Bone fixation plates, fracture healing degree measurement system using bone fixation plates

Abstract

This invention enables the measurement of deformation of bone fixation plates using bone fixation plates that do not require sensors, electronic equipment for transmitting measurement signals from sensors, or a power supply. [Solution] A bone fixation plate having a main body portion that supports the fracture site, characterized in that the main body portion contains a stress-emitting material that emits electromagnetic waves according to the magnitude of deformation of the main body portion. Because the main body portion of the bone fixation plate contains a stress-emitting material, when deformation occurs in the bone fixation plate fixed to the fracture site, the bone fixation plate emits electromagnetic waves of an intensity corresponding to the magnitude of the deformation, and the deformation of the bone fixation plate can be measured by the intensity of said electromagnetic waves.

Description

[Technical Field]

[0001] The present invention relates to a bone fixation plate for fixing a fracture site, the bone fixation plate being capable of measuring deformation of the bone fixation plate, and a fracture healing degree measurement system using the same. [Background technology]

[0002] During fracture treatment, physicians monitor the patient's progress and make a diagnosis of complete recovery. Traditionally, this diagnosis was made by physicians evaluating radiological images (X-rays, CT scans, etc.). However, physician-based diagnosis of complete recovery relies heavily on the physician's experience, and there is a need for quantitative indicators for diagnosing complete recovery.

[0003] Therefore, as a method to obtain indicators to assist in diagnosing complete recovery, a method has been proposed in which a strain sensor is attached to a bone fixation plate used to reinforce and fix the fracture site, and the deformation that occurs in the metal plate due to load is detected, and the stress on the metal plate is detected, thereby measuring the strength of the bone including the fracture site and determining the state of healing of the fracture site (Patent Document 1).

[0004] Figure 1 shows a conventional bone fixation plate. Figure 1(a) shows the bone fixation plate 12 fixed to the fracture site 11, and Figure 1(b) shows the schematic configuration of the bone fixation plate 12. The bone fixation plate 12 is fixed to the fracture site 11 by screws 14. A strain sensor 13 is attached to the bone fixation plate 12 and is configured to detect deformation of the bone fixation plate 12 that occurs when a load such as body weight is applied to the fracture site 11.

[0005] Since the bone fixation plate is fixed to the fracture site within the living tissue, electronic equipment is required to transmit the detection signal from the strain sensor 13 to a device outside the living tissue. The strain sensor 13 also has built-in electronic equipment for this purpose, as well as a power supply to drive the electronic equipment.

[0006] As shown in Figure 1, the strain sensor 13 is positioned on the side of the bone fixation plate 12 opposite to the fracture site 11, and is located in a position where the amount of deformation of the bone fixation plate 12 increases when a load is applied.

[0007] The amount of strain measured by the strain sensor 13 corresponds to the amount of deformation that occurs in the bone fixation plate. As the fracture site 11 heals, the deformation that occurs in the bone fixation plate 12 decreases when a load is applied to the fracture site, thus allowing us to understand the state of repair of the fracture site 11. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2017-153830 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the conventional technology proposed in Patent Document 1 and other documents has problems with safety when used in living tissue and with examinations such as MRI, because it is equipped with electronic devices such as a strain sensor and a wireless device that transmits measurement signals from the strain sensor to the outside of the body on a plate that fixes the fracture site.

[0010] Furthermore, since strain sensor measurements measure the deformation of the plate at a single point, they can only measure the strain at one point on the plate. Therefore, the strain sensor needs to be appropriately positioned at the point where the plate is most strained, which requires advanced surgical techniques. For example, if the fracture site is perpendicular to the bone, as in the transverse fracture shown in Figure 2, the point where the plate fixed to the fracture site is most strained can be predicted. However, if the fracture site is oblique to the bone, as in the oblique fracture or spiral fracture shown in Figure 2, it is difficult to predict the point where the plate fixed to it is most strained. Also, if the fracture site is located in multiple places or divided into multiple bone fragments, as in the spiral fracture or comminuted fracture shown in Figure 2, the point where the plate is most strained may be multiple or planar. As the fracture site heals, the point where the plate is most strained may also shift.

[0011] In contrast, once the plate was fixed to the bone, it was virtually impossible to change the position of the strain sensor to an appropriate location in response to such circumstances, as this would require another surgery.

[0012] This disclosure aims to solve these conventional problems by enabling easy measurement of the deformation of a bone fixation plate used to fix a fracture site, without being limited by the sensor position.

[0013] Furthermore, this disclosure aims to enable the measurement of deformation of a bone fixation plate using a bone fixation plate that does not require a sensor for measuring the deformation of the bone fixation plate, or electronic equipment or a power supply for transmitting measurement signals from said sensor. [Means for solving the problem]

[0014] One embodiment of the present disclosure for solving the above problems is a bone fixation plate having a main body portion that supports a fractured area, wherein the main body portion is a stress-emitting material that emits electromagnetic waves according to the magnitude of deformation of the main body portion.

[0015] Since the main body part of the bone fixation plate contains a stress luminescent material, when forces such as compression, tension, and impact are applied to the bone fixation plate fixed to the fracture site, the bone fixation plate will deform according to the magnitude of the force, and emit electromagnetic waves with a strength corresponding to the magnitude of the deformation. Therefore, the magnitude of the deformation of the bone fixation plate can be measured based on the intensity of the electromagnetic waves.

[0016] Another one of the embodiments of the present disclosure for solving the above problems includes a bone fixation plate containing a stress luminescent material in the main body part, a detection part for detecting electromagnetic waves radiated from the stress luminescent material, and a processing device for measuring the deformation of the bone fixation plate based on the intensity of the electromagnetic waves detected by the detection part. The processing device is configured to calculate a parameter indicating the degree of fracture healing of the fracture part based on the deformation of the bone fixation plate. It is a fracture healing degree measurement system characterized by this.

Effect of the Invention

[0017] According to the present disclosure, when a load is applied to the fracture site where the bone fixation plate is fixed, the deformation of the bone fixation plate can be accurately measured without restrictions such as the sensor installation position.

[0018] Moreover, the deformation of the bone fixation plate can be directly measured by a photodetector or the like based on the intensity of the electromagnetic waves generated according to its magnitude. Therefore, the bone fixation plate according to the present disclosure does not need to be provided with a sensor, an electronic device for transmitting a sensor signal, or a power source for driving the electronic device.

[0019] Therefore, by using the bone fixation plate according to the present disclosure, it is not necessary to be provided with an electronic device or the like, and it is possible to measure the intensity of the electromagnetic waves corresponding to the magnitude of the deformation generated in the bone fixation plate by the detection part. It is also possible to determine the degree of fracture healing by measuring the magnitude of the deformation of the bone fixation plate.

Brief Description of the Drawings

[0020] [Figure 1]Figure 1 shows a schematic configuration of a conventional bone fixation plate. [Figure 2] Figure 2 is a diagram illustrating typical types of fractures and their fracture conditions. [Figure 3] Figure 3 is a diagram showing the schematic configuration of a bone fixation plate according to the first embodiment of the present disclosure. [Figure 4] Figure 4 is a schematic diagram showing the configuration of a bone fixation plate according to the first embodiment of the first example, where Figure 4(a) is a top view and Figure 4(b) is a cross-sectional view. [Figure 5] Figure 5 illustrates a compression load application experiment method that simulates a fracture site being fixed by a bone fixation plate in the first embodiment. Figure 5(a) is an image taken with the bone fixation plate fixed to a rabbit femur, Figure 5(b) is an image of a normal bone model using a femur without bone defects, enlarged from the area enclosed by the rectangle in Figure 5(a), and Figure 5(c) is an image of a fracture model using a femur with bone defects, enlarged from the area enclosed by the rectangle in Figure 5(a). [Figure 6] Figure 6 shows images of the luminescence state when a load is applied during a compressive load application experiment on the normal bone model and fractured bone model shown in Figure 5. Figure 6(a) shows the normal bone model, and Figure 6(b) shows the fractured bone model. [Figure 7] Figure 7 shows the relationship between applied load and luminescence intensity in a fracture model. Figure 7(a) shows the measurement locations for the luminescence intensity of the stress-luminescent material layer of the bone fixation plate, and Figures 7(b) and (c) show the relationship between applied load and luminescence intensity. [Figure 8] Figure 8 shows the relationship between the healing state of the fracture site and the stress generated in the bone fixation plate. [Figure 9] Figure 9 is a block diagram showing the configuration of a bone fusion state evaluation system using a bone fixation plate according to the first embodiment. [Modes for carrying out the invention]

[0021] Embodiments of this disclosure will be described in detail below with reference to the drawings. The following description is illustrative, and embodiments with modified configurations are possible without departing from the gist of this disclosure. Identical or similar reference numerals indicate identical or similar elements, and repeated descriptions may be omitted. Numerical values ​​in the following description are illustrative, and other numerical values ​​may be used in carrying out this disclosure without departing from the gist of this disclosure.

[0022] (First Embodiment) Figure 3 is a diagram showing the schematic configuration of a bone fixation plate 31 as a first embodiment according to the present disclosure. Figure 3(a) is a schematic configuration diagram of a bone fixation plate according to an embodiment of the present disclosure, viewed from above. The bone fixation plate 31 of this embodiment includes a main body portion 32 for supporting and fixing the fracture site. Screw holes 33, 341 to 344 are formed in the main body portion 32 for fixing the bone fixation plate 31 to the bone. In the following description, the bone fixation plate 31 shown in Figure 3 will be used as an example of the bone fixation plate of this embodiment, but the shape of the main body portion and the shape of the fixing screw holes formed in the main body portion may be other than those shown, as long as the bone fixation plate is a plate used for supporting and fixing the fracture site.

[0023] Furthermore, the bone fixation plate may be fixed by a method other than screw fastening.

[0024] The bone fixation plate 31 of this embodiment includes a main body portion 32 that contains a stress-emitting material that emits electromagnetic waves according to the magnitude of deformation of the main body portion of the bone fixation plate.

[0025] The stress-luminescent material used in this embodiment generates electromagnetic waves (including visible light, ultraviolet light, and near-infrared light) upon mechanical stimulation, and can be a known or unknown material. Examples of known stress-luminescent materials include spinel structures, corundum structures, β-alumina structures, silicates, defect-controlled aluminates, and materials having a structure in which wurtzite-type and zincblende-type structures coexist, and composed mainly of oxides, sulfides, selenides, or tellurides.

[0026] Furthermore, to give a more specific representative example of stress-luminescent materials, for example, LiSrPO4:Eu 2+ Yes, LiBaPO4:Eu 2+ xSrO·yAl2O3·zMO (M is a divalent metal, Mg, Ca, Ba, x, y, z are integers. That is, M is not limited to any divalent metal, but Mg, Ca, Ba are preferred. Also, x, y, z represent integers of 1 or greater.), xSrO·yAl2O3·zSiO2 (x, y, z are integers), BaTiO3-CaTiO3:Pr (red), ZnS:M (M is a divalent metal) While not limited to any particular group, Mn, Ga, Cu, etc. are preferable) (red to yellow), SrAl2O4:Eu (green), CaAl2Si2O8:Eu (blue), Ca2Al2SiO7:Ce (blue), Ca2MgSi2O7:Ce (blue), SrAl2O4:Ce (blue), CaYAl3O7:Eu (blue), ZrO2:Ti (blue), SrAl2O4:HoCe (ultraviolet), general formula Sr {1-(2x+3y+3z) / 2} Al2O4:xEu 2+ , yCr 3+ , zNd 3+ (However, x, y, and z are expressed as 0.25 to 10 mol%, preferably 0.5 to 2 mol%). (Near-infrared, etc. can be used.)

[0027] When the distance from a bone fixation plate such as the metacarpal, wrist, or forearm to the outside of the body is short, the stress luminescent material that generates electromagnetic waves of visible light and ultraviolet rays described above can be used. However, when detecting light from the stress luminescent material generated in a bone fixation plate fixed deep inside the body from outside the body, it is desirable to use a long wavelength stress luminescent material that generates light with a wavelength in the near infrared light region. The long wavelength stress luminescent material is represented by the general formula Sr{1-(2x+3y+3z) / 2}Al2O4:xEu 2+ , yCr 3+ , zNd 3+ (where x, y, and z are represented by 0.25 to 10 mol%, preferably 0.5 to 2 mol%). In addition to this, SrAl2O4:Eu,Er, Sr3Sn2O7:Nd, Li 1-X Na X NbO3:Nd(0.10≦X≦0.98), ZnO:Nd, CaZnOS:Nd, CaZnOS:Er, SrZnSO:Nd, Li X Zn 1-X O:Nd(0.0001<X<0.7), MgGa2O4:Cr,Al, or Lu3Al2Ga3O 12 :Cr, etc. can be used.

[0028] Examples of the mode in which the main body portion 32 of the bone fixation plate contains a stress luminescent material include a mode in which a stress luminescent material layer is formed on the surface of the main body portion 32 (First Embodiment), a mode in which the main body portion 32 is formed of a resin mixed with a stress luminescent material (Second Embodiment), a mode in which the main body portion 32 is formed only of a stress luminescent material (Third Embodiment), and a mode in which the stress luminescent material contained in the main body portion 32 is a long wavelength stress luminescent material that emits near infrared light, which is an electromagnetic wave with a specific wavelength, according to the magnitude of deformation of the bone fixation plate (Fourth Embodiment). Therefore, each embodiment will be described in order below.

[0029] (First Embodiment) Figure 4 is a diagram illustrating a first embodiment according to the first embodiment of the present disclosure. Figure 4(a) is a top view showing the schematic configuration of a bone fixation plate according to the first embodiment, and Figure 4(b) is a cross-sectional view thereof. As shown in Figure 4, the bone fixation plate of the first embodiment has the same structure as the bone fixation plate shown in Figure 3, that is, the bone fixation plate 41 has a main body portion 42 for fixing the fracture site, and the main body portion 42 has screw holes 43, 441 to 444 for fixing the bone fixation plate 41 to the bone. In this embodiment as well, the bone fixation plate 41 will be described as an example, but the bone fixation plate is a plate used for supporting and fixing the fracture site, and the shape of the main body portion and the shape of the fixing screw holes formed in the main body portion may be other than those shown. Also, the bone fixation plate may be fixed by a method other than fixing by screws.

[0030] The first embodiment of the present disclosure is an embodiment in which a stress-luminescent material layer is formed on the surface of the main body portion 42 of a bone fixation plate. Figure 4(b) shows a cross-sectional view of the bone fixation plate of Figure 4(a) along line IVb-IVb. A stress-luminescent material layer 45 is formed on the surface of the main body portion 42 of the bone fixation plate. In the example shown in the figure, the stress-luminescent material layer 45 is formed over the entire surface. This makes it possible to measure the magnitude of deformation occurring at all locations on the main body portion 42 of the bone fixation plate. Note that the stress-luminescent material layer does not necessarily need to be formed over the entire surface of the main body portion 42; it is sufficient to form it on the surface opposite to the surface of the main body portion that is in contact with the bone. Furthermore, it is not necessary to form it on the entire opposite surface; it is sufficient to form it on at least a part of it to measure the deformation caused by the force acting on the main body portion.

[0031] Various methods exist for forming this stress-luminescent material layer, and various techniques can be used. For example, by vacuum sealing or vacuum heat treatment, the luminescent layer containing the stress-luminescent material can be formed as a thin film, and its adhesion strength can be significantly improved.

[0032] As in this embodiment, if the stress-luminescent material layer 45 is formed on the entire surface of the main body of the bone fixation plate, there is no need to worry about which surface has the stress-luminescent material layer when fixing the bone fixation plate. Furthermore, since it becomes possible to measure the deformation occurring at all locations on the main body of the bone fixation plate, there are no constraints on the placement of sensors as in the conventional technology. Moreover, even when fixing oblique fractures, spiral fractures, or comminuted fractures, there is no need to predict the part of the bone fixation plate that will be most distorted.

[0033] In this embodiment, the main body portion 42 may be formed from a metal such as titanium, stainless steel, or an alloy containing these metals, similar to conventional bone fixation plates, but it may also be formed from resin, composite materials, or the like.

[0034] (Measurement of mechanical stress generated in bone fixation plates) Figure 5 is a diagram illustrating a compression load application experiment method using a rabbit femur 50 that simulates the state in which the bone fixation plate 41 of the first embodiment is fixed to the femur.

[0035] Figure 5(a) shows the state in which the bone fixation plate 41 of the first embodiment is fixed to a rabbit femur 50. In this state, the rabbit femur was attached to a testing machine, and the luminescence state of the stress-luminescent material layer of the bone fixation plate was measured while a load F was applied to the femur by displacing the pressing means of the testing machine. Figures 5(b) and (c) are enlarged images of the square area in Figure 5(a), respectively. Figure 5(b) shows a normal bone model 51 with no bone defect as the rabbit femur 50, and Figure 5(c) shows a fracture model 52 with a bone defect (fracture site) 53 as the rabbit femur 50. In this experiment, a load F was applied to both the normal bone model 51, in which the bone fixation plate was fixed to a rabbit femur without bone defect as shown in Figure 5(b), and the fracture model 52, in which the bone fixation plate was fixed to a rabbit femur with a bone defect 53 as shown in Figure 5(c). Figure 5(b) shows a normal bone model 51 representing a fracture that has completely healed, while Figure 5(c) shows a fracture model 52 representing the initial stage of a fracture.

[0036] Figure 6 shows how the bone fixation plate glows when subjected to different loads. Figure 6(a) shows the case of a normal bone model 51, and Figure 6(b) shows the case of a fractured bone model 52. As shown in Figure 6(a), in the case of the normal bone model 51, the load was 30 kgf when the pressing means of the testing machine was displaced by a maximum of 0.32 mm, but there was almost no glowing. This is because the applied load was absorbed by the femur, resulting in almost no deformation of the bone fixation plate.

[0037] In contrast, as shown in Figure 6(b), in the case of fracture model 52, when the pressing means of the testing machine was displaced by a maximum of 0.41 mm, the load was 9 kgf, and the stress-luminescent material layer formed on the surface of the bone fixation plate emitted light of an intensity corresponding to the magnitude of deformation of the main body of the bone fixation plate (as shown in the legend of the figure, areas with higher density emit light of stronger intensity). This is because the majority of the applied load was absorbed by the bone fixation plate, resulting in deformation of the main body of the bone fixation plate.

[0038] Figure 7 shows the relationship between applied load and luminescence intensity in the case of fracture model 52 shown in Figure 5(b). Figure 7(a) shows the measurement points for the luminescence intensity of the stress-luminescent material layer of the bone fixation plate, and the luminescence intensity at points 1 to 6 in the figure is shown in Figures 7(b) and (c). In Figure 7(b), the luminescence intensity at each point gradually decreases until just before the load is applied. This is because the stress-luminescent material layer was excited by irradiating it with ultraviolet light before the start of the experiment in order to increase the stress luminescence intensity. As indicated by Disp in Figure 7(b), which shows the displacement of the pressing means of the testing machine, the pressing means of the testing machine began to displace after 60 seconds, and was displaced to a maximum displacement of 0.41 mm 2.5 seconds later.

[0039] The greater the displacement of this pressing mechanism, the greater the magnitude of the load applied to the fracture model 52. At the maximum displacement of 0.41 mm, the magnitude of the load applied to the fracture model 52 was 9 kgf.

[0040] Areas 1 through 6 in Figure 7(b) correspond to the luminescence intensity at positions 1 through 6 in Figure 7(a), and in each location, the luminescence intensity increases in proportion to the magnitude of the applied load.

[0041] Figure 7(c) shows the relationship between the luminescence intensity and the displacement of the test machine in Figure 7(b).

[0042] As can be seen from the results in Figure 7(c), the luminescence intensity of the stress-luminescent material layer of the bone fixation plate increases in proportion to the magnitude of the deformation (stress) caused by the force applied to the bone fixation plate.

[0043] In this way, by measuring the luminescence intensity of the stress-emitting material of the bone fixation plate in this embodiment, the magnitude of deformation of the main body portion of the bone fixation plate can be measured.

[0044] Figure 8 shows the relationship between the healing state of the fracture site and the stress generated in the bone fixation plate. Figure 8 shows how the stress generated in the main body of the bone fixation plate changes according to the level of fracture healing when a certain load is applied to the bone including the fracture site.

[0045] As described above, in the initial stages of a fracture, a bone defect exists at the fracture site, and most of the load applied to the bone including the fracture site is absorbed by the bone fixation plate, resulting in a large deformation (stress) caused by the force applied to the main body of the plate. As the fracture site heals, the strength of the bone including the fracture site increases, and it becomes able to withstand the load. As a result, the deformation (stress) in the bone fixation plate decreases. Thus, by measuring the magnitude of the stress caused by mechanical stimulation in the main body of the bone fixation plate 41 of this embodiment, it becomes possible to measure parameters for determining the degree of fracture healing at the fracture site according to the magnitude of deformation of the bone fixation plate.

[0046] In this specification, the example of fixing a bone fixation plate to the femur is used for explanation, but the same method is applicable when fixing fracture sites of other bones.

[0047] Applying weight to a fracture site is not a problem if the fracture site can be naturally weight-bearing due to body weight in a standing position (for example, a fracture of the femur or other bones in the foot). However, if the fracture site cannot be naturally weight-bearing (for example, a fracture of the hand or finger bones), it is necessary to artificially apply weight to the fracture site. In this case, artificial weight-bearing can be achieved, for example, by having the person taking the measurement or the person themselves apply weight to the fractured bone.

[0048] (Second example) The second embodiment is one in which the main body portion 32 of the bone fixation plate shown in Figure 3 is formed from a resin mixed with stress-luminescent material. This embodiment will also be explained using the bone fixation plate 31 in Figure 3 as an example, but the bone fixation plate is a plate used for fixing a fracture site, and the shape of the main body portion and the shape of the fixing screw holes formed in the main body portion may be other than those shown. Furthermore, the bone fixation plate may be fixed by a method other than fixing with screws.

[0049] The main body portion 32 of the bone fixation plate in this embodiment can be manufactured, for example, by uniformly mixing a resin, a curing agent and solvent for controlling the crosslinking and curing reaction of the resin, a stress-luminescent material, and a dispersant and auxiliary agent for uniformly dispersing the stress-luminescent material, and then curing the mixture.

[0050] In this case, the stress-luminescent material may be included in the resin base in a proportion of 10 to 90% by weight, more preferably 50 to 80% by weight. By adding it in such proportions, a bone fixation plate that can emit light sufficiently and uniformly in response to deformation caused by mechanical stimulation can be formed.

[0051] In addition, the particle size of the stress luminescent material added to the resin base can be 10 nm to 100 μm. By setting the particle size in this way, it is possible to suppress the embrittlement of the main body part resulting from the addition of the stress luminescent material, and to form a bone fixation plate that exhibits a better response to deformation caused by mechanical stimuli.

[0052] Examples of the stress luminescent material that can be used in this example include those exemplified in the first embodiment.

[0053] There is no particular limitation on the resin used in this example, but as a resin material having the strength as a bone fixation plate, for example, epoxy resin, urethane resin, silicone resin, acrylic resin, ultra-high molecular weight polyethylene, polyether ether ketone, polymer alloy (PC / PE, PC / PMMA), etc. can be used. In addition, in order to enable in-situ shaping of the bone fixation plate, it may be formed using a photocurable resin or the like that can be used in a 3D printer.

[0054] Similar to the first embodiment, the bone fixation plate of this example can measure the magnitude of deformation of the main body part of the bone fixation plate by measuring the intensity of electromagnetic waves from the stress luminescent material.

[0055] (Third Example) The third example is one in which the main body part 32 of the bone fixation plate shown in FIG. 3 is formed only of the stress luminescent material. Examples of the stress luminescent material that can be used in this example include those exemplified in the first embodiment, but as a material having the strength as a bone fixation plate, for example, ZrO2:Ti, CaYAl3O7:Eu, CaAl2Si2O8:Eu, ZnO:Nd, Li X Zn 1-X ZnO:Nd (0.0001 < X < 0.7) is desirable.

[0056] In this embodiment, the bone fixation plate 31 shown in Figure 3 was used as an example for explanation. However, the bone fixation plate may have a different shape for the main body and the shape of the fixing screw holes formed in the main body, as long as it is a plate used for fixing a fracture site. Furthermore, the bone fixation plate may be fixed by a method other than fixing with screws.

[0057] Similar to the first embodiment, the deformation of the main body portion of the bone fixation plate in this embodiment can be measured by measuring the intensity of electromagnetic waves from the stress-luminescent material.

[0058] (Fourth embodiment) In the fourth embodiment, the stress-emitting material contained in the main body portion 32 of the bone fixation plate 31 shown in Figure 3 is a long-wavelength stress-emitting material that emits near-infrared light, which is electromagnetic wave of a specific wavelength in the range of 650 nm to 1800 nm, depending on the magnitude of deformation of the bone fixation plate 31.

[0059] The long-wavelength stress-emitting materials are not limited to those exemplified in the first embodiment, but include SrAl2O4:Eu,Cr,Nd,SrAl2O4:Eu,Er,Sr3Sn2O7:Nd, and Li 1-X Na X NbO3:Nd(0.10≦X≦0.98), ZnO:Nd, CaZnOS:Nd, CaZnOS:Er, SrZnSO:Nd, Li X Zn 1-X O:Nd(0.0001 <X<0.7)、MgGa2O4:Cr,Al、またはLu3Al2Ga3O 12 :Cr etc. can be used.

[0060] Furthermore, when using a long-wavelength stress-emitting material, the embodiment in which the main body portion 32 includes the stress-emitting material includes, similar to the embodiments shown in the first to third embodiments, an embodiment in which a stress-emitting material layer is formed on the surface of the main body portion 32, an embodiment in which the main body portion 32 is formed from the stress-emitting material, and an embodiment in which the main body portion 32 is formed from a resin mixed with the stress-emitting material.

[0061] Similar to the first embodiment, the deformation of the main body portion of the bone fixation plate in this embodiment can be measured by measuring the luminescence intensity of the stress-luminescent material.

[0062] In this embodiment, since a long-wavelength stress-emitting material is used, near-infrared light can be used to measure the magnitude of deformation of the main body portion of the bone fixation plate. Near-infrared light easily penetrates biological tissues such as skin, making it suitable for detecting near-infrared light emitted from the stress-emitting material of a bone fixation plate fixed to a fracture site within biological tissue such as skin, using a light detection unit placed outside the biological tissue.

[0063] This embodiment will also be explained using the bone fixation plate 31 shown in Figure 3 as an example. However, the bone fixation plate may have a different shape for the main body and the shape of the fixing screw holes formed in the main body, as long as it is a plate used for fixing a fracture site. Furthermore, the bone fixation plate may be fixed by a method other than fixing with screws.

[0064] (Second embodiment) Next, as a second embodiment, a system for measuring electromagnetic waves emitted by the stress-luminescent material of the bone fixation plate of the first embodiment will be described.

[0065] Figure 9 is a block diagram showing the configuration of a fracture healing degree measurement system 90 using a bone fixation plate according to the first embodiment. The fracture healing degree measurement system of this embodiment consists of a bone fixation plate 94 according to the first embodiment, a photodetector 95 that detects the light emission intensity of the stress-emitting material contained in the main body of the bone fixation plate, and a processing device 96 that processes the signal from the photodetector.

[0066] The photodetector 95 is composed of a one-dimensional photodetector such as a photodiode or a photomultiplier tube module. Alternatively, the photodetector 95 may be composed of a two-dimensional light distribution detector such as a camera. It is desirable that the photodetector 95 be configured to detect only the wavelength of electromagnetic waves emitted by the stress-emitting material contained in the bone fixation plate.

[0067] The processing unit 96 includes an interface for receiving signals from the photodetector, storage means for storing signals from the photodetector and program instructions, a processor for executing program instructions stored in the storage means, and display means for displaying measurement results, etc. The processor executes the program instructions stored in the storage means to process the signals from the photodetector and generate a light intensity signal. The processing unit is configured to output a parameter indicating the degree of fracture healing according to the magnitude of deformation (stress) caused by mechanical stimulation in the bone fixation plate from the generated light intensity signal. The display means is controlled by the processor and is configured to display instructions regarding operation and measurement results, etc. The display means may be provided independently of the processing unit.

[0068] A bone fixation plate 94 is fixed to the bone 93, which includes the fracture site 92 located inside the biological tissue 91 such as skin. This bone fixation plate 94 is a bone fixation plate in which the main body portion described in the first embodiment contains a stress-luminescent material.

[0069] When a load is applied naturally or artificially to the bone 93, including the fracture site to which the bone fixation plate 94 is fixed, deformation occurs in the bone fixation plate 94 according to the degree of healing of the fracture site 92. The stress-emitting material contained in the bone fixation plate 94 emits electromagnetic waves of an intensity corresponding to the magnitude of this deformation of the bone fixation plate 94. By measuring the intensity of these emitted electromagnetic waves with the photodetector 95, the magnitude of deformation (stress) in the main body of the bone fixation plate can be measured.

[0070] As described above, the bone fixation plate 94 is fixed to the fracture site 92 and is located inside the biological tissue 91, such as the skin. Therefore, the electromagnetic waves emitted from the stress-emitting material of the bone fixation plate 94 are detected as light transmitted to the body surface by the photodetector 95 located outside the biological tissue.

[0071] In areas where the thickness of biological tissue 91 is thin, visible light and other types of light can be measured on the body surface. However, by using long-wavelength light such as near-infrared light, it is possible to detect light that has been transmitted through the body surface even in areas where the thickness of biological tissue 91 is thick. In this case, it is desirable to use near-infrared light with a wavelength of about 700 nm to 1600 nm as the long-wavelength light, and in particular, OTN-NIR with a wavelength of 1000 nm or more is desirable.

[0072] Furthermore, when detecting electromagnetic waves that penetrate from the inside of biological tissue to the body surface, correction is necessary to take into account the penetration distance through the biological tissue and the ambient temperature during measurement. In this case, the correction coefficient should be determined in advance through actual measurements.

[0073] (Measurement of fracture healing degree) As a parameter used to determine the degree of fracture healing, we focused on the relationship between the level of fracture healing and the magnitude of stress generated in the plate when a certain load is applied to the fracture site, as shown in Figure 8. As shown in Figure 8, when a load is applied to the fracture site, the smaller the level of healing at the fracture site to which the bone fixation plate is fixed, the greater the deformation (stress) of the bone fixation plate.

[0074] Therefore, the relationship between the magnitude of stress generated in the bone fixation plate at each stage of fracture healing and the degree of fracture healing can be determined in advance by actual measurement, and conversion coefficients can be calculated and stored in the storage means of the processing device 96. The processing device can then calculate parameters for determining the degree of fracture healing based on the light intensity signal measured using the conversion coefficients.

[0075] Alternatively, instead of calculating a conversion factor, machine learning or similar methods may be used to calculate parameters for determining the degree of fracture healing from the measured luminescence intensity. [Explanation of symbols]

[0076] 31, 41... Bone fixation plates 32,42...Body part 33, 43... screw holes 34, 44... screw holes 45. Stress-induced luminescence material layer 50...Rabbit femur 51······Normal bone model 52.. Fracture model 53. Bone defect (fracture site) 90..Fracture Healing Degree Measurement System 91······Living tissue 92...Fracture site 93······Bone 94. Bone fixation plate 95······Light detection unit 96.... Processing Unit

Claims

1. A bone fixation plate having a main body portion that supports a fractured bone, wherein the main body portion contains a stress-emitting material that emits electromagnetic waves according to the magnitude of deformation of the main body portion.

2. The bone fixation plate according to claim 1, characterized in that the main body portion comprises a stress-luminescent material layer formed on at least a portion of the surface of the main body portion opposite to the surface in contact with the bone, which is made of the stress-luminescent material.

3. The bone fixation plate according to claim 2, characterized in that the stress-luminescent material layer is formed over the entire surface of the main body portion.

4. The bone fixation plate according to claim 1, characterized in that the main body portion is formed solely of the stress-luminescent material.

5. The bone fixation plate according to claim 1, characterized in that the main body portion is formed of a resin mixed with the stress-luminescent material.

6. The bone fixation plate according to any one of claims 1 to 5, characterized in that the fractured portion can be subjected to load-bearing naturally or artificially.

7. The bone fixation plate according to any one of claims 1 to 5, characterized in that the stress-emitting material is a long-wavelength stress-emitting material that emits electromagnetic waves of a specific wavelength in the range of 650 nm to 1800 nm.

8. The long-wavelength stress luminescent material is SrAl 2 O 4 :Eu,Cr,Nd, SrAl 2 O4:Eu,Er, Sr 3 Sn 2 O 7 :Nd, Li 1-X Na X NbO 3 :Nd(0.10 ≦ X ≦ 0.98), ZnO:Nd, CaZnOS:Nd, CaZnOS:Er, SrZnSO:Nd, Li X Zn 1-X O:Nd(0.0001 < X < 0.7), MgGa 2 O 4 :Cr,Al, or Lu 3 Al 2 Ga 3 O 12 :Cr, which is the bone fixation plate according to claim 7, characterized in that.

9. A fracture healing degree measurement system comprising a bone fixation plate according to any one of claims 1 to 5, a detection unit for detecting electromagnetic waves emitted from the stress-luminescent material, and a processing unit for measuring the magnitude of deformation occurring in the main body portion of the bone fixation plate based on the intensity of the electromagnetic waves detected by the detection unit, wherein the processing unit is configured to calculate a parameter indicating the degree of fracture healing of the fractured area based on the magnitude of deformation occurring in the main body portion of the bone fixation plate.

10. A fracture healing degree measurement system comprising a bone fixation plate according to claim 7, a detection unit for detecting electromagnetic waves emitted from the stress-luminescent material, and a processing unit for measuring the magnitude of deformation occurring in the main body portion of the bone fixation plate based on the intensity of the electromagnetic waves detected by the detection unit, wherein the processing unit is configured to calculate a parameter indicating the degree of fracture healing of the fractured area based on the magnitude of deformation occurring in the main body portion of the bone fixation plate.

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