FOOT PROSTHESIS

Abstract: The invention relates to an adaptable forefoot part for use in a foot prosthesis, wherein the forefoot part is adapted to be used together with a prosthesis socket, (tidigare casing tror jag) and an elongated support part, wherein said forefoot part (13) has a fastening part (20) with at least one fastening element (41, 42) adapted to be attached to said support part (11), an adaptable and resilient intermediate part (15) and a front part (19). The invention also relates to a foot means comprising an adaptable forefoot part, wherein a heel part (12) is attached to the fastening part (20) and the fastening part placed on a support part (11) by means of a fastening element (41), as well as a system intended for individually adaptable foot prostheses, wherein an adaptable forefoot part according to the invention, a heel part, a support part and an outer casing of predetermined size can be combined in order to provide one adapted for the user.

Description: Foot prosthesis The invention relates to a forefoot part intended to be comprised in a foot means adapted to cooperate with a support part comprised in a foot prosthesis, and a foot means comprising a combined heel part and forefoot part for fastening onto the support part. Foot prostheses of different types are known. The prostheses are usually to designed so that an ordinary shoe can be used on the prosthesis. At a certain heel height, which can be adjusted during manufacturing of the prosthesis adapted to an individual, the prosthesis feels comfortable to walk on and to load, but without a shoe or with a different heel height the prosthesis is no longer comfortable to use since the angle of the foot with respect to the ground is no longer correct. The most common solution to the above problem is to either angle the whole foot prosthesis downwards and forwards, or to lower the heel part when, for example, one is to walk without a shoe. Angling the prosthesis downwards does not produce an anatomically correct foot shape, i.e. one does not achieve the type of foot shape which is necessary during the use of a higher heel, and if alternatively the heel part is lowered, this instead results in a lengthening of the leg which will cause discomfort, especially in the back. WO93/24080 (same applicant) describes the general design of a foot prosthesis with a support part and a foot means which cooperates with the support part, wherein the foot means comprises a forefoot part arranged so that it is slidably fixed to the support part in its axial direction and separately a heel part intended to be arranged at the lower end of the support part. SE-B-8504225-5 a foot prosthesis is described having a central part which supports the sole, heel and leg parts. In this prosthesis the heel is movably arranged in relation to the central part of the prosthesis and to the part of the sole of the foot which is fixedly joined with the central part. Movement of the heel is obtained by the latter being connected with the rear part of the central part by means of a bar which can be locked in a hole in said part and which in the unlocked position is displaceable in relation to the central part for adjusting the heel in relation to the foot sole. In this device a lengthening of the leg is obtained by the hole being moved downwards in relation to a reference point, e.g. the knee of the user. US-A-4 547 913 describes a completely different solution to the problem. Here the prosthesis is made of three rigidly connected parts, the leg part, the foot part and the heel part made of fibre reinforced resin, where the material and design of the parts gives flexibility to the prosthesis. During the production of foot and leg prostheses a number of factors have to be taken into account. The normal foot can move in all planes, individually or in com- bination. The lower leg of a person consists of two bones which by cooperation with each other and with the ankle joint permit a rotational movement, torsion of the lower leg, which continues in a rotation of the foot. Furthermore, the calf muscles of the lower leg provide a variable pushing off force, i.e. adapted for the specific purpose. There are today technical solutions for solving this problem to some extent, e.g. in SE-B-8201389-7, where the foot prosthesis consists of a continuous hollow core, which is secured directly onto the leg prosthesis adapter and which, by virtue of its design, with rigid and elastic regions provides mobility in the dorsal plantar direc- tion. The foot, however, does not have any capacity for energy storage, it has no adjustable heel and it is not made from a light but strong composite material. Moreover, in the natural foot an adjustment of the attitude of the heel takes place when the height of the heel increases. This can be illustrated most clearly through observing the movement which takes place when the foot is being introduced into a shoe or when walking on tiptoe. What happens is that the muscles on the back of the J lower leg contract and in this way the heel is lifted, while at the same time as the heel is lifted an angling of the forefoot takes place in the case of a normal walking movement. The higher the heel is lifted, the greater is the angle obtained between the forefoot and the adjoining part of the foot. An object of the invention is to provide an improved forefoot part to a foot prosthesis or an improved foot means. Another object of the invention is an improved forefoot part of a foot prosthesis which can be rigidly or slidably attached onto a support part. A further object of the invention is to provide a forefoot part which is easy to adapt to an individual who is using the prosthesis. Another object is to provide a forefoot part to the type of prosthesis which is described in the preamble so that a variable starting force is achieved. Yet another object is to provide a certain torsion capacity in the forefoot so that the prosthesis will be comfortable to use and will have a physiologically correct shape. Another object is to make it possible to exchange forefoot parts adapted for special conditions. A further object is to be able to adapt the size of the adaptable forefoot part and to be able to use the forefoot part in both a left and a right prosthesis. A further object is to provide a system for producing foot prostheses of different sizes and left and right variants of these. A further object of the invention is to avoid the above mentioned problems of the prior art foot prostheses and in this way provide a a prosthesis which always is com- fortable for the user, independent of the heel height, and which can satisfy varying demands on the starting force of the user of the prosthesis. These objects are achieved through the features stated in the independent claims. Preferred embodiments have the features which are mentioned in the subclaims. In order to provide the desired elasticity and adaptability of the characteristics of the prosthesis depending on use and user of the prosthesis, the forefoot part of the prosthesis is made of three distinct parts: a rigid part, a resilient and/or adaptable inter- mediate part and a front part. Before adaption to the individual the parts can be completely separate. The adaptable and resilient part can, however, be permanently fixed to one of the two other parts. According to the invention the problem with resilience and torsion capacity in the forefoot part is solved through a special construction of the intermediate part. The intermediate part according to the invention is formed of at least one elongated element wherein the first end of this or these elongated elements are intended to be fastened to the fixed part and the other end of this or these elongated elements to be fastened to the front part. The forefoot part according to the invention can be used both in a prosthesis in which the forefoot is permanently fastened to the support part and in adjustable foot prostheses, in which the forefoot part can be adjusted in height by being slidably attached to the support part. The forefoot part can thereafter be manually adjusted and locked into place in many ways, e.g. by using bolts or the like, or can be moved by means of a motor which is operatively connected to the forefoot part, wherein the motor itself when stationary forms a stop. The foot means, forming a combination of the forefoot part and a heel part accord- ing to the invention, can be used together with a support part of normal construction. A special advantage of the forefoot part and the foot means according to the invention is that the constituent parts after adaption to the individual are provided with suitable cosmetics, i.e. an outer casing which then forms the complete prosthesis together with the forefoot part and the heel part. This means that with the help of a system containing only a few parts it is possible to produce foot prostheses of different sizes and of left and right shape. These foot prostheses are subsequently provided with a cosmetic adapted to the right size, viz. a casing which looks like a normal foot. The invention is described in more detail below with reference to the accompanying drawings where: Fig. 1 shows an embodiment of a foot means according to the invention fixed to a support part on die foot prosthesis; Fig. 2 shows a cross-section through the fastening means of an embodiment of the forefoot part along the line II-II in Fig. 1 ; Fig. 3 shows a cross-section through the fastening means of a second embodiment of the forefoot part along the line II-II in Fig. 1; Fig. 4 shows an embodiment of the shape of the support part in a second embodiment: Fig. 5 shows a foot means according to the invention. Fig. 1 shows a prosthesis equipped with a foot means comprising a forefoot part according to the invention. The prosthesis has a prosthesis socket 10, a tube 11 (support part), a heel part 12 and a forefoot part 13. The tube 1 1 is preferably formed of a normal standard tube of the type which is normally used for fastenmg prosthesis feet into prosthesis sockets and which can be said to be a replacement either completely or partially for the lower leg The forefoot part 20 is arranged in a movable way on the tube which below is referred to as the support part 1 1, and a heel part 12 is arranged on the lower end of the support part 1 1 In this embodiment the support part 11 is shown as a tube with a circular cross- section, which is the most common shape for this part This, however, does not mean that the support part used m the invention could not have some other cross- section, such as e g quadratic, triangular or oval etc The forefoot part 13 comprises a front part 14, an intermediate par 15 and a fastening part 20 The intermediate part 15 forms the part of the forefoot part which is specially shaped in order to be individually adaptable to the individual who uses the prosthesis In order to achieve this, the intermediate part 15 is arranged in the shape of elongated resilient elements 22, which have a circular, oval oi rectangular cross- section This makes it possible to adjust the stiffness, torsion, the resilient ability and the give in the foiefoot part In one embodiment the intermediate part can be formed of a single element The ability to adjust the elasticity m the forefoot part is important as the wearers of the prostheses can have a wide spread of weights and foot sizes and, in addition, different types of activities place different requirements on the elastic characteπstics of the forefoot part The element 22 is fixed to the front part 14 so that the element 18 is permanently or removably attached to a holder 19 The second end of the element is fastened (not shown) under the fastening part 20 The holders can be constructed in such a way that the elements can be partially introduced through the holder and thereafter cut off to the light length and thereafter fastened in a perma- nent way to the holders and in this way to the fastening part 20 It is important for the strength of the forefoot part that the elongated elements 18 introduced into the holder, which is mounted under the fastening part 20. are fixed in such a way, and that the end of the fastening part 20. under which the holder 18 is mounted, is so shaped that no sharp bending of the elements occurs at the front edge 17 of the fastening part. The front part of the fastening part 20 therefore has a gently bent profile in order to allow the elements to yield. Fig. 2 shows the cross-section along the lme II-II in Fig 1 in a first embodiment. A fastening element, the annular part 41 of the fastening part 20. can be seen sur- rounding the support part 11. The fastenmg part 20 is also visible. The fastening element 41 has an opening 48 which can be closed with a bolted joint 49 which is shown on the drawing. The method for closmg the annular part 41 and lockmg it around the support part 1 1 is not important as long as the fastenmg element 41 and the forefoot part 13 remain in the predetermined position along the support part 1 1 Fig. 3 shows the same cross-section, along the lme II-II m a second embodiment. This second embodiment comprises a remote-controlled motor (not shown) mounted inside the support part 1 1 As in the first embodiment an outer annular fastenmg element 41, belonging to the fastening part 20, is adapted to be moved up and down along the support element depending on the motor which is mounted stationary in the support part 11 A second annular fastening element 42 is adapted to move up and down on the inside of the support part 1 1 depending on the same motor The two fastening elements 41, 42 are each connected through a joining piece 45. which is arranged to move up and down in a vertical elongated opening (not shown) in the support part 1 1. The inner annular fastening element 42 cooperates with an intermediate concentrically arranged annular part 43 which has a concentrically arranged threaded circular opening through which opening a rotatable threaded rod 44 passes, which is actively connected to the motor. When such a motor is activated, the threaded rod will rotate and the forefoot part, which is prevented from performing a rotating movement by means of the connecting part 45, will move up and down along, for example, the support part 1 1 Fig. 4 shows the support part 11 and the elongated vertical opening 52 (the fastening element 20 and the forefoot part 13 are removed). Through the opening the motor 53 and the threaded rod 44 as well as an elongated part 54 can be seen. The projec- ting part 54 forms a part of a washer (not shown) on which the motor 53 is mounted. The projecting part 54 prevents the motor from rotating in the support part. The second end 56 of the threaded rod is rotatably fastened to the lower end of the support part 11, e.g. at the heel part. For the sake of clarity the motor is shown in the drawing displaced to the bottom of the tube. Normally the projecting part 54 has a position at the top in the opening 52. Fig. 5 shows a combined forefoot part 13 and heel part 12 according to the invention, where the foot means via the fastening part 20 is arranged on the support part 11 by means of a fastening element 41. The forefoot part 13 comprises a front part 14, an intermediate part 15 and a fastening part 20. The intermediate part 15 forms the part of the forefoot part which is specially shaped in order to be individually adaptable to the individual who is using the prosthesis. In order to achieve this, the intermediate part 15 is arranged in the shape of elongated elastic elements 22 which have a circular, oval or rectangular cross-section. In one embodiment the intermediate part can be a single element. The elements 22 are placed on the front part 14 so that the elements 18 are permanently or removably attached in a holder 19. The other end of the element is fas- tened in a holder 18 (not shown) under the fastening part 20. The holder can be constructed in such a way that the elements can be partially introduced into the holder and thereafter be cut to the right length and subsequently fastened in a permanent manner to the holder and thereby to the fastening part 20. It is important for the strength of the forefoot part that the elongated elements 18, introduced into the holder which is mounted under the fastening part 20, are fixed in such a way, and that the end of the fastening element 20, under which the holder 18 is mounted, is so shaped that no sharp bending of the elements occurs at the front edge 17 of the fastening part. The front part of the fastening part 20 consequently has a gently bent profile in order to permit the elements to yield. The material which is chosen for the support part is the usual type of material known within the art. The forefoot part and the foot means can be manufactured of composite material, injection-moulded plastic etc. with appropriate characteristics and also of metal or the mixture of these materials.

Claims: Claims 1. Adaptable forefoot part for use in a foot prosthesis, wherein the forefoot part is adapted to be used together with a prosthesis socket and an elongated support part, characterized in that said forefoot part (13) has a fastening part 20 with at least one fastening element (41,42) adapted to be attached to said support part (1 1), an adaptable and resilient intermediate part (15) and a front part ( 19). 2. Adaptable forefoot part according to Claim 1, characterized in that said fastening part (20) compπses a first fastening means ( 18) for fastening a first end of said adaptable and resilient intermediate part ( 15) to said fastening part (20), and a second fastening means (19) for fastening a second end of said adaptable and resilient intermediate part ( 15) to said front part (14). 3. Adaptable forefoot part according to any of the previous claims, characterized in that said adaptable and resilient intermediate part (15) comprises at least one elongated resilient element (22). 4. Adaptable forefoot part according to any of the previous claims, characterized in that said adaptable and resilient intermediate part (15) comprises several elongated resilient elements (22), wherein these parts have an essentially rectangular, circular or oval cross-section. 5. Adaptable forefoot part according to any of the previous claims, characterized in that said at least one or more elongated resilient parts are fixed to some of the fastening means (18, 19), wherein during adaption of the forefoot, the resilient element or elements (22) are cut to predetermined length and fastened in the second fastening means ( 18, 19). 6. Adaptable forefoot part according to any of the previous claims, characterized in that said at least one or more elongated resilient elements (22) are fixed to both fastening means (18, 19). 7. Adaptable forefoot part according to Claims 1-6, characterized in that the fastening element (41) of said fastening parts (20) is adapted to slidably move to a predetermined position on said support part (13), wherein the fastening part has an opening (48) with a fastening locking means (49). 8. Adaptable forefoot part according to Claims 1-6, characterized in that said fastening element (41 ,42) adapted to the support part (11) comprises two essentially concentrically arranged fastening elements adapted to the support part, a fust element (41) adapted to be slidably placed on the outside of said support part (11) and a second element (42) on the inside of said support part ( 1 1), wherein said concent- rically arranged fastening elements are joined with each other over a short distance and said connection (45) is adapted to move upwards and downwards in a vertical elongated opening (52) in the support part ( 11). 9. Foot prosthesis, characterized by an adaptable forefoot part according to Claim 8, wherein said part of the fastening part (20) adapted to the support part ( 11) comprises two essentially concentrically arranged fastening elements adapted to the support part, a first element (41 ) adapted to be slidably placed on the outside of said support part ( 11) and a second element (42) on the inside of said support part ( 11), wherein said concentrically arranged fastening elements are joined with each other over a short distance and said connection (45) is adapted to move upwards and downwards in a vertical elongated opening (52) in the support part (11), and that the second inner element (42) adapted to the support part is actively connected to a motor arranged in the support part ( 11) for upward and downward movement in said support part (11), wherein said forefoot part (13) is slidably movable in an axial direction along said support part ( 1 1). 10. Foot means comprising an adaptable forefoot part according to Claims 1- 6, wherein a heel part (12) is attached to the fastening part (20) and which fastening means is attached to a support part (1 1) by means of a fastening element (41). 11. System intended for individually adaptable foot prostheses, characterized by an adaptable forefoot part according to Claims 1-8, a heel part, a support part and an outer casing of predetermined size. 12. Use of an adaptable forefoot part according to any of Claims 1- 6, character- ized in that the forefoot part can be attached movably or permanently on the supporting part. 13. Use of an adaptable forefoot part according to Claim 8 in an adjustable foot prosthesis, characterized in that the second fastening element (42) adapted to the support part is actively connected to a motor arranged in the support part (11) for movement upwards and downwards in said support part (11), wherein said forefoot part (13) is slidably movable in an axial direction along said support part (11). AMENDED CLAIMS [received by the International Bureau on 17 November 1997 ( 17.11 .97) ; original claims 1 -13 replaced by amended claims 1 -10 (3 pages) ] 1 Adaptable forefoot part foi use in a foot prosthesis, wherein the forefoot part is adapted to be arranged on an elongated support part which is aπanged to cooperate with a prosthesis socket and a heel part, wherein the piosthesis socket is intended to be arranged at the lower part of the support part, and the heel part to be arranged at the distal end of the support part, characterized in that said foiefoot part (13) has a fastening part 20 with at least one fastening element (41 42) adapted to be movably arranged on said support part (1 1) between its distal and its proximal ends, wherein the fastening part is provided with means for temporary locking of the forefoot part in any position, an adaptable and lesihent intermediate part ( 15) and a front part ( 19) 2 Adaptable foiefoot part accoiding to any of the previous claims, characterized in that said forefoot part ( 13) comprises a fust fastening means ( 18) foi fastening a fust end of said adaptable and resilient intermediate part ( 15) to said fastening part (20), and a second fastening means ( 19) foi fastening a second end of said adaptable and lesihent intermediate part ( 15) to said front part ( 14) 3 Adaptable forefoot part according to any of the previous claims, characterized in that said adaptable and resilient intermediate part ( 15) comprises at least one elong- ated resilient element (22) 4 Adaptable forefoot part according to any of the previous claims, characterized in that said adaptable and resilient intermediate part (15) comprises several elongated resilient elements (22), wherein these parts have an essentially rectangular, circular or oval cross-secnon 5. Adaptable forefoot part according to Claims 1- 4, characterized in that said fastening element (41 ,42) adapted to the support part ( 1 1 ) comprises two essentially concentrically arranged fastening elements adapted to the support part, a first element (41 ) adapted to be slidably attached on the outside of said support part (1 1) and a second element (42) on the inside of said support part (1 1), wherein said concentrically arranged fastening elements are joined with each other over a short distance and said connection (45) is adapted to move upwards and downwards in a vertical elongated opening (52) in the support part ( 1 1 ). 6. Foot prosthesis, characterized by an adaptable forefoot part according to Claim 5. wherein said part of the fastening part (20) adapted to the support part (1 1) comprises two essentially concentrically arranged fastening elements adapted to the support part, a first element (41 ) adapted to be slidably placed on the outside of said support part ( 1 1 ) and a second element (42) on the inside of said support part (1 1), wherein said concentrically arranged fastening elements are joined with each other over a short distance and said connection (45) is adapted to move upwards and downwards in a vertical elongated opening (52) in the support part ( 1 1), and that the second inner element (42) adapted to the support part is actively connected to a motor arranged in the support part ( 1 1 ) for upward and downward movement in said support part ( 1 1 ). wherein said forefoot part ( 13) is slidably movable in an axial direction along said support part ( 1 1 ). 7. Use of an adaptable forefoot part according to Claim 5 in an adjustable foot prosthesis, characterized in that the second fastening element (42) adapted to the support part is actively connected to a motor arranged in the support part ( 1 1 ) for movement upwards and downwards in said support part (11), wherein said forefoot part (13) is slidably movable in an axial direction along said support part (11). 8. System intended for individually adaptable foot prostheses, characterized by an adaptable forefoot part according to Claims 1-5, a heel part, a support part and an outer casing of predetermined size. 9. System intended for individually adaptable foot prostheses. characterized by an adaptable forefoot part according to Claim 6. a heel part, a support part and an outer casing of predetermined size. 10. Use of an adaptable forefoot part according to any of Claims 1 -5. characterized in that the forefoot part can be movably or permanently attached on the supporting part.

Inventors: LINDH LEIF, LINDH, LEIF
Applicants: LINDH LEIF, PRO PEL AB, LINDH, LEIF, PRO-PEL AB
Application year: 1997
Main classification: A61F2
IPC codes: A61F2