Upper limb technical terminology

Abduction


This generally refers to a movement away from the centre of the body. In hand prosthetics, it describes moving the fingers apart (opening the hand), or spreading or separating the fingers.

Adduction


A movement towards the centre of the body. In hand prosthetics, moving the fingers together (closing the hand).

ADL (activities of daily living)


Activities of daily living such as getting dressed, eating, sleeping, going to the toilet

Amputation


An amputation is the severing of a bone in healthy tissue or the severing of a body part in a joint (disarticulation). There are various amputation levels.

Amputation level


The amputation level is the level (height) at which a body part is severed. Amputation levels in upper limb prosthetics are:

  • Finger/thumb amputation
  • Partial hand amputation
  • Transcarpal/carpal amputation
  • Hand disarticulation
  • Transradial amputation (below-elbow amputation)
  • Elbow disarticulation
  • Transhumeral amputation (above-elbow amputation)
  • Shoulder disarticulation and interthoracascapular amputation

Axon-Bus system


The word "Axon-Bus" refers to a uniform communication standard between the prosthetic components. Furthermore, the Axon-Bus system is a self-contained prosthesis system. Its most important component is the Michelangelo Hand. Users benefit from the enhanced functionality of the hand.

Bilateral


On both sides, i.e. both arms or legs for example are affected.

Digital communication of prosthetic components


This is a type of communication between the prosthetic components. Benefits include:

  • High interference resistance
  • Fast and secure data transmission

Digital control of a prosthesis


The speed of the prosthesis, e.g. when opening and closing, rotating or raising and lowering can be varied.

Dysmelia


A congenital malformation, differentiated according to the following levels:

  • Amelia: the entire extremity is missing.
  • Phocomelia: the hand or parts thereof are connected directly to the shoulder.
  • Ectromelia: an intermediate section the length of a long bone is missing, the hand is retained (longitudinal defect).
  • Peromelia: part of the arm is missing.

Hybrid prostheses


Hybrid prostheses always use two different technologies together at the same time. For example, an externally powered prosthesis (MyoHand) can be combined with a body-powered prosthesis (elbow joint) in an upper arm fitting. Opening and closing the hand is externally powered by electricity (myosignals), while flexing and extending the forearm in this case is performed using a body-powered harness.

Integral battery system


A permanently installed battery that is not removed for charging.

Contralateral


The side that is opposite the affected side.

Lock system


The locking pin and adapter for locking the liner and prosthesis together.

Liner


The liner is a sock-like cover for the residual limb and acts as a sort of "second skin" between the movable soft tissue of the residual limb and the hard shell of the socket. It protects and cushions delicate and pressure-sensitive areas of the residual limb and connects the residual limb to the prosthesis. Liners are pliable and skin-friendly, yet firm enough to prevent unwanted elongation. Arm liners provide wearer comfort and safety.

Myoelectric arm prosthesis


Myoelectric prostheses are externally powered prostheses. Every muscle contraction generates electrical voltage on the skin, which is used to control the electrically driven prosthesis.

Passive arm prostheses


Passive arm prostheses are worn to restore the outward appearance, and are preferred by users to whom their external image is particularly important. However, the functional possibilities are limited to simple counter-support when grasping objects.

Proportional


The gripping force and gripping speed can be controlled by muscle signals of various strength.

Proprioception


Feedback from receptors in the tissue (skin, muscle, capsule, tendon).

Supination


Outward rotation of the hand by turning the forearm, so that the radius and ulna are parallel to each other after the rotation. With the arm hanging down, the palm now faces forward (for feet: lifting the inner edge of the foot while simultaneously lowering the outside edge of the foot).

Test prosthesis


A prosthesis intended to test the socket shape, volume, function and design of the final prosthesis.

Cable-controlled arm prosthesis


Cable-controlled arm prostheses are body-powered prostheses. They are "active prehensile arms" whose prosthetic function is controlled by the patient's own body power, e.g. the residual limb and/or the shoulder girdle. Movements are triggered via a body harness on the prosthesis.