Background:
'Omnipresent' is a common word that people living with knee osteoarthritis (KOA) use to describe the associated pain, with its unpredictability causing physical, social and emotional disruption. For many, KOA pain leads to limited mobility, reduced quality of life and increased healthcare costs KOA pain and its mechanisms are known to be complex, with alterations in nervous system signaling (ANSS) leading to persistent pain, and treatment failure to guideline-based care. Unfortunately, there is a lack of effective conservative treatments for KOA pain, including exercise which elicits only modest analgesic effects and has little impact on ANSS. To improve conservative pain management for people with KOA, it is imperative to design mechanism informed interventions and explore bold new ways to modulate ANSS to optimize patient outcomes.
The investigators' novel intervention is focused on addressing the biomarker of ANSS. The investigators' solution involves using non-invasive brain stimulation (NIBS) in the form of transcranial direct current stimulation (tDCS), paired with the mind-body practice of yoga, to modify neural pathways. This is a promising and safe alternative to medications - which risk habituation, adverse events, and addiction - and that builds on the limited efficacy of performing/examining exercise in isolation. To the investigators' knowledge, this is the first trial to use this combination for chronic pain and in people with KOA. The investigators have chosen this combination as tDCS has the potential to produce synergistic nervous system effects with yoga and bolster impacts on pain.
tDCS alleviates pain in older adults with KOA, particularly when combined with strengthening exercise or mindfulness. tDCS has demonstrated improved efficiency of conditioned pain modulation (CPM) resulting in pain reduction in older adults with KOA displaying deficient CPM. Meta-analyses of tDCS for the treatment of chronic pain report small to moderate effects on pain reduction, while a meta-analysis of NIBS (including tDCS) plus exercise showed moderate to large effect sizes (-0.62) compared to sham NIBS plus exercise.
The investigators' approach combining 13 sessions of tDCS with yoga provides the benefits of strengthening and mindfulness in addition to nervous system regulation with the potential to produce large effects for pain reduction.
Yoga modulates brain networks and is safe and accessible for many with KOA Importantly, yoga is safe for people with comorbidities through its combination of physical postures, breathing exercises, meditation and relaxation that are hypothesized to reduce pain by regulating top down and bottom-up input into the physiological systems modulating nociceptive signals. Evidence from fMRI studies indicates that yoga modifies functional connectivity in networks involved in chronic pain. Yoga is conditionally recommended by KOA guidelines due to low quality evidence and few studies.
The current project seeks to shift the current paradigm for conservative pain management for people with KOA by assessing a pain mechanism informed treatment strategy in a multi-center pilot and feasibility randomized controlled trial. The investigators hypothesize that real tDCS and yoga will provide clinically meaningful reductions in pain compared to sham tDCS and yoga.
This is a feasibility and pilot double-blind, randomized sham-controlled multi-center, two-arm clinical trial with a 1:1 allocation ratio. Participants will be randomized to receive active or sham tDCS and yoga for 9 weeks. Follow-up will occur at the end of the intervention and at 3 months. The Conceptual Framework for Defining Feasibility and Pilot studies, and the Standard Protocol Items- Recommendations for Intervention Trials will be used. Study results will be reported using the extended CONSORT guideline for pilot trials and the Check List Standardizing the Reporting of Interventions For Yoga (CLARIFY).
