A comparison of static and dynamic wrist splints using electromyography in individuals with rheumatoid arthritis.

This study compared strength, dexterity, and the muscle activation of individuals with rheumatoid arthritis (RA) when different splints were worn. Five persons with RA were observed in four splint conditions (none, static, hinged, spiral) during grip, pinch, and dexterity tests by recording muscle activity of eight muscles in the upper extremity using electromyography (EMG). Statistically significant differences were found in clinical tests when hinged (p<0.001) and spiral splints (p=0.02) were worn. Grip strength decreased when hinged splints were worn, whereas two-point pinch increased and dexterity improved on the Nine-Hole Peg Test with the spiral splint. Although no significant EMG differences were found during different splint conditions, wrist muscles were recruited more for grip, and shoulder muscles were used most during pinch and dexterity tests. Individuals with RA who wore splints had decreased grip when wearing hinged splints, but improved pinch and dexterity were found when the spiral splint was worn. Increased use of proximal shoulder muscles was observed during pinch and dexterity tests with and without splints.