Sandblasted silicone prosthesis liner

Abstract

A silicone prosthetic liner for a prosthetic assembly that acts as an interface between a residual limb of an amputee and a socket assembly. The prosthetic liner includes an open proximal end, a closed distal end, and a sidewall that includes a molded silicone inner layer. The silicone is molded onto a mandrel that has been blasted with #36 grit at 100 psi to create micro-pits and reduce the coefficient of static friction.

Description

[0001] CITATION OF RELATED APPLICATION

[0002] This application claims the benefit of pending provisional application number 62 / 844,253 and provisional application number 62 / 844,296, filed May 7, 2019, the disclosures of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to liners for prosthetic components. In particular, the described invention relates to liners with silicone inner liners that have a smooth touch by the use of sandblasting of the mold used to manufacture the liner. BACKGROUND

[0004] Since the 1980s, silicone liners have been introduced in the prosthetic industry, such as those described in U.S. Patent No. 4,923,474 to Klasson and Kristinsson. Other examples of such liners include U.S. Patent No. 5,728,168 to Laghi et al., U.S. Patent No. 5,830,237 to Kania, U.S. Patent No. 5,507,834 to Laghi et al., U.S. Patent No. 5,443,525 to Laghi et al., and U.S. Patent No. 5,728,168 to Laghi et al.

[0005] However, silicone liners have historically been difficult to put on and take off due to the high static coefficient of friction of silicone. As a result, they tend to stick to the skin of the residual limb. This impedes the relative movement at the interface skin / liner, thus causing high shear forces on the skin of the local part of the residual limb when the ground reaction to walking is transmitted through the silicone interface and the skin to the skeleton. These generated shear forces, particularly for sensitive skin patients, increase the likelihood of skin blistering. Therefore, there is a need to develop silicone inner liners with reduced friction effects so that users can easily put on and take off their prosthetic liners.

[0006] In addition, most amputees are amputated for vascular reasons rather than trauma. This means that the amputation is due to poor circulation. Most amputees are also elderly. Therefore, most amputees have thinner, more fragile skin that is easily damaged and reduced blood flow to the extremities, resulting in their reduced ability to heal sores and wounds. Some elderly amputees end up with repeated amputations due to skin damage and infection of the residual limb.

[0007] One approach developed to address these problems is to include an additive that exudes from the silicone matrix and acts as a lubricant between the liner and the skin. The problem with this solution is that the exudate can collect dirt on the inner surface of the liner, thus exacerbating skin damage. The exudate also requires more thorough cleaning and makes the liner slippery.

[0008] The present invention utilizes a novel sandblasting technique that creates "micro-pits" in the silicone of the prosthetic liner during molding, which allows the liner to be easily donned and doffed and is skin friendly. The method described herein is particularly effective for silicone liners because silicone has a low surface tension when in liquid form, which allows them to penetrate tiny pores and cracks, creating micro-pits. The viscosity of silicone is also inversely proportional to temperature, which makes the silicone flow more easily when it is close to the surface of the hot mold. As a result, the silicone creates a faithful mirror image of the dimpled mold surface.

[0009] It is therefore an object of the present invention to provide an improvement which overcomes the above-mentioned deficiencies of the prior art devices and which provides an improvement that makes a significant contribution to the advancement of the art of liners.

[0010] It is another object of the present invention to provide a silicone liner with a more comfortable internal silicone lining.

[0011] It is another object of the present invention to provide a method of manufacturing a silicone liner with reduced friction properties.

[0012] It is another object of the present invention to provide a liner with micro-pits.

[0013] It is another object of the present invention to describe a method of manufacturing a silicone liner by molding the liner using a sandblasted mold mandrel.

[0014] The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as merely illustrative of some of the more prominent features and applications of the intended application. Many other beneficial results can be attained by applying the disclosed application in a different manner or modifying the application as will be suggested to those skilled in the art. Accordingly, other objects and a fuller understanding of the application can be had by referring to the summary of the application and the detailed description of the preferred embodiment in addition to the scope of the application defined by the claims taken in conjunction with the accompanying drawings. SUMMARY

[0015] The present invention relates generally to a liner for use in a prosthetic assembly having a silicone interior that includes micro-pits by sandblasting a silicone mandrel using #36 grit at 100 psi. Using a sandblasted mold mandrel, a silicone liner can be made with improved friction properties. The liner of the present invention can optionally include a fabric cover adhered to the outer surface.

[0016] The foregoing has outlined rather broadly the more relevant and important features of the present application so that the detailed description of the application that follows can be better understood with the contribution of the present application to the art being more fully appreciated. Further features of the present application will be described hereinafter which can form the subject of the claims of the present application. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed can be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present application. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the application as set forth in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0017] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which:

[0018] FIG. 1 is a front view of an improved silicone liner.

[0019] Figure 2 is a cross-sectional view of a silicone sheet formed using a mandrel that was not blasted.

[0020] Figure 3 is a cross-sectional view of a silicone sheet formed using a mandrel that was blasted with #36 grit at 100 psi.

[0021] Figure 4 is a cross-sectional view of a silicone sheet formed using a mandrel that was blasted with #320 grit at 100 psi.

[0022] Figure 5 is a chart showing the effect of blasting on the force required to remove a silicone sheet from a steel substrate, showing the effect on the static coefficient of friction.

[0023] Throughout the several views of the drawings, like reference numerals will be used to refer to like components. DETAILED DESCRIPTION

[0024] The following description is that presently contemplated best mode for carrying out the present application. This description is not to be taken in a limiting sense but is merely made to provide one or more preferred embodiments of the present application. The scope of the present application should be referred to the claims.

[0025] The present application relates to a liner 100 for prosthetic devices. As Figure 1The liner 100 for a prosthetic assembly includes an open upper end 12 for receiving a residual limb not shown, a closed bottom end 14, and a sidewall 16 of predetermined thickness, as shown. The liner is air tight when fitted over the residual limb. The preferred thickness of the sidewall 16 is about 1.5 mm to 3.0 mm. Note that the thickness of the bottom end is greater than the thickness of the sidewall; the preferred thickness of the silicone of the bottom end 14 is about 3.0 mm to 12.0 mm. The sidewall 16 has an inner layer 18 of the improved silicone described herein. The sidewall 16 can be a fabric or another layer of more durable and higher friction silicone.

[0026] Prior to molding the silicone, the mandrel is blasted with #36 grit at 100 psi. The particular grit and pressure used provide the beneficial properties of the present invention. Other grits and pressures do not provide the advantages of reduced friction retention and reduced opportunities for skin irritation. After the mandrel is blasted, the silicone is molded over it, allowing the silicone to penetrate the micro-pits created by the blasting. As Figures 2-4 shown, the grit size used during the blasting has a significant impact.

[0027] Figure 2 A piece of silicone 20 that has not been blasted is depicted. As can be seen from cross-section 2-2, the mandrel was not blasted, resulting in a smooth outer surface 22 that maintains the high friction properties of the silicone. On the other hand, Figure 3 and 4 A microscopic view of the outer surface 22 after the mandrel has been blasted is shown. Figure 3 A micro-pit of the outer surface 22 after it has been blasted with #36 grit at 100 psi is shown. Along line 3-3, the micro-pit created typically has a depth of about 0.0195 mm. Figure 4 A micro-pit of the outer surface 22 after it has been blasted with #320 grit at 100 psi is shown. Along line 4-4, the micro-pit created typically has a depth of about 0.0100 mm. The deeper micro-pit results in a lower coefficient of static friction for the silicone because there is less surface area in contact with the outer surface 22, as can be seen by comparing Figure 3 the piece in Figure 4 to the piece in

[0028] Three tests were conducted to demonstrate the beneficial properties of the present invention, the results of which are shown in Figure 5 . First, a mold was blasted with #36 grit at 100 psi, and it required a force of 1.6 N to pull apart. In the second test, the mold was blasted with #320 grit. The result was a force of 2.33 N to pull apart. In the final test, the mold was not blasted at all, requiring a force of 9.33 N to pull apart. The tests were conducted using a 1 inch wide and 7 inch long piece of silicone on a smooth stainless steel, while applying a 100 gram weight.

[0029] The present disclosure includes the subject matter contained in the following clauses and the foregoing description. Although the present invention has been described in its preferred form herein, it is to be understood that the present disclosure is not to be limited to the preferred form described but is to be given the full scope of equivalence of the appended claims.

Claims

1. A lining comprising: The upper part of the opening; Closed bottom; and The fabric sidewall has a thickness, wherein the sidewall further includes a silicone inner layer having a silicone thickness, wherein the silicone has micropits with a depth of 0.0100 to 0.0195 mm.

2. The lining according to claim 1, wherein, The thickness of the sidewall is 1.5 to 3 millimeters.

3. The lining according to claim 1, wherein, The thickness of the silicone at the bottom end is 3 to 12 millimeters.

4. The lining according to claim 1 further includes a tensile strength of less than 2.4 N.

5. A method for manufacturing a silicone liner, comprising: Sandblast the mandrel with #36 grit at 100 psi; Silicone is molded onto the mandrel; Fabric sidewalls are formed on the silicone to form a composite material, wherein the composite material further includes an open upper end, a closed bottom end and fabric sidewalls with thickness, wherein the sidewalls further include a silicone inner layer with silicone thickness, wherein the silicone has micropits with a depth of 0.0100 to 0.0195 mm.

6. The method for manufacturing a silicone liner according to claim 5, wherein, The thickness of the sidewall is 1.5 to 3 millimeters.

7. The method for manufacturing a silicone liner according to claim 5, wherein, The thickness of the silicone at the bottom end is 3 to 12 millimeters.

8. The method of manufacturing a silicone liner according to claim 5 further includes a tensile strength of less than 2.4 N.

9. A method for manufacturing a silicone liner, comprising: Sandblast the mandrel with #320 grit at 100 psi; Silicone is molded onto the mandrel; Fabric sidewalls are formed on the silicone to form a composite material, wherein the composite material further includes an open upper end, a closed bottom end and fabric sidewalls with thickness, wherein the sidewalls further include a silicone inner layer with silicone thickness, wherein the silicone has micropits with a depth of 0.0100 to 0.0195 mm.

10. The method of manufacturing a silicone liner according to claim 9, wherein, The thickness of the sidewall is 1.5 to 3 millimeters.

11. The method of manufacturing a silicone liner according to claim 9, wherein, The thickness of the silicone at the bottom end is 3 to 12 millimeters.

12. The method of manufacturing a silicone liner according to claim 9, further comprising a tensile strength of less than 2.4 N.

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