DE9112005U1 - Prosthesis for the limbs of a body, especially leg prosthesis - Google Patents

Description

Prosthesis for the limbs of a body, especially leg prosthesis

The invention relates to a prosthesis for the limbs of a body, in particular a leg prosthesis, which is essentially straight in at least some areas or sections.

In the case of leg prostheses, it is known that the lower leg can be pivoted in relation to the upper leg via a swivel joint in order to enable better walking, but the disadvantage of these known leg prostheses is that when the prosthesis is placed on solid ground or floor, an abrupt and therefore undamped impact occurs, which subsequently leads to an impairment of the various joints, for example knee joints, thigh joints, hip joints, etc. and results in premature wear.

Based on this, the invention is based on the object of creating a possibility for a prosthesis for the limbs of a body and in particular for a leg prosthesis to avoid hard impacts when the prosthesis is placed on solid ground or floor.

As a technical solution, the invention proposes that the prosthesis has a damping device in a straight partial area or section for axially damping this straight partial area or section.

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Postgiroamt Karlsruhe (bank code 66010075) Account No. 438 69-752

A prosthesis for the limbs of a body, and in particular a leg prosthesis, designed according to this technical teaching has the advantage that it prevents the prosthesis from being placed on solid ground or floor without being cushioned. This provides the wearer with a subjectively noticeable relief when putting on the prosthesis and thus when walking. As a result, joints directly affected by the prosthesis, such as knee joints, thigh joints or hip joints, are protected and any premature wear that may occur is prevented or delayed. This ultimately leads to cost savings for medical care.

As already mentioned, the invention is preferably suitable for a leg prosthesis consisting of a lower leg and possibly a thigh, in which case the damping device is arranged in the lower leg and/or possibly in the thigh to dampen this part or these parts. Preferably, however, the damping device will be arranged in the lower leg of the leg prosthesis, since this is the place closest to the ground where the damping device can be arranged and thus the damping takes place, so to speak, at the place where the abrupt impact on the leg prosthesis occurs.

In a preferred embodiment of the damping device, this is a hydraulic damping device, which in a further development has a hydraulic shock absorber. Such a hydraulic shock absorber, which can be of a conventional type, as is also used for other industrial purposes, can be easily inserted into a tubular prosthesis, wooden prosthesis, plastic prosthesis or into a prosthesis of another type. With such a hydraulic shock absorber, a different deceleration or reduction in speed and reduction in force over the damper stroke occurs depending on the damper use (arrangement of the throttle holes). If the body weight is placed on the prosthesis, the entire part located above the shock absorber rests on the shock absorber when resistance is reached, for example when it comes into contact with solid ground, and the retracting piston rod-piston head connection displaces the medium in the shock absorber, for example oil into a cylinder, through throttle holes or an edge gap.

Preferably, the damping characteristic of the damping device is self-compensating, linear, progressive or a combination of these. A self-compensating damping characteristic is preferred, i.e. the damping characteristic changes only insignificantly when the prosthesis is applied to the hydraulic shock absorber at different speeds. The advantage for the prosthesis wearer with such a self-compensating damper type is that even when the prosthesis is placed hard, they do not feel any force or pressure peaks in the joints, for example in the thigh/pelvic joint.

In a preferred development, the prosthesis has two prosthesis parts that can move relative to one another in their longitudinal extension, between which the damping device is arranged. This represents a simple technical possibility for integrating the damping device into the prosthesis, with two defined prosthesis parts being connected as an interface via the damping device, for example via a damper housing using an adapter.

The two prosthetic parts can be suitable parts. Preferably, however, the two prosthetic parts are tubular parts, as these are optimally able to accommodate a hydraulic shock absorber.

In a preferred design, a cylinder of the hydraulic shock absorber is fixed in one part of the prosthesis, while a piston rod of the hydraulic shock absorber in the other part of the prosthesis is supported on a counter bearing when under load. This represents a technically simple way of connecting the two parts of the prosthesis in a dampening manner when under load using the hydraulic shock absorber.

Preferably, a guide device is provided between the two prosthetic parts so that the two prosthetic parts can be moved against each other in a reproducible manner.

In a preferred design of this guide device, it has a sleeve fixed in one part of the prosthesis, in which the cylinder of the hydraulic shock absorber is fixed on the one hand, and on which the other part of the prosthesis can be moved on the other hand.

Such a sleeve therefore basically functions as an adapter, which on the one hand provides the hydraulic shock absorber and on the other hand ensures that the two parts of the prosthesis can be moved smoothly against each other. The sleeve can be screwed into one part of the prosthesis. Other fastening options are equally conceivable.

A further development of this proposes that the cylinder of the hydraulic shock absorber is screwed into the sleeve. For this purpose, the sleeve is provided with an internal thread and the cylinder of the hydraulic shock absorber with a corresponding external thread. Because the cylinder of the hydraulic shock absorber is screwed into the sleeve, exact positioning of the shock absorber is possible in a technically simple way.

In order to ensure that the sleeve is held immovably on one part of the prosthesis, the sleeve preferably has a projection that rests on one part of the prosthesis.

A further development proposes that the prosthetic part that can be moved on the sleeve has elongated holes that extend lengthwise with guide bolts fixed in the sleeve and that pass through the elongated holes. These elongated holes with the corresponding guide bolts form a movement limit between the two prosthetic parts and also prevent twisting if the two prosthetic parts are tubes. In a structural design, for example, three elongated holes can be evenly distributed around the circumference of one prosthetic part.

Finally, in a further development it is proposed that an elastic plastic or rubber part, in particular an O-ring, is arranged between the two prosthesis parts in the area of the damping end position. This additional damping part has the advantage that when a very large force is applied to the prosthesis and thus to the damping device, it does not exert an abrupt impact when it reaches its end position, so that damping is also provided in the critical damping end position.

An embodiment of a prosthesis according to the invention in the form of a leg prosthesis is described below with reference to the drawings. In these:

Fig. 1 a partial view of the leg prosthesis in

Longitudinal section and in the area of the damping device arranged in the lower leg of the leg prosthesis;

Fig. 2 a diagram to illustrate the damping characteristics

teristics.

In Fig. 1, a leg prosthesis 1 is shown in detail in the lower leg area, so that one has to imagine the foot at the bottom and the knee joint at the top, whereby the foot can be rigidly connected to the lower leg.

The lower leg of the leg prosthesis 1 consists of two tube parts 2, 2', which are connected to one another via a hydraulic damping device 3. In the illustrated embodiment, this hydraulic damping device 3 consists of a hydraulic shock absorber 4 with a cylinder 5 and a piston rod 6.

To fix these parts within the two pipe parts 2, 2', a sleeve 7 is first placed on the lower pipe part 2' and secured using screws 8. The sleeve 7 has a ring-like projection 9 on the outside, which sits flush on the upper edge of the lower pipe part 2', while the part of the sleeve 7 located underneath is flush within the lower pipe part 2'. The upper pipe part 2 is mounted so that it can move axially on this sleeve 7, which is thus firmly connected to the lower pipe part 2'. For this purpose, the upper pipe part 2 has three elongated holes 10 that are evenly distributed around the circumference and extend in the longitudinal direction. A guide bolt 11 is screwed through each of these, so that on the one hand an anti-twist device is created between the upper pipe part 2 and the lower pipe part 2' and on the other hand a limited movement guide is created.

The sleeve 7 is provided with an internal thread and the cylinder 5 of the hydraulic

The cylinder 5 of the hydraulic shock absorber 4 is provided with a corresponding external thread, so that the cylinder 5 of the hydraulic shock absorber 4 is screwed into the sleeve 7 in the manner shown, whereby an exact positioning can be carried out according to the screw-in depth. The cylinder 5 of the hydraulic shock absorber 4 is thus fixed in the sleeve 7 and thus in the lower tube part 2'. The piston rod 6, which is arranged on the piston head 12 that can be moved in the cylinder 5, is fixed with its free end protruding from the cylinder 5 to a connection cap 13 of a counter bearing 14, whereby this counter bearing 14 is fastened to the connection cap 13 in the upper tube part 2 by screws 15.

The hydraulic shock absorber 7 has the already mentioned cylinder 5 and the already mentioned piston rod 6, at the end of which, located in the cylinder 5, the piston head 12 is arranged so that it can move. A compression spring 16 is supported between the bottom of the cylinder 5 and the piston head 12. The cylinder 5 also has throttle bores 17 and an edge gap 18 and is also filled with a fluid 19, for example oil. This is a hydraulic shock absorber 4 of a conventional type, so that the details do not need to be discussed further.

The leg prosthesis 1 with the damping device 3 functions as follows:

Fig. 1 shows the basic position, i.e. when no load is applied. In this state, the compression spring 16 presses the piston rod 6 into its maximum extended position, i.e. the upper tube part 2 is pushed as far upwards as possible in relation to the lower tube part 2'.

As soon as a load occurs when hitting hard ground, the upper tube part 2 presses the piston rod 6 downwards via the counter bearing 14, so that the piston head 12 inside the cylinder 5 is moved downwards in the drawing towards the bottom of the cylinder 5. Since the fluid 19 is located inside the cylinder 5, particularly in the form of oil, this is displaced in the conventional way via the throttle holes 17 and the edge gap 18. The compression spring 16 is fully tensioned and at the same time the upper tube part 2, which is moved downwards, is supported on an O-ring 20 which is on the projection 9.

the sleeve 7 is placed. This position represents the end position of the damping system. When the leg prosthesis 1 is relieved of pressure, i.e. when the lower tube part 2' is no longer supported, the piston head 12 and thus the piston rod 6 are reset via the previously fully tensioned compression spring 16.

The damping device 3 shown in Fig. 1 corresponds in its damping characteristics (damping characteristic curve) to the characteristic curve type a shown in Fig. 2. In the diagram in Fig. 2, the damping force is plotted against the stroke. This characteristic curve type a is characterized by the fact that the counterforce (damping force) remains relatively constant over the stroke. With different impact speeds of the leg prosthesis 1 on the hydraulic shock absorber 4, the damping characteristics change only insignificantly, which is why this type of damper is also called self-compensating. The advantage for the prosthesis wearer is that even when the leg prosthesis 1 is placed down hard, he or she does not feel any force or pressure peaks in the joints, for example the thigh/pelvic joint.

Other damping characteristics can also be selected, as shown in Fig. 2. Characteristic type b shows a linear characteristic and characteristic type c a progressive characteristic. Intermediate stages are certainly conceivable.

In any case, the basic principle of damping is that the unit formed by the piston rod 6 and the piston head 5 moves into a cylinder 5 filled with a fluid 19 and displaces the fluid via differently arranged throttle holes 17 or edge gaps 18. In this process, part of the kinetic energy is converted into thermal energy. The efficiency of these dampers is between μ 0.4 - 0.8 depending on the type of damper, i.e. depending on the arrangement and type of throttle holes 17.

Reference list

1 Leg prosthesis 2 Pipe part 2' Pipe part 3 Damping device 4 hydraulic shock absorber 5 cylinder 6 Piston rod 7 Sleeve &thetas; screw 9 head Start 10 Long hole 11 Guide bolt 12 Piston head 13 Connection cap 14 Counter bearing 15 screw 16 Compression spring 17 Throttle bore 18 Marginal gap 19 Fluid 20 O-ring

Claims (14)

Expectations 1. Prosthesis for the limbs of a body, especially a leg prosthesis (D, which is essentially straight at least in some areas or sections, characterized, that the prosthesis has a damping device (3) in a rectilinear partial area or section for axially damping this rectilinear partial area or section. 2. Prosthesis according to claim 1 in the form of a leg prosthesis (1) consisting of a lower leg and optionally a thigh, characterized in that the damping device (3) is arranged in the lower leg and/or optionally in the thigh for damping this part or these parts. 3. Prosthesis according to claim 1 or 2, characterized in that the damping device (3) is a hydraulic damping device (3). 4. Prosthesis according to claim 3, characterized in that the hydraulic damping device (3) has a hydraulic shock absorber (4). 5. Prosthesis according to one of claims 1 to 4, characterized in that the damping characteristic of the damping device (3) is self-compensating, linear, progressive or a combination thereof. 6. Prosthesis according to one of claims 1 to 5, characterized in that the prosthesis has two prosthesis parts which are movable relative to one another in their longitudinal extension and between which the damping device (3) is arranged. 7. Prosthesis according to claim 6, characterized in that the two prosthesis parts are tubular parts (2,2'). 8. Prosthesis according to claim 4 and according to claim 6 or 7, characterized in that a cylinder (5) of the hydraulic shock absorber (4) is fixed in one prosthesis part (tube part 2'), while a piston rod (6) of the hydraulic shock absorber (4) in the other prosthesis part (tube part 2) is supported on a counter bearing (14) under load. 9. Prosthesis according to one of claims 6 to 8, characterized in that a guide device is provided between the two prosthesis parts (tube parts 2, 2'). 10. Prosthesis according to claim 8 or 9, characterized in that the guide device has a sleeve (7) fastened in one prosthesis part (tube part 2'), in which on the one hand the cylinder (5) of the hydraulic shock absorber (4) is fixed and on which on the other hand the other prosthesis part (tube part 2) is displaceable. 11. Prosthesis according to claim 10, characterized in that the cylinder (5) of the hydraulic shock absorber (4) is screwed into the sleeve (7). 12. Prosthesis according to claim 10 or 11, characterized in that the sleeve (7) has a projection (9) supported on one prosthesis part (tube part 2'). 13. Prosthesis according to one of claims 10 to 12, characterized in that the prosthesis part (tube part 2) which can be moved on the sleeve (7) has longitudinally extending elongated holes (10) with guide bolts (11) fixed in the sleeve (7) and passing through the elongated holes (10). 14. Prosthesis according to one of claims 6 to 13, characterized in that an elastic plastic or rubber part, in particular an O-ring (20), is arranged between the two prosthesis parts (tube parts 2, 2') in the region of the damping end position.