Session Title: Rehabilitation Sciences (ARHP)
Session Type: Abstract Submissions (ARHP)
To determine changes in muscle activation in the upper extremity using electromyography (EMG) when static and dynamic orthoses are worn by adults with and without rheumatoid arthritis (RA) during hand function skills and functional tasks.
Ten adults with Rheumatoid Arthritis and five controls were tested in four orthosis conditions (no, static, hinged, spiral) during hand function measures of grip, pinch and dexterity as well as functional tasks of drinking from a 12 ounce soda can, pouring from a 1 liter pitcher, turning a knob on a simulated door, and inserting a coin in a slot. Each participant completed three trials for the strength, dexterity and functional tasks. The order in which the orthoses were worn and was counterbalanced to control for effects of practice and fatigue. Muscle activity of eight muscles involved with reach and grasp were recorded in the dominant upper extremity using surface electromyography (EMG) during execution of the hand function measures and functional tasks. Computer software calculated average integrated EMG of muscles for each participant in each orthosis condition for each measure and functional task which were converted to percentage of maximum voluntary contraction (%MVC). EMGs by shoulder, elbow and wrist muscle groupings were expressed as combined %MVC during grip, pinch, dexterity and functional tasks and were compared across orthotic conditions using multivariate analyses of variance (MANOVAs).
Orthosis use on individuals with RA and controls did not increase or hinder grip or pinch strength or increase speed in dexterity tasks. Compared to the controls, adults with RA demonstrated lower strength on grip and pinch measures and took longer to complete the dexterity task in all orthosis conditions (p < .05). Other group differences were noted in muscle activation (% MVC in shoulder, elbow and wrist muscles) with individuals with RA having less muscle recruitment than controls in all strength, dexterity and functional tasks and in all orthosis conditions (p < .05). EMG differences varied when individuals wore orthoses. During grip, wrist and elbow muscle recruitment was greater than shoulder muscles in both groups in all orthosis conditions. Increased muscle activation in all muscles was noted during two point pinch in both groups when orthoses were worn (p < .05). When all subjects wore orthoses, muscle activation decreased at the wrist during drinking (p < .01). Similarly, individuals used more muscle activation in all muscles during pouring when no orthosis was worn (p< .05). There were no differences in EMG activity between the groups or orthosis conditions for turning the door knob or inserting a coin.
Adults with RA showed less muscle activation than controls during all strength, dexterity, and functional tasks. Both groups had greater EMG activity in the elbow and wrist as compared to the shoulder muscles in all orthosis conditions. Our findings suggest therapists might want to consider the type of tasks their patients need to perform when recommending orthoses as muscle activation may vary depending on the tasks.
J. L. Poole,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/use-of-wrist-hand-orthoses-during-hand-function-skills-and-functional-tasks-by-adults-with-and-without-rheumatoid-arthritis/