Intra-articular Posteromedial Surgeon Administered (IPSA) Block in this study describes a new type of medical procedure where a surgeon provides anesthetic medication directly into a specific area inside a knee joint to numb the pain during knee surgery. Intra-articular refers to inside of knee joint, posteromedial refers to the back and inner side of a knee joint, and surgeon administered means a surgeon is performing the procedure.

Patients You will be randomly assigned to one of these three treatment groups:

Group 1:

Patients in this group will receive IPSA block and Local Infiltration Analgesia (LIA).

IPSA block is a pain numbing medication given by surgeon and injected inside the back and inner side of the knee joint. Local Infiltration Analgesia is a pain numbing medication injection given by the surgeon around the surgical knee area. The medications used in the procedure will be EXPAREL, and Bupivacaine HCL.

Group 2 (Control):

Patients in this group will receive Adductor Canal Block (ACB) and Local Infiltration Analgesia (LIA). ACB is a pain numbing injection given by anesthesiologist near the adductor canal, a passage in the mid-thigh that contains nerves connecting the knee region. Local Infiltration Analgesia is a pain numbing medication injection given by the surgeon around the surgical knee area. The medications used in the procedure will be EXPAREL, and Bupivacaine HCL.

Group 3:

Patients in this group will receive Local Infiltration Analgesia (LIA). Local Infiltration Analgesia is a pain numbing medication injection given by the surgeon around the surgical knee area. The medications used in the procedure will be EXPAREL, and Bupivacaine HCL.

The study will evaluate;

• How effective the pain relief is after surgery.
• How much extra pain medication you need.
• Your satisfaction with pain management and recovery
• Any side effects.

The study is a single-center, randomized, pilot study and will recruit up to 60 adult subjects undergoing unilateral total knee arthroplasty. Subjects will be randomized (1:1:1) to receive the treatments. The study participants will be followed for up to 90 days.

Information on analgesic use, pain, satisfaction with pain management will be obtained from patients. Participation begins when you sign the consent form. The treatment will begin on the day of the surgery. Follow up calls will be done 14 days and 90 days after surgery. Your involvement will last about 123 days.

Background and Rationale for the Study:

This study is being conducted to evaluate the clinical effectiveness of the Intra-articular Posteromedial Surgeon Administered (IPSA) block in subjects undergoing total knee arthroplasty (TKA). This study aims to demonstrate that a surgeon administered IPSA block can provide equivalent pain control to an anesthesiologist administered adductor canal block (ACB).

Method of Assigning Subjects to Treatment Randomization Scheme

Randomization Procedures Once a subject is identified as being qualified for the study in accordance with the eligibility criteria, the Investigator or designee will obtain a randomization assignment on the day of surgery. The subject will be considered randomized to the study once the study treatment is assigned.

Replacement of Subjects Subjects who withdraw from the study before the study treatment procedure may be replaced. Once a subject number is assigned, subject numbers will not be reused; subjects enrolled to replace those who withdraw will be assigned a unique subject number and randomized to treatment according to the procedures outlined above.

Subjects who are randomized but are withdrawn from the study before receiving the study drug may be replaced. Additionally, subjects may be replaced if insufficient and/or incomplete data are noted on safety or clinical outcomes.

Inclusion Criteria: Inclusion Criteria:

Subjects must meet all of the following inclusion criteria to be eligible for participation:

1. Subjects ages 18 or older at screening 2. Indicated to undergo primary unilateral total knee arthroplasty under spinal anesthesia 3. Primary indication for TKA is degenerative osteoarthritis of the knee 4. American Society of Anesthesiologists (ASA) physical status 1, 2, or 3 (see Appendix 6) 5. Able to provide informed consent, adhere to the study schedule, and complete all study assessments 6. Body Mass Index (BMI) ≥18 and <40 kg/m2

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Exclusion Criteria:

• Subjects who meet any of the following exclusion criteria will not be eligible for participation in this study:

  1. Allergy, hypersensitivity, intolerance, or contraindication to any of the study medications for which an alternative is not named in the protocol (e.g., amide-type local anesthetics, opioids, bupivacaine HCl, NSAIDs)
  2. Planned concurrent surgical procedure (e.g., bilateral TKA)
  3. Undergoing unicompartmental TKA or revision TKA
  4. Concurrent painful physical condition (e.g. arthritis, fibromyalgia, cancer) that may require analgesic treatment with NSAIDs or opioids in the post dosing period for pain that is not strictly related to the knee surgery and which, in the Investigator's opinion, may confound the post dosing assessments
  5. Inadequate sensory function below the knee as assessed by the Investigator
  6. History of contralateral TKA within 1 year
  7. Previous open knee surgery on the knee being considered for TKA. Prior arthroscopy is permitted
  8. History of, suspected, or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years
  9. Administration of an investigational drug within 30 days or 5 elimination half-lives of such investigational drug, whichever is longer, prior to study drug administration, or planned administration of another investigational product or procedure during the subject's participation in this study
  10. Previous participation in an EXPAREL study
  11. Uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the Investigator, could interfere with study assessments or compliance
  12. Currently pregnant, nursing, or planning to become pregnant during the study
  13. Clinically significant medical disease that, in the opinion of the Investigator, would make participation in a clinical study inappropriate. This includes diabetic neuropathy, coagulation or bleeding disorders, severe peripheral vascular disease, renal insufficiency, hepatic dysfunction or other conditions that would constitute a contraindication to participation in the study.
  14. Any use of marijuana [including Tetrahydrocannabinol (THC) and Cannabidiol (CBD)] within 30 days prior to randomization, or planned use during the course of the study
  15. Chronic opioid use (average ≥30 oral morphine equivalents/day) within 30 days prior to surgery