GRANULATE PRODUCTION WITH ROUNDED PARTICLES FOR MANUFACTURING IMPLANTS OR TOOL MANUFACTURING

Abstract

The invention relates to a method for producing a plastic object (1) for surgical use, comprising the following steps: a) providing a plastic powder (2); b) heating and pressing the plastic powder (2) thus forming at least one intermediate piece (3); c) mechanically comminuting the at least one intermediate piece (3) to form a granulate (4); and d) joining the granulate (4) to form an integral base body (6). The invention also relates to an implant or to an auxiliary means having at least one base body (6) comprising a UHMWPE material.

Claims

1. A method for producing an object (1) comprising plastic material and being provided for surgical use, the method comprising at least the following steps: a) providing a plastic powder (2); b) heating and pressing the plastic powder (1) thus forming at least one intermediate piece (3); c) mechanically comminuting the at least one intermediate piece (3) to form a granulate (4); and d) joining the granulate (4) to form an integral base body (6).

2. The method according to claim 1, characterized in that the base body (6) has a porous structure.

3. The method according to claim 2, characterized in that the porous structure is an open-cell or closed-cell structure.

4. The method according to any one of the claims 1 to 3, characterized in that the plastic powder has a grain size between 20 m and 900 m.

5. The method according to any one of the claims 1 to 4, characterized in that the at least one intermediate piece (3) is plate-shaped, has a porous material structure and/or is formed of solid material.

6. The method according to any one of the claims 1 to 5, characterized in that step c) includes a first partial step c1) in which the at least one intermediate piece (3) is pre-comminuted to form single pieces and a second partial step c2) in which the single pieces are further comminuted to form granulate (4), or that in step c) a granulate (4) is produced directly from the intermediate pieces (3).

7. The method according to claim 6, characterized in that, after carrying out the second partial step c2), plural particles (5) forming the granulate (4) have a grain size between 20 m and 2000 m.

8. The method according to any one of the claims 1 to 7, characterized in that step d) comprises sintering of the granulate (4), preferably porous sintering and/or selective laser-sintering (SLS process).

9. The method according to any one of the claims 1 to 9, characterized in that a surface treatment is carried out on the base body (6).

10. An implant or auxiliary means having at least one base body comprising UHMWPE material.

Description

[0052] A preferred method according to the invention for manufacturing an object made from plastic/plastic material and provided for surgical use shall be described in detail hereinafter by way of a figure in an example configuration, wherein

[0053] FIG. 1 shows a schematic view of the manufacturing method set forth in an example configuration according to the invention,

[0054] FIG. 2 shows a microscopic detailed sectional view of a section across a finished base body of an object forming an implant, as it is manufactured according to the manufacturing method set forth in FIG. 1, wherein especially the shape of the granulate used in the form of balls is evident,

[0055] FIG. 3 shows a microscopically detailed sectional view of a section across a finished base body of an object forming an implant, as it is manufactured according to a manufacturing method set forth in a second example configuration, wherein said manufacturing method differs from the manufacturing method according to FIGS. 1 and 2 by the use of polygonal particles of the granulate, and

[0056] FIG. 4 shows a perspective view of a human skull for illustrating the possible attaching areas of the manufactured object/implant.

[0057] The figures are merely schematic and serve exclusively for the comprehension of the invention. Like elements are provided with like reference numerals.

[0058] In FIG. 1 a preferred manufacturing method according to the invention as set forth in a first example embodiment is clearly evident. For manufacturing an ultimately finished base body 6 which forms an object 1 provided for surgical use, i.e. a medical implant, in this method the method steps a) through g), marked by arrows, are carried out in time succession. For manufacturing the base body 6, at first the method steps a) through d) have to be carried out. As in the two example configurations described in the following the object 1 is in the form of an implant, hereinafter the implant as the object is provided with reference numeral 1. As an alternative to the manufacture of the implant 1, in further configurations also different objects, especially auxiliary means for an operation such as surgical tools are manufactured by said manufacturing method.

[0059] As is evident from FIG. 1, initially a plastic powder 2 in the form of an UHMWPE powder 2 is provided (arrow a)), wherein said plastic powder 2 has a grain size/average grain size of less than 300 m.

[0060] The free-flowing plastic powder 2 immediately thereafter is pressed, marked by arrow b), by means of a sinter-like process. This results in one-piece/coherent intermediate pieces 3. Especially, the intermediate pieces 3 are obtained by pressing with simultaneous heating of the plastic powder 2, the intermediate pieces 3 finally forming rectangular plates. The temperature of the intermediate pieces 3 during said sintering/primary forming of the intermediate pieces 3 is always below the disintegrating temperature of the plastic powder 2 used (in plural plastic materials below the disintegrating temperature of the lowest-melting material component of the plastic powder 2 used). Of preference, for producing the respective intermediate piece 3 a female mold is provided into which the plastic powder 2 is initially filled and which is subsequently heated as well as compressed, with a compacting force being applied, so that a solid structure in the form of the intermediate pieces 3 is formed.

[0061] Following the manufacture of the intermediate pieces 3, according to arrow c) each intermediate piece 3 is comminuted again in a defined manner. The intermediate pieces 3 are comminuted into plural particles 5 while forming a granulate 4. The particles 5 have a substantially uniform shape which is brought about by the concrete execution of the mechanical comminution. In this example configuration, round particles 5 in the form of spherical particles 5 or of particles 5 being oval in cross-section are produced.

[0062] The method step c) is subdivided into two partial steps not shown in detail here for the sake of clarity. In a first partial step (referred to as first partial step c1) the at least one intermediate piece 3 is pre-comminuted by cutting so that a plurality of sharp-edged single pieces is produced in turn from one intermediate piece 3. Alternatively, it is also considered in further example configurations to produce said single pieces by machining, such as milling or turning, and/or by punching rather than by cutting or in addition to cutting.

[0063] Following the first partial step c1), the plural single pieces are mechanically further comminuted, viz. ground, in a second partial step (referred to as second partial step c)). The single pieces are ground until the uniform granulate 4, i.e. especially uniform as to size and shape, forms from a plurality of particles 5. The grinding process is preferably realized by means of a rotor mill, wherein a rotor moves relative to an area that is stationary/fixed to the housing, viz. a screen, and the single pieces disposed therebetween are comminuted due to the mechanical shear forces. The rotor and the screen in that case include plural holes which already predetermine the circumferential geometry of the finished granulate 4. Since here round particles 5 are formed, the holes/through-holes equally take a round shape. By pressing the respective single pieces through the holes, the round shape is imparted to the particles 5.

[0064] According to arrow d), then joining of the granulate 4 set as to its form will follow to form the one-piece base body 6. In this example configuration, a sintering operation, viz. a selective laser-sintering operation, will serve for joining. As an alternative, it is also possible, however, to make use of different sintering techniques, for example porous sintering or even different joining techniques, e.g. adhesive joining techniques such as welding.

[0065] After step d), the base body 6 consists of a coherent stable plastic material in the form of the UHMWPE which was present before in powdered form. As is evident from the partial representation of the schematic view according to FIG. 1 between the arrows d) and e), a substantially plate-shaped implant 1 of any configuration is already pre-shaped in the form of said base body 6. In said base body 6 the individual, previously free-flowing granulate particles 5 are adhesively tightly joined (detailed representation I). The base body 6 in this process exhibits substantially the finished shape of the implant 1 to be manufactured already after carrying out step d). Accordingly, the implant 1 is typically configured as an implant 1 for osteosynthesis and, resp., fracture repair, e.g. as a cranial implant. Sintering is carried out such that the implant/the base body 6 has a porous, preferably open-pore structure. Alternatively, also closed-pore structures may be realized.

[0066] In addition to the steps a) through d) which already serve for completely configuring the implant 1/base body 6, in the example configuration according to FIG. 1 the steps e) through g) are further realized. By step e) the base body 6 is further exposed, subsequent to step d), to a radiation operation, viz. to a sterilizing radiation. Said sterilizing radiation serves for additional cross-linking of the UHMWPE material, which is evident from the partial representation following arrow e) of FIG. 1 by means of a detailed cutout II. Accordingly, the individual particles 5 nestle even more closely to each other and, resp., enlarge their mutual contact faces.

[0067] After the sterilizing radiation according to the method step f), the base body 6 is cleaned, which is visible between the partial representations before and after the arrow f) by the detailed representations Ill and IV of the surface.

[0068] After cleaning the surface, by step g) a thermal surface finishing of the base body 6 is carried out. Finally, this results in the implant 1 finished in the wake of step g) according to the preferred example configuration.

[0069] In FIG. 2, a microscopic detailed representation of a section across the finished implant 1 from FIG. 1 is illustrated once again in detail. Here especially the round/oval cross-sectional shape of the individual particles 5 is visible.

[0070] In combination with FIG. 3 it is also possible, however, to basically provide shapes other than said round shape. In FIG. 3 showing a cross-section of a different implant 1, the particles 5 take a polygonal shape. An implant 1 of such polygonal design of its particles 5 would be feasible by a method similar to the one shown in FIG. 1, wherein merely the grinding operation according to step c2) would have to be adapted. Instead of round holes in the rotor and in the screen, angular through-holes would have to be provided. The latter may as well vary in size so that finally the particles 5 according to FIG. 3 are designed to be somewhat larger than those shown in FIG. 2.

[0071] The finished implant 1 may be used, for example, at the cranial bone or in the jaw area, as is evident from FIG. 4, or in similar areas of the mammal. Also, the implant 1/the base body 6 may be manufactured in accordance with specific geometrical data of a patient. For this purpose, it is possible to design the appropriate sintering mold already as a patient-specific female mold and thus to produce already the finished shape of the implant 1 according to step d) and, resp., according to step g). As an alternative to this, it is also possible to geometrically adapt the finished base body 6 in size by bending or cutting immediately during operation.

[0072] In further configurations it is also possible to manufacture the base body 6 from materials other than the selected UHMWPE, such as PE, PP or HOPE. Basically, also other thermoplastic materials, thermosetting and/or elastorneric resins are suited for manufacture. Also, material mixtures such as mixtures of UHMWPE, PP, PE and/or HOPE may be chosen for manufacture.

LIST OF REFERENCE NUMERALS

[0073] 1 object/implant

[0074] 2 plastic powder

[0075] 3 intermediate piece

[0076] 4 granulate

[0077] 5 particle

[0078] 6 base body