Influence of static wrist orthosis on muscle activity and shoulder and elbow range of motion during a functional task: a biomechanical study

ABSTRACT Orthoses are therapeutic resources that are appropriate to protect and remedy deformities or to help in the performance of certain functions; however, its use may lead to proximal compensations in the shoulder. Thus, this study aims to evaluate the influence of dorsal static 30° extension orthoses on the shoulder and elbow biomechanics in 25 asymptomatic individuals during a functional task. The range of motion and muscle activation was collected by simultaneous and synchronized analysis during the Elui functional test related to feeding, under the conditions with and without the orthosis. In order to allow a comparison of the different subjects and muscles, the data were analyzed by EMG signal of each muscle and, for kinematic analysis, pre-defined marker coordinate systems were constructed. The captured signals were filtered and processed by custom software, and the t-test for paired samples, SPSS® software, p<0.05, was used. We found significant increase in activation of the anterior deltoid and pectoralis major muscle in the reach phase and upper trapezius, anterior and posterior deltoid in the release phase with the orthosis. The kinematic analysis showed a significant increase in the range of motion of shoulder abduction movements, elbow flexion and pronation in the displacement phase and shoulder extension and elbow flexion movements in the release phase. Our findings suggest that the use of static wrist orthosis while performing a task can lead to compensations, with predominant activation of more proximal muscles of the upper limb.