Interchangeable pump-lock for prosthetic socket and method of use

An interchangeable lock-pump prosthetic system that includes a universal dummy, vacuum pump, and mechanical lock. Each of the three objects have similar geometries for the purpose of fitting into a prosthetic, whereupon a user may for instance, swap the vacuum pump with the lock, depending on the needs of the user and without changing to a separate prosthetic. The universal dummy is an inactive component and acts as a placeholder during manufacturing of the socket, for the eventual inclusion of the vacuum pump or mechanical lock. The vacuum pump is a pressure dependent object that acts to remove any residual air between the socket and the elastomeric liner. The lock takes advantage of a mechanical locking pin which receives a properly configured liner, thus securing the user within the prosthetic socket.

TECHNICAL FIELD

This disclosure relates to a prosthetic socket and prosthetic socket lock. More specifically, this disclosure relates to a prosthetic socket lock and prosthetic socket vacuum pump set that are constructed to have similar geometry and thereby the same construction dummy for the purpose of providing interchangeability within the same prosthetic socket.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to an interchangeable pump-lock system for a prosthetic socket. More specifically, this invention relates to a system in which a prosthetist may interchange a dummy with either a vacuum pump or a mechanical locking mechanism, thus providing an amputee multiple options when using a prosthetic socket.

Description of the Background Art

Within the field of prosthetics, a variety of locking mechanisms and vacuum pumps exist to secure the amputees' residual limb within a socket. Traditionally, the socket is made from either a thermoplastic or composite material. The process for constructing a socket is labor intensive and complicated and requires extensive training. Prior to socket construction the prosthetist takes into account the device that will be utilized for securing the amputee's residual limb within the socket, whether a vacuum pump or mechanical lock hereinafter “securing device.” In some applications, the securing device is molded into the socket. Still in others, a construction dummy, or component without functionality, but having the geometric properties of the securing device, is obtained and used during construction. After construction has been completed the construction dummy is removed and the securing device is installed into the volume created by the dummy.

The majority of prosthetic sockets are constructed to accommodate a mechanical lock. This requires the prosthetist to take into account that the liner required will be a locking liner. Said locking liner having a distal attachment suitable for receiving a threaded pin. The threaded pin has serrations that interfere with the mechanical lock when inserted therein. Said prosthetic assembly, that utilizes a mechanical locking device, is generally more cost effective and easier to use than a prosthetic assembly that utilizes a vacuum pump.

Prosthetic sockets that accommodate a vacuum pump also require the prosthetist to take into account the specific make and model of the vacuum pump that will be utilized for the socket build. Additionally, the prosthetist must take into account the prosthetic liner that will be used. In the case of a socket utilizing a vacuum pump, the liner would not have a mechanical locking device at the distal end.

U.S. Pat. No. 8,197,555 (“'555 Patent”) issued to Laghi et al. discloses a vacuum pump of the type listed above and is incorporated by reference herein. However, the '555 Patent does not address the fundamental difficulty of allowing a prosthetist to manufacture a prosthetic that can use either a mechanical locking mechanism or a vacuum pump. Furthermore, the '555 Patent only discloses using an elastomer material for the spring mechanism within the vacuum pump, thus an elastomeric material only allows for a certain volume of air to be present within the vacuum pump versus having a more dense and compressible material, such as a metal, or a more porous material, such as foam.

The fundamental problem is that if a prosthetist builds a socket utilizing a vacuum pump and afterwards determines it is incompatible with the amputee (for any number of reasons), the socket must be rebuilt. Not only is cost a consideration, but patient health becomes a factor as the build time is significant and the patient is generally immobile during that time period. The dilemma can equally be viewed from the other perspective in which a prosthetist builds a socket utilizing a mechanical lock and afterwards determines is incompatible with the amputee for any number of reasons. Again, the socket must be rebuilt.

The present invention overcomes the aforementioned inadequacies by providing the prosthetist with a universally shaped securing device. In other words, the securing device is a vacuum pump and mechanical lock that are geometrically similar so as to be able to interchangeable with another. This allows for a single socket construction to accommodate either securing device.

The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

For the purpose of summarizing this invention, this invention comprises a interchangeable vacuum pump and mechanical lock securing device for use in prosthetic applications to properly secure the residual limb within the prosthetic socket.

Embodiments of the present invention are herein described by way of example and directed to a interchangeable pump-lock prosthetic securing device. The aforementioned state of the art of prosthetic securing shows the need for improvements, specifically in the ability of the user to switch between a mechanical locking mechanism to a vacuum pump mechanism, depending on the user's needs and applications.

The pump-lock system of the present invention satisfies the aforementioned deficiencies because of its unique, interchangeable design and ability to properly distribute externally applied forces.

Therefore, it is an object of this invention to provide a prosthetic socket that is easily manufactured to use either a mechanical lock or a vacuum pump as the securing means to a prosthetic socket.

Another object of this invention is to provide a construction dummy as a placeholder for the mechanical lock or vacuum pump, with the dummy, lock and pump having similar outer dimensions.

Another object of this invention is to provide a foam/metal spring or cushion for the purposes of having a larger reservoir of air to be used during the pumping action of the user.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. The various components of the present invention, and the manner in which they interrelate, are described in greater detail hereinafter.

As shown inFIG. 1, a dummy10, vacuum pump12, and mechanical lock14each have similar geometries, providing the basis for the invention that each are interchangeable depending on the needs of a user of the prosthetic limb.

As shown inFIG. 2, the dummy10has an upper flat surface18and a lower flat surface22that are in contact with an annularly extending side wall20. The dummy10may be tapered or straight based on vacuum strength desired. During the manufacturing of the socket70, a prosthetist may firmly position the dummy10into the distal end of a socket71(FIG. 14) whereupon a pin or other grasping means is inserted into a pin hole16. The purpose of the pin hole16is to provide a channel for an eventual mechanical locking pin64(FIG. 13). Thus, once the socket70has been molded to the shape of the user's residual limb, the prosthetist may then remove the dummy10, leaving a void within the distal end71of the socket70having dimensions similar to either the vacuum pump12or the mechanical lock14.

As shown inFIG. 3, the vacuum pump12has similar dimensions to that of the dummy10; however, the vacuum pump12can include a concave upper exterior surface26that extends conically around the upper portion28and down towards the lower portion30. In another embodiment, the vacuum pump12may have a convex upper exterior surface48(FIG. 9) in place of the concave upper exterior surface26. The vacuum pump12includes a fluid inlet24that receives air from a residual space or vacuum68(FIG. 16) between the vacuum pump12and socket70(FIG. 16). The fluid inlet24may have any geometry sufficient to receive fluids such as, circular, square, oval, or any irregular shape with respect to standard geometric shapes. The fluid inlet24may also have an attached cover, grate, or filter to provide a means to prevent dust, dirt, or any other foreign substance from entering into the interior of the vacuum pump12. The fluid inlet24may also be located at any point along the concave upper exterior surface26, depending on the shape of the user's residual limb for the purpose of providing a perfected location at which the user's residual limb seals the fluid inlet24during the user's ambulation.

Preferably, the vacuum pump12has a housing that is made of an elastomeric material to provide the stretch needed when a user applies pressure during ambulation. Any elastomeric material known or yet to be discovered may be used in the manufacture of the elastomeric housing72provided that the proper stretch characteristics are present. This elastomeric housing72is the same shape as the dummy10to allow for proper fitting by a prosthetist.

As shown inFIG. 4, the upper portion28is connected via a male end connector32to the lower portion30via the outer fluid channel44. The upper portion28may be connected to the lower portion30by simply applying any adhesive used in the industry in order to properly seal the interior portion of the vacuum pump12from any external factors such as air, dirt, dust, etc. A spring member34is disposed within the volume of the lower portion30and may be composed of a porous material such as foam, or a material such as a metal or elastomer which does not encompass the entire volume of the lower portion30, thus allowing fluid to readily circulate throughout the lower portion30. The spring member34may further be either a helical spring or a device that provides an opposing force proportional to the reduction of the overall height of the spring device. Suitable materials for such a device are elastomers, plastics, foam, bladders, and the like. Furthermore, the vacuum pump12may be made of any flexible material to allow for deflection while still being rigid enough to remain secure within the socket. In another embodiment, the spring member34may be removed entirely and the vacuum pump12may act as the spring member provided it is made of material which provides an opposing force proportional to the reduction of the overall height of the vacuum pump12.

As shown inFIGS. 5 and 6, the vacuum pump12includes an upper one-way check valve38near the upper portion28and a lower one-way check valve39near the lower portion30. The vacuum pump12may include more than two valves, depending on the needs of the user such as needing a more flexible vacuum pump12to account for varying weights of the user. Sealing element42extends annularly relative to the vacuum pump12to provide a sealing means between the vacuum pump12and the socket70(shown inFIG. 16). The sealing element42may have widely varying geometries such as, finger-like projections, upwardly or downwardly-extending projections, or any other geometry used to create a seal between the vacuum pump12and the socket70. Moreover, more than one sealing element may be placed as ribs around the vacuum pump12.

Additionally, the lower portion30includes a side wall41, annularly extending upwards to receive the upper portion28via the male end connector32. The side wall41is spaced from the spring member34via the outer fluid channel44, which provides a volume sufficient to receive the male end connector32. As such, channel44acts as a female connector to receive the male end connector32of the upper portion28. The outer fluid channel44may have varying dimensions according the manufacturing techniques such that its volume may vary from small to large and may have a conical formation. Although outer fluid channel44has a function of allowing male end connector32to attach to the lower portion30, it may also allow fluid flow because its volume is primarily composed of air, as opposed to a porous material such as foam or a dense material such as a metal.

The fluid inlet24allows a fluid to enter the interior of the vacuum pump12and specifically, the inner fluid channel40which is the main conduit to which the fluid is further dispersed either into outer fluid channel44or throughout the spring member34. Once enough pressure has accumulated within the vacuum pump12, the fluid then exits the vacuum pump12via the lower one-way valve39and out through the fluid outlet36. In general, the fluid moving through the fluid inlet is air.FIG. 6further shows a triangular void43that functions to further improve air flow as its volume is primarily composed of air, as opposed to a porous material such as foam or a dense material such as a metal.

As shown inFIGS. 7-10, the system may also incorporate a convex vacuum pump46having a convex upper exterior surface48. The overall design of the convex vacuum pump46is identical or substantially similar to that of the vacuum pump12, except for the dimensions of the convex spring member50. The convex spring member50of the convex vacuum pump46has a convex geometry. Thus, the convex spring member50extends throughout the interior of the convex vacuum pump46, excluding the volume encompassed by the fluid channels40fluidly connected to the fluid inlet24.

As shown inFIG. 11, the spring member34is generally positioned within the interior of the vacuum pump12. Furthermore, this figure is used inFIGS. 16 and 17to show the placement of the vacuum pump12when used in conjunction with the socket70(FIG. 16) and liner66(FIG. 17).

As shown inFIG. 12, the system incorporates a mechanical lock14which includes an upper portion56that has a concave upper surface53extending conically down towards a lower portion58. The upper portion56includes an inlet52that is configured to receive a male end76(FIG. 18) of a liner72(FIG. 18) configured to be fitted with the mechanical lock14. The upper portion56additionally includes multiple access points54to receive a screw or any other grasping means, to firmly secure the mechanical lock14to the socket70.

As shown inFIG. 13, the lower portion58of the mechanical lock14further includes a mechanical locking pin64that extends laterally within the lower portion58to coincide with the distal end62of the inlet52. The mechanical locking pin64is configured to extend to the exterior of the socket70such that the user may push or press the mechanical locking pin64to release the male end76of the liner72configured to be fitted with the mechanical lock14. Thus, the mechanical locking pin64is configured to be engaged when the male end76is fitted within the mechanical lock14and disengaged when the male end76is absent within the mechanical lock14. Specifically, a clasping mechanism61is removably housed within the distal end62of the inlet52and functions by grasping the male end76when engaged. When the user desires to remove the liner72from the mechanical lock14, the mechanical locking pin64is pressed, which disengages the clasping mechanism61by sliding the clasping mechanism61into the bottom portion58, thus temporarily removing the clasping mechanism61from the distal end62of the inlet52. The lower portion58also includes connections60for the purpose of using a set screw, rivets, adhesives, or any other grasping means to connect the lower portion58to the upper portion56.

Now that the method of action of the mechanical locking pin64has been described, the dummy's 10 pin hole16(FIG. 2) can more easily be understood. The purpose of the pin hole16is to provide a channel or placeholder for the mechanical locking pin64. During manufacturing, the manufacturer places a pin or other place-holding means, partially into the dummy10and extending to the exterior of the socket70. Thus, once the manufacturing process of the socket70is complete, a channel exists for the mechanical locking pin64to extend from the mechanical lock14to the exterior of the socket70, allowing the user to repeatedly push or press the mechanical locking pin64.

As shown inFIGS. 14 and 15, the dummy10is firmly positioned relative to the distal end71of the socket70. Notably, the residual space or vacuum68is shown to represent the amount of air between the socket70and the liner66, that exists before the introduction of the vacuum pump12. InFIG. 15, the dummy10is designed to fit in a snug manner to the liner66.

As shown inFIG. 16, the vacuum pump12is incorporated into the distal end71of the socket70system. The sealing element42is shown to represent a seal between the vacuum pump12and the socket70. An outlet73coincides with the fluid outlet36to provide a means of escape for the discharged fluid from within the vacuum pump12. As shown inFIG. 17, the vacuum pump12is designed to fit in a snug manner to the liner66.

As shown inFIG. 18, the socket70is not shown; however, the mechanical lock14is shown for the purposes of showing that the male connector76connects relative to the mechanical lock14via the inlet52. As such, once the user dons the liner66having mechanical connector72, the system can then connected to the mechanical lock14.

FIGS. 19-22each show a separate embodiment from the previous figures. Each of the three main components, the dummy10, vacuum pump12, and mechanical lock14are manufactured such that they have tapered exteriors. For example,FIG. 19shows a tapered dummy79fitted within the distal end71of the socket70.FIG. 20shows a tapered vacuum pump80fitted within the distal end71of the socket70and furthermore, the distal end71of the socket70includes a third one-way check valve78for purposes of having an increased outlet for any fluid between the socket70and liner66.FIG. 21shows a tapered mechanical lock82that receives the liner66having mechanical connector72.FIG. 22shows the vacuum pump12in a cylindrical configuration fitted within the distal end71of the socket70and furthermore, the distal end71of the socket70includes a socket one-way check valve78for purposes of having an increased outlet for any fluid between the socket70and liner66. The circumferential shape of vacuum pump12may be any geometry that allows for the creation of a level of vacuum68and allows the liner66to rest. Such geometries include, but are not limited to, circular, hexagonal, and octagonal.

As represented in the above figures, the invention provides a secure connection between the user's residual limb74and the socket70during the user's ambulation. As such, the cross section and modulus of elasticity of the chosen material used for the vacuum pump12determines the spring rate of the vacuum pump12, which then determines the level of vacuum68that will be present between the socket70and the liner66generated during the user's ambulation. The level of vacuum68is important because the secure connection between the socket70and the liner66is dependent on the level of vacuum68present.

Furthermore, the functioning principle of the vacuum pump12involve multiple steps, of which include (1) the material within the pump is compressed during the heel strike and the stance phases of the user's gait and (2) then the material returns to a full length during the toe-off and the swing phases of the user's gait. These steps are repeated each full cycle of the user's ambulation and thus, the spring member34within the vacuum pump12must be rigid yet durable enough to last for many cycles. The level of vacuum68achieved during the swing phase of the user's gait is equal to the spring rate multiplied by the length of the achieved compression and collectively divided by the cross sectional area of the vacuum pump12.

More specifically, after the socket is fully donned by the user and as the user begins to ambulate, with the initial downward step, the downward force of the residual limb within the socket will force any remnant air within the lower section of the socket out through fluid inlet24(FIG. 6), through the upper one-way valve38, into the fluid channel40and out through the lower one-way valve39while simultaneously compressing the spring member34downwardly. As the user lifts his limb off the ground for the next step, the spring member34expands causing lower one-way valve39to close and upper one-way valve38to open and draw more air from within the socket70in the fluid channel40. As the user takes the next step, causing spring member34to compress again, the air pressure in fluid channel40causes lower one-way valve39to open while maintaining upper one-way valve38closed thereby relieving air from within fluid channel45to be vented through fluid outlet36. The cycle is repeated as the user ambulates creating a continuous evacuation of air from within the socket.

Moreover, many pumps in the industry have been manufactured to include elastomeric springs or cushions; however, metal springs are either equivalent or more efficient due to their density. That is, since the metal springs are denser (requiring less volume) than elastomeric springs or cushions, air may travel more readily throughout the pump, thus providing a more fluid pumping action within the pump and therefore, a more comfortable experience for the user. The metal springs have a spring rate, or pumping action, determined by the shape of the coils, the Young's modulus of the metal used, and the thickness of the wire that is used to make the coils. Thus, the character of the metal spring is determined from its material and construction.

The spring rate for either elastomeric springs, metal springs, or foam cushion is determined by the cross sectional area of the material multiplied by the modulus of elasticity of the material. The number of steps required to reach steady state of the vacuum pump12(or the state at which the user's limb is securely attached within the socket70) is a function of (1) the free volume of the socket, (2) the required vacuum level (varying from 5 to 20 inches Hg, preferably 5 to 10 inches Hg), and (3) the volume of air that is displaced inside the pump during the stance aspect of the user's gait (the volume displaced for a given pump geometry is directly proportional to the compression allowed during the stance phase, the length of compression is fixed by the height ratio of the pump at rest versus the length of the dummy10and has values ranging from 3 to 20 mm and preferably 7 to 8 mm).

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.