Medical bone implant and method for monitoring the condition of the implant - Patents.com

Abstract

The medical bone implant (1; 11, 14) for stabilizing a bone area is provided, comprising an implant body made of a thermoplastic composite material for fixing in or on a human or animal bone for stabilizing the bone area, and further comprising at least one sensor (2) for measuring one or more parameters of the healing process and / or the state of the implant (1; 11, 14). The at least one sensor (2) is a passive magnetoelastic sensor (2). Furthermore, a method for monitoring the state of the implant (1; 11, 14) is provided, in which the passive magnetoelastic sensor (2) is used for monitoring the state of the implant (1; 11, 14) during the manufacturing process of the implant (1; 11, 14) and / or during storage of the implant (1; 11, 14).

Description

[Technical field]

[0001] The present invention relates to a medical bone implant for stabilizing a bone region, in particular as is often used for spinal reinforcement or for the treatment of trauma, having an implant body manufactured from a thermoplastic composite material. Furthermore, the present invention relates to a method for monitoring the condition of the implant. [Background technology]

[0002] In the medical field, implants are used more and more frequently and for various reasons. Implants are artificial devices that are inserted into the human or animal body for a certain period of time, usually for a long period of time. Implants can serve for example to support or replace bodily functions, as is the case for example with cardiac pacemakers, cochlear implants or prosthetics. Implants can also serve to replace destroyed or augment body parts (plastic surgery) or to monitor the user, as is often the case with RFID chips for pets.

[0003] An important group of implants are bone implants, which are often used for spinal reinforcement or for treating traumatic injuries. Bone implants are placed at least partially, but often completely, within the body and thereby fixed in or against the bone, i.e. attached to the bone.

[0004] With implants, in general, and especially with bone implants, attention is paid to the condition of the implant as well as the healing process of the patient throughout the entire period of application of the implant in the body. The condition of the implant can relate, for example, to deformations of the implant and thus to forces acting on the implant, on the basis of which conclusions can be drawn about the healing process. Conversely, the healing process can affect the condition of the implant, for example its lifespan.

[0005] It is therefore known to provide sensors not only on trial implants, but also on implants which are inserted in the body for long periods of time, so that medical personnel can receive information regarding the healing process.

[0006] The document US 2007 / 0133634 describes the provision of sensors in or on the spinal implant. The sensors may in particular be accelerometers and / or tension meters, which may be placed at various points in the pedicle system in order to monitor the healing process. In particular, the use of passive MEMS (micro-electromechanical) sensors is proposed.

[0007] Further documents, each by the same applicant or owner as US Patent No. 6,233,663, which also disclose providing passive MEMS sensors in implants, are US Patent No. 6,233,663, ... and US Patent No. 6,233,663.

[0008] However, MEMS sensors are relatively complex to manufacture and require additional electronic components for wireless readout.

[0009] US Pat. No. 5,399,633 discloses a screw that can be screwed into bone, in which sensors are disposed as well as processing means, memory devices and energy storage devices.

[0010] US Patent No. 5,399,633 discloses a pedicle system with sensors attached to the connecting rods to measure the compression, flexure and / or torsion of the connecting rods. Similarly, an intervertebral placeholder with sensors is disclosed. The sensors are tension meter strips or piezoelectric sensors. Both types of sensors are relatively complex to manufacture and therefore expensive. Furthermore, additional electronic components are required to allow wireless reading of the sensor data.

[0011] Patent Document 14 relates to a spinal implant that is inserted between two adjacent vertebral bodies and includes a sensor for measuring load. An exemplary sensor is a tension gauge strip.

[0012] US Pat. No. 5,999,366 discloses an implantable sensor between the two vertebral bodies in each case to measure the loads occurring there. The reading of the sensor can be done wirelessly, for example via RFID.

[0013] US Patent No. 5,399,633 discloses the attachment of sensors to orthopedic bone implants, particularly intramedullary nails, to measure the flexure, torsion and compression of the implant. The sensors are inserted into recesses provided on the outside of the implant. The measurement data can be wirelessly transmitted to the outside.

[0014] The '693 patent application discloses a pedicle system with sensors located on the connecting rods to measure and transmit force, deformation and displacement data.

[0015] Furthermore, US Pat. No. 5,399,663, US Pat. No. 5,499,703, US Pat. No. 5,599,626, US Pat. No. 5,613,096 and US Pat. No. 5,711,366 each disclose implants with active sensors, i.e. sensors that are powered, for example, via a battery mounted in the implant, for performing measurements and storing the measurement data in a memory chip also arranged in the implant, where readings are typically performed via a transmitting unit that is also powered by the battery.

[0016] The documents US Pat. No. 5,399,623 and US Pat. No. 5,499,633 each propose placing passive sensors in the implant, but do not further state which measurement principle these sensors are based on.

[0017] Two documents, US Pat. No. 5,399,633 and US Pat. No. 5,499,663, both from different technical fields, respectively describe the use of microwires to measure the mechanical properties of components by utilizing the Barkhausen effect.

[0018] Patent Document 27 proposes the use of microwires in medical devices developed for administering medicines, such as insulin pumps. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] US Patent Application Publication No. 2017 / 0196508 [Patent Document 2] International Publication No. 2015 / 20070 [Patent Document 3] International Publication No. 2015 / 200723 [Patent Document 4] International Publication No. 2015 / 200707 [Patent Document 5] International Publication No. 2015 / 200722 [Patent Document 6] International Publication No. 2015 / 200720 [Patent Document 7] International Publication No. 2014 / 209916 [Patent Document 8] International Publication No. 2014 / 144107 [Patent Document 9] International Publication No. 2014 / 144070 [Patent Document 10] International Publication No. 2014 / 100795 [Patent Document 11] International Publication No. 2015 / 200718 [Patent Document 12] U.S. Pat. No. 9,629,583 [Patent Document 13] International Publication No. 2017 / 004483 [Patent Document 14] International Publication No. 2007 / 090005 [Patent Document 15] International Publication No. 2007 / 098385 [Patent Document 16] International Publication No. 2007 / 025191 [Patent Document 17] International Publication No. 2017 / 116343 [Patent Document 18] International Publication No. 2021 / 15485 [Patent Document 19] European Patent Application Publication No. 3772350 [Patent Document 20] International Publication No. 2020 / 247890 [Patent Document 21] International Publication No. 2017 / 165717 [Patent Document 22] U.S. Pat. No. 11,042,916 [Patent Document 23] International Publication No. 2020 / 206373 [Patent Document 24] International Publication No. 2016 / 044651 [Patent Document 25] International Publication No. 2007 / 116218 [Patent Document 26] European Patent No. 3150998 [Patent Document 27] International Publication No. 2020 / 035217 Summary of the Invention

[0020] The object of the present invention is to provide a medical bone implant which is easy to manufacture, serves to stabilise the bone area, is manufactured from a thermoplastic composite material and comprises an implant body with at least one sensor allowing wireless reading of the sensor measurement data. To achieve this object, a bone implant is proposed as disclosed in claim 1. A further object of the present invention is to provide a simple method for monitoring the state of the implant. A method for achieving this further object is defined in claim 12. Further embodiments are defined in the dependent claims.

[0021] Thus, the present invention relates to a medical bone implant for stabilizing a bone region, comprising: an implant body made of a thermoplastic composite material for fixing in or against a bone of a human or animal body for the purpose of stabilizing the bone area; at least one sensor for measuring one or more parameters of the healing process and / or the condition of the implant; A bone implant comprising:

[0022] At least one sensor is a passive magnetoelastic sensor.

[0023] By using passive magnetoelastic sensors, the implant can be manufactured particularly simply and therefore inexpensively. A further advantage is that passive magnetoelastic sensors usually require relatively little space in the implant and therefore have a minimal effect on the properties of the implant. Nevertheless, passive magnetoelastic sensors can optionally read the sensor data wirelessly from outside the patient's body. No additional electronic components, such as electrical circuits or separate transmission units, are required. In particular, the implant does not require any energy storage devices, such as batteries.

[0024] As already mentioned, the bone implant is placed at least partially, but usually completely, in the body and is therefore fixed in or on the bone, i.e. attached to the bone. Here, the fixation of the implant in or on the bone can also take place indirectly, i.e., via further components, which are artificially produced, in particular via further implants, which preferably also have an implant body made from a thermoplastic composite material. This is usually the case, for example, in the case of pedicle systems, where a first bone implant in the form of a connecting rod is fixed to the vertebral bodies via a number of second bone implants in the form of pedicle screws.

[0025] As a result, the bone implant serves to stabilize a bone region when it supports and / or strengthens the bone region. The bone region preferably concerns at least the region of the bone in or against which the implant body is fixed. The bone region to be stabilized may thus concern only one or, alternatively, several bones or bone parts. In particular, the bone region may concern several vertebral bodies of the spine. The bone region to be stabilized may also concern, for example, a single bone, which has to be stabilized, for example with a bone implant, after a fracture, so that the bone parts can grow together again as desired. The bone implant may also be, for example, a vertebral body prosthesis or an intervertebral disc prosthesis, since these are also usually fixed against or in at least one bone, i.e. attached to the bone. Artificial vertebral body prostheses and artificial intervertebral disc prostheses serve to replace the thoracic vertebrae or intervertebral discs, respectively, and therefore are usually fixed against and in at least one adjacent vertebral body, usually against or in two adjacent vertebral bodies. Thus, the vertebral body prosthesis and the intervertebral disc prosthesis in each case serve to stabilize the spine, and in particular the bony region comprising two adjacent vertebral bodies.

[0026] The implant body usually forms the main component of the implant and preferably provides the implant with structural stability. The implant may in particular consist of only the implant body and at least one sensor.

[0027] At least one sensor forms a component capable of recording certain properties, in particular physical properties, of its surroundings qualitatively or quantitatively as measured variables. The surroundings here are usually formed by the implant body and / or the immediate area of ​​the human or animal body around the implant body, respectively. The surroundings may also be formed, for example, by a compression moulding tool (during the manufacturing process), or a mounting arrangement and a transport arrangement, or other such implants (during storage or transport), before implanting the implant in the human or animal body, respectively. The variables measured there are recorded based on the magnetoelastic effect and are usually converted into electrical signals during reading. The implant may comprise a single magnetoelastic sensor or multiple magnetoelastic sensors.

[0028] The one or more parameters of the healing process and / or of the state of the implant can in particular be the mechanical load of the implant, such as compression, tension, flexure or torsion, etc., and / or the temperature. The one or more measured parameters can alternatively or additionally be, for example, the body temperature of a human or animal in the immediate vicinity of the implant, respectively. In general, the sensor can be designed to measure any parameter that can lead to a change in the magnetic properties of the sensor material. Thus, by means of the one or more parameters, conclusions can be drawn regarding the state of the implant, i.e. information can be obtained regarding, for example, pressures, tensile stresses and / or torsional forces that affect the implant. In particular, conclusions can be drawn regarding the stability of the implant area, i.e. the area directly surrounding the implant. For this reason, the implant area can be particularly related to other implants and / or body structures that connect to the implant, such as bones. In the case of several measurements made at different times, the chronological sequence of these parameters and thus any possible changes in the state of the implant can be evaluated. In this case, conclusions regarding the healing process can then be drawn from the measured parameters or the state of the implant, respectively, in particular from their course. For example, by measuring the temperature, it may be possible to draw conclusions regarding infections in the immediate vicinity around the implant.

[0029] The measurement is based in particular on a change in the magnetic properties of the sensor material. In particular, the loading of a force on the implant changes the magnetic permeability of the sensor material. The change in magnetic permeability of the sensor material can also be the result of a change in temperature. The sensor material here is preferably pre-magnetized. Due to the magnetoelastic effect, also known as the "Villari effect", a load and / or temperature applied to the sensor material leads to a change in the magnetic field of the sensor material, which can be measured. The measurement is particularly advantageous, since it can be performed in particular wirelessly and without touching from outside the body.

[0030] To enable measurements based on the magnetoelastic effect, at least one sensor comprises a sensor material, usually in the form of a ferromagnetic material, preferably a ferromagnetic alloy, with inverse magnetostriction, which changes its magnetic properties, in particular its permeability, under mechanical or thermal stress, respectively, which can be detected and measured by a suitable measuring or reading device, respectively.

[0031] It has been found that particularly accurate measurements are possible if at least one sensor for measuring one or more parameters utilizes the Barkhausen effect. Due to the Barkhausen effect, a continuously changing magnetic field discontinuously changes the magnetization of a ferromagnetic material. The reason for this is the presence of areas of uniform magnetization direction, so-called magnetic domains (German: "Weiss-Bezirke"), which are separated by Bloch walls. For example, a slow increase in the magnetic field strength leads to a sudden reversal of the magnetic moment of the entire area, i.e. the magnetic domain (German: "Weiss-Bezirke"), resulting in a sudden change in the magnetic field of the respective material. Preferably, at least one sensor utilizes the Barkhausen effect, making it possible to measure these sudden changes in the magnetic field.

[0032] Particularly sensitive and accurate measurements are possible if at least one sensor is a microwire. The usual geometric dimensions of the microwire can result in a particularly strong signal during the measurement due to the magnetoelastic effect. In the case of the microwire, the signal is also particularly strong if the Barkhausen effect is utilized for the measurement. The microwire can furthermore be particularly advantageously arranged inside the implant, for example extending along its main longitudinal centerline.

[0033] The microwires preferably have a diameter of 10 μm to 250 μm. The length of the microwires is preferably more than 25 times the diameter, particularly preferably more than 50 times, most preferably more than 100 times.

[0034] In a preferred embodiment, the at least one sensor is arranged at least partially, more preferably completely, inside the implant body, whereby the sensor is optimally protected from external influences and can transmit the indicated measurement variables from inside the implant, and conversely, the surrounding body tissue is isolated from the sensor, preventing any intolerance to the sensor material. To achieve optimal measurement results, the at least one sensor can be embedded in particular in the material of the implant body.

[0035] In a particularly preferred embodiment, the implant body is manufactured from a fiber-reinforced plastic material. The fiber-reinforced plastic material is preferably a carbon fiber-reinforced plastic material, such as, for example, polyetheretherketone (PEEK). The manufacture of the implant body from a thermoplastic material, in particular a fiber-reinforced plastic material, has the advantage, on the one hand, that it allows the manufacture of a structurally very stable implant, which is furthermore biocompatible and advantageous for visualization procedures, such as, for example, MRI. On the other hand, thermoplastic materials, in particular fiber-reinforced plastic materials, are also transparent to electromagnetic radiation, for example compared to metals. Thus, sensor measurements can be easily performed when the sensor is arranged completely inside the implant body.

[0036] If the implant body is manufactured from a fiber-reinforced plastic material, the length of the fibers is preferably at least 1 mm, preferably at least 5 mm. Particularly preferably, however, the length of the fibers is so great that it corresponds to the entire length of the implant body in the main direction of extension, which gives the implant body a particularly high rigidity and structural stability.

[0037] Good implant stability is achieved if the volume fraction of fibres is in the range of 20-80%, preferably in the range of 35-70%, particularly preferably in the range of 45-60%.

[0038] As plastic materials, preferably thermoplastics are used, particularly preferably so-called high-temperature thermoplastics from the family of polyaryletherketones, polyimides and / or polysulfones.

[0039] Particularly preferred are embodiments in which the implant has a main longitudinal centerline and the at least one sensor extends substantially along the entire longitudinal extension of this main longitudinal centerline. The main longitudinal centerline constitutes a line extending along the entire longitudinal extension of the center of the interior of the implant, in particular the interior of the implant body. The at least one sensor therefore preferably has substantially the same length as the implant. If the implant exhibits, for example, a generally curved or spiral morphology, the main longitudinal centerline also has a correspondingly curved or spirally shaped design, respectively, so that the at least one sensor also has a generally curved or spirally shaped design. This has the advantage that measurements along the entire longitudinal extension of the implant are possible, which can cover the entire implant and is not limited to individual points of the implant. In this way, the implant can be fully controlled and monitored over its entire length.

[0040] If at least one sensor is a microwire, it can extend substantially along the entire longitudinal extension of this main longitudinal centerline, completely continuous or piecewise as adjacent aligned sections. In other words, the implant can comprise a plurality of sensors, i.e. microwires, arranged at regular intervals along the main longitudinal centerline. If several aligned sections are provided, they are preferably arranged at regular intervals from each other. One advantage of several aligned sections can be that separate measurements on different sections are possible, for example so that differences in load distribution along the main longitudinal centerline of the implant body can be measured.

[0041] The implant may also include several such sensors extending parallel to one another. Preferably, the sensors extend not only parallel to one another but also parallel to the main longitudinal centerline, which may have a curved configuration depending on the design of the implant. By providing several sensors arranged parallel to one another it is possible to detect torsional forces acting on the implant.

[0042] The implant may in particular be a spinal implant, such as a vertebral prosthesis, a disc prosthesis, a dowel, a screw anchor, a fixation plate, a pedicle screw or a connecting rod of a pedicle system. In the case of a fixation plate, the fixation plate may be a plate for fixing the spine in the anterior, lateral or posterior region. Alternatively, the implant may also be a trauma implant, such as a particularly general anchor system, in other words for example a screw anchor or dowel, or a bone plate or bone screw.

[0043] The at least one sensor preferably has a temperature stability up to at least 450 ° C. That is, the at least one sensor is not damaged as long as it is exposed to a temperature not exceeding 450 ° C. Advantageously, measurements up to a temperature of 450 ° C by the at least one sensor are also possible. Such an arrangement of the at least one sensor has advantages in terms of the implant manufacturing process. Thereby, the at least one sensor can be integrated into the implant at an early point during the manufacturing process without being damaged by an increase in temperature value. Thereby, advantageously, it is also possible to carry out measurements by the at least one sensor already during the manufacturing process in order to monitor the manufacturing process. For example, the influences acting on the implant body during the manufacturing process, such as, in particular, pressure and temperature, can be measured in order to draw conclusions regarding the quality of the implant.

[0044] The invention further relates to a method for monitoring the state of an implant and / or the state of the healing process of a human or animal body in which an implant is inserted, the implant may in particular be a bone implant as described above, the implant comprising at least one passive magnetoelastic sensor for measuring one or more parameters of the healing process and / or the state of the implant, wherein the sensor is used to monitor the state of the implant during the manufacturing process and / or during storage.

[0045] Preferably, in particular the pressure and temperature progressions are measured during the manufacturing process and / or storage of the implant, and advantageously further recorded. In this way, the integrity and intactness of the implant can be guaranteed. Implants whose pressure and / or temperature do not progress within certain tolerances, for example during the manufacturing process and / or storage, can be discarded. In this way, implants with manufacturing defects and / or damaged during storage can be prevented from being implanted in the human or animal body. Such monitoring of the implant by at least one sensor is possible not only for bone implants, but also for any other implants, already during the manufacturing process and / or storage.

[0046] Preferably, the condition of the implant is controlled not only during the manufacturing process and / or during storage, but also immediately after implantation in the human or animal body. "Immediately after implantation" means, for example, that the forces acting on the implant are measured immediately after insertion into the body and thus at the very beginning of the healing process. In this way, the exact position of the implant in particular in the body can be ascertained.

[0047] Alternatively or additionally, but preferably, the healing process after implantation of the implant in the human or animal body is monitored by at least one sensor. The monitoring by at least the sensor, and thus for example the measurement of the forces acting on the implant and / or the measurement of the temperature, can be carried out in particular with a regular time lag. For example, by the course of the forces acting on the implant, conclusions can be drawn regarding the healing process and the treatment can for example be terminated or adjusted accordingly.

[0048] For the manufacture of the implant, preferably a plurality of prepregs, in particular unidirectional prepregs, are used, which are pressure-grouted together under pressure and heat. A prepreg is understood to be a fiber-matrix semi-finished product, and thus a semi-finished product that preferably comprises reinforcing fibers arranged in a plastic matrix. The reinforcing fibers are preferably carbon fibers. The prepregs can be present, for example, in the form of strands, bands or plates. By pressure-grouting the prepregs under pressure and temperature, the prepregs are preferably continuously fused together and take the final form of the implant. After pressure-grouting, the prepregs preferably form the implant body.

[0049] Prior to pressure grouting, at least one sensor can be placed between the prepregs, which are then pressure grouted together so that during the pressure grouting process the sensor is likewise placed between the prepregs, and is thus at least partially, preferably completely, located inside the implant body of the final implant. Alternatively, at least one sensor can already be embedded in one of the prepregs during the pressure grouting process. In that case, the embedding of the sensor in one of the prepregs is already performed before pressure grouting. In this way, the sensor can be optimally positioned within the implant.

[0050] Preferred embodiments of the present invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. [Brief description of the drawings]

[0051] [Figure 1] 1 is a schematic diagram of a bone implant in the form of a pedicle fixation system, fixed to a vertebral body of a spine, according to a first embodiment of the present invention. FIG. [Figure 2a] FIG. 2 is a side view of a connecting rod of the pedicle fixation system of FIG. 1 . [Figure 2b] FIG. 2b is a cross-sectional view of the connecting rod of FIG. 2a in plane II-II. [Figure 3a] FIG. 13 is a side view of a bone implant in the form of a connecting rod of a pedicle fixation system according to a second embodiment of the present invention. [Figure 3b] FIG. 3b is a cross-sectional view of the connecting rod of FIG. 3a in plane III-III. [Figure 4a] FIG. 13 is a side view of a bone implant in the form of a connecting rod of a pedicle fixation system according to a third embodiment of the present invention. [Figure 4b] FIG. 4b is a cross-sectional view of the connecting rod of FIG. 4a in the plane IV-IV. [Diagram 5] FIG. 1 is a flow diagram of a manufacturing process for a bone implant according to a first variant of the invention. [Figure 6] FIG. 2 is a flow diagram of a manufacturing process for a bone implant according to a second variant of the invention. [Figure 7a] 2A-2C are schematic cross-sectional views of several prepregs inserted into a pressure grouting tool immediately prior to pressure grouting for the purpose of producing different bone implants according to the invention; [Figure 7b] FIG. 7b is a schematic cross-sectional view of the pressure grouting tool of FIG. 7a during pressure grouting of the prepreg. [Figure 8] FIG. 7b is a schematic diagram of the manufacturing process during sensor reading for the purpose of monitoring the pressure grouting process. [Figure 9] FIG. 2 is a schematic diagram of the bone implant of FIG. 1 during sensor readings for the purpose of monitoring the healing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] 1 to 9 show different embodiments of a medical bone implant according to the invention as well as different preferred modes of manufacture of such an implant. Elements of the different embodiments having the same or similar effect are designated below with the same reference numbers.

[0053] 1 shows a dynamic pedicle fixation system 1 fixed to several vertebral bodies W of a patient's spine. The vertebral bodies W are separated from one another by intervertebral discs B. The pedicle fixation system 1 serving to stabilize the illustrated bone region comprises several pedicle screws 11 which together form a bone implant and each are screwed into a screw shank 12 of a pedicle of a vertebral body W. Each screw is attached to a succession of connecting rods 14 by means of a tulip head 13 which is advantageously polyaxially adjustable. Each of the pedicle screws 11, the tulip head 13 and the connecting rods 14, by their placement in the body and their attachment (directly or indirectly) to the spine, forms a bone implant in itself.

[0054] Other embodiments of the fixation system shown in Fig. 1 are also conceivable, whereby the number of pedicle screws 11 can be varied, in the sense that, for example, instead of the five shown, only two pedicle screws are applied. Likewise, the number of pedicle screws can be more than five. Furthermore, the pedicle system can comprise two parallel rows of pedicle screws, each connected to a connecting rod, as is usually the case.

[0055] One or more sensors are arranged inside the slightly bent connecting rod 14. In this case, the sensors are formed by microwires 2 which run continuously in the longitudinal direction along the main longitudinal centerline of the connecting rod 14. Passive sensors, for example also in the form of microwires, can also be embedded in the respective pedicle screws 11.

[0056] The microwire 2 is made of a ferromagnetic material with inverse magnetostriction. When the forces and / or temperature acting on the connecting rod 14 and thus on the microwire 2 change, the microwire 2 is for example slightly deformed, compressed, twisted and / or stretched. As a result, due to the magnetoelastic effect, the magnetic permeability of the material of the microwire 2 changes, which is detectable and measurable by the reading device 5 (see FIG. 11 ).

[0057] Figure 2a shows in side view only the connecting rod 14 of the pedicle fixation system of figure 1. A slight curvature of the connecting rod 14 can be seen. The dashed line indicates the position of the microwire 2 which runs over the entire length of the implant, directly above its main longitudinal centreline.

[0058] In the cross-sectional view of Fig. 2b, the internal structure of the same connecting rod 14 is shown diagrammatically. The implant body is formed by a plastic matrix 31 in which a number of carbon fibres 32 are embedded. The carbon fibres 32 run parallel to one another along the main longitudinal centre line of the connecting rod 14. This gives the connecting rod 14 a particularly good structural stability. The microwires 2 run centrally in the middle of the connecting rod 14.

[0059] A thermoplastic, preferably a so-called high-temperature thermoplastic from the family of polyaryletherketones, polyimides or polysulfones, is used as the plastic matrix 31. The carbon fibres have a fibre length of at least 1 mm, but preferably a length corresponding to the entire length of the connecting rod 14 in the main direction of extension.

[0060] The volume fraction of fibres is in the range of 20-80%, preferably in the range of 35-70%, particularly preferably in the range of 45-60%. The connecting rod 14 shown in Figure 4b has a circular cross section. Other cross-sectional shapes, such as rectangular or hexagonal, are also conceivable.

[0061] The diameter of the connecting rod 14 shown in Figures 2a and 2b is preferably in the range of 2 to 10 mm, preferably in the range of 4 to 6 mm. The geometric embodiment in the longitudinal direction of the connecting rod 14 can be straight or curved, or a combination of both, in which a longitudinal section is straight and an adjacent section is curved. A geometric embodiment in the longitudinal direction is also conceivable, in which one longitudinal section is convexly curved and an adjacent section is concavely curved. The radius of curvature of the curved embodiment is preferably in the range of 50 to 600 mm. Other radii of curvature are also conceivable. The length of the connecting rod 14 is preferably in the range of 50 to 500 mm. Other lengths are also conceivable.

[0062] The sensor 2 used in the connecting rod 14 of Fig. 2a and Fig. 2b is a passive sensor, which changes its specific material properties, in particular under the effect of thermal load, which are subsequently recorded wirelessly and transmitted from the body to the outside. Preferably, for this purpose, magnetoelastic microwires with ferromagnetic alloys and inverse magnetostriction are used, which microwires 2 change their magnetic properties under thermal load. The change in magnetic properties can be recorded and measured, in particular by the magnetic permeability. The physical phenomena known here are mainly the Villari effect, preferably the Barkhausen jump. The skilled person knows how to design at least one sensor, i.e. in this case the microwire 2, and how to take the readings, since the measurement is based on the Barkhausen effect. The skilled person takes such suggestions, for example, from WO 2007 / 116218 and EP 3150998.

[0063] Here, an embodiment of the microwire 2 is preferably used, which has a diameter in the range of 10 μm to 250 μm and which preferably runs completely continuously or piecemeal in adjacent sections over the entire length of the implant, so that the entire length of the components of the connecting rod 14 can be fully controlled and monitored. Particularly preferred embodiments of such passive sensors are those which have a temperature stability up to at least 450° C. and a temperature recording accuracy of at least ±0.1 K. The preferred arrangement of the microwire 2 in the connecting rod 14 is central, although non-central arrangements are also conceivable. With this embodiment of the microwire 2 in the connecting rod 14, it is also possible to record and wirelessly transmit the temperature during the manufacturing process and / or storage of the connecting rod 14 before implantation.

[0064] The number of sensors in the embodiment of Fig. 2b is one. However, it is possible to incorporate several sensors of the same type in the connecting rod 14.

[0065] The embodiment shown in figures 3a and 3b differs from the embodiment of figures 2a and 2b in that the connecting rod 14 is provided with several, in particular four, microwires 2 which run parallel to one another along the main longitudinal centre line of the connecting rod 14. Moreover, all four microwires 2 are arranged at a distance from the main longitudinal centre line, i.e. they run off-centre within the connecting rod 14. Here, the microwires 2 serve to measure mechanical loads, for example tension, pressure, deflection and / or torsion. Of course, in other embodiments it is also possible to incorporate more or less than four microwires 2 in the connecting rod 14. A central arrangement of the microwires 2 is also conceivable, in particular when they serve to record and measure tensile and compressive forces.

[0066] Thus, when the microwire 2 is positioned centrally, as in the embodiment of Figures 2a and 2b, tensile and compressive forces can be measured, and when the microwire 2 is positioned off-center, as in the embodiment of Figures 3a and 3b, bending and torsional forces can additionally or alternatively be recorded.

[0067] The embodiment shown in Figures 4a and 4b differs from the embodiment of Figures 2a, 2b and 3a, 3b in that here five microwires 2 are provided which run parallel to one another in the connecting rod 14, one of which is arranged approximately in the center of the connecting rod 14 and the others are arranged at a distance. The four microwires 2 arranged off-center serve to measure mechanical loads, for example tension, pressure, deflection and / or torsion, and the microwire 2 arranged approximately in the center serves to measure thermal loads. Naturally, other arrangements and different numbers of microwires 2 are also possible.

[0068] The passive sensors provided in the embodiments of Figures 2a-4b do not necessarily have to be in the form of microwires but can have other forms as well.

[0069] Figures 5 and 6 represent in each case a flow diagram visualizing the manufacture of an implant according to the invention, from raw material to the final part. The manufacture of a connecting rod 14 shown in Figures 2a and 2b is taken as an example. Here, two variants of the manufacture of the connecting rod 14 exist and may be equally preferred.

[0070] In the first variant shown in FIG. 5, unidirectional fibre-reinforced prepregs 3 are used in this example, which in each case comprise carbon fibres 32 embedded in a plastic matrix 31. Likewise, textured prepregs can also be used. The unidirectional fibre-reinforced prepregs 3 used in this first variant are in each case geometrically layered, with a preferred width of 1-50 mm and a preferred thickness of 0.1-0.5 mm. Other dimensions are possible for width and thickness. Other geometrical embodiments are also possible, such as for example circular. The prepregs 3 are usually adapted in the longitudinal direction, the length of which preferably corresponds at least to the length of the connecting rod 14. For the fibres, preferably carbon fibres 32 are used, with a fibre length of at least 1 mm, but preferably with a length corresponding to the entire length of the connecting rod 14 in the main direction of extension.

[0071] The volume fraction of fibres is in the range of 20-80%, preferably in the range of 35-70%, particularly preferably in the range of 45-60%. As material for the plastic matrix 31, thermoplastics are used, particularly preferably so-called high-temperature thermoplastics from the family of polyaryletherketones, polyimides and polysulfones.

[0072] The prepregs 3 are in a second step respectively preformed and placed or laminated, between which the microwire 2 is placed centrally. The placement of the prepregs 3 can be done manually or automatically, for example by a tape laying process or a 3D printer. The placement of the sensor, in this case the microwire 2, can be done manually or automatically, for example with a 3D printer. The precision of the placement of the prepregs 3 and the sensor can be improved by pressure and temperature, in the sense that the prepregs 3 are pre-welded to each other and to the microwire 2 and subsequently cooled.

[0073] In a third step, for example the preform is heated in a pressure grouting tool to a processing temperature above the melting point of the plastic matrix 31, pressure grouted to the end contour of the connecting rod 14 and cooled, where the integrated microwires 2 can wirelessly transmit production data relating to the pressure and temperature of the connecting rod 14 beforehand for recording purposes.

[0074] In the second variant shown in FIG. 6, two different types of unidirectional fibre-reinforced prepregs 3 are used in this example as starting materials. The composition of one type of prepreg 3 is similar to that of the prepreg 3 used in the first variant. Also in this second variant, a prepreg 3 is used first, which has the same composition as the other prepreg 3, but which additionally comprises a sensor in the form of a microwire 2 embedded in its centre. The length, thickness and shape of this prepreg correspond to those of the first variant. The length of the microwire 2 corresponds at least to the entire length of the connecting rod 14.

[0075] The prepregs 3 are also in this second variant respectively geometrically precisely arranged or stacked on the preform, but now the prepreg 3 with the microwires 2 is sandwiched and centrally arranged. The arrangement of the prepregs 3 can be done manually or automatically, for example by a tape-laying process or by a 3D printer.

[0076] In a third step, for example the preform is heated, again in a pressure grouting tool, to a processing temperature above the melting point of the plastic matrix 31 or the prepreg 3, respectively, pressure grouted to the end contour of the connecting rod 14 and cooled. Again, the integrated microwires 2 can be wirelessly transmitted beforehand for the purpose of recording manufacturing data related to pressure and temperature of the connecting rod 14.

[0077] The variant for the manufacture of a connecting rod 14 with an integrated sensor shown and described in Figures 5 and 6 is preferably a manufacturing process close to the end contour, i.e. the implant so manufactured usually requires only minor post-processing in terms of shape and dimensions, during which the arrangement of the sensor remains unchanged.

[0078] 7a and 7b show diagrammatically a preferred manufacturing process for a connecting rod 14 incorporating microwires 2 according to the invention.

[0079] Here, a moulding tool 4 is used, made for example of steel or another material and comprising two moulding parts. One of the two moulding parts forms a stamp 41, which together form a cavity 42 with a quadratic cross section. According to a second variant shown in Figure 6, the prepregs 3 are geometrically precisely arranged in the preform or laminated respectively in the cavity 42 at room temperature or at a temperature much lower than the melting point of the plastic matrix 31. The prepreg 3 with the microwires 2 is arranged in the cavity 42 so that it is centred with respect to the other prepregs 3.

[0080] The preform is then heated in a pressure grouting tool 4 to a processing temperature above the melting point of the plastic matrix 31 or the prepreg 3, respectively, and pressure grouted to the end contour of the connecting rod 14 by closing the two molded parts, followed by cooling. The integrated microwires 2 allow pre-measurement and wireless transmission of production data during the pressure grouting process for recording purposes.

[0081] Figure 8 shows a schematic diagram of data recording and transmission during the manufacturing process of a preferred implant according to the invention. This is exemplarily explained by the manufacturing step shown in figure 7b. Besides the passive sensors, present in this case as microwires 2, the monitoring system comprises a reading device 5 with a transmitter 51 and a receiver 52, and a computing unit 6. The reading device 5 is spaced apart from the pressure grouting tool 4 and does not have any cable connection associated with it.

[0082] Here, already during the pressure grouting process with the pressure grouting tool 4, the transmitter 51 wirelessly generates an electromagnetic excitation 53, which also covers the microwire 2 arranged inside the connecting rod 14. This excitation 53 causes a signal 54 to be sent back from the microwire 2 and recorded, for example oscillographically, by the reading device 5 via the receiver 52. Due to the magnetoelasticity of the microwire 2, the signal 54 here depends on the pressure and temperature to which the connecting rod 14 and thus the microwire 2 are subjected during the pressure grouting process. Based on the signal 54 received from the reading device 5, data is therefore collected on the pressure and temperature of the connecting rod 14.

[0083] These collected data are then transmitted by cable transmission 61 or wireless transmission 62 to a computing unit 6 for subsequent analysis and recording.

[0084] In Fig. 9 a schematic diagram of data collection and transmission of an implant according to the invention in the implanted state is shown, where data collection and transmission serve to monitor the healing process. Here the monitoring system is shown in combination with the pedicle fixation system 1 shown in Fig. 1, in which a passive magnetoelastic sensor in the form of a microwire 2 is integrated in the connecting rod 14. Besides the microwire 2, the monitoring system here also comprises a reading device 5 with a transmitter 51 and a receiver 52, and a computing device 6. The reading device 5 and the computing device 6 are placed outside the body and separated from the pedicle fixation system 1 by the skin H.

[0085] The transmitter 51 wirelessly generates an electromagnetic excitation 53, which also affects in particular the microwire 2 present in the pedicle fixation system 1. The excitation 53 causes the microwire 2 to send back a signal 54 through the skin H, which is detected by the reading device 5 via the receiver 52. The signal 54 depends, due to the magnetoelastic properties of the microwire 2, on the mechanical load and the temperature to which the connecting rod 14 and thus the microwire 2 are subjected. Based on the received signal 54, the reading device 5 can therefore determine data relating to the mechanical load and temperature of the connecting rod 14.

[0086] The data thus determined are then transmitted to a computing unit 6 for subsequent analysis by cable transmission 61 or wireless transmission 62. Based on the measurement data, a doctor or medical personnel can, for example, adjust or terminate the treatment. [Explanation of symbols]

[0087] 1 Pedicle Fixation System 11 Pedicle screw 12 Screw shaft 13 Tulip Head 14 Connecting rod 2 Microwire 3 Prepreg 31 Plastic Matrix 32 Carbon Fiber 4. Pressure Grouting Tools 41 Stamp 42 Cavity 5 Reading device 51 Transmitter 52 Receiver 53 Excitation 54 signal 6 Calculation Units 61 Cable Transmission 62 Radio Transmission W vertebra B Intervertebral disc H skin

Claims

1. A medical bone implant (1; 11, 14) for stabilizing a bone area, comprising: an implant body made of a thermoplastic composite material for fixation in or against a bone (W) of a human or animal for the purpose of stabilizing said bone area; at least one sensor (2) for measuring one or more parameters of the healing process and / or the condition of said implant (1; 11, 14); The bone implant (1; 11, 14) comprises: Bone implant (1; 11, 14), characterized in that said at least one sensor is a passive magnetoelastic sensor (2).

2. 2. The bone implant (1; 11, 14) according to claim 1, wherein said at least one sensor (2) utilizes the Barkhausen effect to measure said one or more parameters.

3. Bone implant (1; 11, 14) according to claim 1 or 2, wherein said at least one sensor is a microwire (2), preferably having a diameter between 10 μm and 250 μm.

4. 3. The bone implant (1; 11, 14) according to claim 1 or 2, wherein the at least one sensor (2) is arranged at least partly or completely inside the implant body.

5. 3. The bone implant (1; 11, 14) according to claim 1 or 2, wherein the implant (1; 11, 14) has a main longitudinal centerline and the at least one sensor (2) extends substantially along the entire longitudinal extension of the main longitudinal centerline.

6. 6. A bone implant (1; 11, 14) according to claim 5, characterized in that the implant (1; 11, 14) comprises several such sensors (2) arranged at regular intervals along the main longitudinal centre line.

7. Bone implant (1; 11, 14) according to claim 1 or 2, characterized in that the implant (11, 14) comprises several such sensors (2) extending parallel to one another.

8. 3. A bone implant (1; 11, 14) according to claim 1 or 2, wherein the implant is a spinal implant, in particular a vertebral body prosthesis, an intervertebral disc prosthesis, a dowel, a screw anchor, a fixation plate, a pedicle screw (11) or a connecting rod (14) of a pedicle system.

9. 3. A bone implant (1; 11, 14) according to claim 1 or 2, wherein the implant is a trauma implant, such as a screw anchor, a dowel, a bone plate or a bone screw.

10. 3. A bone implant (1; 11, 14) according to claim 1 or 2, wherein the parameter or parameters relate to mechanical loads, in particular compressive and / or bending forces, and / or temperature.

11. 3. The bone implant (1; 11, 14) according to claim 1 or 2, wherein the at least one sensor (2) has a temperature stability up to at least 450°C.

12. 1. A method for monitoring the condition of an implant (1; 11, 14), in particular a bone implant (1; 11, 14) according to claim 1 or 2, the implant (1; 11, 14) comprising at least one passive magnetoelastic sensor (2) for measuring one or more parameters of the condition of the implant (1; 11, 14), 10. A method, characterized in that the sensor (2) for monitoring the condition of the implant (1; 11, 14) is used during the manufacturing process of the implant (1; 11, 14) and / or during storage of the implant (1; 11, 14).

13. 13. The method according to claim 12, wherein the condition of the implant (1; 11, 14) is further checked by the at least one sensor (2) immediately after implantation in the human or animal body.

14. 13. The method according to claim 12, further comprising monitoring the healing process after implantation of the implant (1; 11, 14) in the human or animal body by means of the at least one sensor (2).

15. 13. The method according to claim 12, wherein for the production of the implant (1; 11, 14), a plurality of prepregs (3), in particular unidirectional prepregs, are pressure grouted together under pressure and heat, and during the pressure grouting process the at least one sensor (2) is arranged between the prepregs (3) or embedded in one of the prepregs (3).

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