Browsing by Author "Bertels, Thomas"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    BIOMECHANIC ASPECTS AND PATIENT NEEDS LEAD THE PATH TO A UNIQUE WRISTJOINT FOR MYOELECTRIC PROSTHESIS
    (2005) Bertels, Thomas
    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.
  • Thumbnail Image
    ItemOpen Access
    BIOMECHANICAL ANALYSIS IN ARM PROSTHETICS 􀂱 OBJECTIFYING OF FUNCTIONAL ADVANTAGES OFFERED BY WRIST FLEXION
    (2008) Bertels, Thomas; Fiedler, Kerstin; Schmalz, Thomas
    By means of flexion wrists the functionality of prosthetic fittings for upper extremities can be improved significantly. Objects can be manipulated more favourably. Furthermore an optimized gripping position allows an improved body posture. Reaching objects or other dynamic processes are essential in amputee􀂶s ADL􀂶s. The path of motions influences the whole extremity in a physiological manner. Biomechanical measuring results demonstrate the advantages in movement by individual hand positioning. Measurements were conducted by means of an optoelectronic camera system for recording motion kinematics (VICON 460, VICONPEAK Oxford, GB). The subjects were fitted with myoelectric arm prostheses and performed predefined motion tests. Position of flexion angle and hand rotation varied systematically. Depending on the posture of the hand the optimization of certain motion patterns could be proved. Repeating action is supported and can be performed more persistently. Some activities confirmed the significance of optimized interaction between wrist rotation and flexion.
  • Thumbnail Image
    ItemOpen Access
    Breathable Liner For Transradial Prostheses
    (2011) Bertels, Thomas; Kettwig, Thomas
    The socket as the link between residual limb and prosthetic components is the crucial part of the prosthesis influencing the amputee’s acceptance considerably. In addition to protection from outside influences, the skin is responsible for regulating the body temperature. As parts of the skin are missing due to amputation, this functionality is minimized. This effect is increased by common liners consisting of silicone or equivalent materials, covering the residual limb surface. A new developed liner is made of spacer fabric in combination with partial silicon coating for suspension. This way the functionality of the skin inside the socket is supported to regulate temperature based on permeability to gas and humidity. The cushioning effect of the liner reduces pressure peaks and shear forces to prevent skin breakdown. The new approach of an interface design combines the comfort of using the conventional liner technique with the support provided by natural skin functionality.