Determining the risk factors for hyperglycemia and glucose variability after total knee arthroplasty with continuous glucose monitoring: An observational cohort study

Introduction: Periprosthetic joint infection after total knee arthroplasty (TKA) is a devastating complication and different risk factors, including hyperglycemia and increased glucose variability, have been suggested for this condition in previous literature. Our study aims to investigate the risk factors for postoperative hyperglycemia and glucose variability in patients undergoing unilateral primary TKA with continuous glucose monitoring (CGM) technology. Methods: Demographic factors, diabetic statuses, hemoglobin A1c (HbA1c) levels, and fructosamine levels of patients undergoing unilateral primary TKA were recorded preoperatively. These patients would either received 16 mg intravenous dexamethasone or no dexamethasone before their surgery as part of perioperative management. From the day of admission to postoperative day 4, CGM device monitored these patients’ blood glucose level, time of hyperglycemia, and glucose variability. Correlation and multivariate regression analysis were performed between the risk factors and the outcome measures, with multicollinearity between the predictor variables checked, to find out the most potent risk factors for postoperative hyperglycemia. Results: Eighty-three patients with primary unilateral TKA were analyzed. Diabetic, prediabetic, and nondiabetic patients were composed of 26.5%, 47.0%, and 26.5%, respectively. The average of HbA1c and fructosamine level was 6.0% and 249.3 mmol/L, respectively; 65.1% of the patients received 16 mg dexamethasone perioperatively. Multivariate regression analysis found that HbA1c, fructosamine, and dexamethasone injections are the significant risk factors for the percentage of time in hyperglycemia ( R2 = 0.374, p < 0.001) and average blood glucose level ( R2 = 0.493, p < 0.001), with HbA1c having the highest standardized coefficient, followed by fructosamine and dexamethasone injections. Although dexamethasone usage was significant in multivariate regression analysis on predicting glucose variability, the effect size of the model is very weak ( R2 = 0.05, p < 0.05). Conclusion: The most potent risk factor for hyperglycemic time and increased average blood glucose is HbA1c level, followed by fructosamine level and dexamethasone injections. No strong correlation was found between the factors in our study and patients’ glucose variability.