FR2469917A1 - Passive articulated hand prosthesis - permits simultaneous external adjustment of grip and traction force exerted on rope - Google Patents

Abstract

The passive hand prosthesis is for a congenitally or traumatically handicapped child, having an adjustment at the proximal end allowing simultaneous regulation from outside both of the grip and traction force exerted on the rope. The adjustment mechanism can comprise a bolt (10) screwing into a nut (8) and acting on a compression spring (9). A stationary but easily detachable thumb(P) can be provided, to allow easy fitting of a glove. The prosthesis can be arranged to open without actuation of the rope, and the thumb (P) and fingers (D) can be interchangeable, allowing the same mechanism to be used for hands of different sizes.

Description

DESCRIPTION a) Aesthetic hand prosthesis with passive grip for children.

b) The present invention relates to the apparatus of the upper limb of a young disabled child
congenital or traumatic cap.

c) The gripping device currently on the market which is offered to amputated children
of upper limb is summarized in a clamp constituted by two metallic fingers of which
one is fixed, the other mobile. An elastic allows the recall in closing. A cable connected to
a lug placed on the movable finger allows the opening of the clamp by traction. This system
is unsightly and can be dangerous.

d) The prosthesis according to the invention allows a physiological grip carried out by a set of four fingers movable around an axis, in opposition with a thumb pulls.

The gripping force can be adjusted from outside the prosthesis.

The thumb is detachable, which facilitates the installation of a covering glove made of synthetic material imitating the skin.

The weight of the covered hand is less than 150 grams. This low inertia is appreciable when it comes to fitting a short stump. On the other hand, the size of the mechanical assembly is small, which makes it possible to fit the long stumps, up to a level corresponding to a disarticulation of the wrist.

The module containing the mechanism can be used for prostheses from 2 to 8 years old.

e) The prosthesis which is the subject of the invention can be made of injected plastic or of a light alloy. It is made up of five elements:
- a frame C representing the metacarpal part of the hand serving as support
to the other elements
- a comb of four fingers D movable around an axis
- a retractable thumb P fixed by two parallel plugs 7
- a mechanism M allowing passive closure of the clamp formed by the fingers
and thumb, and its active opening.

- a flexible synthetic coating glove intended to protect the mechanic
nism, to improve the grip and to give a good esthetics to the prosthesis.

The mechanism comprises a bearing R fixed on a movable segment 2 around an axis 3 acting on a pusher 4 articulated by two parallel connecting rods 5 secured to the fingers via an axis 6.

The fingers moved by the connecting rods pivot around axis 1.

The pusher 4, recalled by a spring 9 housed inside, enters the fixing sleeve.

A bolt 10 whose head is wider than the diameter of the spring ensures compression.
The bolt rod passes through the axis of the spring, crosses the bottom of the plunger and leaves the socket. The proximal end of the bolt is threaded, thus allowing adjustment 8 of the compression of the spring and by the same of the gripping force by a nut.

The opening of the hand is controlled by means of a cable 12 fixed to the movable end of segment 2.

The cable is returned by a pulley 13 to the outside of the proximal end of the hand.

Activation of the prosthesis via the cable can be done either by the movement of the contralateral shoulder moving away from the shoulder girdle, or by traction provided by a mechanical or electromechanical device attached.

Claims (5)

1 Aesthetic hand prosthesis with passive grip for children, characterized by the fact  that it includes an adjustment device located at the proximal end making it possible to  simultaneously apply the pinch force and the pulling force from the outside  deed on the cable. 2 Aesthetic hand prosthesis with passive grip for children, according to claim  1, characterized by the fact that the adjusting device is a visZcrou system acting  on a compression spring. 3 Passive esthetic hand prosthesis for children characterized by the fact  that it has a fixed but detachable thumb allowing easy installation of the covering glove. 4 Passive esthetic hand prosthesis for children, characterized by the fact that the hand can be opened without action on the cable. 5 Passive esthetic hand prosthesis for children characterized by the fact that the mechanical module can be identical for several sizes; thumb and fingers being interchangeable.