Obesity as a predictor of postoperative pain and prothrombotic changes in patients following arthroscopic anterior cruciate ligament reconstruction

Abstract

Background. Anterior Cruciate Ligament (ACL) injury is one of the most common causes of knee joint instability. Aim. To determine the clinical and laboratory characteristics of patients with isolated anterior cruciate ligament injury and obesity prior to arthroscopic reconstruction and to identify predictors of increased postoperative pain intensity in this population. Materials and Methods. A single-center prospective controlled study was conducted involving 90 patients with isolated ACL injury of the knee joint treated between 2022 and 2024 at the Department of Traumatology, Municipal Non-Profit Enterprise of Kharkiv Regional Council "Regional Clinical Hospital". The study group included 38 patients with obesity (Body Mass Index (BMI) ≥30 kg/m²), while the control group comprised 52 non-obese patients. Blood glucose levels and coagulation parameters (Prothrombin Time (PT), ProThrombin Index (PTI), International Normalized Ratio (INR), activated Partial Thromboplastin Time (aPTT), Thrombin Time (TT), and fibrinogen) were assessed. Pain intensity at 1 month after ACL reconstruction was evaluated using the Visual Analog Scale (VAS), and factors associated with pain intensity were analyzed. Statistical analysis was performed using SPSS Statistics 25.0 (IBM, USA), nonparametric methods, and multiple linear regression. This study was conducted as part of the author’s dissertation research without external funding or formal clinical trial registration. Research Ethics. All participants provided informed consent. The study was conducted in accordance with the principles of the Nuremberg Code and the World Medical Association Declaration of Helsinki (1964–2024). Ethical approval was obtained from the Bioethics Committee of Kharkiv National Medical University (Protocol No.4 of April 01, 2025). Results. Patients with obesity demonstrated a statistically significant but small absolute reduction in aPTT – 31.00 [30.70÷32.25] s versus 31.50 [31.30÷31.70] s in the non-obese group (p=0.014). Both values were within the laboratory reference range. In the final exploratory regression model, obesity (β=0.475; 95% CI [0.205÷0.745]; p=0.001) and higher preoperative pain level (β=0.234; 95% CI [0.062÷0.406]; p=0.008) were the most clinically consistent factors associated with pain intensity at 1 month after ACL reconstruction. Conclusions. Obesity was independently associated with more severe pain at 1 month following reconstruction. Patients with obesity demonstrated a statistically significant but small absolute difference in aPTT, while other coagulation parameters remained comparable between groups. Clinical thrombotic events were not assessed.