Objectifying the Functional Advantages of Prosthetic Wrist Flexion

In Brief The functionality of a prosthetic device for the upper limb may be increased by incorporation of an additional degree of freedom. A prosthetic wrist joint with flexion and extension allows the manipulation of objects in different ways. Reaching for objects or other dynamic movements is essential in the activities of daily living for all amputees. The range of motion of the upper limb is influenced in a physiological manner by the addition of such a degree of freedom. Measurements were conducted by means of an optoelectronic camera system for recording motion kinematics. The subjects were fit with myoelectric arm prostheses and performed predefined motion tests with the sound limb and with the prosthetic side. The position of flexion angles of the prosthetic wrist were varied systematically. There may be evidence that an optimized prosthetic wrist flexion device supports physiological motion patterns in contrast to a prosthetic hand without the wrist flexion. The functionality of an upper-limb prosthetic device may be increased by incorporation of an additional degree of freedom. In this pilot study, subjects were fit with myoelectric arm prostheses and performed predefined motion tests with both the sound limb and the prosthetic side. Motion analysis results show that compensatory movements may be reduced by wrist flexion in most of the cases. Reduced compensatory movements support more physiological loading of the unaffected joints of the locomotor system. Also, the more natural subjective impression is an important psychological aspect for the prosthetic user.