BIOMECHANIC ASPECTS AND PATIENT NEEDS LEAD THE PATH TO A UNIQUE WRISTJOINT FOR MYOELECTRIC PROSTHESIS Thomas Bertels, Graduate Biomedical Engineer R&D – Upper Limb Prosthetics

The wrist plays an important role for the function of the human hand. The wrist joint is a complicated anatomical unit, consisting of various bones, ligaments and muscles. The distal and proximal joints combined with the rotation of the forearm excite movements at various levels that bring the hand into different positions. Apart from the rotation, the newly developed wrist with low construction height for myoelectric prostheses allows for volar and dorsal flexion at various locking positions. Besides those typical functions which allow positioning of the hand, the joint must meet further technical requirements. Therefore the prosthetic wrist joint clearly differs from its natural model. The most important difference is the exchangeability of the terminal device. This flexion joint with its additional degrees of freedom in motion considerably enhances the radius of action and thus increases the practical value of the myoelectric system to the patient