Study subjects
From December 2020 to November 2021, consecutive patients were evaluated for primary knee osteoarthritis and scheduled for a TKA at the Department of Orthopedic
Surgery,Hunan Provincial People‘s Hospital. All patients gave informed consent to the research protocol, which was approved by the hospital ethics committee (ethics number: LL-20211206-3). Inclusion criteria: ①The diagnosis met the diagnostic criteria for osteoarthritis; ②The patient underwent unilateral total knee arthroplasty; ③The patient had no history of open trauma, fracture, or surgery in both knees; ④No patella replacement was performed during the operation. Exclusion criteria: ① Patients underwent joint arthroplasty due to joint deformity caused by rheumatoid arthritis; ② Patients had immunodeficiency diseases, diseases of important organs such as heart, liver and kidney, history of gastrointestinal bleeding, abnormal coagulation function, etc.; ③ There is the occurrence of deep vein thrombosis of lower extremities during perioperative period; ④ The patient has a history of mental illness, mental retardation, language and communication disorder, and mental illness.
Surgical methods
All patients were classified according to the ASA (American Society of Anesthesiologists' Physical Status Classification) scoring system and administered general anesthesia by the same senior anesthesiologist using the same anesthesia protocol. After successful tracheal intubation under general anesthesia, a tourniquet was applied with a pressure of 40 kPa. The standard anterior median incision of the knee joint and the medial approach of the patella were used for the surgical approach. The length of the incision was about 10 cm, and the joint cavity was fully exposed. Patelloplasty was performed afterward to make it an "I" type patella, followed by electrocautery and denervation along the periphery of the patella. After checking the flexion and extension of the knee joint and the sliding of the patella, the tourniquet was released to completely stop the bleeding. After closing the incision, 1 g of tranexamic acid was injected into the joint cavity. No negative pressure drainage tube was placed at the wound. All operations were performed by the same surgical team.
Pain management
After the patients were admitted to the hospital, all patients were given pain-related health education training, and the patients were instructed to use the pain scoring tool correctly. The 1st day before the operation, the patients were informed of the whole procedure of the operation, the method of postoperative rehabilitation training, the possible risks and complications of the operation, etc., so as to help the patients to eliminate tension and anxiety. Different patients will suffer from different degrees of pain during the rehabilitation training process. In order to reduce the deviation of the research results, the rehabilitation training of all patients in this study was guided by the same rehabilitation practitioner. After returning to the ward, the patients will be instructed to perform ankle pump exercise, quadriceps contraction, and passive lower limb massage after anesthesia and waking up. On the 1st postoperative day, straight leg raising exercises, ground activities, and active and passive knee bending exercises will be performed. All patients received oral celecoxib at 8 pm preoperatively and at 6 am in the morning, 200 mg/d. After surgery, all patients received intravenous parecoxib sodium 40 mg added to saline 100 ml at a rate of 60 drops/min, 2 times/d, for 7 d. Ice packs were applied 3 times/d, 20 min/d, after rehabilitation exercises. Patients were temporarily given the opioid prednisolone 100 mg or dulcolax 50 mg as a remedy in case of sudden onset of severe pain.
Pain assessment
Pain at rest (supine position) and pain at exercise (5 min after walking) of the patient's knee joint was assessed. Evaluation time: at admission (T0), 1 day after surgery (T1), 3 days after surgery (T2), 5 days after surgery (T3), and 7 days after surgery (T4). Pain was scored by 2 investigators using the Numeric Rating Scale (NRS). "0" means no pain, "10" means the most severe pain (intolerable). After the operation, 2 investigators used a numerical scale (NRS, 0 represents no pain, 10 represents the most severe pain) to score. A score of 1~3 indicates mild pain, indicating that the patient can tolerate it; a score of 4~6 indicates moderate pain, indicating that the patient suffers from pain and the pain affects sleep; a score of 7~9 indicates severe pain, indicating that the patient has severe pain and the pain is unbearable.
Skin temperature measurement point and measurement time
Temperatures were determined using a non-contact infrared sensor thermometer at four different locations on the front of the knee (supermedial, superior lateral, inferior medial, and inferior lateral patella). Take the average of the temperature of four positions as the final temperature. The same measurement method was used for the measurement of the contralateral knee joint. 14:00 p.m. is the time point when the temperature difference between the two sides of the skin is the largest, and this time point is used as the standard measurement time point [13]. For each patient, the same measuring instruments were used throughout the study. The ambient temperature was 24℃-26℃ during measurement, and the measurement time was: admission (T0), 1 day after operation (T1), 3 days after operation (T2), 5 days after operation (T3), and 7 days after operation (T4) .
Quantitative analysis of inflammatory cytokines
Venous blood samples were collected on an empty stomach in the morning at the time of admission (T0), 1 day after surgery (T1), 3 days after surgery (T2), 5 days after surgery (T3), and 7 days after surgery (T4). The levels of inflammatory cytokines, including ESR, CRP, IL-6, PCT were measured by the Department of Laboratory Medicine of our hospital certified by the College of American Pathologists.
Statistical analysis
SPSS 25.0 statistical software was used to carry out statistical analysis and processing of the collected data. The statistical description of measurement data is represented by, Comparison of postoperative pain and skin temperature with preoperative pain and skin temperature, and comparison of skin temperature between healthy knee and operated knee at the same time point use paired samples t-test. C-reactive protein, erythrocyte sedimentation rate, procalcitonin and other indicators were compared with preoperative Wilcoxon signed rank test. Spearman rank correlation was used to analyze the correlation between pain, skin temperature, C-reactive protein, erythrocyte sedimentation rate, and procalcitonin. P<0.05 indicated a statistically significant difference.