The present disclosure relates to prosthetic devices and related methods of fabrication.
The use of prostheses by amputees is well known. Prostheses include a socket to receive a residual limb, a typically modular prosthetic extremity, such as a foot-ankle system, and an interface between the socket and the prosthetic extremity. A variety of sockets and prosthetic extremities are available, which can be combined in any suitable manner to produce a prosthesis that is tailored to meet the individual needs of different amputees.
The socket generally acts as the component of the prosthesis that contains and provides structural support for the residual limb. Specifically, the socket is instrumental as an interface between the residual limb and the prosthetic extremity. For lower limb amputees, the socket is involved in transferring the amputee's weight to the ground by the way of the prosthesis. For upper limb amputees, the socket is the essential component that allows the transfers movement of the residual limb to controlled movement of the prosthetic extremity. If the socket does not fit and operate properly, utility of the prosthesis can be severely compromised. Several factors are considered in the design of a socket, including whether the socket satisfactory transmits the desired load, provides satisfactory stability, provides efficient control for mobility, is easily fitted, and/or is comfortable.
Recent prostheses address these needs using a socket construction including several longitudinal struts, a residual limb interface, a distal base, and an anatomically-shaped fill cup. The struts are connected to a distal base of the socket using a variety of hardware that permits adjustment by the prosthetist for the user. A modular distal extremity also can be adjustably coupled to the distal base. The interface is supported at the interior of the struts and distributes contact and force between the residual limb and the struts. The fill cup is provided at the lower distal end of the interface to maximize support of the residual limb. Such prostheses are described in detail in U.S. Pat. No. 8,978,224 (Hurley et al.), which is incorporated by reference herein in its entirety.
The separate and distinct layers of the interface and the struts add thickness and bulk to the socket of the prosthesis. The thinnest socket is limited to the thinnest struts that are able to provide the necessary radial and longitudinal support to the prosthesis.
A prosthetic system includes a socket and a modular distal extremity. For a transtibial prosthesis, the modular distal extremity can include foot and ankle components. The foot and ankle components may also be provided with a tubular pylon element for adjustable attachment to the socket. For a transfemoral prosthesis, the modular distal extremity can include an articulable knee component, as well as foot and ankle components.
The socket of the system includes a weight-bearing structural frame, a residual limb interface, a distal base, and a fill cup. The structural frame defines a receiver with sufficient strength and stiffness to support the residual limb and transfer forces applied from the residual limb to the modular distal extremity. The limb interface is a softer, more form fitting aspect of the socket that is adapted to closely accommodate the anatomical contours and tissue density of the residual limb and/or is adapted to apply/receive force at locations that result in least irritation for the patient and provide the best user results for the prosthesis. The fill cup is an anatomically-shaped soft component provided at the interior of the interface for weight support and weight transfer from the residual limb, through the interface, and to the structural frame.
In accord with one aspect of the system, the structural frame and the interface are integrally molded together as a multi-matrix composite. A matrix is a combination of a polymer resin integrated with fibers. The fibers may be individual strands, fiber bundles, yarns, or cables, or formed as a fabric. The fabrics, by way of example, may be knits, weaves, spacer mesh or open mesh. The fibers create spaces to hold the resin, and the fibers functionally reinforce the resin. A matrix composite is a molded integration of two or more matrices.
The structural frame is preferably comprised of a base and a plurality of longitudinal struts. The base is adapted to support the distal ends of the struts and provides a modular interface with the distal component. The structural frame is made from a first matrix defined by a first resin and first fibers.
The limb interface is a second matrix defined by a second resin and second fibers, such that the second matrix is softer and less rigid than the first matrix. The second matrix is provided at at least one of the interior and exterior sides of the struts. In the second matrix, at least one of, and preferably both of, the second resin and second fibers are different from the first resin and the first fibers. The interface is preferably formed as an inner layer at the radial interior of the struts as well as an outer layer at the radial exterior of the struts. The interface may fully surround the struts or at least partially surround the struts. The first and second matrix together, forming at least the structural frame and the interface, define a multi-matrix composite.
In accord with a method of manufacturing the socket, a positive mold of a residual limb is made. A release agent is provided onto the positive mold. The second fibers (preferably in the form of a second fabric) are placed over the positive mold and the release agent. The structural frame is then placed onto the mold over the second fabric. Third fibers (preferably in the form of a third fabric) is then placed over the structural frame. A vacuum bag, having at the inside thereof a release agent, is positioned over the third fibers.
A curable liquid resin is provided into the vacuum bag and a vacuum source is applies negative pressure to the interior of the system to draw the resin through the third fabric, about the assembled struts and base, and through the second fabric. The resin is allowed to cure. Then, the socket is removed from the mold. Other manufacturing methods, including layered thermoplastic sheets, can also be used.
The constructed socket includes the first matrix of the structural frame at least partially sandwiched between and within the second matrix of the interface. The fill cup is provided within a cavity defined at the interior of the interface and functions as a softer, lower durometer, boundary layer between the residual limb and the remainder of the socket.
Additional matrix layers can be added to the socket construction. For example, additional struts, strips, bands, panels, etc. that are premanufactured fiber resin matrices can be inserted between structural frame and the interface or within a portion of the interface to define areas of intermediate or greater rigidity. Further, fabric strips, fabric bands, fabric panels, etc. can be inserted between the structural frame and the layers of the interface and the vacuum bag to define areas of greater rigidity or which have different properties once the resin permeates therein.
Non-matrix layers and/or components can be added to the construction. For example, stiffening plates, closures, guideways and channels, housing, retention mechanisms including portions of vacuum systems, pin lock systems, magnetic latching systems, and buckle systems, adjustment systems, sensing systems, and communications systems can be molded integral with the socket by positioning the components on the mold and in relation to the appropriate layer during the molding process.
After removal from the positive mold, the multi-composite matrix socket can be finish-shaped by cutting, grounding, sanding, buffing or otherwise shaping to accommodate necessary components and receiving the residual limb. Further, because the composite matrix is thermoplastic, the socket alternatively or additionally can be heated for shaping (and re-shaping) to better accommodate receiving, supporting and interfacing with the residual limb.
For the sake of convenience, much of the following disclosure is directed to prosthetic systems that are configured for use with a residual portion of an amputated leg, such as a leg that has undergone a transfemoral (i.e., above-knee) or transtibial (i.e., below-knee) amputation. It should be appreciated that the disclosure is also applicable to other prostheses, such as those configured for use with the residual limb of an amputated arm (e.g., after an above-elbow or below-elbow amputation).
Referring to
The socket 12 of the system includes a weight-bearing structural frame 20, a residual limb interface 22, and a fill cup 24. The structural frame 20 defines a longitudinally extending receiver that has sufficient strength and stiffness to support the residual limb and transfer force applied from the residual limb to the modular distal extremity. The limb interface 22 is of a softer durometer, and more form fitting than the frame such that it is adapted to more closely accommodate the anatomical contours and tissue density of the residual limb and/or is adapted to apply/receive force at locations that result in least irritation for the patient and provide the best user results for the prosthesis. The fill cup 24 is an anatomically-shaped, lower durometer component provided at the interior of the interface 22 for weight support and weight transfer from the residual limb, through the interface 22, to the structural frame 20.
In accord with one aspect of the system 10, the structural frame 20 and the interface 22 are integrally molded together as a multi-matrix composite. For purposes of the following description and claims, and as described in more detail below, a matrix is a combination of a polymer resin integrated with fibers. By way of example only, the resin may be a polymethylmethacrylate (PMMA) or a polyurethane. The fibers may be individual strands, fiber bundles, yarns, or cables, or formed as a fabric. The fiber, by way of example only, may be natural fibers such as cotton fibers, or manufactured fibers such as carbon fibers, nylon fibers, rayon fibers, NY-GLASS, POLY-GLASS, and highly elastic nylon fibers such as sold under the tradename EXTENDA, and/or heat and flame-resistant fibers such as synthetic aromatic polyamide polymer, e.g., sold under the tradename NOMEX (Dupont). The fabrics, by way of example, may be knits, weaves, spacer mesh or open mesh. The fibers create spaces to hold the resin, and the fibers functionally reinforce the resin. The fibers can also create decorative or mechanically useful patterns on the surface of the cured resin. The fibers can also create decorative colors patterns within the interior of the cured resin, particularly where the cured resin is transparent or translucent. A matrix is defined as being different from another matrix if it comprises different a resin, a different Shore hardness, a different modulus of elasticity, a different color of a same resin, a different cured thicknesses of the same or different resin, different fiber materials, different dimensions of the same or different fibers (i.e., different fiber diameters or substantially different cut lengths), different fabric constructions of the same or different fibers (knits, weaves, or meshes of fibers), and/or any combination of the previous. A composite matrix is a molded integration of two or more matrices.
The structural frame 20 is preferably comprised of a base 26 and a plurality of longitudinal struts 28. In one embodiment, the struts 28 are provided as relatively flat, separate and distinct longitudinal components. The struts 28 are made from a first matrix of a resin and fibers. The first matrix has thermoplastic properties such that, on heating to a defined deformation temperature, it becomes plastic and can be reshaped; subsequently, on cooling it re-hardens. The first matrix is able to have these processes repeated. In accord with a preferred construction, the first matrix includes a polymethylmethacrylate resin and carbon fibers retained with the resin.
Turning also to
According to another embodiment, the base 26 and struts 28 are provided separately and applied separately during the socket molding process. In such embodiment, the base 26 and struts 28 can be assembled relative to the socket at different steps during a socket molding procedure, described below, and the struts can be separately heat formed, cut, and bent relative to a mold without interference from other integrated struts or the base.
The interface 22 is a second matrix defined by a second resin and second fibers provided at at least one of the interior and exterior sides of the struts. In the second matrix, at least one of, and preferably both of, the second resin and second fibers are different from the first resin and first fibers. More preferably, the interface is formed as an inner layer at the radial interior of the struts as well as an outer layer at the radial exterior of the struts. The interface 22 may fully surround the struts 28 or at least partially surround the struts 28. By “partially surround” it is meant that the interface may partially, but not fully, cover portions of a plurality of struts, as well as the interface fully surrounds at least one of the struts and is absent from at least one of the struts. By “at least partially surround” it is meant that the interface may be located in relation to the struts as defined by either “partially surround” or further surround the struts up to what is commonly considered to fully surround or to fully encompass the struts. The second matrix is softer and less rigid than the first matrix. The first and second matrix together, forming at least the struts and the interface, define a multi-matrix composite with properties of both the first and second matrices.
Turning now to
Once the size and shape of the residual limb are measured or otherwise determined and the needs of the patient have been analyzed, a structural frame is made or otherwise provided for use in manufacture of the socket 102, and an appropriate physical model of the residual limb is made at 104 and as discussed below.
The structural frame is manufactured for the patient at 102. In such manufacture, an appropriate base and struts are required for the patient. The base and struts are selected from an inventory of bases and struts. The base may be selected at 106 on the type of prosthesis, the size and weight of the patient, the defined channel angle, and the struts to be attached thereto. The struts may be selected at 108, e.g., in length and/or thickness, based on the type of prosthesis, the size and weight of the patient, and/or the location (anterior, posterior, medial, lateral, or some intermediate position) at which the strut is to be attached to the base. The distal ends of the struts are inserted into the channel at the proximal end of the base, and secured thereto at 110. They are preferably secured with an adhesive that, once cured, has a higher melting point that the melting point of the first matrix.
In one step of the method, the base with straight struts is inverted at 112 (such that the struts 28 extend downward from the base 26, as shown in
In another step of the method, the positive mold of the residual limb is made at 104. The positive mold may be made from any suitable process. By way of example, first a cast of the residual limb may be made by wrapping the limb in a fabric provided with a preferably non-caustic first molding material. The fabric and first molding material may include a fabric provided with plaster of Paris, or a fabric provided with a low temperature curing polymer, or other suitable fabrics and first molding materials. After curing, the cured first material which covered the appropriate portion of the residual limb for the socket is carefully removed from the residual limb to define at its interior surface a negative mold in the shape of the residual limb. The negative mold is then filled with a curable second material and the second material is allowed to cure. Once the second material is cured, the negative mold is removed from over the cured second material to expose the positive mold.
In accord with another example for manufacture of the positive mold, data representing the three-dimensional contours of the residual limb is used in association with a CNC system to cut the positive mold from a block of suitable material, including plaster, plastic, wood, etc. In accord with yet another exemplar method, data representing the three-dimensional contours of the residual limb is used to print in three dimensions the positive mold from one or more suitable stock material(s). Other methods, including combinations of the methods, can be used.
Next, a release agent is provided onto the positive mold at 120. The release agent is adapted to assist in removal of the cured socket (described below) from over the mold.
A second fabric comprised of second fibers is placed over the positive mold and the release agent at 122. The second fabric is an eventual component of the second matrix which will overmold with the base and struts. The second fabric may be in the form of an open-ended sock, bands, strips, panels, or any other generally flat fiber-form.
The assembled unit of the base and struts 20 is then positioned at 122 over the second fabric and onto the mold in accord with a desired alignment relative to the mold.
A third fabric comprised of third fibers is then placed at 124 over the structural frame. The second and third fabrics may be the same or different, depending on whether the interface is intended to have different properties at its interior and exterior.
A vacuum bag, having at the inside thereof a release agent 126, is positioned over the third fabric at 128. A resin is released to, poured into, injected into or otherwise provided to the interior of the vacuum bag at 130. A vacuum source coupled to the vacuum bag is activated to apply at 132 a negative pressure to the interior of the system to draw the resin through the third fabric, about the assembled struts and base, and through the second fabric. In addition, external pressure is preferably also applied about the outside of the vacuum bag and onto the system by wrapping the system tightly in a compression member such as a fabric wrapping, a belt, a band, elastics, etc. The resin is allowed to cool or otherwise cure at 134 to form a composite matrix that includes the structural frame. Then, the vacuum bag is removed from over the cured resin. The socket is removed from the mold at 136.
From the above, turning to
In addition, second and third resins can be different from each other by modifying the process the change the resin part way through the socket molding. In such manner, the second resin is applied earlier in the process and is drawn to a deeper layer, i.e., the inner layer, and third resin is applied later in the process and is at the outside of the socket. For example, it may be advisable to use a softer more accommodating resin at the inner layer, and a stiffer resin at the outer layer.
Further, additional matrix layers can be added to the socket construction. For example, additional struts, strips, bands, panels, etc. that are premanufactured composite matrices can be inserted between the second fabric and the struts, or between the third fabric and the vacuum bag to define areas of intermediate or greater rigidity. By way of further example, fabric strips, fabric bands, fabric panels, etc. can be inserted between the struts and the first fabric, or the second fabric and the vacuum bag to define areas of greater rigidity or which have different properties once the resin permeates therein.
Moreover, non-matrix layers and/or components can be added to the construction. For example, metal stiffening plates can be molded in the structure. By way of another example, closures 60, guideways and channels 62, lacings, housings for components, adjustments, sensors, pressure applicators, adjustable or fixed fluid bladders, magnets, mechanical receivers, release mechanisms, drainage ways, displays, electronic signal transmitters and/or receivers, etc. can be molded integral with the socket by positioning the components on the mold and in relation to the appropriate layer during the molding process.
After removal of the socket from the positive mold, the multi-composite matrix socket can be finish shaped at 138 by cutting, grinding, sanding, buffing or otherwise shaping to accommodate receiving the residual limb. Further, because the composite matrix is thermoplastic, the socket alternatively or additionally can be heated for shaping (and re-shaping) to better accommodate receiving, supporting and interfacing with the residual limb.
Moreover, even after molding and before or after finish shaping the socket may be provided with closure components, including tension elements such as straps, bands, and cables, and housing and/or routings for such tension elements, all to modify the shape the socket to facilitate retention of the socket on the residual limb and adjustment of the socket to the residual limb. Also, the socket may be adapted or modified to allow the socket to accommodate other types of socket retention mechanisms including vacuum systems, pin lock systems, magnetic latching systems, buckle systems, etc., adjustment systems, sensing systems, and communications systems.
After manufacture of the composite matrix portion of the socket, the fill cup 24 is inserted at 140 into the interior cavity of the socket.
In accord with an alternative manufacture process, in which an initially flowable resin for the second and third matrices is not required, thermoplastic sheets are provided over the positive mold at the interior and exterior of the structural frame. Heat and vacuum are then applied to cause the sheets to flow, melt, mold or otherwise form about the structural frame. The thermoplastic sheets may be pre-provided as matrices with a fabric or fiber layer therein. Alternatively, the second fabric layer is provided between an inner thermoplastic sheet and the structural frame and a third fabric layer is provided between the structural frame and the outer thermoplastic sheet. Then, upon application of heat and vacuum, the thermoplastic sheet materials also flow within the second and third fabrics and form respective matrices. Optionally, the adjacent surfaces of one or both of the inner and outer thermoplastic sheets may be surface roughened to facilitate adhesion between the sheet layers. Further optionally, an adhesive may be applied to one or both of the outer surface of the inner thermoplastic sheet, the inner surface of the outer thermoplastic sheet, the inner surface of the structural frame, or the outer surface of the structural frame.
In accord with another method of manufacture of a prosthetic device, data regarding the patient residual limb is obtained and a positive mold of the residual limb is made, both in accord with any method described above.
Then, as shown in
Turning to
Referring to
It has been identified that a physical step 272 forms between the proximal end of the outer distal cup 246 and the surface of the third fabric layer 208. This physical step presents a substantially large space for thermoplastic resin to enter and fill in the subsequent stage of the manufacturing procedure. The resin is relatively dense and, if filled into all such space would result in a socket that is heavier than desirable. Therefore, in accord with one aspect of the method, a void filler 274 is filled into spaces present adjacent the base 226 as well as over selected distal portions of the third fabric 208. The void filler 274 is an expandable, relatively low-density, hardenable foam that is adapted to occupy space otherwise fillable by a thermoplastic second resin to reduce weight of the socket.
Turning to
As shown in
Then, referring to
The second resin is cleanly cut at the elongate structure 212 tying off the base 226. The tape 276 is removed from over the base 226, providing a clean appearance to the base.
The areas of the socket provided with void filler 274 have a reduced density in relation to the areas of the socket with thermoplastic resin; thus, the void filler operates to significantly reduce the weight to the socket.
A shown in
The first and second resins may be the same or different from each other. The fabric may be the same or different from each other. However, in accord with the composite resin matrix aspect of the described system and method, at least one of the fabrics and/or resins should be different from another.
There have been described and illustrated herein embodiments of a system and methods of manufacturing the system. While particular embodiments have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its scope as claimed.
This application claims benefit to U.S. Provisional Ser. No. 62/736,876, filed Sep. 26, 2018, and U.S. Provisional Ser. No. 62/701,310, filed Jul. 20, 2018, which are hereby incorporated by reference herein in their entireties.
Number | Date | Country | |
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62736876 | Sep 2018 | US | |
62701310 | Jul 2018 | US |