This invention relates generally to orthopedic prosthetics, and more particularly to fittings for prosthetic feet.
One feature of the human ankle is its ability to permit movement in multiple axes. For example, the ankle permits dorsiflexion/plantarflexion, or the flexing of the foot up and down, medial/lateral movement, or the rolling of the ankle to the sides, and torsion, or rotating the foot with respect to the lower leg. These movements are especially important when traveling over uneven surfaces or engaging in generally athletic activities. In particular, they permit the lower leg to remain relatively stable even as the foot moves over uneven terrain.
In lower leg amputees, a lower limb prosthesis is fastened over the lower leg residuum and coupled to a prosthetic foot to form a prosthetic lower extremity. The prosthetic lower extremity allows an amputee self-propelled ambulation. Prosthetic “ankle” fittings are generally used to couple the prosthetic foot to the lower limb prosthesis. Thus, it is important that prosthetic fittings be capable of imitating the human ankle as much as possible to provide the most natural and stable gait or stride, particularly when traveling over uneven surfaces and engaging in athletic activities.
In one embodiment, the present invention is a multi-axial fitting for use with a lower limb prosthesis. The fitting includes a base and a mount, each adapted for coupling to a lower limb prosthesis, an intermediate member fixed to the mount and pivotally and rotatably coupled to the base, and a resilient member disposed between the mount and the base.
In one embodiment, at least a portion of the resilient member is fixed to the base and to the mount while a central portion is compressible and torqueable. The intermediate member includes a bolt having a shaft fixed to the mount and a head movable within a cavity formed under a central portion of the base. A spherical washer may be disposed between the bolt head and the base within the cavity. The bolt head is movable within the cavity relative to the base.
In another embodiment, the intermediate member includes a shaft member and a hinge member. The hinge member is pivotally coupled to the base. The shaft member is fixed to the mount and has a shaft portion slidable within a slot formed in the hinge member. A resilient member may be disposed between the mount and the hinge member, the hinge member and the base, or both. The hinge member is pivotal relative to the base about an axis extending in a lateral direction to permit the base to move relative to the mount in plantarflexion and dorsiflexion.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
Returning to
As shown in
The base 230 includes a centrally located base aperture 236. An annular region of the base 230 surrounding the base aperture 236 is configured at an upward angle, forming a rim or lip 238 on an upper surface 232 of the base 230. The rim 238 defines a cavity 240 between the rim 238 and the lower surface 234 of the base 230. A circular ridge 242 is provided on the base upper surface 232 and is axially aligned with but spaced apart from the rim 238, defining a trough 244. A portion of the lower surface 254 of the resilient member 250 resides within the trough 244, which assists in preventing the resilient member 250 from dislocating from the base 230. The ridge 242, along with the flange 218, defines the aforementioned gap 258 between the mount 210 and the base 230.
The mount 210 includes four mount notches 213 and the base 230 includes four base notches 233 in the flange 218 and upper surface 232, respectively. The resilient member 250 has four corresponding interlocking members 251 sized to be received in the aligned notches 213 and 233. In combination, the notches 213, 233 and interlocking members 251 prevent rotation of the mount 210 with respect to the resilient member 250 and rotation of the resilient member 250 with respect to the base 230.
The mount 210, the resilient member 250, and the base 230 are coupled to one another via a bolt 270 and a spherical washer 280. The spherical washer 280 has a curved inner profile 282. A head portion 272 of the bolt 270 resides within the spherical washer 280. The washer 280 is positioned within the cavity 240. A shaft portion 274 of the bolt 270 is provided with threads 276 and extends upward through the washer 280 and into the mount aperture through the base aperture 236 and the resilient member bore 256. The bolt 270 is secured to the mount 210 via the threads 276. When a downward force is applied to the mount 210, for example, when the wearer transfers weight to the prosthetic foot 30, the resilient member 250 compresses, absorbing some of the force. As the resilient member 250 compresses, the mount 210 migrates toward the base 230, as does the bolt 270. In particular, the bolt 270 moves within the cavity 240 with respect to the base 230. The foregoing arrangement advantageously provides a secure mechanical coupling between the mount 210 and the base 230 while yet permitting movement of the mount 210 with respect to the base 230 when the resilient member 250 compresses and absorbs energy.
When a lateral force is applied to the mount 210, for example, when the wearer walks over uneven terrain, or engages in athletic activities, the resilient member 250 undergoes greater compression in some regions than in others as the force is absorbed. That is, the resilient member 250 compresses on generally the left side or the right side (from the wearer's point of view), providing medial/lateral rollover of the lower limb prosthesis 14 with respect to the prosthetic foot 30, or compresses on generally the front or the rear side (from the wearer's point of view), providing dorsiflexion/plantarflexion of the prosthetic foot 30 with respect to the lower limb prosthesis 14. The bolt 270 correspondingly tilts in response to the uneven compression of the resilient member 250. The foregoing are merely by way of example; the resilient member 250 is compressible all about its circumference, advantageously providing 360 degrees of movement. The spherical washer 280 curved inner profile 282 permits tilting of the bolt head 272 all about its circumference. The amount of compression in a particular region of the resilient member 250 is dependent upon the characteristics of the material and the dimensions of the resilient member 250. Generally, a thicker region of the resilient member 250 is capable of compressing more than a thinner region.
According to one embodiment, as shown in
When torsional force is applied to the mount 210, for example when the wearer exerts rotational force on the lower limb prosthesis 14 while the prosthetic foot 30 is stationary, the torsional force is transferred generally evenly from the first coupling means 212 to the flange 218. The flange 218 in turn transfers torsional force to the upper surface 252 and to the interlocking member 251 of the resilient member 250. In other words, the resilient member lower surface 254 and the interlocking member 251 remain immovably fixed to the base 230, while the resilient member 250 twists. The interlocking member 251 in the resilient member 250 deforms, absorbing the torsional force. As the force is released, the interlocking member 251 returns to its original shape. The bolt 270 and spherical washer 280 rotate along with the resilient member 250 with respect to the base 230 within the cavity 240. This feature advantageously provides rotational movement of the lower limb prosthesis 14 with respect to the prosthetic foot 30.
The mount 210 and base 230 are constructed of rigid materials able to accommodate the wearer's weight and activity level. Examples include titanium, steel, stainless steel, aluminum, composite, cast metal or molded composite or any other like material.
The resilient member 250 is constructed of urethane, elastomer, rubber, silicone or other durable foam-type material capable of resilient compression and torsion. In particular, the resilient members 250 is adapted to compress when subject to force, for example, when the wearer transfers weight to the prosthetic lower extremity.
The mount 310 as shown in
The rocker 330, as shown in detail in
The rocker 330 is coupled to the mount 310 and first bumper 320 by a fastener, for example, shoulder bolt 324. Shoulder bolts 324 each have a head portion 326 and a shank portion 328 provided with threads 329 complementary to inner mount inner threads 316. The head portion 326 resides at the lower surface 334 of the rocker 330 while the shank portion 328 extends through the rocker apertures 336, through the first bumper apertures 322 and into the mount apertures 314.
The shoulder bolt 324 is coupled to the mount 310 via the threads 316 and 329. The shoulder bolt head 326 is slidable along the lower surface 334 of the rocker 330 the length of the rocker apertures 336 so that the lower surface 313 of the mount 310 slides over the upper surface 321 of the first bumper 320. This feature advantageously provides a rotatable coupling between the mount 310 and the rocker 330. The degree of rotation permitted depends on the length of the rocker apertures 336 and the first bumper apertures 322, and may be adapted to accommodate the needs of various users.
The lower surface 334 of the rocker 330 is provided with a hinge member 340. Hinge member 340 is a generally curved protrusion having a orifice or hole 342 therethrough. As shown in
The pivot or rocking feature advantageously provides, for example, medial/lateral motion or dorsiflexion/plantarflexion, of the mount 310, and thus the prosthetic leg 14, with respect to the base 360, and thus the prosthetic foot 30. The base 360 is further provided with means 377 of coupling the fitting 300 to a prosthetic foot 300. As shown in
The second bumper 350 is a ring-like member having a ring opening 352 located in between the rocker 330 and the base 360. The hinge 376 is located in the ring opening 352. The second bumper 350 is made of a resilient material adapted to cushion rocking forces between the rocker 330 and the base 360. The second bumper 350 advantageously provides shock absorption and a smooth rocking motion as the rocker 340 pivots about the hinge 376.
The mount 310, rocker 330 and base 360 are constructed of rigid materials able to accommodate the wearer's weight and activity level. Examples include titanium, steel, stainless steel, aluminum, composite, cast metal or molded composite or any other like material.
The first and second bumpers 320 and 350 are constructed of urethane, elastomer, rubber, silicone or other durable foam-type material capable of resilient compression and torsion. In particular, the first and second bumpers 320 and 350 are adapted to compress when subject to force, for example, when the wearer transfers weight to the prosthetic lower extremity.
The resilient member 630 is further provided with a plurality of tongues 631, 632 protruding outwardly adjacent the mount 610 and base 620, respectively. The mount 610 is likewise provided with corresponding inwardly protruding notches 611 sized to receive the tongues 631. The tongues 631 and notches 611 interlock to prevent rotation of the mount 610 with respect to the resilient member 630. Notches 621 protrude inwardly from the base 620 adjacent the resilient member 630. The notches 621 and tongues 632 likewise interlock to prevent rotation of the resilient member 630 with respect to the base 620.
The base 620 includes a second coupling means 625 complementary to the first coupling means 615 for coupling the fitting 600 to a prosthetic lower extremity, for example a socket or a pylon of a lower limb prosthesis, prosthetic fitting or prosthetic foot. The second coupling means 625 is thus configured generally similar to the mounting portion of the prosthetic lower extremity coupled to the mount 610. This feature advantageously provides a universal type fitting such that the fitting is mountable in a variety of configurations. For example, a fitting according to the present embodiment is mountable to a prosthetic knee or socket as well as to a prosthetic ankle or prosthetic foot.
Although the present invention has been described with reference to exemplary embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. In addition, the various embodiments described include numerous components which may be provided in various combinations to achieve similar functionality. All such combinations are within the scope of the present invention. Also, various of the components may be eliminated from one or more embodiments to achieve the same function, as described above.
The present application claims the benefit of U.S. Provisional Application Ser. No. 60/572,322 entitled “Multi-Axial Fitting with Shock Absorption for Prosthetic Foot,” filed May 19, 2004, which is herein incorporated by reference.
Number | Date | Country | |
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60572322 | May 2004 | US |