Comparison of the analgesic effect before and after injection of hyaluronic acid in patients with knee osteoarthritis in Amir A\'alam hospital

Background: One of the most important issues for patients with osteoarthritis is reducing pain and returning them to normal life. In addition to losing weight and improving daily activities, pain management treatments may be needed. One of these treatments is the injection of hyaluronic acid gel into the knee joint, which has been studied in this study. Methods: In this study, 61 patients with knee osteoarthritis were included and the Then, they received the injection of hyaluronic acid gel, and the intensity of pain, range of motion of the knee joint, and inflammation of the knee joint were measured. The numeric rating scale was used to measure pain intensity, and movement angle was used to measure the range of motion Results: The mean age of patients in this study was 60.52±11.77 years. Pre-injection pain index in patients was 7.90±0.99, which decreased to 5.49±1.91 on the third day, 5.98±1.98 on the seventh day and 3.77±2.91 on the 30th day (P<0.001). The amplitude of painless movement based on the degree before injection in patients was 38.85±19.44 which increased to 60.25±21.65 on the third day to 65.25±22.65 on the seventh day and to 71.07±24.17 on the 30th day (P<0.001). Inflammation rate was reported before injection in 29 patients which decreased to 6 patients on the third day after injection (P=0.009). Conclusion: Injection of hyaluronic acid into the joint has analgesic effects and significantly improves the function and range of motion of patients. It is recommended that hyaluronic acid could be considered as a suitable drug in the treatment process of these patients. Considering that using this method, which is a useful treatment method in reducing patients' pain and improving their function, we recommend this method, especially in the elderly and without the need for surgery.