Thoracic prosthesis and its method of preparation

Abstract

The present invention refers to a thoracic prosthesis constituted by a right hemisphere ED and a left hemisphere ES joined together, or to only one of the two hemispheres, or to only one portion of the latter. The present invention further relates to a method for the preparation of a synthetic thoracic prosthesis PT constituted by a right hemisphere ED and a left hemisphere ES joined together by only one of the two hemispheres or by a single portion of the latter; all of the above being prepared without any direct interaction with human body and prior to implantation therein.

Claims

1. A synthetic thoracic prosthesis, comprising: a plurality of curved rib-like elements spaced apart one from another, each of said rib-like elements having a first end and a second end, the first ends being fixed to a first portion of a perimeter frame, the second ends being fixed to a second portion of the perimeter frame, and a continuous reinforcement meshwork structure extending (a) through said rib-like elements and fixed inside the first and second portions of the perimeter frame, and (b) within intercostal spaces formed between said rib-like elements and said perimeter frame; wherein said synthetic thoracic prosthesis includes a concave-shaped inner surface and a convex-shaped outer surface.

2. The synthetic thoracic prosthesis according to claim 1, wherein the continuous reinforcement meshwork structure is tensioned in an extension plane.

3. The synthetic thoracic prosthesis according to claim 1, wherein the continuous reinforcement meshwork structure is perforated or pierced so as to allow tissue integration and the drainage of body fluids.

4. The synthetic thoracic prosthesis according to claim 1, wherein the perimeter frame is formed by a plurality of segments, two of said plurality of segments being spaced apart from one another by the rib-like elements and the intercostal spaces.

5. The synthetic thoracic prosthesis according to claim 1, constituted (a) by a right hemisphere and a left hemisphere joined together, or a portion thereof, or (b) by one of the two hemispheres, or a portion thereof.

6. The synthetic thoracic prosthesis according to claim 5, wherein the right hemisphere and the left hemisphere are joined together via a connection sternal region.

7. The synthetic thoracic prosthesis according to claim 1, wherein the rib-like elements and the perimeter frame are made of a same polymeric material.

8. The synthetic thoracic prosthesis according to claim 1, wherein a perimeter of the synthetic thoracic prosthesis is defined by the perimeter frame.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows an overall view of a thoracic prosthesis PT, which in this example is a prosthesis of an entire chest. The size of the prosthesis may vary and are decided by the surgeon before the intervention according to the specific needs of each patient.

(2) FIG. 2 shows a front view of the thoracic prosthesis PT constituted by a right hemisphere ED and a left hemisphere ES joined together only in the front part by a connection sternal region RS; said right and left hemispheres ED and ES respectively, comprise intercostal spaces SI occupied by a meshwork made of synthetic material RMS (reinforcement mesh-like structure RMS).

(3) FIG. 3A shows an external view of a left hemisphere ES having a major axis which extends along the largest dimension from left to right, and a minor axis which extends along the minor dimension from the top downwards.

(4) FIG. 3B shows an internal view of the same left hemisphere ES (FIG. 3A) which is obtained by a 180 rotation about the minor axis. FIG. 3B shows the ribs C1, C2, C3, C4, C5, C6, C7 and C8 (rib-like elements Cn), a meshwork (continuous element) of a synthetic material RMS and an outer closed frame T formed by five segments SG1, SG2, SG3, SG4 and SG5.

(5) Each rib C1-C8 has a larger dimension and a minor dimension. The larger size runs along the minor axis, while the minor dimension runs along the major axis. The perpendicular section, compared to the larger size of each rib C1-C8, has an irregular elliptical shape which is more or less flattened along the minor dimension.

(6) The ribs C1-C8 preferably have curved shapes, which generally differ from one another and further exhibit different extensions along the largest dimension thereof.

(7) The ribs C1-C8 are spaced apart from one another in a substantially uniform manner along the larger dimension thereof and interspersed by a intercostal space SI. Synthetic material meshwork RMS portions (reinforcement mesh-like structure RMS) extend within the intercostal spaces SI, see FIG. 3B.

(8) The synthetic material meshwork RMS is a continuous element passing through the ribs C1-C8 and intersecting the latter internally thereof, and fixed inside the SG1-SG5 segments forming a continuous closed frame T, see FIG. 3B.

(9) The ribs C1-C8 are connected one to another along their major dimension via portions of said synthetic material meshwork RMS and along their lower dimension by the segments SG2, SG3 and SG5 which form part of the external closed frame T, see FIG. 3B.

(10) The frame T is formed by five segments SG1, SG2, SG3, SG4 and SG5. The segment SG1 and SG4 are spaced apart from one another by the ribs C1-C8 and the intercostal spaces SI. Although part of the frame, said two segments SG1 and SG4 perform the functions of the first (upper) rib and last (lower) rib within the thoracic prosthesis PT, see FIG. 3B.

(11) FIG. 4 shows a top view of the left hemisphere ES, in particular the segment SG1.

(12) FIG. 5 shows an internal view of the left hemisphere ES, in particular the segment SG4 opposite to the segment SG1, and of the segment SG5.

(13) FIG. 6 shows the lower portion of a mould device 1 that serves as a container for containing a concave-shaped base 2, wherein a first portion 3 of a mould (female mould) is housed as shown in FIG. 7.

(14) FIG. 8 shows a convex-shaped base 4, on which outer surface a second portion 5 of a mould (male mould) is housed as shown in FIG. 9.

(15) FIG. 10 shows the upper portion 6 of said device 1 acting as a cover.

(16) The lower portion of the device 1 and the upper portion of said device 1 are disposed one above the other in a close arrangement and held together via closing devices signified by the letters a, b and c, shown in FIG. A1.

(17) FIGS. 11 to 25 show a sequence of activities for the preparation of an hemisphere.

(18) FIG. 11 shows the mould device 1 with a first mould portion 3 (female mould), arranged internally thereof, and a convex-shaped base 4, on which outer surface a second mould portion 5 (male mould) is housed, thereby forming the element 6 of FIG. 9.

(19) FIGS. 12-17 show the element 6 of FIG. 9, whereon the synthetic material meshwork RMS was placed in order to perfectly adhere on the outer surface of a second portion 5 of a mould (male mould).

(20) FIG. 18 shows the mould device 1 containing internally thereof a first portion 3 of a mould (female mould) and the cover 6a.

(21) FIGS. 19 and 20 show preparation of the polymeric material.

(22) FIG. 21 shows pouring of the polymeric material in its liquid state into the mould device 1.

(23) FIG. 22 shows the polymeric material passing from its liquid state to the solid state once the polymeric material was poured and cooled inside the mould device 1.

(24) FIGS. 23 and 24 show the right hemisphere extraction ED from the mould device 1 once its preparation is terminated.

(25) FIG. 25 shows three-dimensionality of the synthetic material meshwork RMS in detail once the same is tensioned between two rib-like elements.

DETAILED DESCRIPTION

(26) The method of preparation of the thoracic prosthesis PT devised by the Applicant allows to prepare said prosthesis in compliance with the specific morphological and structural requirements of each subject. The present invention provides the following: i) a first mould S, which reproduces the left hemisphere ES comprising a first (female) portion 3 of said mould S and a second (male) portion 5 of said mould S, as well as a method of preparing said mould S; ii) a second mould S* (not shown in the figure), which reproduces the right hemisphere ED comprising a first (female) portion of said second mould S* and a second (male) portion of said mould S*, as well as a method of preparing said mould S*. It should be appreciated that said mould S*, said first (female) portion and said second (male) portion are all specular to the mould S, to said first (female) portion 3 and to said second (male) portion 5 respectively. Hence, the method of preparation of said mould S* corresponds, in terms of step sequence, to the method of preparation of said mould S and the right hemisphere ED obtained from said mould S*, is prepared with a method corresponding to that used and described for obtaining the left hemisphere ES from said mould S; iii) a thoracic prosthesis PT which provides joining, in a solidly constrained manner, between said left hemisphere ES, obtained from said first mould S, and said right hemisphere ED obtained from said second mould S*, wherein the segment SG2 of said left hemisphere ES (FIG. 3B) is joined with the segment SG2* of said right hemisphere ED; a method of preparation of said thoracic prosthesis PT is further provided.

(27) The thoracic prosthesis PT referred to in point (iii) is obtained by use of a first mould S, which reproduces the left hemisphere ES and a second mould S*, which reproduces the right hemisphere ED.

(28) The mould S and S* are made solely with materials, that in addition to being biocompatible, allow excellent tightness of the male element with the female element and provide easy detachment once the prosthesis was obtained.

(29) Advantageously, the selected materials are chosen from among the elastomers polysiloxane or soft (i.e. non-rigid) silicone materials. The mould S, reproducing the left hemisphere ES, comprises a first (female) portion 3 of said mould S shown in FIG. 7 and a second (male) portion 5 of said mould S shown a FIG. 9.

(30) Said first (female) portion 3 of said mould S shown in FIG. 7, is a unitary element and exhibits a curved shape about the major axis extending from left to right.

(31) Furthermore, said first (female) portion 3 of said mould S illustrated in FIG. 7, exhibits a plurality of grooves En which is equal to the integer n of ribs taken into account and to be reproduced in the left hemisphere ES, by way of example on the basis of n=8 there is obtained E1-E8. Said grooves En being interspersed from one another and spaced apart by the presence of a plurality of elements in relief Rn+1 arranged in a manner substantially parallel to each other, for example for n=8 there is obtained R1-R9. Each groove En being extended and semicircular in shape, thereby reproducing the shape and the section of a human rib. The elements in relief Rn+1 have a rectangular cross section with rounded corners and are arranged alternately with the grooves En, thereby forming the following structure: R1-E1-R2-E2-R3-E3-R4-E4-R5-E5-R6-E6-R7-E7-R8-E8-R9, see FIG. 7. Between a first element in relief R1 spaced apart from a second element in relief R2, the groove E1 is formed, and so on. It is important that the grooves En present in said first (female) portion 3 of said mould S (FIG. 7), are provided with a concave base with no sharp angles. The same applies to the grooves En present in said second (male) portion 5 of said mould S (FIG. 9). The above is aimed at preventing formation of any irregular shaped ribs or cutting elements.

(32) The grooves E1-E8 are connected to one another via an external groove P1, P2, P3, P4 and P5 (P5 is only hinted at in FIG. 7), which external groove is delimited by the elements in relief R1-R9 and the long sides of the elements in relief R1 and R9.

(33) Said second (male) portion 5 of said first mould S shown in FIG. 9 is a unitary element and exhibits a convex shape about the major axis extending from left to right.

(34) In addition, said second (male) portion 5 of said mould S shown in FIG. 9 exhibits a plurality of grooves E9-E16 arranged in a substantially parallel manner one to another, which are formed by a plurality of elements R10-R18 arranged in substantially parallel manner with each other; the elements R10-R18 have a rectangular cross-section and are arranged in an alternating manner, thereby forming following structure: R10-E9-R11-E10-R12-E11-R13-E12-R14-E13-R15-E14-R16-E15-R17-E16-R18, see FIG. 9. Between a first element R10 spaced from a second element R11, the groove E9 comes to be formed and so on. Said plurality of grooves Sn reproduces the ribs, whilst said plurality of elements in relief Rn+1 reproduces the intercostal space SI existing between at least two of said ribs.

(35) The grooves E9-E16 are connected one to another via an outer groove P6, P7 (not shown in FIG. 9), P8 (not shown in FIG. 9), P9 and P10, which is delimited by the end of the elements in relief R10-R18 and via the long sides of the elements in relief R10 and R18.

(36) Said second (male) portion 5 of said mould S is covered externally by a layer of a synthetic material meshwork RMS (reinforcement meshwork structure RMS) so that the meshwork adheres perfectly and firmly on its outer surface.

(37) The meshwork is preferably a meshwork made of a non-woven polymeric material, composed for example of a polypropylene fiber matrix (SURGIMESH).

(38) Depending on necessity, a woven polymeric material meshwork may however be also used. The synthetic material meshwork RMS selected for the purposes of the present invention, is preferably a meshwork made of 100% polyester multifilament (P3X and PET2D) or a multifilament combination with 100% polyester monofilament (P4X) known as Surgimesh (ASPIDE MEDICAL France). The meshwork of selected synthetic material exhibits a perforated and pierced three-dimensional structure that allows tissue integration and drainage of body fluids such as blood and plasma which are formed following implantation of the thoracic prosthesis or a part thereof in a patient. Alternatively it can also be used a polypropylene non-woven fabric 100%, or a warp-knitted polypropylene monofilament mesh 100% or a mixed meshwork, all of them being materials of the known type such as Surgimesh Esyplug (ASPIDE MEDICAL France).

(39) Subsequently, said second (male) portion 5 of said mould S, shown in FIG. 9, which was coated with said layer of a synthetic material meshwork RMS, is inserted into the cavity formed by said first (female) portion 3 of said mould S shown in FIG. 7, thus being obtained the mould S, which reproduces the left hemisphere ES. Said first portion 3 and said second portion 5 being coupled together and held firmly together.

(40) When said second (male) portion 5 is put in contact with said first (female) portion 3, the elements in relief Rn+1 present on said first (female) portion 3 and said second (male) portion 5, shall be perfectly matching with one another and superimposed, in order that formation of any unwanted passages or irregularities is prevented, which may result in clogging the mesh of the synthetic material meshwork used. A perfect matching and superposition of the grooves Sn is further required, which are present on said first (female) portion 3 and said second (male) portion 5, in order that formation of any ribs with irregular shape or cutting elements may be prevented that may result in a friction with the muscles and organs during breathing once the thoracic PT prosthesis has been implanted.

(41) Finally, the upper portion 6 of said device 1 acting as a cover (FIG. 10), is positioned above the lower portion of said device 1 acting as a container (FIG. 7) of the mould S.

(42) The lower portion of the device 1 (FIG. 7) and the cover 6 of said device 1 (FIG. 10) are disposed one above the other in a close arrangement and held together by means of fastening means and/or clamping devices such as screw terminals a, b and c (see FIG. 7).

(43) At this point the mould S is ready to be used in the method of preparation of a left hemisphere ES.

(44) What disclosed above for the mould S also applies to the mould S*, which reproduces, in a specular manner, the right hemisphere ED.

(45) Once prepared the right hemisphere ED and the left hemisphere ES according to a method that will be described in a later section, these hemispheres are joined together only at the front thereof through a connection sternal region RS, see FIG. 2.

(46) The left hemisphere ES is prepared with a polymeric composition developed by the Applicant being introduced into the mould S, which mould S has been obtained as previously described; in this manner the volume is filled which was created after that the lower portion of the device 1 (FIG. 7) and the upper portion of said device 1 (FIG. 10) were put in contact with one another in a closed arrangement. On one hand the perfect matching and superposition between the grooves En, for example E1-E8, with the grooves E9-E16, in particular creates a volume through which a layer of synthetic material is disposed, which divides the volume into two portions, see FIG. 3B. This volume is then filled with the polymer composition, thus being tapered elements obtained, which imitate the ribs of the thoracic prosthesis. On the other hand, the perfect matching and superposition between the elements in relief R1-R9 with the elements in relief R10-R19 separated only by the presence of the perfectly adherent layer of synthetic material meshwork RMS, ensures that, after said volume having being filled, the polymeric composition does not infiltrate, thereby impregnating also the portion of said layer of synthetic material meshwork RMS existing between the elements in relief.

(47) The Applicant has devised a polymeric composition, which is the subject of the present invention, comprising: a monomer selected from methyl methacrylate (methacrylic acid ester and methanol), and hydroquinone as a stabilizer; a polymer selected from the polymethyl methacrylates (PMMA) obtained from the polymers of methyl methacrylate, ester of methacrylic acid.

(48) In common parlance the term methacrylate generally refers to these polymers.

(49) Advantageously, the polymethyl methacrylate has an average molecular weight of about 1,000 Kda.

(50) The polymeric composition is prepared at the time, by disposing the monomer in a first container at room temperature and the polymer in a second container at room temperature.

(51) Subsequently, the contents in liquid form of said first container is put in contact with the contents in solid powder form of said second container, all of that under continuous stirring. The contact of the two contents gives rise to a polymeric exothermic reaction of crosslinking resulting in the formation of a polymeric composition in the liquid state and at low viscosity. Once the two contents have been put in contact with one another, said polymeric composition in its liquid state shall be promptly poured into the mould S, prepared as described above, in order that the volume can be filled, which was created after that the lower portion of the device 1 (FIG. 7) and the upper portion of said device 1 (FIG. 10) were put in contact with one another in a closed arrangement.

(52) It is of the outmost importance that the polymeric composition remains as much as possible in its liquid state and within a certain viscosity range (at an ambient temperature of 25 C.), so as to freely flow through the meshes of the synthetic material meshwork RMS, which is located within the volume created by the perfect matching and superposition between the grooves En, for example, the grooves E1-E8 with the grooves E9-E16.

(53) By flowing in its liquid state through the meshes of the meshwork, the polymeric composition incorporates the latter without creating any inhomogeneities or voids, see FIG. 3B. At the same time the perfect matching and superposition between the elements in relief Rn inside said first (female) portion 3 of said mould S shown in FIG. 7, and inside said second (male) portion 5 of said mould S shown in FIG. 9, prevents the passage of said polymeric composition, while maintaining the free meshwork devoid of any polymer. It is important that the mesh element interposed between said elements in relief Rn remains with its meshes free and without any polymer composition internally thereof, in order to prevent the meshes of the meshwork from becoming occluded, thereby being prevented formation of biological fluids pockets such as blood and plasma or stagnation of the same.

(54) The RMS meshwork, with its three-dimensionality, confers to the synthetic thoracic prosthesis TP notable scaffolds characteristics, i.e. of a real scaffold aimed at cells engraftment, mostly mesenchymal cells. In addition, the RMS meshwork inside the synthetic thoracic prosthesis TP is acting as a scaffold also for autologous stem cells from the same patient, since it promotes incorporation thereof. RMS meshwork three-dimensionality allows and helps transposition of the thoracic muscle tissue, furthermore, due to the fact that the meshwork is virtually poured and incorporated into the polymeric material used for the synthetic thoracic prosthesis TP thus becoming a single piece, an optimum mechanism during breathing is maintained, which is allowed by RMS meshwork elasticity. The polymeric material used to realize the synthetic thoracic prosthesis TP based on polymethyl methacrylate, has been identified as the best carrier for obtaining aforementioned characteristics, namely to maintain a large free surface for the purpose of cells repopulation, with the meshwork being incorporated into a chest hemisphere of high mechanical strength. Finally, the considerable permeability of the prosthesis owing to the meshwork incorporated internally thereof, allows a much more rapid recovery of the patient, thus being prevented any rejection phases and/or formation of fluid (i.e. blood/plasma) pockets which may generate outbrakes and inflammatory processes.

(55) Once all of the polymeric composition was poured, the same is left inside the mould S for a time sufficient to bring the polymer composition from the initial liquid state to a solid state.

(56) At this point the cover 6 of said device 1 (FIG. 10) is removed from the lower portion of said device 1 acting as a container (FIG. 7) of the mould S, thereby obtaining the left hemisphere ES which exhibits a number of ribs Cn (rib-like elements) corresponding to the number n of grooves, said ribs being spaced by said meshwork element portions in a number equal to the elements in relief Rn+1.