Mepivacaine Versus Low-Dose Bupivacaine For Primary Total Hip and Knee Arthroplasty

Inclusion criteria

• American Society of Anesthesiologists (ASA) physiological status I-III (patient must meet criteria of a status I-III in the ASA Physical Status Classification System: I=Normal Healthy Patient, II=Mild Systemic Disease, and III=Severe Systemic Disease)
• Unilateral primary TKA or THA
• 18+ years of age
• Able to provide informed consent

Exclusion criteria

• Chronic pain syndromes such as fibromyalgia or complex regional pain syndrome
• Chronic opioid use (>1 mos) with OME >5 mg/day OR acute opioid use (< 1 mos) with OME > 30 mg/day.
• Body mass index (BMI) > 45 kg/m2
• Severe drug allergy* to medications used in this study, including non-steroidal anti-inflammatory drugs (i.e. celecoxib and ketorolac), and local anesthetics (defined as an immune reaction resulting in shortness of breath, hives, anaphylaxis, wheezing, and fever)
• Major systemic medical comorbidities such as:

• Pre-existing severe renal disorder defined as glomerular filtration rate (GFR) <50 units/m2 (if labs are available), currently on dialysis, or highly suspected based on history.
• Severe hepatic disorder defined as current or past diagnosis of acute/subacute necrosis of liver, acute hepatic failure, chronic liver disease, cirrhosis (primary biliary cirrhosis), chronic hepatitis/toxic hepatitis, liver abscess, hepatic coma, hepatorenal syndrome, other disorders of liver
• Contraindication to spinal anesthesia technique (e.g., known spinal stenosis, coagulopathy, sepsis, infection at site of injection, uncooperative, refusal, anticoagulation medications not held within appropriate time frame*). *Per ASRA guidelines, Clopidogrel (Plavix) held for at least 7 days, Dabigatran (Pradexa) held for at least 5 days, Rivaroxaban (Xarelto)held for at least 3 days, Warfarin (Coumadin)held for at least 5 days or recent INR of less than 1.4, Enoxaparin (Lovenox) with doses > 1 mg/kg held for close to 24 hours.
• Known to be currently pregnant or actively breastfeeding. Patients that have a previous history of menopause, hysterectomy, or tubal ligation will not be required to perform a pregnancy test. Female patients that do not meet this criterion will be asked to submit a urine sample, and will require a negative urine sample in order to proceed with study protocol. Urine sample be collected pre-procedurally.
• Impaired cognition