Prosthesis with foam block ankle

Prosthetic limb with foam block foot and ankle joint

This creation is about prosthetic feet, and more specifically, it is about low-profile prosthetic feet with a simple structure with enhanced dynamic performance characteristics.

In the prosthetic market, the traditional SACH foot has become the most widely prescribed artificial foot in the past 35 years. The SACH foot usually includes a solid ankle and a padded heel foot attached to the lower extremity along approximately the hinge axis of the ankle. SACH is being popularized by its simplicity and therefore economy, but it also includes defects in terms of kinetic reaction characteristics. In particular, the lower SACH foot does not provide as much energy storage and release as the more sophisticated prosthetic foot.

Some patients undergo what is technically called Symm's amputation, in which the foot is amputated from the leg close to the ankle area. Because Symes patients calf and tibia are used as residual limbs for orthopedic purposes, the orthopedic device used by the patient must be quite tight so that it can be attached below the amputation point, or it must be configured so that it is next to or higher than the amputation point. The patients tibia and calf can be accommodated when the wearers leg is pulled out. The prior art prostheses available to Sym's amputees generally include artificial feet that are glued or bolted to the bottom of the joint seat worn by the patients residual limb. These compact prosthetic feet can also be connected to the lower part of the temporary prosthetic leg that is fixed by the joint seat at the upper end of the amputee's leg. For this kind of compact prosthesis, due to the lack of available vertical space, it is difficult to provide a dynamic response level close to the original ankle. Some attempts to provide appropriate original ankle and foot response characteristics in Syms foot treatment include the use of rubber-lined mattresses, or bumpers, between the calf and the foot. Many of these require the addition of a pivot bolt attachment between the leg and the foot. Unfortunately, many of these rubber pad devices have limited durability because it is difficult to bond the rubber part to the solid leg or foot part, or increase the cost due to their complexity and the need for several mechanical parts.

In summary, there is a need to come up with a cheap and durable Syme prosthetic foot with improved performance characteristics.

In order to cope with the problems of the prior art, this creation proposes a simple and inexpensive prosthetic foot, which has a foot element, an ankle element, and an ankle block of compressible material sandwiched and connected between the foot element and the ankle element. Preferably, the foot element has a length approximately equal to the length of a human foot, while the ankle element is relatively short. The foot element is constructed of an elastic material that can bend along its length. The prosthetic foot further has an attachment connected to the opposite side of the ankle block on the ankle element to couple the foot to the downwardly attached leg. In a preferred embodiment, the ankle element can also bend along its long axis. In addition, the size of the ankle block is roughly the same as the length of the ankle element, and the span of the ankle block and the ankle element is about one-third the length of the foot element.

In a preferred embodiment, both the foot element and the ankle element contain plates. In addition, the ankle block body is preferably a monolithic element composed of foam. In addition, where appropriate, the foot plate and ankle plate have a width approximately equal to the width of the amputated foot of the wearer.

In another form, this creation proposes a basic prosthetic foot with improved performance characteristics, which generally includes a lower foot plate, an upper ankle plate, and a single foam block connecting the two plates. Both the foot plate and the ankle plate are made of strong and flexible materials, preferably made of glass fiber. The size of the footplate is approximately equal to the size of the human foot it is to make up for, while the ankle plate has a similar width but has a shorter length than the footplate. The length and width of the ankle block are approximately equal to and juxtaposed with the ankle plate, both of which are installed behind the center line of the foot plate. A connecting post extends upward from the ankle plate to fix the connecting element or other coupling element for mating with the residual limb of the wearer. In a walking step, the combination of the foam block ankle and the flexible plate provides a smooth rolling from the heel to the far toe position.

According to a preferred embodiment of the present invention, the foam block ankle is made of polyurethane foam with a thickness of about two inches. The connecting column is installed behind the center of the ankle plate to mimic the correct line of force through the actual ankle. During a walk, most of the compressive force exerted by the wearer will be absorbed by the foam block ankle, and a small part will be absorbed by the flexible board itself. The foamed block is preferably a high-density cellular polyurethane foam.

<p>20Prosthetic Foot</p><p>22Foot Plate</p><p>24Ankle</p><p>26Elastic foam material layer</p><p>28External flexible beauty products</p><p>30Bottom liner</p><p>32Connecting components</p><p>34Coupling Button</p><p>36Substrate</p><p>38Threaded hole</p><p>40Screw</p><p>42Hole</p><p>44Tongdong</p><p>46Screw head</p><p>47Connecting shaft</p><p>48Locating pin</p><p>50Back part</p><p>52Ground</p><p>54Back end area of foam block</p><p>56Ankle back area</p><p>58The front part of the foam block</p><p>60Bump area</p><p>62toe area</p><p>64Front tip of foot plate</p><p>66Front tip of ankle plate</p>

Figure 1 is a perspective view of the better prosthetic foot of the present creation inside the outer foot beauty product shown in dotted lines; Figure 2 is a perspective anatomical view of the prosthetic foot in Figure 1; Figure 3a is the prosthetic foot in a walking step Vertical view of the position of the heel on the ground; Figure 3b is the vertical view of the prosthetic foot's flat position on the ground during a walking step; Figure 3c is the vertical view of the heel position of the prosthetic foot during a walking step ; And Figure 3d is a vertical view of the position of the far toe of the prosthetic foot in a walking step.

So far, referring to Figures 1 and 2, the prosthetic foot 20 of the present creation is shown in assembled and anatomical perspective views, respectively. The prosthetic foot 20 generally includes a lower foot plate 22, an upper and smaller ankle plate 24, and an elastic foam material layer or block 26 that connects the foot plate to the ankle plate. The length and width of the foot plate 22 are approximately equal to the length and width of the truncated foot of a particular wearer, and its size should fit within the external flexible beauty product 28 drawn in dashed lines. The ankle plate 24 and the foam block 26 have approximately the same horizontal cross-sectional dimensions. The ankle plate 24 and the foam block 26 are laterally aligned with each other and are generally disposed on the rear half of the foot plate 22. The foam block 26 is sandwiched between the foot plate 22 and the ankle plate 24, and is preferably bonded to the two plates. The foot plate 22 may also have a lower bottom liner 30 to provide the inner surface of the beauty product 28 Protection against the corners of the foot plate.

The prosthetic foot 20 is connected to the wearer's residual limb or lower leg temporary artificial leg (not shown) via a connecting element 32. The connecting element 32 is adapted to be fixed on the upper surface of the ankle plate 24 and includes a coupling button 34 to intersect with the coupling element on the temporary prosthetic leg. In the illustrated embodiment, the connecting element 32 includes a base plate 36 with an upright coupling button 34 integrally formed therewith. The connecting element may further include a pair of upright positioning pins 48 which can help temporarily use the torsion transfer between the prosthetic leg and the prosthetic foot 20.

The central threaded hole 38 in the coupling button 34 can receive a fixing screw 40 extending upwardly through the hole 42 in the foot plate 24. The foam block 26 preferably has a cavity 44 formed on its upper surface to receive the downwardly protruding screw head 46. Other connecting elements, as those skilled in the art can understand, can also be fixed through upwardly directed fixing screws. 40 Make the connection. The center of the screw 40 defines a connecting shaft 47, which is substantially juxtaposed with the vertical center line of the imaginary ankle to more realistically simulate the position of the force transmission between the leg and the foot. The center line is located behind the center line of the longitudinal axis of the ankle plate 24 and the foam block 26, and preferably, is approximately two-thirds from the front end of the ankle plate 24 and the ankle block 26. In this way, there is substantially more foamed block material at the center line 47 and the front of the connecting element 32 than at the rear.

Both the foot plate 22 and the ankle plate 24 are preferably constructed of glass fiber, which can provide strength and flexibility. In addition, the plates 22 and 24 can be formed by embedding many layers in a hardened flexible polymer. In other configurations, the plates 22 and 24 may be formed of other materials, such as carbon fiber, as known to those skilled in the art. The necessary properties of the plates 22, 24 are that they must have considerable elasticity to endure cracks under repeated bending stresses, but still have enough flexibility to match the properties of the foam block 26 to enhance the wearers perception Performance characteristics.

In order to more fully explain the improved performance characteristics of the prosthetic foot 20 of the present creation, Figures 3a-3d show "snapshots" of several positions of the prosthetic foot in a walking step. More specifically, Figure 3a shows the position of the heel on the ground, Figure 3b shows the position that is substantially flat on the ground, Figure 3c shows the position of the heel off the ground, and Figure 3d shows the position of the distal toe end. Through the various positions shown in a walking step, the creative prosthetic foot 20 provides the wearer with a smooth and generally living response. In a walking step, the foamed block 26 can transmit the force exerted on the foot plate 22 and the ankle plate 24, and experience the gradual rolling or migration of the pressure zone from the back to the front.

With particular reference to Figure 3a, the first position of a walking step generally requires heel landing, where the wearer transfers his whole body weight to the heel of the forefoot. In this case, the rear part 50 of the foot plate 22 is in contact with the ground 52, although through the bottom pad 30 and the beauty product 28. The flexible nature of the foot plate 22 allows it to bend slightly in the rear part 50. However, most of the compressive stress from the wearer's weight through the prosthetic foot 20 to the foot plate 22 is absorbed by the rear end area of the foam block 26 54 absorbed. In addition, the rear end region 56 of the ankle plate 24 may be slightly bent, but the bending will be limited by the short lever arm between the connecting shaft 47 and the effective center of the walking surface of the prosthetic foot 20. In addition, the foam block 26 will reinforce the whole but is a small part of the rear part 50 of the prosthetic foot against bending. The front end portion 58 of the foam block 26 undergoes a stretch, or stretch, which comes from the connection with the foot plate 22 along the entire lower edge of the foam block.

Secondly, in Figure 3b, the wearer reaches a position that is substantially flat on the ground, where the foot plate 22 contacts the ground 52 substantially along its entire long axis, similarly through the bottom pad 50 and the beauty product 28. In this position, the weight of the wearer is directed generally downward, so that the compression along the length of the foam block 26 will be slightly larger at the rear end 54 due to the off-center force. Although this figure freezes the compressive stress distribution as described, in reality, the weight of the wearer is continuously shifted from behind the centerline 47 of the connecting element 32 to the front of it. Therefore, when the wearer continues to step, the compression of the foam block 26 will shift from the rear end portion 54 to the front end portion 58. This migration of the compression zone is called "roll-over".

In the next snapshot of walking, Figure 3c shows the prosthetic foot 20 in the "heel off the ground" position. This is the moment when the wearer draws the foot with the cue zone 60 and toe zone 62 of the foot. Therefore, a large compressive force is generated in the front end region 58 of the foam block 26, causing the rear end region 54 to experience a large amount of separation or expansion. The front tip 64 of the foot plate 22 can be substantially bent to absorb some compressive stress. Likewise, the front tip 66 of the ankle plate 24 can be quite bent at this point. The important point is that although the foam block 26 absorbs most of the compression generated by the wearer, the foot plate 64 and the ankle plate 66 are designed to work with the foam block to provide improved dynamic performance. . In addition, the bending of both the front tip 64 of the foot plate and the front peak 66 of the ankle plate can release the extreme shear stress exerted on the interface between the foam block 26 and the two plates, thereby prolonging the life of the bond formed therebetween. .

In the final position of a walking step shown in Figure 3d, the prosthetic foot 20 remains in contact with the ground 52, but some of the wearer's weight is being transferred to the other foot, which is now moving forward. In this position, the front tip 64 of the foot plate 22 has less curvature and the front end 58 of the foam block 26 has less compression. Likewise, the front tip 66 of the ankle plate 24 may be slightly curved, depending on the material and thickness used. The highest compression zone of the foam block 26 remains at the farthest front end zone 58, but the compression level is lower than that of the heel lift position in Figure 3c. Therefore, the rear end portion 54 of the foam block 26 undergoes a small amount of stretching or spreading.

Although the foot plate 22 is shown to be generally flat, it can also be configured to have a slightly curved shape in the central area, with the toe and heel area slightly curved upward to mimic the natural curve of the bottom surface of the foot. However, even with the flat footboard 22 used to reduce the cost of the final product, the prosthetic foot 20 still performs substantially better than other SACH feet.

The foam block 26 is preferably composed of a relatively densely-celled polyurethane foam, and more preferably is a polyurethane foam with a density in the range of 25-35 pounds/cubic foot. The foam body has a preferred density of 30 pounds per cubic foot. The bubble foam provides sufficient elasticity to produce a natural feel with some elastic response without the restrictive compression defects associated with solid elastomer bumpers. In addition, the bubble structure of the block 26 also makes it lighter than a solid elastomer.

The foam block 26 can be made into different heights or thicknesses, but the most effective one is a thickness between 1 to 3 inches, and more preferably, the foam block has a thickness of about two inches. The foam block 26 thus provides a relatively tough but flexible ankle area, which can be customized for different wearers. More specifically, heavier wearers may need denser urethane foam to make the foam block 26, while lighter wearers may need less dense foam or Smaller thickness.

The drawings in Figures 3a-3d show a typical compression sequence of the foamed block 26 that occurs in one step. However, although not illustrated, the foam block 26 also provides the wearer with enhanced performance during inversion or eversion. The prior art SACH foot is often limited to rotating around the horizontal axis of the ankle and has a relatively small flexibility from one side of the foot to the other side of the foot. The foam block 26 of the present invention allows the wearer to walk up the slope laterally. For example, the foot plate conforms to the terrain and the ankle plate is kept relatively level due to the lateral compression of the ankle block 26. Similarly, when the wearer lifts his foot, the foamed block 26 returns to its original shape, and energy can be stored and released to help the wearer.

So far, it can be understood that the "feel" of the prosthetic foot 20 in this creation will be greatly enhanced by the synergy between the foot plate 22, the ankle plate 24, and the foam block 26. When the wearer steps continuously, the prosthetic foot 20 has a smooth dynamic response as the foam block 26 is compressed in different areas. In addition, the bending of the plates 22, 24 helps smoothly pass various bumps and vibrations that exist on the uneven walking surface.

Although this creation has been described in some preferred embodiments, other entities that can be clearly known to those who are familiar with this technique are also included in the scope of this creation. Therefore, the scope of this creation is intended to be defined by the scope of the following patent applications.