Phase Ⅱ, randomized, double-blind, comparator-controlled study to evaluate the efficacy, safety and pharmacokinetics of single injection adductor canal block with HR18034 for postoperative pain management compared with ropivacaine.

Inclusion Criteria:

1. Able and willing to provide a written informed consent
2. Scheduled to undergo primary unilateral total knee arthroplasty under general anesthesia.
3. Male or female，aged 18-75 years inclusive
4. Body mass index (BMI) 18-28 kg/m2 inclusive
5. American Society of Anesthesiologists (ASA) Physical Status Classification Ⅰ~Ⅱ

Exclusion Criteria:

1. Subjects with deformity of the involving operative limb, or other neuropathy
2. Subjects with a history of new myocardial infarction or unstable angina within 6 months prior to randomization;
3. Subjects with a history of ischemic stroke or transient ischemic attack (TIA)
4. Subjects with a history of mental system diseases and cognitive dysfunction
5. Combination of other pain conditions that may affect postoperative pain assessment
6. Persistent or recurrent nausea and/or vomiting due to other etiologies, including, but not limited to gastric outlet obstruction, hypercalcemia, or active peptic ulcer
7. Subjects with a history of deep vein thrombosis-related disease
8. Clinically significant abnormal clinical laboratory test value
9. Allergic to a drug ingredient or component
10. Use of any of medications, which affect drug metabolism or analgesia evaluation, within 5 half-lives or as specified prior to the study surgical procedure
11. History of alcohol abuse or prescription and/or illicit drug abuse
12. Subjects with special diets (including tobacco, grapefruit and caffeine)
13. Pregnant or nursing women
14. No birth control during the specified period of time
15. Participated in clinical trials of other drugs (received experimental drugs)
16. The inestigators determined that other conditions were inappropriate for participation in this clinical trial