Effect of Spinal Ketorolac on Mechanical Hypersensitivity After a Total Hip Replacement

Surgery results in hypersensitivity to mechanical stimuli surrounding the wound and in a subset of patients, also results in chronic pain. The purpose of the study is to test whether intrathecal ketorolac, by selectively and effectively blocking cyclooxygenase in the spinal cord, will reduce hypersensitivity surrounding the surgical wound in patients with high risk for developing chronic pain after surgery. We have chosen to study patients having total hip arthroplasty (THA) because chronic pain seems to be a significant problem after surgery. We will sample cerebrospinal fluid (CSF) prior to injection of the study medication for subsequent prostaglandin E2 (PGE2) analysis in each patient. We will also assess each patient at 48 hours after their surgery for hypersensitivity at their surgical site.