This prospective study is intended to compare the analgesic efficacy, preservation of lower extremity motor power and side-effect profile of L2 Paravertebral lumbar plexus approach compared to Posterior nerve stimulation guided lumbar plexus approach, continuous local anesthetic infusion postoperative analgesia of Total Hip Arthroplasty.

The L2 Paravertebral technique of lumbar plexus block, as part of a multimodal pain treatment, could be a cost-effective alternative with a equal profile of analgesic efficacy and motor power sparing with greater promotion of early achievement of postoperative physical therapy goals.

The nerve stimulator guided technique of continuous lumbar plexus block (LPB) is the accepted standard of care at University of Pittsburgh Medical Center (UPMC) for the management of postoperative analgesia after Total Hip Arthroplasty. Over 900 continuous lumbar plexus blocks were performed at UPMC Presbyterian Shadyside hospital within the last year alone. Continuous thoracic paravertebral block (TPVB) is also commonly performed at UPMC Presbyterian Shadyside . Over 2000 are performed annually for a wide variety of surgical procedures. Recently authors have suggested that a lumbar paravertebral block (LPVB) may represent an alternative approach to the lumbar plexus. Indeed the L2 paravertebral approach of the lumbar plexus has been described to provide adequate postoperative analgesia following hip arthroscopic surgery. However, to date, there is no prospective direct comparison between L2 Lumbar plexus approach and the posterior approach for postoperative analgesia after Total Hip Arthroplasty.

Inclusion Criteria:

• Age between 18-75 years
• No contraindications to placement of a lumbar plexus posterior block or paravertebral block.
• ASA status I-III
• Scheduled for open total hip arthroplasty with the same surgeon.
• Patients without painful conditions or chronic use of opioid or antineuropathic medications.
• Patient who are not expected to receive therapeutic anticoagulation in the postoperative period.
• No Known allergies to the medications used in the study.
• Patients willing to receive spinal anesthesia

Exclusion Criteria:

• Age under 18 years or older than 75 years.
• Any contraindication to a placement of continuous lumbar plexus Block.
• American Society of Anesthesiologist physical status IV or greater.
• Chronic painful conditions.
• Preoperative opioid tolerant use.
• Coagulation Abnormalities or patients who are expected to be on therapeutic anticoagulants postoperatively.
• Allergy to any of the drugs/agents used study protocol.
• Personal or family history of malignant hyperthermia.
• Serum creatinine greater than 1.4 mg/dl.
• Pregnancy
• Having an altered mental status (not oriented to place, person, or time)
• Any comorbid condition that, in the judgment of the consulting orthopedic surgeon, or intraoperative anesthesiologist, would proscribe the patient from any aspect of the study.
• Patient refusal.
• Lumbar plexus block performed with loss of resistance technique
• Patient requiring postoperative management in the ICU