Patent Application
20230125274
Prostheses (or prosthetics) are artificial devices that replace body parts (e.g., fingers, hands, arms, legs, feet, toes, etc.). Generally, prostheses may be used to replace body parts lost by injury, disease or missing from birth.
In one example, an intact human foot connected at an ankle travels through stance and swing phases of a gait cycle during each stride of motion, whether the motion involves walking, jogging, or running. By adjusting the stiffness and damping characteristics of a prosthetic foot and ankle mechanism, the springiness of natural human foot and the corresponding natural human joints may be mimicked, thereby optimizing the prosthesis for the desired motion of the wearer. However, the characteristics that are desired to store and release energy appropriately for walking tend to oppose those best suited for fast walking and running.
Reference will now be made to the examples illustrated in the drawings, and specific language will be used herein to describe the same. It will be understood that no limitation of the scope of the technology is thereby intended. Alterations and further modifications of the features illustrated herein, and additional applications of the examples as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure are to be considered within the scope of the description.
A technology is described that provides a foot and/or ankle prosthesis for individuals with lower limb loss. This technology is able to store and release energy and thus individuals or patients who are using the foot and/or ankle prosthesis are able to expend less energy when walking or running.
The biomimetic prosthetic foot/ankle described herein has the following configurations that may improve the use of a prosthetic ankle/foot for individuals using a prosthetic limb. The device or system can include a prosthetic foot/ankle system with a linear or rotary hydraulic damper such that the hydraulic damper is attached (e.g., rigidly) to dynamic energy storing spring elements. The axis of rotation of the device or system can be estimated to be near to an axis of rotation of an intact human ankle, which may provide better biomimetic function.
The system can utilize spring elements that are curved or have a curved surface (e.g., to provide a fulcrum) based on the vertical displacement of the center of pressure of an intact normal foot. One such spring element may be an energy storing spring that is a leaf spring. The system can further provide user adjustable heel height using a system to provide user adjustable heel height and adaptation to inclines. For example, the system can also provide a user or amputee with an adjustable heel height using an adjustable sliding yoke.
The system may have an adjustable stiffness toe-lift spring to lift the toe of the foot/ankle system rapidly after toe-off to reduce stumbling and hip hiking. The system can allow a user to adjust both dorsiflexion and plantar flexion resistance independently to vary heel strike hydraulic shock absorption and avoid foot slap at the foot flat position.
This technology has a plurality of configurations. In one configuration, the system can utilize a linear hydraulic damper or linear hydraulic cylinder. In a second configuration, the system can utilize a rotary hydraulic damper or rotary hydraulic damping mechanism. A description of configurations that can utilize a linear hydraulic cylinder are provided but the discussion of the linear hydraulic damping may apply to the rotary hydraulic damping system and vice versa.
As the foot support 118 moves, the linkage 120 transfers that motion to the linear hydraulic cylinder 110, displacing hydraulic fluid in the linear hydraulic cylinder 110. The linkage 120 configuration helps reduce the total build height of the prosthesis. The resistances to hydraulic flow in the plantar flexion and dorsiflexion flow directions are controlled by the two independently adjustable manual adjustment valves or electric adjustment valves.
The orientation of the linear hydraulic cylinder 110 and the position of the revolute joint 114 may also improve the functionality of the prosthetic foot/ankle system. The position of the revolute joint 114 is located at a defined position with respect to the remnant limb to mimic the intact human foot/ankle. For example, the revolute joint 114 may be at an estimated position of where the amputee’s intact ankle was located. An individual using this technology can ambulate (i.e., walk) with a more symmetric gait because the position of the revolute joint 114 can be located to be similar to or to match that of the primary axis of rotation of an intact ankle.
In one configuration, the horizontal distance from the heel 130 to the revolute joint 114 may be approximately one third of the overall length of the foot. The vertical distance from the ground or floor to the revolute joint 114 may be approximately one-eighth the length of the total foot length.
The stiffness of the energy storing spring elements 112 may be based on the vertical displacement of the center of pressure of an intact normal foot. The center of pressure is the position of maximum pressure on the bottom of the foot during normal walking. This center of pressure moves from the heel at heel-strike to the toe at toe-off. The shape and stiffness of the spring elements of the foot/ankle system are designed so that the center of pressure progresses from heel to toe in a way that mimics the intact foot. Furthermore, the stiffness of the foot can be designed such that the vertical deflection of the spring elements matches that of the vertical deflection of the intact foot at the center of pressure as the pressure progresses from heel to toe.
The linkages 120 shown in
This foot/ankle system is also capable of heel height adjustment. This heel height adjustment may be accomplished by adjusting where the linkage 120 attaches to the linear hydraulic piston shaft. By adjusting the linkage position on the hydraulic piston shaft using the adjustment yoke or adjustable sliding yoke 122, the foot, ankle and/or housing with a heel can be pitched to the desired heel height. In one configuration, a mounting pyramid 124 can allow for user alignment of the prosthetic foot/ankle with a remnant limb of an amputee.
A second configuration of the prosthetic foot/ankle system will now be described that utilizes a rotary hydraulic damper 202 that is fixed solidly to spring elements 204, including an energy storing foot plate 205.
In this embodiment, the spring elements may wrap around the rotary hydraulic damper 202 to maximize the amount of spring material that can store and release energy. For example, a main spring element 208 may wrap around the rotary hydraulic damper 202. This embodiment allows for a defined number of degrees of hydraulic angular displacement (e.g., 20 degrees) and independent dorsiflexion and plantar flexion manual or electric adjustments.
Both of the configurations illustrated in
When the ankle is dorsiflexed, the linear hydraulic piston 302 in the linear hydraulic cylinder 304 forces fluid through the dorsiflexion hydraulic pathway 320 with its respective dorsiflexion check valve 322 and dorsiflexion resistance adjustment valve 324. The dorsiflexion resistance adjustment valve 324 may be a manual resistance adjustment valve or an electric resistance adjustment valve. The structure and operations that are described with respected to a linear hydraulic piston 302 and linear hydraulic cylinder 304 may also be applied to rotary hydraulic configuration.
Reference was made to the examples illustrated in the drawings, and specific language was used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. Alterations and further modifications of the features illustrated herein, and additional applications of the examples as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the description.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the preceding description, numerous specific details were provided, such as examples of various configurations to provide a thorough understanding of examples of the described technology. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the technology.
Although the subject matter has been described in language specific to structural features and/or operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. Numerous modifications and alternative arrangements can be devised without departing from the spirit and scope of the described technology.
