Effect of Early Postoperative Oral Carbohydrate Intake on Nutritional Metabolism and Insulin Resistance in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Randomized Controlled Trial

Background : Prolonged fasting after total knee arthroplasty (TKA) surgery can lead to complications such as severe thirst, hypoalbuminemia, and increased insulin resistance. However, evidence supporting the benefits of early postoperative oral carbohydrate administration in elderly patients undergoing knee arthroplasty remains limited. This study aims to evaluate the safety and efficacy of early postoperative oral carbohydrate supplementation within this patient population. Methods : This single-center, prospective, single-blind, randomized controlled trial included patients aged ≥ 65 years who were undergoing total knee arthroplasty (TKA). Postoperatively, patients in the Postanesthesia Care Unit (PACU) were randomly assigned in a 1:1 ratio to either the Early Oral Feeding(EOF) group or the Traditional Fasting (C) group. The primary outcome measure was the serum prealbumin level on postoperative day 1. Secondary outcome measures included the insulin resistance index on preoperative day 1, as well as on postoperative days 1 and 3; serum prealbumin and retinol-binding protein levels measured the day before surgery, on postoperative day 1, and on postoperative day 3; thirst scores assessed at 2, 6, and 8 hours postoperatively; degree of abdominal distension within 24 hours postoperatively; incidence and severity of nausea and vomiting; frequency of antiemetic medication use within 24 hours postoperatively; incidence of hypoxemia and aspiration within 24 hours postoperatively; time to first ambulation; time to first flatus; length of hospital stay; and patient satisfaction. Results : A total of 61 patients were analyzed (32 in the EOF group and 29 in the C group), with no significant differences in demographic or surgical characteristics between the groups. Serum prealbumin and retinol-binding protein levels did not differ significantly between the groups on postoperative days 1 and 3 (P > 0.05). However, the insulin resistance index on postoperative day 1 was significantly lower in the EOF group than in the C group (P < 0.05). Additionally, the EOF group had lower blood glucose levels on postoperative day 1 (P < 0.05) and reported higher patient satisfaction and improved thirst scores at 2 and 6 hours postoperatively compared to the C group (P < 0.05). There were no significant differences between the groups in the incidence of postoperative adverse events, including nausea, vomiting, reflux, and aspiration (P > 0.05). Furthermore, no significant differences were observed in the time to first flatus, time to ambulation, or length of hospital stay between the groups (P > 0.05). Conclusions : In elderly patients undergoing knee replacement surgery, the implementation of an early postoperative oral carbohydrate regimen—following the existing Enhanced Recovery After Surgery( ERAS )protocol which already advises preoperative carbohydrate intake 2 hours before surgery—did not lead to improvement in 24-hour nutritional metabolism. However, this regimen significantly reduced early postoperative insulin resistance and alleviated thirst, without increasing the incidence of complications. Moreover, it was associated with higher patient satisfaction. Trial registration: ClinicalTrials.gov on October 16, 2022 (registration number: NCT05603364).