JP5585956B2 - Method of operating fusion strength evaluation device and fusion strength evaluation device - Google Patents

Description

  The present invention relates to a fusion strength evaluation method and a fusion strength evaluation apparatus for evaluating bone fusion strength.

  Diagnosis and evaluation of fracture healing is still based mainly on simple radiographs and clinical symptoms. A simple X-ray photograph means an X-ray photograph obtained by photographing without using a contrast medium. The importance of simple radiographs in the treatment of fractures will not be lost, but as long as there is an interpretation process based on the experience of a doctor, it is difficult to accurately define the strength of bone fusion from simple radiographs alone. (Refer nonpatent literature 1). Evaluation by X-ray CT (Computed Tomography) or MRI (magnetic resonance imaging) is also a kind of morphological evaluation (see Non-Patent Document 2), and the interpretation process cannot be avoided. From such a background, an objective evaluation method of bone union strength has been eagerly desired. However, since the method for evaluating the strength of fusion that can be used differs depending on the treatment method for the fracture, the treatment method for the fracture will be described first.

  Fracture treatment methods are roughly classified into bone fixation by an external fixator and that by internal fixation. External fixation is a method in which the skin is penetrated into the fractured bone and a screw is screwed, and the screw end exposed to the outside of the body is fixed with a fixing device to promote bone fusion. On the other hand, a method of screwing a metal plate so as to contact the fractured bone and suturing the skin while leaving the plate in the body is internal fixation. In order to heal fractures, rehabilitation with external force commensurate with the strength of fusion is necessary. In any treatment method, the fixator or plate is removed after complete cure. Therefore, information on the fusion strength is required to determine the load strength during rehabilitation and the time for removing the fixator. Therefore, an objective evaluation method of the fusion strength adapted to these has been proposed.

For example, a method is known in which the movement between bone fragments in an externally fixed knee joint is observed with a strain gauge attached to the external fixator, and the progress of bone fusion is evaluated based on the degree of strain reduction (Non-Patent Document). 3). In addition, there is known a method for evaluating the progress of bone healing by observing the acoustic emission characteristics of a bone in a healing process (hereinafter referred to as a callus) through an external fixator (see Non-Patent Document 4). Furthermore, a technique is also known in which bone strain is measured based on the intensity of light in an optical fiber, and the progress of bone fusion is evaluated based on the degree of strain reduction (see Patent Document 1). These are all evaluation methods that presuppose external fixation.
By the way, the superiority or inferiority of external fixation and internal fixation should be judged by comprehensive evaluation of the final functional prognosis and healing period, and if treatment is selected from such a viewpoint, the case of internal fixation is overwhelming. It is known that there are many (see Non-Patent Documents 5 and 6). As an objective evaluation method of the fusion strength adapted to internal fixation, for example, a method of quantitatively evaluating the hardness of a callus by wavelet transform of an ultrasonic echo is known (see Non-Patent Document 2). . In addition, a technique for evaluating the progress of bone fusion from the natural frequency of bone is known (see Non-Patent Document 7).

Japanese National Patent Publication No. 11-509428

Watanabe, Y. and Hirasawa, Y., Current Advancement of Non-invasive Monitoring of the Fracture Repair, Pharma Medica, Vol. 16, No.12 (1998), pp. 53-58 (in Japanese). Kawasaki, Y., et al., Influence of Solid Phase Distribution in Articular Cartilage on Ultrasonic Echo, Proceedings of the 2004 Annual Meeting of the Japan Society of Mechanical Engineers, (2004), pp.107-108 (in Japanese). Charnley, J., Biomechanics in Orthopedic Surgery, Biomechanics and Related Bio-Engineering Topics, (1965), pp. 99-110, Pergamom Press. Watanabe, Y., Basic Study on the Evaluation of Biomechanical Properties of Callus by using Acoustic Emission, Journal of Kyoto Prefectural University of Medicine, Vol. 102, No. 10 (1993), pp. 1101-1116 (in Japanese). Matsusita, T., “Internal Fixators”, igaku-shoin, http://www.igaku-shoin.co.jp/bookDetail.do?book=30098, (March, 28, 2009) (in Japanese). Tanaka, T., “Internal Fixators”, igaku-shoin, p.3-12, (in Japanese). Reports of Japan Scienceand Technology Corporation, “The success in development of diagnostic equipment for callus by using characteristic frequency”, http://www.jst.go.jp/pr/report/report115/, (March, 31, 2009) ( in Japanese).

  However, the conventional evaluation method that evaluates the healing strength by utilizing the correlation between the hardness of the callus or the natural frequency of the bone and the bone strength is that the fused bone regains the mechanical strength of normal bone. It does not define whether or not In other words, the emphasis should be on observing the distortion of the callus when a load is applied, and such a quantitative evaluation of the fusion strength is desired.

  In addition, according to the conventional evaluation method, there is a problem that special equipment such as a strain gauge, an optical fiber, and a high sensitivity microphone is required. Therefore, there is a possibility that the medical cost will rise, and it is expected that it will not be widely spread in the medical field.

  In addition, the objective evaluation method of fusion strength should be a safe and safe evaluation method that is easy for the patient to understand, assuming that it is medical care provided to the patient. It is necessary to make a special measurement by wearing the device, which imposes a new burden on the patient.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to observe the strain of the callus when a load is applied without requiring a special device. It is to provide a safe and safe fusion strength evaluation method and fusion strength evaluation device.

A first feature of the present invention is a fracture treatment in which fractured bone included in an affected area is cross-linked by screwing a plate embedded in a wound or by cross-linking a screw outside the wound to promote the healing of the bone. In the operation method of the fusion strength evaluation apparatus for evaluating the fusion strength of the bone in the course of treatment, a first imaging step of imaging the affected area without applying a load to the affected area, and a state in which the load is applied to the affected area A second imaging step of imaging the affected area with the dimension between the screws straddling the fusion site of the affected area based on the image taken in the first imaging process, and between the screws in the healthy site of the affected area The first detection step of detecting the size of the screw and the size between the screws straddling the fusion site of the affected area based on the image taken in the second imaging step and between the screws in the healthy site of the affected area Second to detect dimensions A calculation step of calculating a strain of the fusion site of the affected area and a strain of the healthy site of the affected area based on the detection step and the dimension between the screws detected in the first detection step and the second detection step; The evaluation step of evaluating that the bone fusion strength is higher as the strain of the fusion site of the affected part calculated in the calculation step is closer to the strain of the healthy site of the affected part, and the evaluation of the bone evaluated in the evaluation step And a presentation process for presenting the fusion strength. In addition, the method of screwing the plate embedded in the wound and crosslinking is called an internal fixer, and the method of bridging the screw outside the wound is called fixation by an external fixator (see Non-Patent Document 6). .

The second feature of the present invention is that, in the operation method of the fusion strength evaluation apparatus, in the first detection step, the subset region straddling the fusion site of the affected area from the image taken in the first imaging step When a user designates a subset area in a healthy part of the affected area, the dimension between the screws is detected based on the centroid of the designated subset area.

A third feature of the present invention is that, in the operation method of the fusion strength evaluation apparatus, in the first detection step, a comparison is made with other portions among the portions included in the image photographed in the first photographing step. And specifying a region having a large strain as the union site of the affected area and the other site as a unhealthy site of the affected area, and the centroid of the subset region straddling the union site of the identified affected area and the unhealthy region of the affected area. The dimension between the screws is detected based on the centroid of a certain subset region.

According to a fourth aspect of the present invention, in the method for operating the fusion strength evaluation apparatus, in the second detection step, an image obtained by photographing the subset region most similar to the subset region in the second photographing step. Is searched by pattern matching using an image correlation method, and the dimension between the screws is detected based on the centroid of the searched subset region.

According to a fifth feature of the present invention, in the operation method of the fusion strength evaluation apparatus, in the second detection step, an image photographed in the second photographing step by image processing using edge detection or phase correlation method. The position of the screw is detected from the inside.

According to a sixth aspect of the present invention, in the operation method of the fusion strength evaluation apparatus, in the evaluation step, the bone fusion strength is evaluated based on “strain of the healthy site / strain of the fusion site” * 100 [%]. It is to be.

A seventh feature of the present invention is that, in the operation method of the fusion strength evaluation apparatus, the bone fusion strength is evaluated for each of the left and right or more of the affected part in the evaluation step.

The eighth feature of the present invention is that in the operation method of the fusion strength evaluation apparatus, the affected area is imaged by simple X-rays in the first imaging step and the second imaging step.

A ninth aspect of the present invention, there is provided a method of operating the fusion strength evaluation apparatus, after removal of the screw is to use a screw hole opened in the bone in place of the screw.

According to a tenth feature of the present invention, in the operation method of the fusion strength evaluation apparatus, in the evaluation step, an image magnification of the image photographed in the first photographing step and the image photographed in the second photographing step Is to cancel the change based on the strain at the fusion site and the strain at the healthy site and then evaluate the fusion strength of the bone.

According to an eleventh feature of the present invention, in the operation method of the fusion strength evaluation apparatus, in the evaluation step, the image taken before the load is in a state where the load is released with respect to the image taken during the load. by considered, the change of the imaging magnification x, .DELTA.a 1 elongation dimension a ₁ of the fusion site by load _releasing, if the elongation of the dimension a ₂ of the healthy site by load releasing was .DELTA.a _2, the following equation To increase the strain ε so that the influence of “1” of the numerator and denominator on the rightmost side can be ignored by canceling the change in the imaging magnification.

According to a twelfth feature of the present invention, in the operation method of the fusion strength evaluation apparatus, a crossing angle θ between two bones with the fusion site as a boundary is obtained by image processing, and the load change of the load W applied to the affected area is determined. The rate of change Δθ / ΔW is calculated from ΔW and the angle change Δθ of the crossing angle θ, and the healing strength of the bone is evaluated based on the rate of change Δθ / ΔW .

According to a thirteenth feature of the present invention, in the operation method of the fusion strength evaluation apparatus, in the evaluation step, imaging is performed before and during the load every predetermined period, and “strain of a healthy part of the affected part” / “the affected part” The increase in the fusion strength is evaluated by the increasing tendency of the value of “the strain of the fusion site”.

The first fourth aspect of the present invention, the fractured bone contained in the affected area, the plate crosslinked with screwed embedded in Sonai or encourage healing of the bone by crosslinking the screw external skeletal fractures In the fusion strength evaluation apparatus that evaluates the bone fusion strength in the course of treatment, the imaging is performed in which the affected area is imaged while no load is applied to the affected area, and the affected area is imaged while the load is applied to the affected area. And a dimension between the screws straddling the fusion site of the affected part and a dimension between the screws in the healthy part of the affected part based on an image photographed with no load applied to the affected part by the imaging unit A first detection unit that performs the measurement, and a dimension between the screws that straddles the fusion site of the affected part based on an image taken with the load applied to the affected part by the imaging unit, and a healthy part of the affected part A second detecting means for detecting a dimension between the screws, and a strain at the fusion site of the affected area based on the dimensions between the screws detected by the first detecting means and the second detecting means, and The calculation means for calculating the strain of the healthy site of the affected area, and the strain of the fusion site of the affected area calculated by the calculation means is closer to the strain of the healthy site of the affected area, and the higher the bone healing strength is evaluated. Evaluation means and presentation means for presenting the bone healing strength evaluated by the evaluation means.

  According to the present invention, a safe and safe fusion strength evaluation method and fusion strength evaluation apparatus that do not require special equipment and that place importance on observing the distortion of the callus when a load is applied. Can be provided.

It is a block diagram of the fusion strength evaluation apparatus in Embodiment 1 of this invention. It is explanatory drawing of the to-be-photographed object in Embodiment 1 of this invention. It is explanatory drawing of the to-be-photographed object in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation process in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation process in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 1 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 2 of this invention. It is a figure which shows the fusion strength evaluation method in Embodiment 3 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Although a treatment using an internal fixator will be described as an example, the present invention can be applied to a treatment using an external fixator without any problem.

(Embodiment 1)
As shown in FIG. 1, the fusion strength evaluation apparatus according to Embodiment 1 of the present invention includes an X-ray source 10, an imaging plate 30, an image processing apparatus 40, and a display apparatus 50. The X-ray source 10 is a light source portion of an X-ray apparatus generally provided in a medical institution, and irradiates the subject 20 with X-rays. The imaging plate 30 is a photosensitive part of an X-ray apparatus generally provided in a medical institution, converts X-rays transmitted through the subject 20 into a digital image, and outputs the digital image to the image processing apparatus 40. As the imaging plate 30, an FPD (Flat Panel Detector) introduced in a part of a medical institution, a scanner that reads a conventional X-ray film, and outputs a digital image to the image processing apparatus 40 can be adopted. . The image processing apparatus 40 is a personal computer or the like that performs predetermined image processing on the digital image from the imaging plate 30 to evaluate the fusion strength. The display device 50 is a display or the like that displays various data (for example, fusion strength) from the image processing device 40.

  The subject 20 is specifically a broken part (affected part). In the first embodiment, the process up to the calculation of the fusion strength value will be described taking the fusion strength quantification at the time of fracture treatment of the lower leg bone as shown in FIG. 2 as an example. As shown in FIG. 3, a plate 22 for promoting fracture healing is screwed to the bone 21 with screws 23. The present invention provides doctors and patients with objective data when determining the appropriate rehabilitation time or the removal time of the plate 22 and the screw 23. In general, if the bone 21 is sufficiently fused, the movement is allowed in the state shown in FIG. 3, and the plate 22 and the screw 23 are removed after about one year has passed. Therefore, since it is important to quantify the fusion strength with the screw 23 screwed in, the method will be described in detail below. After the plate 22 and the screw 23 are removed, the fusion strength can be quantified by replacing the “screw 23” in the following process with a “screw hole”. Although the screw hole is naturally closed, it takes about half a year or more until it is completely closed. Therefore, it is considered that the present invention can be applied continuously during this period.

(Fusion strength evaluation process)
First, the patient is seated on a chair so that the load is not applied to the affected area as much as possible, and as shown in FIG. 4, both the fusion site 24 and the healthy site 25 are made as large as possible and simple X-ray imaging is performed so as not to blur. (FIG. 5, S1). More specifically, if it is difficult for the rectangle R1 in FIG. 4 to have the finished size of the X-ray photograph, photographing is performed so that the rectangle R2 in FIG. 4 has the finished size as much as possible. As a result of the experiment, there was a tendency for lack of clarity when zoomed in. It is preferable to consider in advance which of the imaging magnification (magnification rate) and the sharpness should be emphasized.

  When the rectangle R1 in FIG. 4 has a finished dimension, “L1” is replaced with “L1 ′” and “L2” is replaced with “L2 ′” in step S4 described later. Further, in step S41 and later described below, a case where L1 and L2 are used, that is, a case where the rectangle R2 in FIG.

  Next, if the affected area is a foot, simple X-ray imaging is performed at the same angle as in step S1 with a load of about 1/3 to 1/4 of the weight applied to the affected area (FIG. 5, S2). Specifically, the image may be taken with a weight applied to the weight. The angles of both steps S1 and S2 do not need to be extremely coincident. Shoot in the same way as long as it doesn't have time.

  Next, only the image is extracted from the DICOM file (S3 in FIG. 5). DICOM (Digital Imaging and Communication in Medicine) is an image file format generally used in the medical field. Since the DICOM file includes not only the image but also data related to the image, only the image, that is, only the luminance information is extracted from the DICOM file. Of course, when an image file format other than DICOM is employed, the step S3 for extracting only the image may be unnecessary.

  Finally, the fusion strength is evaluated (FIG. 5, S4). Specifically, using the image processing technique, “L1 size strain” and “L2 size strain” shown in FIG. 4 are calculated from two photographs before and during loading. If “L2 strain / L1 strain” is obtained, it represents the fusion strength value. Hereinafter, this process S4 is demonstrated in detail.

  First, in the photograph before the load, as shown by the three rectangles in FIG. 6, the right half of the screw 23 is set as the subset areas S1 to S3 (FIGS. 7 and S41). The subset area is a small area cut out for pattern matching. Pattern matching is usually done between subsets. These subset areas S1 to S3 are designated by the operator (physician) of the image correlation software. Specifically, about the right half of the screw 23 is completely included in the subset areas S1 to S3, and it is specified that images other than the screw 23 are not included so much. The area designation may be arbitrary as long as it is protected. The image correlation software is software using an image processing technique such as a digital image correlation method, and is hereinafter simply referred to as “software”.

  Next, the software calculates the centroid (here, the intersection of the diagonal lines) of each of the designated subset areas S1 to S3, and how many pixels are “L1 dimension” and “L2 dimension” before the load shown in FIG. Is calculated (FIG. 7, S42). This calculation calculates to 1/100 digit. The reason for calculating up to 1/100 digit is that generally about 1/50 pixel is considered as a displacement detection limit by image processing.

  After that, the software searches for the three subset areas most similar to the previous three subset areas S1 to S3 from the photograph after loading (FIG. 7, S43). Since only three subsets need to be matched, it can be processed by a rather inefficient computer. Since the displacement in this case is predicted to be less than about ± 1 pixel, first specify the same position as each subset position before loading in the photograph after loading, and then limit about ± 1 pixel to the search range from there Then, pattern matching is performed with sub-pixel order accuracy at each of the three locations. By limiting the search range in this way, the possibility of matching with different screws 23 can be made zero. If the similarity method is used in the image correlation method, even if the brightness of the image is different before and after the load, matching can be performed without the influence. As a result of experiments, it has been found that it is difficult to take X-ray photographs with exactly the same brightness every time. In addition, the brightness may be intentionally changed for interpretation by a doctor. Therefore, it can be expected that a similarity method that is not affected by the change in brightness in principle is effective. Here, the search range is about ± 1 pixel. However, in the case of a child's fracture, the search range is about ± 10 pixels. This is because the Young's modulus of a child's bone may be about 1/10 of that of an adult.

  Next, after determining the three subset positions in the photograph after loading, the software calculates how many pixels are “L1 dimension” and “L2 dimension” after loading (S44 in FIG. 7). This calculation calculates to 1/100 digit.

  Next, the software calculates “L1 dimensional strain” and “L2 dimensional strain” using the results of steps S42 and S44, and obtains “L2 strain / L1 strain” * 100 [%]. (FIG. 7, S45). This “L2 strain / L1 strain” * 100 [%] represents the fusion strength value of the right half of the fusion site. For example, if the strain “L1 strain” which is the strain at the fusion site is equal to the strain “L2” which is the strain at the healthy site, the fusion strength 100%, and the strain “L1” at the fusion site is If the strain is twice the strain “L2 strain”, the result is very easy for the patient to understand, such as 50% fusion strength. Alternatively, the fusion rate is evaluated every predetermined period (for example, one month), and the degree of healing can be evaluated numerically from the tendency of the change in the value. This is because, for example, the physical properties and geometric shapes of the fracture site and the healthy site are different, so that the fusion strength may exceed 100% before the complete cure.

  Next, the target is changed to the left half and steps S41 to S45 are repeated (FIG. 7, S46). That is, here, as a case that tends to be in the healing process, it is assumed that the right half near the plate 22 is efficiently fused, and the left half far from the plate 22 is not sufficiently fused. In order to estimate this state from a photograph, a skilled intuition is necessary. If the plate 22 and the screw 23 are removed in this state, there is a high possibility that a re-fracture will be required and a cross-linking operation using the plate will be required again. In order to respond to this, the fusion strength has been quantified by targeting only the right half so far. Therefore, thereafter, in order to quantify the fusion strength with respect to the left half of the fusion site, the target is changed to the left half and steps S41 to S45 are repeated.

  The above clear analysis result is shown to the patient (FIG. 7, S47). The doctor can promote understanding of the patient to resolve anxiety, can instruct an appropriate rehabilitation load, permission to exercise, and the like, and can easily determine an appropriate removal timing of the plate 22 and the screw 23.

  Although the method of pattern matching using the similarity method has been described here, the image processing method is not necessarily limited to pattern matching. For example, a method of determining the position of the screw 23 by edge detection can be used. What is necessary is just to clarify an edge using a filter in the case of edge detection. Well-known filters include Sobel, Prewitt or Laplacian. In addition, image processing using a phase correlation method and a phase only correlation method can also be used. It is preferable to consider in advance what kind of image processing should be used.

  Here, the idea of the photographing method will be described in more detail. First, radiography is performed on the screw hole 23a of the bone 21 shown in FIG. Ideally, the image is taken as large as possible so that the frame R3 in FIG. If it is impossible to shoot as shown in FIG. 8 and the shooting magnification is three times as much as the limit, the shoot is not particularly concerned as shown in FIG. Next, when the fracture history part 24a is on the foot, a compression load is applied to the patient by placing a weight or the like, and an image is taken so that the image is as similar as possible with care so as not to be troublesome. In the case of a broken arm, a compressive load is applied in a posture where a wall or the like is pushed.

  Next, the analysis principle will be described in more detail. As described above, the “L2 strain / L1 strain” of FIG. 8 or FIG. 9 caused by a load is calculated using an image processing technique such as a digital image correlation method. Since L1 = fracture history site and L2 = healthy site, the degree of healing can be quantified by this ratio. Here, “strain” is defined as “stretched dimension / original dimension”. That is, “L2 strain / L1 strain” takes a value of 0, and the greater the “L2 strain / L1 strain”, the higher the degree of healing, and the closer to 0, the lower the degree of healing.

  Next, countermeasures against out-of-plane rotation will be described. According to the present invention, the fusion strength can be evaluated without any problem even when out-of-plane rotation occurs. That is, when an out-of-plane rotation A occurs in FIG. 8 or FIG. 9, the dimensions of L1 and L2 change at the same ratio, so the value of “L2 strain / L1 strain” is not affected. Even if out-of-plane rotation B occurs, there is no problem because the dimensions of L1 and L2 do not change.

  Next, the minimum line of the load to be applied to the patient will be described. The positions of the three screw holes 23a indicated by bold lines in FIG. 8 or FIG. 9 are specified by image processing, and the strains of L1 and L2 are calculated. The positioning resolution of image processing is generally 1/10 pixel, and the limit is about 1/50 pixel, which depends on the image quality such as whether or not it is in focus. Based on this, the following values are assumed.

Positioning resolution = 1/40 pixels Adult healthy bone Young's modulus = 20 GPa
Young's modulus of adult healing bone = 10 GPa
Cross-sectional area of adult tibia and fibula = 6 cm ² and 1.5 cm ²
Load sharing ratio of tibia and fibula = 9: 1
These values are used to estimate the minimum load required for the healing degree quantification experiment.

In general, since one pixel of the imaging plate is about 100 microns square, in the case of FIG. 8, the dimension on the photograph at L1 and L2 is 268 mm, which is 2680 pixels. Since the positioning resolution is 1/40 pixel, the resolution of distortion is (1/40) [pixels] / 2680 [pixels] = 9.33 με. The load P [kgf] necessary to generate 9.33 με in a healthy tibia is as follows.

  Here, the left side 0.9 is load distribution to the tibia, A is the cross-sectional area of the tibia, E is Young's modulus, and ε is strain. When the above is solved, P = 12.7 [kgf]. Specifically, a load is applied by placing a weight on the patient.

  In the case of FIG. 9, the dimension on the photograph in L1 and L2 is 1080 pixels because it is 108 mm. Since the positioning resolution is 1/40 pixel, the resolution of the strain is (1/40) /1080=23.1 με. Since the load P [kgf] required to generate 23.1 με in a healthy tibia is 2.48 times the previous value, P = 31.5 [kgf]. If the patient is an adult and the fracture history site is a foot, the above load can be applied by standing on one foot. By the way, if the subject to be examined is a fracture of a child, the Young's modulus may be about 1/10, and the required load P ′ is 3.15 [kgf]. For example, if the weight of a 6-year-old child with a height of 100 cm is 14.6 kg (the minimum value of the standard weight of each child's age and height), the load can be applied with a weight or the like.

  Next, a technique for automating the designation of the subset area will be described. That is, in the above description, the doctor designates the subset areas S1 to S3, but the image processing apparatus 40 can automatically specify the subset areas S1 to S3. In this case, for example, only the right or left half from the auxiliary line L10 in FIG. In this way, even if the vicinity of the plate 22 is fused, it is possible to cope with a case where the fusion of the part away from the plate 22 is incomplete, which is considered to be extremely useful clinically. An example of a specific automation procedure will be described. First, the position of the screw 23 that is white in the X-ray photograph is obtained. Next, for example, the midpoint of the top and bottom screws 23 is obtained, and a straight line passing through the midpoint is defined as an auxiliary line L10. Here, only the right or left half of the auxiliary line is to be analyzed, the strain is calculated between a plurality of screws, a screw having a strain larger than that between other screws is specified as the fusion site 24, and the other Between the screws is identified as a healthy part 25. In this way, since the fusion site 24 is automatically specified, the same effect as when the doctor designates the subset areas S1 to S3 can be obtained.

  As described above, according to the first embodiment, there is no need for a special device, and the safe and secure fusion is focused on observing the distortion of the callus when a load is applied. A strength evaluation method and a fusion strength evaluation apparatus can be provided. In particular, it can be said that the present invention has a very high practical value in that it can be realized as a quantitative evaluation technique of fusion strength only by X-ray photography and image processing. That is, since only an X-ray photography equipment using an imaging plate and a personal computer that are widely used at present are used and no additional equipment is required, there is a high possibility that the equipment will be widely used in the medical field where the economic burden increases. In addition, according to the present invention, the doctor can promote understanding of the patient to resolve anxiety, instruct an appropriate rehabilitation load and permission to exercise, and can easily determine an appropriate removal timing of the plate and screw. is there. Moreover, since the same bone fusion site and healthy site are compared, it is possible to accurately evaluate the fusion strength without being affected by individual differences in bone strength. Furthermore, since not only screws but also screw holes can be used, it is useful in that the fusion strength can be evaluated even if the plate removal timing is wrong. In addition, since the designation of the subset area can be automated, there is an effect that the doctor is not forced to add a new burden.

  Here, the fusion strength is displayed as a percentage, but the display mode of the fusion strength may be any mode that is easy for the patient to understand, and other display modes may be adopted. For example, the fusion strength may be displayed by ranks such as “A”, “B”, and “C” indicating the fusion strength, or the transition of the fusion strength may be displayed as a graph.

  Here, the fusion strength is displayed. However, instead of displaying the fusion strength, a voice indicating the fusion strength may be output. In other words, as long as the fusion strength is presented to the patient, similar effects can be obtained.

  Moreover, although the case where the X-ray apparatus generally provided in a medical institution was used was demonstrated here, this invention is not limited to this. For example, even when X-ray CT or MRI is used, the same effect can be obtained by analyzing the position of the screw or screw hole from the captured image and comparing the strain at the fusion site with the strain at the healthy site. . However, since the patient's posture is limited when X-ray CT or MRI is used, it can be said that a general X-ray apparatus is suitable for changing the posture of the patient when a load is applied to the affected area.

(Embodiment 2)
By the way, the photographing magnifications of the two photographs before and during loading (including after loading) are not necessarily the same, but are naturally different. Therefore, in the second embodiment, a method for evaluating the fusion strength after canceling the change in the photographing magnification of the two photographs is adopted. Hereinafter, only differences between the second embodiment and the first embodiment will be described.

FIG. 11 is a diagram showing a method for evaluating the fusion strength in the second embodiment of the present invention. FIG. 11 (a) shows a photograph before loading, and FIG. 11 (b) shows a photograph during loading. Here, from FIG. 11 (a) to FIG. 11 (b), it is assumed that the photographing magnification is unintentionally changed to x times (before load = 1, during load = x), and a ₁ due to load release. The strain ratio is calculated as follows, assuming that the elongation of the dimension is Δa ₁ and the elongation of the a ₂ dimension due to load release is Δa ₂ . Here, the image photographed before the load is regarded as a state in which the load is released with respect to the image photographed during the load.

  Looking at the rightmost side of Equation 4, it can be seen that in order to obtain the strain ratio which is the fusion strength, it is only necessary to delete “1” of the numerator and denominator or to enlarge ε so that the influence of “1” can be ignored. . The latter method is described below.

In general, since the strain is a very small amount of 0.1% or less, ε ⁿ can be ignored. therefore,

It becomes. Therefore, the influence of “1” of the numerator and denominator can be freely controlled by raising the number 4 to the nth power. In general, it is difficult to make the photographing magnifications the same before and during loading, particularly when the subject is a human body. However, by applying the above-described concept, the fusion strength can be calculated without being affected by any change in the photographing magnification x.

  As described above, according to the second embodiment, even when the photographing magnifications of the two photographs before and after the load are different from each other, the change in the photographing magnification of the two photographs is determined by the distortion of the fusion part and the healthy part. The fusion strength can be evaluated after canceling based on the strain. Of course, the same effects as those of the first embodiment can be obtained.

(Embodiment 3)
In the first embodiment, the fusion strength is evaluated based on the bone strain, but the method for evaluating the fusion strength is not limited to this. Hereinafter, only the differences of the third embodiment from the first embodiment will be described.

  FIG. 12 is a diagram showing a characteristic curve representing the relationship between the load and the angle, with the horizontal axis representing the load W and the vertical axis representing the bone angle θ. As shown in this figure, it is known that the bone angle θ increases as the load W increases. The bone angle θ is an intersection angle between two bones with the fusion site 24 as a boundary, and this intersection angle can be obtained by image processing of a photograph.

  Therefore, the change rate Δθ / ΔW may be calculated from the load change ΔW and the angle change Δθ. The closer this value is to 0, the higher the degree of healing.

  As described above, according to the third embodiment, it is possible to evaluate the fusion strength based on the change in the intersection angle between two bones with the fusion site as a boundary. Of course, the same effects as those of the first embodiment can be obtained.

  The present invention can be widely used not only for evaluation of bone fusion strength but also for general strength or deterioration evaluation of structures. That is, for example, the degree of deterioration can be managed numerically by observing the strain ratio between specific structurally important members every few years in a state where the automobile is congested on the bridge and a state where it is not. It can be a clear guideline for reinforcement work. In this case, since it cannot be detected when the part assumed to be “sound” and the part assumed to be “deteriorated” are similarly detected, a number of members are simultaneously targeted, and the strain ratio By obtaining the distribution of, I will devise to be able to find a relatively severely deteriorated location.

  Based on the same principle, it is possible to evaluate the deterioration of a multistory parking lot. That is, strain between structurally important members is regularly observed before and during warehousing.

  Alternatively, for example, by applying this method before and after welding repair, it is also possible to evaluate the strain generated by welding repair.

  Further, for example, by applying this method before and after the tightening of the screw, it is possible to evaluate the strain generated by the tightening.

  Furthermore, it can be applied to aircraft safety management. In this case, the degree of deterioration due to flight can be managed by periodically observing after service.

  In any case, since it is only necessary to shoot, it is non-destructive and non-contact, and does not require any special equipment other than the photographic tool and PC, and furthermore can be evaluated without obstructing the operation of the measurement object. The cost can be expected to be low, which is extremely socially beneficial.

10 X-ray source 20 Subject 21 Bone 22 Plate 23 Screw 23a Screw hole 24 Fusion site 25 Healthy site 30 Imaging plate 40 Image processing device 50 Display device

Claims (14)

The bone healing strength in the treatment of fracture treatment that promotes bone healing by screwing the bone embedded in the wound to the fractured bone contained in the affected area, or by cross-linking the screw outside the wound A method for operating a fusion strength evaluation device for evaluating
A first imaging step of imaging the affected area in a state where no load is applied to the affected area;
A second imaging step of imaging the affected area with a load applied to the affected area;
A first detection step of detecting a dimension between the screws straddling a fusion site of the affected part and a dimension between the screws in a healthy part of the affected part based on the image photographed in the first photographing step;
A second detection step of detecting a dimension between the screws straddling a fusion site of the affected part and a dimension between the screws in a healthy part of the affected part based on the image photographed in the second photographing step;
A calculation step of calculating a strain of the fusion site of the affected part and a strain of the healthy site of the affected part based on the dimensions between the screws detected in the first detection step and the second detection step;
An evaluation step for evaluating that the healing strength of the bone is higher as the strain of the fusion site of the affected area calculated in the calculation step is closer to the strain of the healthy site of the affected area;
Method of operating a fusion strength evaluation apparatus according to a presenting step of presenting the fusion strength of the bone is evaluated by the evaluation process. In the first detection step, when a user designates a subset region straddling the fusion site of the affected part and a subset region in a healthy part of the affected part from the images taken in the first imaging step, The method for operating a fusion strength evaluation device according to claim 1, wherein a dimension between the screws is detected based on a centroid of a designated subset region. In the first detection step, a portion having a larger strain than the other portion among the portions included in the image photographed in the first photographing step is specified as a fusion portion of the affected part and the other portion Is determined as a healthy part of the affected part, and the dimension between the screws is detected based on the centroid of the subset region straddling the fusion part of the specified affected part and the centroid of the subset region in the healthy part of the affected part. The operation method of the fusion strength evaluation apparatus according to claim 1. In the second detection step, a subset region that is most similar to the subset region is searched from the images photographed in the second photographing step by pattern matching using an image correlation method. The operation method of the fusion strength evaluation apparatus according to claim 2, wherein a dimension between the screws is detected based on the centroid of the joint. The position of the screw is detected from the image photographed in the second photographing step by image processing using edge detection or phase correlation method in the second detecting step. 3. A method for operating the fusion strength evaluation device according to 3. The operation method of the fusion strength evaluation apparatus according to claim 1, wherein, in the evaluation step, the fusion strength of the bone is evaluated based on "strain of the healthy site / strain of the fusion site" * 100 [%]. The operation method of the fusion strength evaluation apparatus according to claim 1, wherein, in the evaluation step, the fusion strength of the bone is evaluated for each of the left and right sides of the affected part or more. The operation method of the fusion strength evaluation apparatus according to claim 1, wherein in the first imaging step and the second imaging step, the affected part is imaged by simple X-rays. The method for operating the fusion strength evaluation apparatus according to any one of claims 1 to 8, wherein after removing the screw, a screw hole opened in the bone is used instead of the screw. In the evaluation step, a change in imaging magnification of the image taken in the first imaging step and the image taken in the second imaging step is canceled based on the strain at the fusion site and the strain at the healthy site. The operation method of the fusion strength evaluation apparatus according to claim 1, wherein the fusion strength of the bone is evaluated. In the evaluation step, the image taken before the load is considered to be a state in which the load is released with respect to the image taken during the load. When the elongation of the dimension a ₁ of the above is Δa ₁ and the elongation of the healthy part dimension a ₂ due to load release is Δa ₂ , the influence of “1” of the numerator and denominator on the rightmost side is obtained by raising the following expression to the nth power The operation method of the fusion strength evaluation apparatus according to claim 10 , wherein the strain ε is enlarged so that it can be ignored, and the change in the imaging magnification is canceled.

further,
Finding the crossing angle θ of two bones with the fusion site as a boundary by image processing,
The rate of change Δθ / ΔW is calculated from the load change ΔW of the load W applied to the affected area and the angle change Δθ of the intersection angle θ,
Evaluate the bone healing strength based on the rate of change Δθ / ΔW
The operation method of the fusion strength evaluation apparatus according to claim 1. In the evaluation step, imaging is performed before and during loading for each predetermined period, and the increase in the fusion strength is evaluated by the increasing tendency of the values of “strain of the healthy part of the affected part” / “strain of the fused part of the affected part”. The operation method of the fusion strength evaluation apparatus according to claim 1. The bone healing strength in the treatment of fracture treatment that promotes bone healing by screwing the bone embedded in the wound to the fractured bone contained in the affected area, or by cross-linking the screw outside the wound A fusion strength evaluation device for evaluating
An imaging means for imaging the affected area in a state where no load is applied to the affected area, and imaging the affected area in a state where a load is applied to the affected area;
First detecting a dimension between the screws straddling a fusion site of the affected part and a dimension between the screws in a healthy part of the affected part based on an image photographed without applying a load to the affected part by the imaging unit Detecting means of
Secondly, a dimension between the screws straddling a fusion site of the affected area and a dimension between the screws at a healthy site of the affected area are detected based on an image photographed with the load applied to the affected area by the imaging means. Detecting means of
Calculation means for calculating strain at the fusion site of the affected area and strain at the healthy site of the affected area based on the dimensions between the screws detected by the first detection means and the second detection means;
An evaluation means for evaluating that the healing strength of the bone is higher as the strain of the fusion site of the affected area calculated by the calculation means is closer to the strain of the healthy site of the affected area;
A fusion strength evaluation apparatus comprising: presentation means for presenting the bone fusion strength evaluated by the evaluation means.

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