This is a case series to assess the clinical utility of an Intra-articular Posteromedial Surgeon Administered (IPSA) Block in patients undergoing primary unilateral total knee arthroplasty.

EXPAREL is approved by the Food and Drug Administration (FDA) for use in adults to produce postsurgical regional analgesia via an adductor canal block. The purpose of this study is to evaluate the clinical utility of a surgeon administered EXPAREL adductor canal block intraoperatively in patients undergoing primary unilateral total knee arthroplasty (TKA).

Patients will not be randomized - all patients will receive an EXPAREL IPSA block intraoperatively. Visual Analog Scale, patient reported outcomes, and patient's satisfaction with pain management will be recorded. Adverse events will be monitored.

Inclusion Criteria:

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

Exclusion Criteria:

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, non-steroidal anti-inflammatory drugs (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. Previous open knee surgery on the knee being considered for TKA. Prior arthroscopy is permitted.
6. History of, suspected, or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years.
7. Uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the Investigator, could interfere with study assessments or compliance.
8. Currently pregnant, nursing, or planning to become pregnant during the study.
9. 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.
10. Chronic opioid use (average ≥30 oral morphine equivalents/day) within 30 days prior to surgery.