The purpose of this study is to determine whether a new medical technology can help reduce post-operative total knee or hip pain when combined with a Cognitive-Behavioral intervention (CBI).

This new medical technology, is called transcranial direct current stimulation (tDCS), it uses a very small amount of electricity to temporarily stimulate specific areas of the brain thought to be involved in pain reduction. The electrical current passes through the skin, scalp, hair, and skull and requires no additional medication, sedation, or needles.

This study will investigate the effects of tDCS, the Cognitive-Behavioral (CB) intervention and their combination on pain among veterans following total knee arthroplasty (TKA) or total hip arthroplasty (THA). You may benefit in the form of decreased pain and opioid requirements following your knee or hip replacement surgery. However, benefit is only likely if you are randomized to one of the 3 (out of 4) groups.

This study hopes to determine the effects of these interventions and their combined effect on post-operative pain, opioid use and functioning during the 48-hour post-operative period following a total knee or hip replacement.

This study aims to evaluate the effects of odor on pain perception. Specifically, this study will determine whether healthy subjects will indicate greater pain tolerance to a heat stimulus while smelling different odors.

This study is to evaluate the effects of cognitive behavorial therapy in combination with tDCS (transcranial direct current stimulation) improving chronic pain and functionality, reducing severity of opioid use disorders, improve sleep, and reducing impairment in associated mental health areas (e.g., depression, anxiety, PTSD).

This study will investigate whether a new medical technology can help reduce post-operative pain in patients undergoing total knee or total hip replacements. The new technology is called Transcranial Direct Current Stimulation (tDCS) and uses a very small amount of electricity to temporarily stimulate specific areas of the brain. The electrical current passes through the skin, scale, hair, and skull and can temporarily increase or decrease activity in the areas of the brain that are thought to be involved in pain reduction. The tDCS sessions last 20 minutes, and patients will be asked to report pain ratings. This study in specific hopes to determine optimal tDCS dosing parameters before tDCS will become a viable clinical intervention for post-operative pain across surgical specialties.