Prosthetic liner with external fabric seal

A prosthetic liner for use with a prosthetic socket that has a thermoplastic elastomeric (TPE) layer that is in contact with the amputee's residual limb. The TPE layer is not uniform in thickness but has ridges to extend circumferentially around the TPE layer. A fabric layer covers the outer surface of the TPE layer conforming to the ridges and is used as a substrate to form a mechanical bond to an outer seal layer. The outer seal layer is formed by applying an uncured material to the fabric around the ridges thereby creating an air tight boundary layer when inserted into a socket. When vacuum is applied the air is evacuated from the volume below the seal layer.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to liners for use in a prosthetic assembly. More particularly, this invention relates to vacuum sealing liners having a thermoplastic elastomeric layer comprising sealing ridges such that an air tight seal is formed when a vacuum is applied within the area between a prosthetic socket and the sealing liner.

Description of the Background Art

Presently, suspension liners can be configured to provide a sealing means between a residual limb and a prosthetic socket as seen in U.S. Pat. No. 8,097,043 to Egilsson, the disclosure of which is hereby incorporated by reference herein. Such liner sleeves are typically made of an air impermeable elastomer material such as silicone and may include a reinforcement layer intermediate the inner and outer surfaces of the liner sleeve body portion or externally thereof to provide resistance against axial elongation of the elastomer constituting the liner sleeve body. Such reinforcement typically does not restrict radial distension or stretching of the liner sleeve body.

Various arrangements have been considered when configuring the suspension liners to securely remain within the rigid prosthetic socket because the ambulation of the user typically wiggles the prosthetic away from the user's residual limb. Of the various method, such as ambulation-pumping mechanisms to remove any remaining air from the space between the liner to the prosthetic, a most efficient method is to prepare a seal around the liner. This seal suspension liner has an elastomeric material attached to the knitted layer to provide a friction-inducing property to the liner itself. When the user inserts her residual limb, with attached suspension liner, the user would in effect, force her limb into the prosthetic socket and then the ring-like seal, which has a larger circumference than the suspension liner, being jammed into the prosthetic.

In other applications, it may be desired to more positively secure the liner sleeve within the socket by creating a hypobaric (vacuum) pressure within the distal end of the hard socket and the distal end of a suspension liner sleeve inserted into the socket. The hypobaric pressure may be maintained at the distal end of the hard socket and the interior of the socket at its distal end will be isolated from atmosphere during normal retention of the sleeve liner within the socket. Opening the distal end of the socket to atmosphere releases the vacuum or hypobaric pressure within the socket to enable simple withdrawal of a residual limb with a liner sleeve thereon from the socket. A pump or other device may be utilized to evacuate the distal end of the socket between the distal end of a liner sleeve and the distal end of a socket. A valve or other appropriate device typically is used to open and close the distal end of a socket to surrounding atmosphere.

Other arrangements are known in the prior art for providing an appropriate seal between the exterior of the liner sleeve and the interior of the hard socket including external air impermeable sleeves covering the interface area between the proximal end of the hard socket and the adjacent liner sleeve body.

Therefore, it is an object of this invention to provide an improvement which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the liner art.

Another objective of the invention is to create a convenient, improved sealing arrangement between an elastomeric liner sleeve and the interior of a prosthetic socket.

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

The present invention relates generally to a layered liner with ridges for use in a prosthetic assembly. Specifically, the present invention relates to a liner having an elastomer layer, a fabric exterior, and a sealing layer wherein the elastomer layer has a plurality of ridges. The fabric exterior is bonded to the outer surface of the elastomer layer and forms a suitable substrate for the sealing layer. The sealing layer is applied in an uncured state to the fabric with a purpose of having a viscosity such that the sealing layer is able to “wet out” the fabric in the applied area so that once cured, the sealing layer forms an air tight seal intermediate the fabric and socket.

Typically, the sealing ridges are formed by a separate molding process than that of the elastomeric layer. That is, the elastomeric layer does not have any sealing ridges because the sealing ridges are essentially, implanted via bonding agents to the knitted layer or elastomeric layer. In this situation, when the sealing ridges are implanted into the elastomeric layer, they are called raised portions. However, in this invention, having the elastomeric layer configured to be molded to include the plurality of sealing ridges offers an advantage over similar technology. The raised portions are more durable because they are protected by not only the reinforcement layer, but also the outer layer that covers only the sealing ridges. Thus, if the outer layer is eventually removed via continuous use over many years, the suspension liner will still have a slight sealing effect because the raised portions are still within the elastomeric layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1illustrates a thermoplastic elastomeric layer400of the seal liner100in which the thermoplastic elastomer layer400(also known as TPE) having an inner elastomer surface410and outer elastomer surface420is formed within a mold having wall thicknesses between 2 and 9 mm. The liner100preferable has an open proximal end120with a larger circumference and volume than of the closed distal end140.

FIG. 2illustrates a preferred embodiment of the seal liner100in which the thermoplastic elastomer layer400further comprises at least one sealing region430that extends preferably between 3 and 20 mm outward from the interior surface410of the thermoplastic elastomeric layer400and includes at least one raised portion440. If more than one raised portion440is included within the sealing region430, the plurality of raised portions440will be accompanied by at least one recessed portion450. Thus, if there are two raised portions440then three recessed portions450will be distributed as shown inFIG. 1. Alternatively, the sealing region430may begin with a raised portion440instead of a recessed portion450. In this instance, the distribution would be as follows: raised portion440, recessed portion450, raised portion440. Thus, the recessed portions450do not always have to surround distal and proximal ends of the sealing region430.

A fabric exterior300is synonymous with “reinforcement layer” and is bonded to the outer elastomer surface420of the thermoplastic elastomer layer400and conforms to the at least one sealing region430. The fabric exterior300advantageously forms a suitable substrate for bonding a seal layer200. The seal layer200conforms to the shape of the fabric exterior300and thermoplastic elastomer layer400. The seal layer200is applied in an uncured state to the fabric and with a viscosity such that it is able to “wet out” the fabric in that area so that once cured it forms an air tight seal thus isolating the fabric above the seal layer (not shown) from the fabric exterior300below the seal layer200. Thus, this application of the outer sealing layer200to the fabric exterior300provides an air-impermeable interface between the thermoplastic elastomeric layer400and the surrounding exterior area of the liner100. The outer sealing layer200is preferably applied such that it impregnates the reinforcement layer300so as to form a composite.

This outer sealing layer200may be comprised of natural rubber, silicone, polyurethane, latex, polysulfide, vinyl, polyisoprene, or a styrene block copolymer gel, although the preferred material is rubber due to their high abrasion resistance and high force to stretch. The force to stretch this layer is determined by the modulus of elasticity of the sealing material multiplied by the cross-sectional area of the sealing material.

The thermoplastic elastomer layer400is preferably of a type compatible with long periods of dynamic wearer contact. Such materials are known in the art and may include the following polymers, as well as gels which comprise them: silicones polyurethanes; block copolymers such as styrene block copolymer gels, general non-limiting examples of which may include SEBS-, SEPS-, SEEPS-, SEEBS-, and other type styrene block copolymer gels. Further non-limiting examples of styrene block copolymer gels which may be useful in the liner of the present invention include so called “controlled distribution polymers,” such as, for example, those disclosed in U.S. Pat. No. 7,226,484; United States Patent Application Publication No. 20070238835; and United States Patent Application Publication No. 20050008669, the disclosure of which is hereby incorporated by reference herein. Other potentially useful polymers may include certain so-called “crystalline” polymers, such as, for example, polymers disclosed in U.S. Pat. Nos. 5,952,396; 6,420,475 and 6,148,830, the disclosure of which is hereby incorporated by reference herein. The above list is non-limiting, and in general, the list of acceptable polymers and gels includes those known in the art to be useful for the fabrication of prosthetic liners. The term “gel” is defined to be a polymer mixed with a plasticizer. An example of current liner using such gel is the “EZ Gel”™ liner, available from Alps South LLC.

The term “sealing region”430may include only one raised portion440or may include a plurality. If it includes a plurality of raised portions440, the sealing region430will have each raised portion440contiguously adjacent to any other raised portion440. However, if there are a plurality of raised portions440collectively near the distal end of the tubular body portion as well as a plurality of raised portions440collectively near the proximal end of the tubular body portion, there will be two sealing regions430with only continuous lengths among their group. That is, the sealing region430in the distal end will have one continuous length of material while the sealing region430in the proximal end will have its own continuous length of material. The continuous length of material refers to the elastomeric material used to create the durable and flexible sealing region430.

FIGS. 2-11show that the raised portions440within the elastomeric material can have a multitude of different geometries relative to the vertical axis of the invention. For example, the raised portions440can have a square/rectangular (FIGS. 2-4, 6), parabolic (FIG. 11), triangular, oval, spear-like, parallelogram-like (FIG. 5), dome-like (FIG. 11), ripples (FIGS. 7 and 9), or protrusions that resemble “gripping” mechanisms or shapes that one skilled in the art would use to “grip” an object to another object. For example, a finger-like projection (FIGS. 8 and 10) that resembles a hook similar to the “hook” portion of a “hook and loop” configured as used in Velcro®. Each raised portion440preferably is not co-linear with the fabric exterior layer300, as can be seen in the relevant figures.

FIGS. 12 and 13show the seal liner100without recessed portions450in the elastomeric layer400. The raised portions440protrude from the elastomeric layer400without recessed portions450located between, among, or near the raised portions440. This embodiment of the seal liner100is useful because of its ease of manufacturing and slimmer profile. Only the reinforcement layer200and fabric exterior layer300have recessed portions450which correspond to the recesses460between each raised portion440.

When worn by an amputee and inserted into a socket for use with a vacuum system, the volume of air within the socket and below the seal layer is evacuated thereby securing the residual limb within the socket. The present invention thereby preferably reduces any potential for a tourniquet effect created by the vacuum process and provides high abrasion resistance.

Now that the invention has been described,