EVALUATING THE EFFECTS OF SPLINT, PINCH TYPE, AND WRIST POSTURE ON PINCH STRENGTH

ABSTRACT

Pinch strength applied in repetitive tasks was considered to be highly correlated with cumulative trauma disorders (CTDs). To reduce the magnitude requirement of pinch strength is important to avoid such injuries. But whether the peak pinch strength was affected by wearing wrist splints, sometimes used to protect the wrist from CTDs, is still unknown. This study, therefore, intended to evaluate the effect of wrist splints on the maximum volitional contraction (MVC) of pinch. A total of 24 right-handed volunteers (12 males, and 12 females) were recruited, and a nested-factorial design with subject nested within gender was employed. In addition to splint effect, effects of gender, wrist posture (extension 30°, flexion 30°, and neutral), and pinch type (Pulp2, Pulp3, Chuck, and Lateral) were evaluated, and all were considered as fixed variables. There were twenty-four combinations totally, and two replications were conducted. The ANOVA result showed the effects of gender, pinch type and their interaction were highly significant. But the effects of wrist posture and wrist splint were not. Male exerted much greater than female did under all pinch types, and female MVC was averagely about 56% (2.9kg/5.2kg) of male. For both genders, the MVC of Lateral was the largest, followed by Chuck, Pulp2, and Pulp3. Further according to the result of Duncan's multiple range test, female Lateral MVC and male Pulp2 MVC were not different significantly, as well as female Chuck MVC and male Pulp3 MVC. Wearing splints during repetitive tasks was recommended because it did not influence the pinch MVC or carpal tunnel pressure, and it can keep the wrist in neutral position as possible. In addition, the correlations between pinch MVC and anthropometry and among pinch types were discussed.

Keywords:

• pinch strength
• maximum volitional contraction
• wrist extension/flexion
• posture
• wrist splint
• cumulative trauma disorders