A Method of Manufacturing An External Breast Prosthesis and Said Prosthesis

Abstract

A method of manufacturing an external breast prosthesis (12), includes the steps of providing a 3D image of the breast prosthesis, forming the breast prosthesis using an additive manufacturing process, in which additive manufacturing process the breast prosthesis is made by forming a structure of a thermoplastic elastomer, the structure corresponding to the 3D image of the breast prosthesis, wherein the structure is a reticulated solid foam.

Claims

1. A method of manufacturing an external breast prosthesis, the method comprising the steps of: providing a 3D image of the breast prosthesis, and forming the breast prosthesis using an additive manufacturing process, in which additive manufacturing process the breast prosthesis is made by forming a structure of a polymer, the structure corresponding to the 3D image of the breast prosthesis,wherein the polymer used is a thermoplastic elastomer and the structure is formed as a reticulated solid foam.

2. A method according to claim 1, wherein the porosity of the reticulated solid foam is between 50 and 95%.

3. A method according to claim 1 , wherein the porosity of the reticulated solid foam is between 60 and 85%.

4. A method according to claim 1 , wherein the thermoplastic elastomer is a non-biodegradable polymer.

5. A method according to claim 1 , wherein the thermoplastic elastomer is a styrene block copolymer.

6. A method according to claim 1 , wherein the thermoplastic elastomer is a styrene-ethylene-butylene-styrene copolymer.

7. A method according to claim 1 , wherein the additive manufacturing is performed using a 3D printing technology.

8. A method according to claim 1 , wherein the additive manufacturing is performed using an inkjet deposition technology.

9. A method according to claim 8, wherein the thermoplastic elastomer is deposited to become part of the structure in the form of multiple separate droplets that fuse together after being deposited.

10. A method according to claim 1 , further comprising the step of, in the reticulated solid foam structure multiple, providing elongated thermal conductors .

11. A method according to claim 10, wherein each of the multiple elongated thermal conductors extends from a position adjacent an inner surface of the breast prosthesis to a position adjacent to an outer surface of the breast prosthesis.

12. A method according to claim 10 , wherein the elongated thermal conductors are polymer fibers , preferably of an oriented strand polymer.

13. An external breast prothesis comprising as a basic structure a reticulated solid foam made of a thermoplastic elastomer.

14. An external breast prosthesis according to claim 13, wherein the porosity of the reticulated solid foam is between 50 and 95%.

15. An external breast prosthesis according to claim 13 , wherein the thermoplastic elastomer is a styrene block copolymer.

16. An external breast prosthesis according to claim 13 , wherein the breast prosthesis comprises multiple elongated thermal conductors.

Description

EXAMPLES

[0029] FIG. 1 represents a flow scheme of a manufacturing method for an external breast prosthesis.

[0030] FIG. 2 schematically depicts an external breast prosthesis.

[0031] FIG. 3 schematically depicts a reticulated solid foam.

[0032] Example 1 describes a method of manufacturing a breast prosthesis.

[0033] Example 2 describes various tests of breast prostheses.

FIGURE 1

[0034] FIG. 1 represents a flow scheme of a manufacturing method for an external breast prosthesis. The method aims at providing a desired shape for a breast that is partially removed during operation, the desired shape after operation being formed by the remaining breast material plus the external breast prosthesis. Step 1 of the method involves the generation of a 3D scan of the residual breast after a partial mastectomy of the diseased breast in order to generate an image of the desired shape, albeit as a mirror image which means the scanned image will be mirrored in order to correspond to the desired shape (alternatively the breast to be operated upon is scanned before the operation when the shape at this stage is the desired shape).

[0035] In Step 2 a 3D scan is made of the site of operation, thus providing an image of the chest of the patient and remaining breast tissue (if any), on to which the external prosthesis has to be placed in order to arrive at the desired shape for the operated breast.

[0036] In Step 3 a 3D image of the prosthesis is generated using the 3D scan of the residual breast (mirror imaged) and the 3D scan of the site of operation. The part of the image that misses in the latter scan when compared to the former corresponds to the external breast prosthesis.

[0037] In Step 4 this 3D image of the external breast prosthesis is send to the additive manufacturing machine, for example an inkjet deposition printer wherein a molten polymer is deposited in the form of multiple separate droplets that fuse together after being deposited to become part of the printed structure.

[0038] In Step 5 This machine manufactures a structure that corresponds to the 3D image of the breast prosthesis. This way, a unitary structure is made that can be used as an external breast prosthesis (for example in a brassiere), to arrive at the desired shape when positioned on the site of the operated breast.

[0039] The method can be adapted to meet any individual desire for shape, feel, heat and moist conducting properties etc. depending on how the unitary structure is configured and depending on the use of any additional materials in the manufacturing process. For example, a structure according to the invention is a reticulated solid foam, of which foam the porosity can be varied significantly, typically from 5 to 95%. This has a significant influence on the ultimate physical properties of the prosthesis. Also, the droplet size can be varied, as well as the polymer material used. Next to this, various additional materials can be added after or during the manufacture of the basic unitary structure. For example, thermal conductors can be dispersed in the structure during (or after) the printing process. Also, padding can be added if desired. This way, the prosthesis can be completely individualized and even adapted to the occasion. For example, it is envisioned that for different levels of physical exercise, different prostheses are made for the same patient. Also, different prostheses may be made to fit different garments of the same patient.

Figure 2

[0040] FIG. 2, consisting of subfigures 2A, 2B and 2C schematically depicts an external breast prosthesis 12. In FIG. 2A, the complete reconstructed breast 10 is depicted including the remaining breast tissue 11 after partial mastectomy, and the external prosthesis 12, including its inner surface that coincides with the tissue 11, and the opposing outer surface 14 that provides the outer visible shape of the reconstructed breast 10.

[0041] In FIG. 2B only the external breast prosthesis 12 is depicted, the inner surface 13 and outer surface 14 being indicated as such. This is a unitary (single-piece) structure of a reticulated solid foam made of a thermoplastic elastomer, in this case CAWITON PR13620 (available from Wittenburg, Zeewolde, The Netherlands). The average porosity is 75%, ranging from 55% near the inner surface 13 to 85% near the outer surface 14.

[0042] In FIG. 3B an alternative breast prosthesis is depicted, in which prosthesis multiple elongated thermal conductors 15 are provided that each extend from a position adjacent the inner surface 13 of the breast prosthesis to a position adjacent to the outer surface 14 of the breast prosthesis to conduct heat away from the patient's body 11 towards surface 14. In this case, after having performed an IR scan of the body 11, it appeared that there was a small site of body 11, corresponding to section 13a of the inner surface, that produced significantly more heat than average, possibly an effect of the mastectomy operation. In order to make sure there is no significant local temperature deviation at this site, the density of the heat conductors is somewhat higher at site 13A. In the shown embodiment the elongated thermal conductors 15 are polymer fibres of DYNEEMA (available from DSM, Heerlen, The Netherlands) an oriented strand polyethylene that has a very good thermal conductivity (20 W/mK in axial direction). The conductors are provided in the prosthesis after the printing process of Step 5 (FIG. 1) by a sewing operation.

Figure 3

[0043] FIG. 3 schematically depicts a reticulated solid foam. The walls of the cells are made from the thermoplastic elastomer. As can be seen, the structure is porous and the cells are interconnected to form a so called open-cell-structured foam. Open-cell-structured foams contain pores that are connected to each other and form an interconnected network. Open-cell foams fill with whatever gas surrounds them. In the reticulated foam as depicted the pores are thus continuous, as opposed to local pores.

Example 1

[0044] This example describes a method of manufacturing a breast prosthesis according to the invention (see FIG. 2B). In this case the AM machine used was the ARBURG Freeformer 200-3X (Arburg, Lossburg, Germany), using CAWITON PR13640 (differing from PR1620 mainly in that the tensile moduli and tear strength are somewhat higher; the melting point is about the same, around 152° C.) as the thermoplastic elastomer. Using a jet nozzle with a diameter of 0.2 mm, various structures were made by depositing individual droplets of the molten thermoplastic elastomer at an ejection temperature of 210° C. towards a substrate to form a reticulate solid foam of fused droplets of the elastomer. A first reticulated solid foam structure was made by imposing 255 layers of droplets of 0.2 mm diameter to result in a prosthesis of about 248 cm.sup.3, weighing 35 grams (corresponding to a porosity of about 85%). The total manufacturing process took about 20 hours.

[0045] The same way, various variants were made of the breast prosthesis, all reticulated solid foams of the same material, but differing in porosity from very high (95%) to low (25%). Table 1 gives an overview of the various structures.

TABLE-US-00001 Various reticulated solid foam TPE's Prosthesis Porosity A 95% B 85% C 75% D 50% E 25%

Example 2

[0046] This example describes various test performed on prostheses A through E as described in Example 1. The first two tests pertain to the resilience after compression, and the third test pertains to the property to transport heat through the prosthesis.

Test 1

[0047] In this test the resilience after repeated compression and decompression is measured. For this a sample of each prosthesis A though E, having a thickness of about 19-20 mm, was subjected to 15 compression cycles (same force for every sample, leading to nearly full compression, i.e. 80-40% compression depending on porosity). After this, the sample height for each type of prosthesis was remeasured. As a positive control the height for a commercial silicon breast prosthesis sample was measured, which appeared to be 19.5 ± 0.4 mm. So any change at this level was found acceptable. The results are indicated in Table 2.

TABLE-US-00002 Sample height in mm after compression cycles Prosthesis 0 cycles 15 cycles A 19.7 19.4 B 19.4 19.2 C 19.8 19.4 D 20.0 19.5 E 19.7 19.3

[0048] It can be seen that all types of prosthesis have an acceptable resiliency, albeit that at a porosity of 50% or lower there seems to be a tendency of less resilience (however still acceptable).

Test 2

[0049] In this test the resilience after long term compression (1 cycle) is measured. Given the fact that all types of prosthesis appear to have almost the same resilience against repeated compression, the resilience against long term compression was only measured for prosthesis type C, having a porosity of 75%. The compression used was of the same level as that used in Test 1, but it was maintained for 24 hours. After this, the recovery was measured by measuring the sample height as a percentage of the original sample height before compression. A recovery to at least 90% in 3 hours was set as a threshold for adequate recovery after long term compression for an external breast prosthesis. The results are indicated in Table 3.

TABLE-US-00003 Recovery (%) after long term compression and X hours:minutes recovery time Prosthesis 0 h recovery 1:13 h recovery 2:12 h recovery 15:36 h recovery C 54 92 95 96

[0050] It appeared that the recovery was acceptable, being already over 90% after 1 hour and 13 minutes recovery time.

Test 3

[0051] The third test pertains to the property to transport heat through the prosthesis, based on mere unforced conduction through the bulk of the prosthesis. For this samples of a common commercially available silicon breast prosthesis and prosthesis of type C (having the same dimensions) were heated one sided with a common air flow heat gun. After heating up the one side to a temperature 16° C. above the opposing side, the samples were left and the difference in temperature of the two opposing sides was monitored for half an hour (1800 seconds). The results are indicated below in Table 4.

TABLE-US-00004 Temperature difference in °C after static heat transport for X sec. Prosthesis 0 200 400 800 1800 C 16 13 9 7 5 Silicon 16 15 16 15 13

[0052] It appeared that the novel prosthesis material has a significantly increased capability of heat regulation. This contributes significantly to mitigation of the problem of an external breast prosthesis getting uncomfortable by heat build up at the surface where the chest and prosthesis coincide. It is expected that by applying thermal conductors in the prostheses as tested (cf. FIG. 2C) the temperature difference can be further decreased. When a conductor based on DYNEEMA fibres is used, it is expected that for both types of prostheses (according to the invention and common silicon type) the temperature difference can be lowered to less than 1 or 2° C. in 200-400 seconds given the very large heat conducting capacity of DYNEEMA fibres. If desired the heat regulation can be even further improved by increasing the density of the fibres.