Total hip replacement (THR) is a common and major surgical procedure performed in elderly patients with significant comorbidities. Optimizing a patient's anesthetic and analgesic modalities could play a significant role in minimizing the risk of adverse events in the perioperative period and potentially shorten time to discharge and recovery.

Establishing a safe and effective post-operative analgesic plan is of central importance to successful THR anesthesia care. The application of ultrasound visualization has improved the efficacy of the fascia iliaca compartment block (FICB). However, ultrasound-guided suprainguinal FICB has not yet been evaluated clinically in a large trial as a method of providing post-operative analgesia following THR.

The investigators hypothesize that by performing the suprainguinal fascia iliaca block with ultrasound, it will be possible to achieve superior and more reliable analgesia in the first 24 hours than without a block.

The search for the optimal pain treatment strategies is a work in progress. As techniques and technology evolve so should our approach for the best analgesic regimen that would minimize unwanted side effects and potential risk and more importantly improve patient satisfaction.

The literature has supported the use of peripheral nerve blocks for analgesia as well as improved functional outcome after total knee arthroplasty. The addition of peripheral nerve blocks for THR has been more controversial, as the only effective nerve block, the posterior approach to the lumbar plexus, is an advanced regional technique with potential for serious complications. The application of ultrasound visualization has improved the efficacy of the infrainguinal fascia iliaca block. However, ultrasound guided suprainguinal fascia iliaca block has not yet been evaluated clinically in a large trial as a method of providing post-operative analgesia following primary hip arthroplasty.

The investigators hypothesize that by performing the suprainguinal fascia iliaca block with ultrasound, it will be possible to achieve superior and more reliable analgesia than that obtained using the landmark "2-pop" technique and the infrainguinal blocks.

The aim of this study is to assess whether the ultrasound guided suprainguinal fascia iliaca block can provide superior early postoperative analgesia in patients undergoing primary hip arthroplasty, and minimizing the pain immediately after the resolution of the spinal anesthetic.

The investigators propose to perform the first triple-blinded RCT examining the early analgesic efficacy of ultrasound-guided suprainguinal FICB after THR (lateral approach) under spinal anesthesia.

Inclusion Criteria:

• Patients aged 18-75, ASA I-III scheduled to undergo unilateral total hip arthroplasty.

Exclusion Criteria:

• Patients not providing informed consent.
• Refusal of treatment plan.
• Pre-existing medical/neurological/hematologic conditions contraindicated for spinal anesthesia or peripheral nerve blocks.
• Revision total hip arthroplasty.
• Known allergy to any of the medications being used.
• History of drug or alcohol abuse.
• Patients with chronic pain on slow-release preparations of opioid in excess of 30mg of morphine equivalence per day.
• Patients with Rheumatoid Arthritis.
• Patients with psychiatric disorders.
• Patients with prior surgery in the inguinal region or inguinal hernia
• Patients unable or unwilling to use Patient Control Analgesia.
• Diabetic patients with diabetic neuropathy or those with impaired renal function (Creatinine >106).
• Patients with BMI >45.
• Patients with body weight <65kg.