Analgesic Efficacy of Preemptive Stepwise Infiltration Anesthesia for Perioperative Analgesia After TKA

Inclusion Criteria: Patients must meet all of the following criteria to be eligible for inclusion: 1. Clinical diagnosis of primary unilateral knee osteoarthritis (KOA), confirmed by imaging as KOA (Kellgren-Lawrence score ≥2). The patient was scheduled for initial unilateral total knee arthroplasty (TKA) at our hospital. 2. Preoperative American Society of Anaesthesiologists (ASA) score ranging from 1 to 3. Surgeons deemed the patient eligible for TKA based on the evaluation criteria. 3. Participants aged 18 years or older, both male and female. 4. Ability to provide informed consent and sign a written informed consent form. 5. The ability to comprehend the research requirements and willingness to cooperate with the study instructions. Exclusion Criteria: Patients will be excluded if they meet any of the following criteria: 1. Previous knee surgery on the operative knee or a history of infection in the operative knee. 2. Patients diagnosed with conditions other than osteoarthritis (including rheumatoid arthritis, traumatic arthritis, septic arthritis and haemophilic arthritis). 3. Severe osteoarthritis (including flexion contracture \>30° or varus/valgus deformity \>30° and the use of unconventional arthroplasty components due to complex joint pathology \[e.g., restrictive prostheses\]). 4. Allergy to the investigational drug. 5. The presence of neuromuscular dysfunction on the operative side. 6. Dependence on anaesthesia drugs (defined as the use of opioid or local anaesthetic drugs exceeding 100 mg of morphine equivalents per week to control preoperative pain for more than 3 months). 7. Poor overall health conditions, including but not limited to a glycated haemoglobin level exceeding 12%; blood pressure exceeding 170/110 mmHg; myocardial infarction, stroke, transient ischaemic attack, acute congestive heart failure, or any acute coronary events within the past 6 months; severe hepatic or renal dysfunction; and pregnancy or lactation. 8. Concurrent participation in clinical trials other than this trial.