Mepivacaine vs Bupivacaine Spinal Anesthesia for TKA

This study is a prospective, double-blind prospective randomized controlled trial comparing mepivacaine and bupivacaine spinal anesthesia for same-day discharge readiness following a unilateral primary elective TKA procedure.

Study data will be collected during the patient's hospital stay for their TKA procedure, and the primary outcome of same-day discharge readiness will be assessed the day of surgery. Patients will also be contacted at Day 3 post-op to assess for any complications, current level of pain, and pain medication utilization.

The purpose of this study is to evaluate the two different spinal anesthesia agents, mepivacaine and bupivacaine, and determine whether there are significant differences in their effects on readiness for same day discharge following a total knee arthroplasty.

This study is a prospective, double-blind prospective randomized controlled trial comparing mepivacaine and bupivacaine spinal anesthesia for same-day discharge readiness following a unilateral primary elective TKA procedure.

Study data will be collected during the patient's hospital stay for their TKA procedure, and the primary outcome of same-day discharge readiness will be assessed the day of surgery. Patients will also be contacted via telephone or RedCap at Day 3 post-op to assess for any complications, current level of pain, and pain medication utilization.

In this double-blind (patients and assessors) study, the patients will be randomly assigned 1:1 to receive one of the following: mepivacaine 1.5% (4.5ml, 67.5mg) or 2% (3.4ml, 67.5mg), (depending on availability from pharmacy) or hyperbaric bupivacaine 0.75% (1.4ml, 10.5mg) from the spinal kit. Randomization will be computer-generated in RedCap. These doses are the currently the standard doses used for our total knee arthroplasty patients. Patients with a height of 74 inches or greater or with body mass index of 35kg/m2 or greater will be given an extra 0.5ml of local anesthetic. The intraoperative anesthesia team will not be blinded to the group assignment, but patients, surgeons, and assessors are blinded. All patients will receive the standard preoperative multimodal analgesia, consisting of celecoxib 400mg po and acetaminophen 1gm po. Research staff will unblind the study investigators immediately if requested for any potential safety concerns.

Eligibility Criteria:
Inclusion Criteria:

* Patient is at least 18 years of age who are scheduled for a primary elective TKA.
* Patient can ambulate at least 10 feet independently without human assistance.
* Patient must be a candidate for same day discharge as determined by American Society of Anesthesiologists (ASA) Physical Status Classification I and II

Exclusion Criteria:

* Patients scheduled for bilateral TKAs
* Contraindication to spinal anesthesia
* Revision TKAs
* Allergy or contraindication to NSAIDs (e.g. chronic anti-coagulant use)
* Workers' Compensation patient
* Type I Diabetes
* Type II Diabetes requiring insulin medication.
* Pre-operative narcotics use with the exception of tramadol.
* Renal insufficiency (GFR \< 60) that may impact post-operative protocol
* Cognitive deficiencies that prevent the patient from providing their own informed consent
* Language barrier preventing completion of study forms in English