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

Study Overview
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Brief Summary
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Chronic pain in patients following total hip replacement seems to be a significant problem. Previous research has shown that more effective pain management in the early postoperative period may decrease the incidence of the development of chronic pain states. This study will evaluate whether ketorolac (a non steroidal anti-inflammatory drug) given into the spinal fluid before surgery will reduce the area of sensitivity (or pain to light touch) following surgery. Patients will be monitored during their postoperative hospital stay and then contacted by telephone at 8 weeks and 6 months after surgery and questioned about any pain they are having at their surgical site. Patients that are still experiencing pain at 6 months will be asked to return to the medical center for the study staff to assess their pain or sensitivity at the surgical site.

Detailed Description
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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.

Official Title
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Effect of Intrathecal Ketorolac on Mechanical Hypersensitivity After Total Hip Arthroplasty

Conditions
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Hip Arthroplasty

Intervention / Treatment
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* Drug: ketorolac tromethamine opthalmic solution
* Drug: placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists (ASA) physical status I, II, III > Age 18 Primary unilateral total hip arthroplasty under spinal anesthesia Exclusion Criteria: Known allergy to study medication Weight > 300 pounds Obstructive sleep apnea Patients with severe renal (kidney) or hepatic (liver) disease, allergy to ketorolac, amino amide local anesthetic, or contraindications to spinal anesthesia Patients on dialysis for kidney failure or patients that are jaundice or have a diagnosis of liver failure Patients routinely taking narcotic pain medications for pain other than their primary hip pain Patients that are taking Lyrica (pregabalin) or Gabapentin (neurontin) for the treatment of seizures

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Ketorolac<br>ketorolac 2 mg ketorolac tromethamine opthalmic solution | Drug: ketorolac tromethamine opthalmic solution<br>* ketorolac 2 mg will be added to the patient's routine spinal anesthetic for surgery<br>* Other names: Ketorolac;|
| Placebo Comparator: Placebo<br>placebo will be added to the patient's routine spinal anesthetic for surgery | Drug: placebo<br>* placebo will be added to the patient's routine spinal anesthetic for surgery<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Area of Hypersensitivity to Mechanical Stimuli Surrounding the Wound 48 Hours After Surgery | Hyperalgesia (using a von Frey filament) and allodynia (using a cotton swab) were evaluated around the surgical site 48 hours after surgery. | 48 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Present Pain Intensity | Pain was assessed preoperatively, 2 days, and 2 and 6 months after surgery using a 0-10 (10 being worse) verbal Present Pain Intensity (PPI) scale | 6 months | 
| McGill Pain Intensity | Pain was assessed 2 days and 2 and 6 months after surgery using a validated questionnaire wherein subjects rate the degree to which adjectives describe the intensity of their pain experience. This is termed the McGill Pain Intensity Score and is scored from 0 to 33 with 33 being the highest pain intensity. | 6 months | 
| McGill Affective Pain | Pain was assessed 2 days, and 2 and 6 months after surgery using a validated questionnaire wherein subjects rate the degree to which adjectives describe the emotional component of their pain experience. This is termed the McGill Pain Affective Score and is scored from 0 to 12 with 12 being the highest pain emotional impact. | 6 months | 
| Neuropathic Pain Symptom Inventory | Pain was assessed 2 days, and 2 and 6 months after surgery using a validated questionnaire to assess the degree of neuropathic characteristics of pain. This is termed the Neuropathic Pain Symptom Inventory which is scored 0-100 with 100 being the worst possible pain. | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Total hip arthroplasty, Total hip replacement, Pain, postoperative, Ketorolac, Patients undergoing unilateral total hip arthroplasty