical outcomes. Therefore, it is important to identify these patients who are at risk so that appropriate nutritional support can be implemented.

A range of options for nutritional status assessment have been proposed; a comprehensive assessment may include measurements of dietary intake, clinical assessment, anthropometric measurements, and biochemical measurements of serum protein, micronutrients and metabolic parameters . Many of the signs of malnutrition, however, only manifest in extreme cases. Thus it is crucial to identify sensitive markers that can be utilized to screen for clinical as well as subclinical malnutrition patients.

In orthopaedic patients, the prevalence of clinical and subclinical malnutrition has been reported to be up to 42.4%. Common markers of malnutrition that have been studied include low serum albumin as a marker of protein status, low total lymphocyte count (TLC), and excessively high or low body mass index (BMI). They have been compared against various adverse surgical outcomes, including surgical site infections (SSI), delayed wound healing, unplanned intubation and ICU admission , postoperative anemia and cardiac complications , and length of hospital stay. However, conflicting results have been reported; for example, while hypoalbuminemia (serum albumin <3.5mg/dL) have been associated with increased risk of SSI and longer than average hospital stay, its effect on wound healing is less clear - Marin et al. reported no significant predictive value of hypoalbuminemia on wound healing, yet Greene et al. reported a 5-time increase in frequency of major wound complication.

The purpose of this retrospective cohort study was to identify biomarkers of malnutrition in patients undergoing elective total knee arthroplasty (TKA) that are predictive of adverse in-hospital postoperative complications, which would facilitate the identification of at risk patients for nutritional optimization before surgery.

Six-hundred and twenty-six patients who underwent elective TKA between 2013 and 2017 in the Prince of Wales Hospital in Hong Kong were reviewed; the preoperative serum albumin, TLC, and BMI were compared against in-hospital postoperative complications.