The early and delayed analgesic effects of ketamine after total hip arthroplasty: a prospective, randomized, controlled, double-blind study.

BACKGROUND:Ketamine has been shown to have a morphine-sparing effect soon after surgery. Nevertheless, whether this effect still exists after being combined with nonsteroidal antiinflammatory drugs and acetaminophen, and whether ketamine can decrease chronic pain after nononcologic surgery remain un