JP2997400B2 - Lower leg prosthesis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates generally to foot prostheses and, more particularly, to a lower leg prosthesis for the lower leg and foot from the knee.

[0002]

BACKGROUND OF THE INVENTION There are many different types of devices in the prior art for solving problems with foot prostheses. Since this type of lower leg prosthesis does not include the knee joint, its primary function is to support vertical loads, and rods and pipes have been used as simple structures. Has led to the development of prostheses with elastic and deformable heels and toes similar to those of real humans,
Although various prior arts can be mentioned, they are basically roughly classified into the following two types.

[0003] The rear part of the foot from the corresponding part of the toe main joint is basically hard, and the toe part beyond it is wrapped with a material having an appropriate elasticity, for example, a rubber material. (For example, Japanese Patent Application Laid-Open No. 5-123348,
-344994). In the case of this prior art, it is possible to rotate in the vertical warp direction at the position of the toe main joint, and an appropriate rotation resistance is obtained by the deformation of this material, so that it is close to the actual deformation behavior of the foot and a smooth walking can be expected. . "Elastic plate" that has a constant elasticity up to the fingertips equivalent to the toe bones
Is a type introduced into a skeleton member (see JP-A-4-285551 and JP-A-5-285166). In this type, the rigidity does not change suddenly from the heel to the toe,
At the position of the toe main joint, there is an advantage that fatigue destruction is difficult.

[0004]

In the prior art of the present invention,
There is a problem in that a material having elasticity and generally forming a soft portion is liable to fatigue fracture at the boundary between a hard material and the end of the toe main joint, resulting in a short service life. On the other hand, in the case of the prior art, the elastic plate as a whole has an average rigidity with the hard part in the center part, and it is difficult to rotationally deform at the position of the toe main joint at the fingertip, so that it is smoother than the one in the prior art. I cannot get a good walking interval. Therefore, this type has a limited use problem for the type of heavy exercise.

The present invention has been made to solve such problems, and an object of the present invention is to provide a practical leg prosthesis having elasticity close to that of an actual foot and high fatigue strength. In a simple structure and at low cost. The elasticity close to the actual foot here means that the toe deforms so as to bend around the toe main joint position as the weight moves forward in the walking motion. Of course, appropriate resistance and bending angle corresponding to the reaction force from the ground are required.

[0006]

The present invention has the following configuration to achieve the above object. That is, the present invention provides a lower leg prosthesis including an internal skeletal member that carries a load, and a jacket member that surrounds the internal skeletal member in a shape simulating a foot and a lower leg, wherein the internal skeletal member includes a lower leg It consists of a lower leg strut with rigidity and a foot core material with the rigidity of a locally deformable foot bone, and this foot core material is
Rigid having a toe curved plate portion, a heel curved plate portion, a sole plate portion connecting the lower end portions of both curved plate portions, a foot deck plate portion and an ankle plate portion also connecting the upper end portions of the both curved plate portions. A high hollow core member, a toe elastic plate attached to the sole plate portion of the hollow core member and extending below the toe curved plate portion and capable of being deformed in a bending direction of a toe; And a heel elastic plate that is attached to the heel curved plate portion and extends below the heel curved plate portion and is deformable in a warp direction.The toe elastic plate is fixed to the sole plate portion at a position corresponding to the toe main joint. The distal end side is formed at a free end that can be brought into contact with and separated from the forefoot curved plate portion, and the heel elastic plate is fixed to the sole plate portion at a position on the lower extension of the lower leg support fixing portion of the ankle plate portion. The rear end side is formed at a free end that can come in contact with and separate from the heel curved plate part. A thigh prosthesis.

The present invention also provides a lower leg prosthesis as described above, wherein the lower surface portion of the toe curved plate portion and the lower surface portion of the heel curved plate portion are bent in an arc shape, and the lower surfaces of the toe elastic plate and the heel elastic plate are both curved. A prosthetic leg characterized by forming limiting elements for limiting the amount of upward bending in a direction approaching the part to a fixed value, and the toe elastic plate and the heel elastic plate are integrally formed. A prosthetic leg comprising a single plate as described above.

[0008] The present invention also provides a lower leg prosthesis as described above, wherein the free end on the tip side of the toe elastic plate and the free end on the rear end of the heel elastic plate are connected to the tip of the forefoot curved plate and the heel curved plate. A lower leg prosthesis characterized in that it is located at substantially the same level in the longitudinal direction of the prosthesis with respect to the rear end portion, and the internal skeleton member is made of fiber reinforced plastic, and its rigidity and elasticity are thickness or fiber A lower leg prosthesis characterized by being adjusted by adjusting the volume ratio, and the reinforcing fibers in the fiber-reinforced plastic forming the toe elastic plate and the heel elastic plate are mainly oriented in the plate longitudinal direction perpendicular to the bending direction. A lower leg prosthesis characterized by being made.

[0009]

According to the present invention, the lower leg prosthesis is provided with the internal skeletal member and the covering member surrounding the internal skeletal member, and the load is carried by the internal skeletal member which is not visible from the outside, so that the appearance is not restricted. It is possible to employ a structure and a material having a necessary deformability and having a high fatigue strength. on the other hand,
The outer member carrying the appearance deforms following the large deformation at the heel and toe, but since it can be formed relatively thin in relation to the form of the internal skeletal member, the stress generated even if it is greatly deformed is Low, no fatigue failure. Further, the internal skeletal member is divided into a hollow core member of a rigid body portion that does not deform while supporting a load and a toe and a heel elastic plate of an elastic body portion that positively deforms in response to an external force. Due to the structure, the toe and the heel can be given elasticity independently adapted to their elasticity performance.

Further, according to the present invention, the elasticity of the prosthesis is changed at the position of the toe main joint by attaching the toe elastic plate to the rigid sole plate at the position corresponding to the toe main joint of the toe. The elasticity of the foot can be made closer to that of the actual foot. The same applies to the heel, and by attaching the heel elastic plate to the sole plate at a position on the extension of the lower leg column corresponding to the lower leg, elasticity close to the actual deformation of the heel of the foot can be obtained.

Further, according to the present invention, the lower surface portion of the toe curved plate portion and the lower surface portion of the heel curved plate portion of the lower leg prosthesis are bent in an arc shape, and the toe elastic plate and the heel elastic plate are bent upward. By forming a limiting element to limit the amount to a constant value, the amount of deformation of both elastic plates is kept constant at the rigid part, so that even if an excessive load acts on the prosthesis, their elasticity Prevents static fracture of the plate and avoids fatigue fracture. To further explain this point, as described above, if the means for suppressing the amount of deformation of both elastic plates at a rigid part is taken, the bending rigidity of the foot part of the prosthesis in the vertical direction at the toe main joint position of the toe is Changes sharply (when viewed from the heel, it is easy to turn sharply in the vertical direction at the joint position). As a result, when the center of gravity of the body moves forward with the weight still on the foot, a situation is obtained in which the foot is bent just about the joint position. This is because the stiffness is sufficiently high on the heel side from the joint position, while the flexural rigidity of the elastic plate having a relatively thin structure on the toe side from the joint position.

Since the elastic plate has a certain bending rigidity at the same time, it generates resistance to bending. This resistance can be freely designed by adjusting the thickness and elastic modulus of the elastic plate so as to be close to the actual bending resistance of the foot. Further, by limiting the amount of bending (bending angle) of the elastic plate to a certain value and providing an upper limit, the stress at the joint root where the bending stress becomes highest can be suppressed to a certain value or less. This is the only reason that the maximum stress at the point is determined by the bending angle. About this bending angle, it is necessary to bend to a value required for actual walking. Therefore, in order for the maximum stress to be equal to or less than the fatigue strength of the material at the bending angle, the thickness is naturally limited. That is, as the thickness increases, the stress generated for the same bending angle increases, and it goes without saying that it is necessary to reduce the plate thickness in order to reduce the stress.

According to the present invention, the rigidity against bending can be dealt with by increasing the elastic modulus of the material when the plate thickness must be reduced. That is, since the elastic modulus of the fiber-reinforced plastic is determined by the orientation and the content of the reinforcing fiber by forming both elastic plates with the fiber-reinforced plastic, it is necessary to keep the maximum stress at the time of maximum bending to a certain value or less. Bending rigidity can be secured. According to the present invention, by forming a portion that keeps the deformation amount of both elastic plates constant, an arc shape, a toe curved plate portion of a toe elastic plate and a rigid portion, and a heel curved plate portion of a heel elastic plate and a rigid portion, It is always in tangential contact with the toe and heel bend, and the contact point moves according to the degree of the bend angle, so the place where the maximum stress occurs during the deformation process of the elastic plate moves, resulting in fatigue damage Are dispersed in each part of the plate and fatigue fracture hardly occurs. In this respect, fatigue strength is further improved by using a unidirectional fiber reinforced plastic for the elastic plate. This is because only a thin plate is required to obtain the same rigidity, and the maximum stress for bending can be reduced. In addition, the fiber-reinforced plastic itself is resistant to fatigue.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the internal perspective of the lower leg prosthesis according to the embodiment of the present invention, and FIG. 2 is a perspective view showing the internal skeleton member 1 of the lower leg prosthesis shown in FIG. With reference to FIGS. 1 and 2, the lower leg prosthesis according to the embodiment of the present invention includes an internal skeleton member 1 and jacket members 2 and 3 surrounding the internal skeleton member 1. The internal skeleton member 1 forms a skeleton body that carries a load such as a load. The internal skeleton member 1 has a rigid lower leg column 4 that is substituted for the lower leg bone and a local leg like a toe that is substituted for the foot bone. And a foot core material 5 having rigidity, which is mainly deformable. On the other hand, the foot covering member 2 and the lower leg covering member 3 are formed in a relatively thin outer covering using synthetic rubber, foamed plastic, or the like as a material, and simulate the human foot and lower leg. It has an external shape and is surrounded and covered by the foot core 5 and the lower leg support 4, respectively.

The foot core member 5 includes a hollow core member 6 corresponding to a portion having high rigidity as a whole foot portion, and a toe elastic plate 7A corresponding to an elastically deformable portion as a toe portion. And a heel elastic plate 7B corresponding to a deformable portion having elasticity as a heel portion. In order to reduce the weight of each of these members, for example, a member finished in a predetermined shape by a material formed by a draw molding method using glass fiber reinforced plastic (GFRP) as a raw material is used.

The hollow core member 6 is a hollow short cylindrical body having a complex shape with a vertical cross section in the longitudinal direction corresponding to the front-rear direction of the foot and having a complicated shape. Toe curved plate portion 8 forming a shape, a heel curved plate portion 9 having a substantially horizontal U-shape located at the rear, and a lower end portion of the curved plate portions 8 and 9 are connected therebetween to connect them. A foot sole plate portion 10 having a flat shape, and a laterally shaped foot deck plate portion 11 and an ankle which are also provided between the curved plate portions 8 and 9 to connect the upper end portions thereof to each other. And a plate portion 12. The hollow core member 6 can be easily formed into a complicated shape by manufacturing by drawing as described above, and is made of a material having an appropriate length from a long cylindrical body as shown in FIG. Then, a piece having a predetermined shape is obtained. In this case, in order to increase rigidity, the thickness of the GFRP was set to about 8 mm.

In the hollow core member 6, a lower surface portion 8 connected to the sole plate portion 10 of the toe curved plate portion 8 and the heel curved plate portion 9
A and 9A are bent in a forwardly-sloping arc shape in the forefoot curved plate portion 8 and in a diagonally backward-sloping arc shape in the heel curved plate portion 9, respectively, so that the toe elastic plate 7A and the heel elastic plate 7B are upwardly bent. Limiting elements for limiting the amount of bending to a fixed value are formed. Reference numeral 19 denotes a notch provided corresponding to a gap between the first toe and the second toe.

As shown in FIG. 3 (C), the toe elastic plate 7A is cut into an appropriate length from a material formed of a long flat band and formed into a predetermined shape. 10 and fixed to the sole plate portion 10 by fixing members 13A and 13B realized by, for example, rivets at a position (a) corresponding to the toe main joint, and the toe curved plate portion 8 Is provided extending below the lower surface portion 8A. The toe elastic plate 7A is provided in such a state that its front end, which is its free end, is positioned at substantially the same level in the longitudinal direction of the artificial leg with respect to the tip of the curved toe plate 8.

On the other hand, the heel elastic plate 7B has substantially the same shape as the toe elastic plate 7A, and is cut into an appropriate length from a long flat band-shaped material as shown in FIG. 3 (C). A predetermined shape is formed, which is attached to the rear end of the sole plate portion 10 and attached thereto, and is realized by, for example, rivets at a position (b) on the lower extension of the lower leg support 4 fixing portion of the ankle plate portion 12. It is fixed to the sole plate portion 10 by fixing members 14A and 14B, and is provided to extend below the lower surface portion 9A of the heel curved plate portion 9. The heel elastic plate 7B is provided in such a state that its front end, which is its free end, is located at substantially the same level in the longitudinal direction of the prosthesis with respect to the tip of the heel curved plate 9.

When pressure is applied from the lower surface side, the free ends of the two elastic plates 7A and 7B are pushed upward and are deformed in the upward warp direction. When the pressure is removed, the elastic plates 7A and 7B return to their original planar shape. It is elastically restored and has elasticity that can be deformed in the warp direction. Therefore, in consideration of the ability to withstand the average weight of a person wearing the prosthesis of 60 kg and elasticity, the plate thickness of, for example, GFRP was set to about 2.5 mm. However, in this case, the orientation of the reinforcing fiber in the GFRP is made to match the longitudinal direction of the prosthesis. In this embodiment, the two elastic plates 7A and 7B are formed as one integrated plate, but they are formed separately and fixed to the sole plate 10 separately. Is also good.

The lower leg support 4 is formed by a column member 15, a lower connecting member 16 and an upper connecting member 17, and the column member 15 is a trough-shaped member having a U-shaped cross section orthogonal to its longitudinal direction. As shown in FIG. 3C, for example, a material having a predetermined shape is formed by cutting a material having a long trough shape made of GFRP having a thickness of 3 mm into an appropriate length. The lower connecting member 16 and the upper connecting member 17 are engaged with the lower end and the upper end of the column member 15, and are integrally fixed by a fixing member 18 realized by, for example, a bolt and a nut. Is formed. The lower leg support 4 is fixed to the ankle plate portion 12 of the foot core member 5 via the lower connecting member 16 to be in an upright arrangement, and is used as a substitute for the lower leg bone.
7 is applied to the stump of the wearer.

As shown in the conceptual model diagram in FIG. 4, the artificial leg of the embodiment having such a configuration has a hard portion L of the foot body, a hard portion M of the lower leg, a toe portion N having a spring, and a spring. A basic structure formed from a heel portion O having
When walking with this prosthesis, when first landing on the ground from the heel, the heel elastic plate 7B comes into contact with the ground from the tip side, and as the weight increases, as shown in the analysis diagram of FIG. The deformation becomes large, and finally the heel curved plate 9
Then, the heel elastic plate 7B substantially comes into contact with the heel elastic plate 7B, during which a buffering action is performed. When the load exceeds a certain level, the heel elastic plate 7B hits the heel curved plate portion 9, so that no further deformation occurs and no destruction occurs. Here, if the rigidity of the heel elastic plate 7B is adjusted so that the heel elastic plate 7B comes into contact with the maximum load during normal walking, a buffering effect having a stable fatigue fracture resistance can always be obtained.

On the other hand, when the weight moves to the toe in the latter half of one step of walking, the toe elastic plate 7A is gradually deformed from the tip side as shown in the analysis diagram of FIG. , The deformation increases, and finally the heel elastic plate 7A substantially contacts the heel curved plate portion 9, during which a necessary reaction force can be generated. Also in this case, the toe elastic plate 7A hits the toe curved plate portion 8 for a load exceeding a certain value, so that no further deformation occurs and no destruction occurs. Here, if the rigidity of the toe elastic plate 7A is adjusted so that the toe elastic plate 7A comes into contact at the time of the maximum reaction force in normal walking, a buffering effect having stable fatigue fracture resistance can be obtained at all times. In some cases, the thickness and the elastic modulus of the elastic plates of the heel and the toe may be different values.

In the embodiment according to the present invention described above, the required bending angle, bending rigidity and fatigue strength can be obtained at the same time by providing the toe portion and the heel portion with a bending reinforcing structure. 7 and 8 show experimental data according to this example. In both figures, the shaded area indicates the number of comparative examples based on the prior art. It is a range where a smooth walking feeling can be obtained for the prosthesis of the species. In FIG. 7, the decrease in the reaction force of the toe portion with the increase in the bending angle is because the weight acting on walking moves to the other leg That's why. The load acting on the toe elastic plate 7A is a part of the total load applied to the legs, and changes with the movement of the weight. Therefore, the greater the bending angle, the more the load acts on the toe elastic plate 7A, and the greater the bending, the smaller the apparent load.

As is clear from FIGS. 7 and 8, according to this embodiment, an average characteristic can be obtained in a substantially central area in the hatched area, and a smooth walking feeling and an improvement in fatigue strength can be obtained. was gotten.

[0026]

As described above, according to the present invention, the heel portion and the toe portion are constituted by the highly rigid hollow core member and the elastically deformable elastic plate, so that the conventional rubbery material is used. It has the same elasticity and deformability as a prosthetic leg, and also reliably prevents fatigue failure due to frequent deformation. Further, the present invention changes the elasticity of the prosthesis at the toe main joint position by attaching the toe elastic plate to the rigid sole plate at the position corresponding to the toe main joint of the toe,
The elasticity before that can be made closer to that of the actual foot. The same applies to the heel, and by attaching a heel elastic plate to the sole plate at a position on the extension of the lower leg column corresponding to the lower leg, elasticity close to the actual deformation of the heel of the foot can be obtained. Thus, a smooth walking sensation substantially close to the actual foot of the person can be obtained.

Further, according to the present invention, the lower surface portion of the toe curved plate portion and the lower surface portion of the heel curved plate portion are bent in an arc shape, and the toe elastic plate and the heel elastic plate have a predetermined amount of bending, respectively. By forming the limiting element for limiting the elasticity, the place where the maximum stress occurs in the deformation process of both elastic plates moves, so that the fatigue damage is dispersed to each part of the plate and it is difficult for fatigue fracture to occur. In addition to the fact that the elastic deformation of the elastic plate is not caused even when an excessive load acts on the prosthetic leg by suppressing the deformation amount of the rigid portion to a constant value in the rigid portion, the effect of further preventing the fatigue failure can be obtained. Further, according to the present invention, by forming the internal skeleton member from fiber reinforced plastic, it is possible to provide a prosthetic limb which is lightweight, low cost, has high rigidity, and particularly has excellent bending rigidity.

[Brief description of the drawings]

FIG. 1 is an internal perspective view of a lower leg prosthesis according to an embodiment of the present invention.

FIG. 2 is a perspective view of the internal skeleton member 1 of the lower leg prosthesis of FIG. 1;

FIG. 3 is a perspective view showing a molding material of the internal skeleton member 1 in the lower leg prosthesis of FIG. 1;

FIG. 4 is a conceptual model diagram of the lower leg prosthesis of FIG. 1 shown in comparison with the lower leg of a person.

FIG. 5 is an analysis diagram at the time of landing on the heel of the lower leg prosthesis according to the embodiment of the present invention.

FIG. 6 is an analysis diagram at the time of landing on a toe of a lower leg prosthesis according to an embodiment of the present invention.

FIG. 7 is a graph showing a relationship between a bending angle of a toe portion and an applied weight load at the time of landing according to the embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the amount of bending deformation of the heel and the applied weight load at the time of landing according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal skeletal member 2 ... Jacket member (foot part) 3 ... Jacket member (crus part) 4 ... Leg support 5 ... Foot core material 6 ... Hollow core member 7A ... Toe elastic plate 7B ... Heel elastic plate 8 ... Toe curved plate portion 8A: Lower surface portion 9: Heel curved plate portion 9A: Lower surface portion 10: Foot sole plate portion 11: Foot deck plate 12: Ankle plate portion 13A: Fixing member 13B: Fixing member 14A: Fixing member 14B: Fixing member 15: Column member 16: Lower connecting member 17: Upper connecting member 18: Fixing member 19: Notch

──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Master Hagiwara 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Institute of Technology (58) Field surveyed (Int.Cl. ⁷ A61F 2/60-2/66

Claims (6)

(57) [Claims] 1. A lower leg prosthesis comprising: an internal skeleton member for carrying a load; and a jacket member surrounding the internal skeleton member in a shape simulating a foot portion and a lower leg portion, wherein the internal skeleton member is a lower leg bone. Consisting of a rigid lower leg support and a locally deformable foot bone material having a foot bone rigidity, the foot core material is formed by a curved toe plate, a heel curved plate, and a lower end of both curved plates. A high rigid hollow core member having an upper deck portion and an ankle plate portion connecting the upper end portions of both curved plate portions to each other, and a sole plate portion attached to the sole plate portion of the hollow core member. A toe elastic plate that can be deformed in the bending direction of the toe that is provided to extend below the toe curved plate portion, and is deformed in a warp direction that is also attached to the sole plate portion and is provided to extend below the heel curved plate portion. A toe elastic plate, wherein the toe elastic plate corresponds to a toe main joint. Is fixed to the sole plate portion at a position where the distal end side is formed at a free end that can come into contact with and separate from the forefoot curved plate portion, and the heel elastic plate is provided on the lower extension of the lower leg support fixing portion of the ankle plate portion. A lower leg prosthesis characterized in that the lower leg is fixed to the sole plate portion at a position, and the rear end side is formed at a free end portion that can come into contact with and separate from the heel curved plate portion. 2. A lower surface portion of a toe curved plate portion and a lower surface portion of a heel curved plate portion are curved in an arc shape, and warp upward in a direction approaching the lower surface portions of the toe elastic plate and the heel elastic plate. The lower leg prosthesis according to claim 1, wherein the lower leg prosthesis has a limiting element for limiting a bending amount to a fixed value. 3. The leg prosthesis according to claim 1, wherein the toe elastic plate and the heel elastic plate are formed as a single plate. 4. The prosthesis in the longitudinal direction with respect to the distal end portion of the forefoot curved plate portion and the rear end portion of the heel curved plate portion, the distal free end of the toe elastic plate and the rear free end of the heel elastic plate. The lower leg prosthesis according to claim 1, wherein the lower leg prosthesis is located at a substantially equal level. 5. The lower leg prosthesis according to claim 1, wherein the inner skeleton member is made of fiber reinforced plastic, and the rigidity and elasticity thereof are adjusted by adjusting the wall thickness or the fiber volume ratio. 6. The lower leg prosthesis according to claim 5, wherein the reinforcing fibers in the fiber-reinforced plastic forming the toe elastic plate and the heel elastic plate are mainly oriented in the longitudinal direction of the plate perpendicular to the bending direction.