The goal of this prospective observational study is to explore the feasibility of preoperative peripheral venous cannulation pain score in predicting acute pain after total knee arthroplasty, including resting pain and movement-evoked pain.

Inclusion Criteria:

1. Patients undergoing the first unilateral total knee arthroplasty surgery under general anesthesia combined with nerve block ;
2. Age : 18 years old ≤ age ≤ 80 years old ;
3. ASA grade I-II ;
4. Informed consent was signed by patients or immediate family members before operation.

Exclusion Criteria:

1. There are known pain abnormalities, mental disorders, cognitive dysfunction ;
2. patients with long-term use of opioids and a history of drug dependence ;
3. patients with alcohol dependence ;
4. the patient refused to use the analgesic pump ;
5. Difficult to understand the VAS score ;
6. body mass index ≥ 40 ;
7. hand nerve abnormalities, hand loss ;
8. plan postoperative ICU patients ;
9. In other cases, the researchers believe that is not suitable for this researcher.

Patients undergoing unilateral total knee arthroplasty for the first time under general anesthesia combined with nerve block