Dose Dependent Effects of tDCS on Post-Operative Pain (tDCS-TKA)

The proper control of acute and chronic pain is one of the most important areas in health care. Despite the profound advances in neuroscience over the past 20 years, the investigators still largely use opiate narcotics, much as was done in the Civil War. Total knee arthroplasty (TKA) is one of the most common orthopedic procedures performed 1. While knee pain is often a complaint that precedes TKA, the procedure itself is associated with considerable post-operative pain lasting days to weeks. Adequate postoperative pain control is an important factor in determining recovery time and hospital length of stay. New analgesic strategies are needed that can be used adjunctively to existing strategies with the potential to reduce reliance on opioid analgesia. Several novel brain stimulation technologies including transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are beginning to demonstrate promise as treatments for a variety of pain conditions. Electricity has no metabolite or other residue, and can be delivered with minimal discomfort and without problems associated with drug-drug interactions. In two independent preliminary pilot studies, the Investigators have shown that tDCS can reduce post-operative PCA use by as much as 46% while simultaneously reducing subjective pain ratings. The present study aims to determine the effects of transcranial direct current stimulation (tDCS) on post-operative pain, patient-controlled analgesia (PCA) use, and post-surgical complications during the 48-hour post-operative period following total knee arthroplasty.

The proposed study employs a randomized, double-blind, sham-controlled design to evaluate the effects of tDCS on pain among Veterans receiving unilateral total knee arthroplasty (TKA) and unilateral total hip arthroplasty (THA). Further, this study will examine dose-dependency of the tDCS analgesic effects. Each tDCS session delivered either 20 min of real or sham tDCS. Real tDCS was administered at 2mA whereas sham tDCS delivered none. 120 patients undergoing TKA will be randomly assigned to one of four groups:Group 1 will have 4 sessions of real tDCS, Group 2 - 2 sessions of real tDCS (+ 2 sham-sessions), and Group 3 - 1 session of real tDCS (+ 3 sham-sessions). Group 4 is "Sham" tDCS, which does not involve any real stimulation. The participants will receive 2 tDCS treatments on the day of their surgery, and 2 tDCS treatments the day after their surgery.

total knee arthroplasty, pain, post-surgical pain, opioid, transcranial direct current stimulation, tDCS, brain stimulation, total hip arthroplasty, TKA, THA

Stimulation of brain areas associated with pain perception using low amplitude direct current of 2mA delivered by electrodes attached to the scalp.

Stimulation of brain areas associated with pain perception using low amplitude direct current of 2mA delivered by electrodes attached to the scalp. 2 real sessions of tDCS and 2 sham.

Stimulation of brain areas associated with pain perception using low amplitude direct current of 2mA delivered by electrodes attached to the scalp. 1 real sessions of tDCS and 3 sham.

Patient Controlled Analgesia pump usage will be measured (mg of morphine-equivalent) during the acute post-operative period.

Patients reported pain intensity using a visual analog scale (VAS) before and after each tDCS session during the 2 day routine postoperative hospital stay. Patients reported pain intensity by marking a line anchored with a minimum of "0- no pain at all" to maximum of "10- worst pain imaginable." Lower values represent a more favorable outcome. This outcome data is the sum of all VAS scores collected before and after each tDCS session during the 2-day hospital stay, thus each participant had a total of 8 VAS scores during the experimental intervention during hospital stay.

Visual analogue scale pain ratings will be collected during the perioperative and post-discharge periods . Visual analogue scale ratings range from 0-10; a blank line is anchored with a 0 and 10 with the following labels: "0- no pain," "10-worst pain imaginable."

Inclusion Criteria: Participants will be 120 patients undergoing TKA or THA surgery at the Ralph H. Johnson VAMC in Charleston SC. Between the ages of 19 and 90 Mentally capable of reading, writing, giving consent, and following instructions Cleared for and scheduled for unilateral TKA or THA surgery Exclusion Criteria: Implanted medical devices above the waist Pregnant History of seizures Allergic to latex rubber Psychiatric conditions other than for depression and/or anxiety disorders