Impact of Plantar Massage and Ankle Mobilization on Visual Reliance in Those With Chronic Ankle Instability : A Randomized Controlled Trial

Context: Those with chronic ankle instability (CAI) rely more on visual information to maintain postural control. Plantar massage and ankle joint mobilization are moderately successful at improving CAI-associated postural control impairments. Manual therapies may have a larger influence on the underlying sensory strategy used to maintain postural control, but their effect on these strategies remains unknown. Objective: To evaluate the effects of separate 2-week plantar massage and ankle joint mobilization interventions on estimates of visual reliance during single-limb stance in those with CAI and determine whether changes in visual reliance estimates were driven by concurrent changes in peripheral-or spinal-level sensorimotor function. Design: Randomized controlled clinical trial. Setting: Research laboratory. Patients: Sixty participants with CAI. Interventions: Participants were equally randomized into plantar massage, ankle joint mobilization, and control (no intervention) groups. The manual therapy groups received six 5-minute treatments of their respective interventions over a 2-week period. Main Outcome Measure: A percentage modulation outcome quantified an individual's reliance on visual information by estimating the weight given to visual information during eyes-open stance based on the magnitude of postural instability that occurs with vision removed. Secondary measures included joint position sense, plantar light-touch thresholds, and the H-reflex. Outcomes were captured before (baseline), immediately after (post), and 1-month (follow-up) after the 2-week intervention. Results: Plantar massage resulted in significant percentage modulation changes in sagittal (P <= .046) but not frontal plane outcomes (P >_ .069) relative to the control group. Joint mobilization did not alter percentage modulation changes (P >_ .413). Significant correlations between percentage modulation changes and peripheral sensorimotor function were noted primarily at the 1-month followup. Conclusions: A 2-week plantar massage but not an ankle joint mobilization intervention alters sagittal plane percentage modulation values during single-limb stance in those with CAI. These changes may be driven by changes in peripheral sensorimotor function.