The Maximum Threshold Value for HbA1c in Diabetic Patients Undergoing Elective Total Knee Arthroplasty.

Objective: To establish an optimal preoperative HbA1c threshold that enhances surgical outcomes and minimises postoperative complications in diabetic patients undergoing elective total knee arthroplasty (TKA).

Study design: Prospective cohort study. Place and Duration of the Study: Department of Orthopaedics, First People's Hospital of Lianyungang, China, from January 2021 to March 2024.

Methodology: A total of 152 diabetic patients scheduled for elective TKA were included. Data on preoperative HbA1c levels were collected and analysed to assess their impact on postoperative outcomes using the Oxford Knee Score (OKS). Patients were divided into groups based on HbA1c levels and compared for functional and pain recovery one year postoperatively. Statistical analyses included binary and multivariate logistic regression, with an emphasis on the minimum clinically important difference for OKS.

Results: Patients with a preoperative HbA1c below 7.35mmol/L exhibited significantly better functional and pain recovery outcomes at one-year post-TKA. The receiver operating characteristic curve (ROC) analysis confirmed the predictive power of HbA1c, with an Area Under the Curve of 0.734 for functional improvement and 0.721 for pain improvement.

Conclusion: The study identifies 7.35mmol/L as the optimal preoperative HbA1c threshold for diabetic patients undergoing elective TKA, with lower levels associated with improved functional and pain outcomes. Maintaining HbA1c below this level preoperatively can significantly enhance postoperative recovery and patient satisfaction.

Key words: Diabetes mellitus, Total knee arthroplasty, Haemoglobin A1c, Oxford knee score.