FOOT PROSTHESIS

Abstract: Foot prosthesis comprising a foot sole, a heel, a lower leg portion or an adapter for connecting the prosthesis to the lower leg portion of a leg prosthesis as well as a central portion of a stiff material to which the adapter is connected and the foot sole with heel is attached. To be able to adapt such a foot prosthesis to shoes having different heel heights the heel (3) is movably supported relative to the part of the foot sole (2) fixedly connected the central portion (1) of the prosthesis and coupled to the rear part of the central portion through an adjusting means (7) associated with the central portion (1) and the heel (3) for moving the heel (3) towards or from the central portion (1) and consequently ad­ justing the heel to a desired position relative to the fixedly mounted part of the foot sole in which at least and pad por­ tion is included, the adjusting means (7) being lockable in each position to retain the heel (3) in its position adjusted relative to said part of the foot sole.

Description: This invention relates to a foot prosthesis comprising a foot sole, a heel, a lower leg portion or adapter for connect­ ing the lower leg portion of the leg prosthesis to the foot prosthesis, and a central portion of a stiff material, e.g. wood, to which the adapter is connected and the foot sole with heel is attached. Foot prostheses of these types have been known for a long time and are usually so made that their carriers can use usual shoes having a definite heel height. These known pros­ theses are felt pleasant to the carrier only with this de­ finite heel height and at any other heel height of the shoe or when walking without shoe they are felt to be unpleasant and almost unusable. This means that carriers of known prostheses are compelled to use shoes with only one definite heel height which is a great disadvantage i.a. for the possibilities of a prosthesis carrier to choose freely among the different types of shoes available in the market for persons not carrying a prosthesis. It is therefore the object of this invention to provide a foot prosthesis not having the above-mentioned shortcomings but being so constituted that it is adaptable to varying heel heights and consequently always will be felt to be pleasant for the carrier independently of heel height and if the carrier walks with or without shoes. This is realized accord­ ing to the invention in that the heel of the prosthesis is vertically adjustable relative to the foot sole of the pros­ thesis, and in this way adaptation of the invention prosthesis is always made possible to the type of shoes carried by the prosthesis carrier on a certain occasion and to walks without shoes. More specifically, the foot prosthesis of the invention is characterized in that the heel is movably arranged relative to the part of the foot sole fixedly connected to the central portion and consequently relative to the central portion as well as the adapter and that the heel is coupled to the rear part of the central portion through an adjusting means lock­ able in a hole in said part and connected to the heel, said adjusting means being movable in unlocked position relative to the central portion for adjusting the heel in a desired posi­ tion relative to the foot sole. It is then advantageous to form the foot sole and the heel in one piece of the same elas­ tic material enabling turning of the heel relative to the foot sole and to have only one part of the foot sole fixedly con­ nected to the central portion so that the heel can move rela­ tive to the part of the foot sole fixedly connected to the central portion of the foot prosthesis. The invention is described below in greater detail with reference to the enclosed drawings in which Fig. 1 shows a section of an embodiment of the present foot prosthesis set for use together with a shoe of a certain heel height, Fig. 2 shows a section of the same prosthesis design as Fig. 1 but adjusted to be used together with a shoe of another heel height than in Fig. 1, Fig. 3 shows a device for adjusting the position of the heel relative to the foot sole and for locking the heel in the set position and Fig. 4 , finally, shows an al­ ternative design of the adjusting mechanism of the heel. The present foot prosthesis comprises a central portion 1 of a stiff material arranged as an ankle, e.g. wood with glued wooden plugs to prevent cracking, a foot sole 2 with heel 3 and an adapter 4 for connecting the foot prosthesis to the lower leg portion or a leg prosthesis. In the embodiment shown the foot sole 2 and the heel 3 are made in one piece of an elastic material, e.g. plastic or rubber having a hardness of about 40-60 shore, the part lying above the line A in Fig. 4 preferably being harder than the lower part being the very foot sole. At its front part the foot sole is fixedly connected to the central portion up to the point B or B′. Otherwise the foot sole 2 together with its heel 3 is loosely arranged relative to the central portion 1. A pressure absorbing disc 5 or the like is fixedly ar­ ranged in the heel 3 and the lower part of an adjusting means 7 in the form of a rod is attached to the disc 5 and conse­ quently the heel 3 by means of a fastening means, e.g. a screw 6 passing the disc. In its longitudinal direction the adjust­ ing means 7 is movably arranged in a sleeve 10 connected to a locking means 8, said sleeve being fixedly mounted in a hole in the rear part of the central portion 1. The adjusting means 7 can be immovably locked by the locking means 8 relative to the central portion 1 in different adjusting positions and, thus, the adjusting means 7 can be displaced in unlocked posi­ tion in its longitudinal direction for adjusting the heel 3 of the prosthesis in the intended position relative to the front part of the foot sole fixedly connected to the central portion 1. In the example shown this adjustment is made possible thanks to the fact that the foot sole 2 and the heel 3 are formed in one piece of an elastic material but in other de­ signs not shown in detail the part of the foot sole which to­ gether with the heel 3 is not connected to the central portion 1 can be articulatedly connected to the part of the foot sole fixedly connected to the central portion through a link con­ nection of e.g. hinge type. The adjustment of the heel relative to the central por­ tion 1 can be carried out in many different ways within the scope of the present invention. A spring not shown on the drawings can for instance be adapted between the heel 3 and the sleeve 10 which is preferably provided at its lower por­ tion with an adjusting ring 11 preferably threaded on the sleeve 10 and lying free of the central portion 1, as shown in Fig. 3. Thus, said spring between the adjusting ring and the disc 5 in the heel 3 can be adjustably clamped to press the heel at unlocked adjusting means 7 in a direction away from the central portion 1 to an outer end position in which the heel 3 is maximally displaced from the central portion 1. By moving the latter, for instance manually or by means of a pressure on the heel 3, towards the central portion 1 it can be simply adjusted to the desired position relative to the part of the foot sole fixedly connected to the central portion 1, after which the locking means 8 is locked to maintain the heel in the adjusted position. Thus, in this way an exact adaptation to the heel height of the shoe which is intended to be carried can be easily made. In order to lock the adjusting means 7 in an adjusted position the rod-shaped adjusting means 7 in the embodiment shown in Figs. 1-3 is formed with a plane side which can ex­ tend from the upper portion of the adjusting means along the whole adjusting means or only along part of its length and which side is provided with a toothing 9 while the very lock­ ing means is arranged to engage this toothing 9 of the adjust­ ing means 7 in locking position and to provide in this way an immovable connection between the central portion 1 and the heel 3 of the prosthesis. In order to secure the engagement between the locking means 8 and the toothing 9 a spring 12 is arranged pressing the locking means 8 against the toothing 9 at locking. By moving the toothing and the locking means from each other against the action of the spring 12 the adjusting means 7 is thus released so that it can be moved in its lon­ gitudinal direction for adjusting the heel in the intended position. In order to achieve displacement of the adjusting means 7 and consequently adjustment of the heel 3 relative to the foot sole with the part fixedly connected to the central por­ tion the adjusting means 7 is formed in an advantageous embo­ diment as a stud 13 (see Fig. 4) with threads for coaction with a sleeve 10 provided with corresponding threads and im­ movably anchored in a hole in the rear part of the central portion. The adjusting means 7 is turnable but not axially movably connected with the disc 5 fixedly arranged in the heel 3. The heel 3 is adjusted relative to the foot sole 2 by turn­ ing the adjusting means 7 in its sleeve 10 provided with threads, and to reduce the force required for turning the ad­ justing means 7 its threads and the threads of the sleeve should have a relatively small pitch. These threads should also be self-restrictive, locking of the adjusting means 7 in the adjusting position automatically being obtained. Thus, when turning the adjusting means 7 this is moved in longitudinal direction and the position of the heel relative to the part of the foot sole fixedly connected to the central portion 1 can be adjusted in the required degree for adaptation of the foot prosthesis to the heel height of the shoe to be carried. In order to make it easier for the carrier of the prosthesis to adjust the foot prosthesis a flexible wire 14 or the like, which is resistant to turning, is fixedly connected to the adjusting means 7, see Fig. 4, and is provided with a turning knob 15 at its upper end. The wire 14 should prefer­ ably have such a length that the turning knob 15 can be placed in such a position, for instance at beneath or above the knee joint of the leg prosthesis, that the carrier of the prosthe­ sis can reach it to adjust the foot prosthesis in the desired position without having to bend. Of course it is also possible within the scope of the invention to achieve the displacement of the adjusting means formed as a stud 13 relative to the central portion 1 of the foot prosthesis by arranging a nut or the like coacting with the threads of the adjusting means and turning this instead of the screw 13. The heel 3 of the foot prosthesis can also be adjusted by an adjusting means arranged between the central portion 1 and the heel 3 of the foot prosthesis, said adjusting means having the form of a pair of bellows or being embodied in another way so that its thicknes can be changed, for instance hydraulically or pneumatically or by means of a simple mecha­ nism. In the illustrative example shown and described the heel 3 is shown to be pivotally arranged relative to the part of the foot sole 2 fixedly connected to central portion 1, but it is also possible within the scope of the invention to arrange the heel so that it can be moved vertically relative to the central portion 1, the whole foot sole 2 except the heel being fixedly connected to the central portion 1, and suitable guides being arranged to prevent the heel from turning. The invention is not restricted to what has been de­ scribed above and shown on the drawings but it can be changed supplemented and modified in several different ways within the scope of the inventive data defined in the claims.

Claims: 1. Foot prosthesis comprising a foot sole (2), a heel (3) and a central supporting portion (1) provided with an adapter (4) for connecting the foot prosthesis to a lower leg prosthesis and supporting the foot sole (2) and the heel (3), characterized in that the heel (3) is movably supported relative to the part of the foot sole (2) fixedly connected to the central portion (1) of the prosthesis and consequently to the latter portion as well as the adapter (4) and that the heel (3) is coupled to the rear part of the central portion through an adjusting means (7) associated with the central portion and the heel for moving the heel towards or away from the central portion and consequently for adjusting the heel (3) in a desired position relative to the part fixedly connected to the central portion (1) of the foot sole, in which at least the pad portion is included, said adjusting means (7) being lockable in each position to retain the heel (3) in its position adjusted relative to said portion of the foot sole. 2. Foot prosthesis according to claim 1, char­ acterized in that the foot sole (2) and the heel (3) are made of an elastically flexible material and that at least a front portion of the foot sole (2) including at least the pad portion is fixedly connected with the central portion (1) of the prosthesis. 3. Foot prosthesis according to claim 2, char­ acterized in that the heel (3) and the foot sole (2) are made in one piece of the same elastic material. 4. Foot prosthesis according to claim 2, char­ acterized in that the heel (3) and the part of the foot sole (2) integral with the heel and loosely supported re­ lative to the central portion is pivotally connected in a joint with the portion of the foot sole fixedly connected to the central portion (1). 5. Foot prosthesis according to claim 1 or 2, characterized in that the heel (3) is formed separately from the foot sole (2) fixedly connected to the central portion (1) and is linearly movably supported by the adjusting means (7), guides being arranged to prevent the heel (3) from turning relative to the central portion (1). 6. Foot prosthesis according to any one of the preceding claims, characterized in that one end of the adjusting means (7) is connected to a pressure absorbing and distributing plate (5) fixedly arranged in the heel (3). 7. Foot prosthesis according to any one of the preceding claims, characterized in that the adjusting means comprises a rod movable in a sleeve (10) in the rear part of the central portion and a spring arranged between the central portion (1) and the heel and allowing a relative mo­ tion in the unlocked position of the rod between the central portion (1) and the heel of the prosthesis, a locking means (8) for locking the rod in the adjusted position being arranged in connection with the sleeve (10) surrounding the rod for an engaging coaction with a toothing (9) on one side of the rod by the action of a spring (12). 8. Foot prosthesis according to any one of the preceding claims 1-6, characterized in that the adjust­ ing means (7) comprises a rod (13) threaded along its whole length or parts of its length which is rotatably connected with the plate (5) arranged in the heel and extends through and cooperates with a nut means (10) provided with correspond­ ing threads to effect the displacement of the rod by turning either the rod or the nut means. 9. Foot prosthesis according to claim 8, char­ acterized in that the threads of the adjusting means have a small pitch and are self-restrictive for locking the adjusting means (7) in the set position. 10. Foot prosthesis according to claim 8 or 9, characterized in that a wire (14) resistant to twisting or a corresponding operating means for the prosthesis carrier is connected to that part of the parts of the ad­ justing means which is arranged to be turned for providing the adjustment of the heel.

Inventors: LJUNGBLAD, YNGVE
Applicants: LJUNGBLAD, YNGVE
Application year: 1987
Main classification: A61F2
IPC codes: A61F2