Orthopedic surgery is reportedly among the most painful surgical procedures. Surgical damage following major orthopedic surgery often involves a large, deep incision with considerable tissue dissection and muscle, bone, and vascular exposure. Post-operative pain after such surgery is exacerbated on movement or by reflex spasms of the muscles, which may delay mobilization, reduce satisfaction, prolong hospitalization, and possibly increase medical costs.

We design a prospective randomized study for postoperative pain control following total hip arthroplasty.

Inclusion Criteria:

• diagnosed for surgery of osteoarthritis of hip
• ability to tolerate surgery under general anesthesia.

Exclusion Criteria:

• refusal or the lack of mental ability to provide informed consent
• neuropathic pain or sensory disorders in the leg requiring surgery
• previous surgery of the hip joint
• coagulation abnormalities
• severe renal or hepatic impairment
• chronic opioid users
• known history of intolerance to the drugs used in the study