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).