JP2017144061A - Orthopedic implant placement strength evaluation method, orthopedic implant, and orthopedic jig - Google Patents

Abstract

The present invention provides an orthopedic implant placement strength evaluation method capable of evaluating an orthopedic implant placement strength appropriately and easily at a clinical site.
An orthopedic implant placement strength evaluation method according to the present invention includes a first step of forming a measurement hole in a target bone, and a second step of installing a measurement body 10 formed of an implant material in the measurement hole. And a third step of obtaining a frequency by vibrating the measurement body 10 and performing a resonance frequency analysis on the frequency.
[Selection] Figure 3

Description

  The present invention relates to an installation strength evaluation method for an orthopedic implant, an orthopedic implant, and an orthopedic jig.

  In recent years, in Japan, due to aging, degenerative diseases such as lumbar spinal canal stenosis, knee osteoarthritis, hip osteoarthritis, and fragile bone fractures such as vertebral fractures, femoral fractures, humeral fractures, forearm fractures, etc. Diseases such as are increasing. Along with this, the number of spinal fusion, artificial joint replacement, fracture open surgery using orthopedic implants (hereinafter sometimes simply referred to as “implants”) has also increased rapidly. .

  In each of the above-described surgical procedures, in particular, when an elderly person whose bone strength is reduced is a patient, loosening or dislodging of the implant after surgery is a serious problem (see Non-Patent Document 1). In order to prevent loosening and slipping, it is desirable that the installation strength can be accurately evaluated when the implant is installed during the operation.

  At present, the installation strength of implants is generally estimated by an operator based on his / her own experience and feeling, and it cannot be said that an objective evaluation has been performed. Further, as an attempt to evaluate the installation strength of the implant, it has been studied and reported to measure the implantation torque and pull-out strength of the implant and use this as an index of the installation strength (see, for example, Non-Patent Document 1). .

Aro HT et al, Acta Orthopaedica 2012; 83 (2): 107-14

  Regarding the above-described attempts, there is a problem that the embedding torque is complicated to measure and is not practical to perform during the operation. Furthermore, since the embedding torque is an index that mainly reflects the frictional force between the screw portion of the implant and the bone tissue, there is a problem in that it may not necessarily correlate with the actual installation strength.

Further, the pull-out strength has a big problem in that it cannot be performed on an actual patient because it may cause bone destruction in the measurement.
Thus, at present, there is no method capable of appropriately and simply evaluating the installation strength of the orthopedic implant in the clinical field.

In view of the above circumstances, an object of the present invention is to provide an orthopedic implant placement strength evaluation method capable of appropriately and simply evaluating the placement strength of an orthopedic implant in a clinical field.
Another object of the present invention is to provide an orthopedic implant and an orthopedic jig that can be suitably used in the above-described method for evaluating the installation strength of an orthopedic implant.

  The first aspect of the present invention includes a first step of forming a measurement hole in a target bone, a second step of installing a measurement body formed of an implant material in the measurement hole, and vibrating the measurement body to vibrate. A third step of acquiring a number and performing a resonance frequency analysis on the frequency, and an installation strength evaluation method for an orthopedic implant.

  The measurement hole may penetrate the cortical bone and reach the cancellous bone, and the depth dimension of the measurement hole may be greater than 10 millimeters and 80 millimeters or less, for example.

  A vibrator may be provided on the measurement body, and the vibrator may be vibrated in a non-contact manner in the third step.

  A second aspect of the present invention is an orthopedic implant including a main body formed of a measuring body formed of an implant material and a vibrator attached to the main body.

The vibrator may be detachable from the main body.
The vibrator may be attached to the main body via a vibrator portion having a fragile portion, and the vibrator may be removable from the main body by breaking the fragile portion.

  A third aspect of the present invention is an orthopedic jig including a main body formed of a measuring body formed of an implant material and a vibrator attached to the main body.

  In the orthopedic implant and orthopedic jig of the present invention, the vibrator may include a magnet.

According to the installation strength evaluation method for orthopedic implants of the present invention, the installation strength of orthopedic implants can be evaluated appropriately and easily in a clinical setting.
The orthopedic implant and orthopedic jig of the present invention can be suitably used for the installation strength evaluation method of the present invention.

It is a schematic diagram which shows the 1st process of the installation strength evaluation method of the orthopedic implant which concerns on 1st embodiment of this invention. It is a schematic diagram which shows the 2nd process of the installation strength evaluation method. It is a schematic diagram which shows the 3rd process of the installation strength evaluation method. It is a schematic diagram which shows the orthopedic implant which concerns on 2nd embodiment of this invention. It is an enlarged view which shows the head periphery in the modification of the orthopedic implant. It is an enlarged view which shows the head periphery in the modification of the orthopedic implant. It is an expanded sectional view showing a modification of the orthopedic implant. It is a perspective view which shows the orthopedic implant which concerns on 3rd embodiment of this invention. It is sectional drawing which shows one process at the time of use of the orthopedic implant. It is a figure which shows the orthopedic surgical jig | tool which concerns on 4th embodiment of this invention. It is a figure which shows the other example of the orthopedic jig. It is a figure which shows typically the modification of the orthopedic jig.

  A first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

(Installation strength evaluation method for orthopedic implants)
First, an installation strength evaluation method (hereinafter simply referred to as “evaluation method”) of an orthopedic implant according to the present invention will be described.
The evaluation method of the present invention includes a first step of forming a measurement hole in a bone on which an implant is to be installed, a step of installing a measurement body having a vibrator in a hole formed in the second step, and the measurement body comprising: And a third step of performing resonance frequency analysis by vibrating.

First, in the first step, as shown in FIG. 1, a measurement hole (measurement hole) 110 is formed in a bone (target bone) 100 where an implant is to be installed. The measurement hole 110 has a depth that penetrates at least the surface cortical bone 101 and reaches the cancellous bone 102, and the depth dimension L1 in the cancellous bone 102 is set to three times or more than the depth dimension L2 in the cortical bone. Is done. The total depth of the measurement hole 110 shown as the sum of the depth dimensions L1 and L2 is preferably equal to the assumed embedding depth. As an example, the size of the measurement hole is larger than 4 millimeters (mm) in diameter and not larger than 10 mm, or not smaller than 5 mm and not larger than 10 mm, and has a depth larger than 10 mm and not larger than 80 mm, or not smaller than 15 mm and not larger than 80 mm.
A guide hole formed when an implant is installed during surgery, a pilot hole before thread formation by a tap, or the like may be used as a measurement hole.

  In the subsequent second step, as shown in FIG. 2, the measurement body 10 including the vibrator 11 is installed in the measurement hole 110. The measuring body 10 is made of an implant material used for an orthopedic implant and has a certain rigidity. Examples of implant materials include various biocompatible metals, various alloys, and various ceramics. Accordingly, the implant itself may be used as the measurement body, or various orthopedic jigs and the like as described later may be used. When using a measuring body different from the implant, it is preferable to use a measuring body formed of the same material as the implant material used for the implant to be installed.

  The measurement body 10 is installed in the measurement hole 110 so as to be held to such an extent that neither rotation in the direction around the axis or advancement / retraction in the depth direction occurs with a small force. Thus, it is preferable that the shape and dimensions of the measurement hole 110 are substantially the same as the outer shape of the measurement body 10 so that the measurement body can be installed.

  The measuring body 10 is installed on the target bone 100 such that the vibrator 11 is positioned outside the measurement hole 110. The vibrator 11 may be anything that can be vibrated by applying energy from the outside. For example, a magnet or the like can be used.

  In the subsequent third step, when the vibrator 11 is vibrated, the measuring body 10 to which the vibrator 11 is attached vibrates. For example, when the vibrator 11 is a magnet, as shown in FIG. 3, the vibrator 11 can be vibrated in a non-contact manner by irradiating the vibrator 11 with a magnetic pulse Mp.

An installation strength index is obtained by acquiring the vibration frequency of the measurement body 10 and performing a resonance frequency analysis on the acquired vibration frequency.
The obtained installation strength index can be used to evaluate the installation strength of the implant with respect to the target bone 100.

One of the installation strength indexes obtained by the third step is ISQ (Impartment Stability Quotient). ISQ is a numerical value obtained by converting the acquired frequency F (Hz) by the following formula (1), and is established as an index for evaluating the installation strength of a dental implant.
(1) ISQ = −2.4 × 10 ⁻¹⁴ × F ⁴ + 7.1 × 10 ⁻¹⁰ × F ³ −7.8 ×
10 ⁻⁶ × F ² + 0.0445 × F-37

In the inventor's study, a pedicle in which a neodymium magnet (cylindrical type, diameter 4 mm, height 2 mm, magnetization direction: height direction, surface magnetic flux density: 345 millitesla (mT)) as the vibrator 11 is fixed to the head. In the examination using a screw (Pedicle Screw, hereinafter referred to as “PS”) as the measurement body 10, the ISQ obtained by the resonance frequency analysis with respect to the acquired frequency is the conventional index of the embedding torque and the pulling strength. Both have been confirmed to show a good correlation. This examination is performed using a simulated bone in order to examine the correlation with the pullout strength.
When a cylindrical magnet is used as the vibrator, for example, a magnet having a diameter of 2 to 6 mm, a height of 2 to 4 mm, and a surface magnetic flux density of 310 to 410 mT can be suitably used.

As described above, according to the evaluation method of the present embodiment, the measurement body 10 installed in the measurement hole 110 is vibrated through the vibrator 11. By performing resonance frequency analysis on the acquired frequency, it is possible to easily obtain the pullout strength that could not be measured in clinical practice and the installation strength index that correlates with the embedding torque that was difficult to measure in the past. can do.
As a result, various clinical judgments such as, for example, evaluating the installation strength using the installation strength index during the operation, adjusting the implant depth, determining the size of the implant to be implanted, and whether or not to perform the implantation, etc. It can be used as a reference.

Furthermore, in the inventor's study, the ISQ obtained using the measuring body 10 has a tendency to reflect the bone density of the target bone around the implant, and therefore, the embedding torque, the pullout strength, etc. It is considered that information that cannot be obtained with conventional indicators is included. In addition, while the insertion torque and pull-out strength reflect only the force when the implant is pulled in the insertion direction, ISQ seems to actually act on the implant in the body due to its mechanism. This reflects the force of pushing down in the direction perpendicular to the insertion direction. From these viewpoints, it can be said that the installation strength index acquired in the present invention is a more appropriate index than the conventional embedding torque and pull-out strength in evaluating the installation strength of the implant.
Therefore, it is possible to contribute to more accurate installation strength evaluation by appropriately evaluating the installation strength index obtained by providing an appropriate cut-off value.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the second and subsequent embodiments, implants and orthopedic jigs that can be suitably used for the evaluation method described in the first embodiment will be described. In the following description, elements that are the same as those already described are denoted by the same reference numerals and redundant description is omitted.

FIG. 4 shows an orthopedic implant 20 of this embodiment. The implant 20 includes a PS (main body) 21 that is formed of an implant material and is used as a measurement body, and a vibrator 11 that is directly fixed on the outer surface of the PS 21.
The external shape of the PS 21 is the same as that of a general PS, and includes a screw portion 22 embedded in the target bone 100 and a head portion 23 connected to the screw portion 22. The head 23 is formed with a lateral hole 23a through which a rod for spinal fixation is inserted. The vibrator 11 made of a neodymium magnet is fixed on the outer peripheral surface of the head 23.

  When the above-described evaluation method is executed using the implant 20, in the first step, an embedding hole in which a screw groove is formed by a tap is used as a measurement hole, and in the second step, the implant 20 is temporarily installed in the embedding hole. do it. The temporary installation may be performed by embedding the screw portion 22 to an assumed embedding depth, or may be embedding to a position shallower than the assumed embedding depth.

  In the implant 20 of the present embodiment, since the vibrator 11 is directly fixed to the outer surface of the PS 21 that is a measurement body, the PS 21 is vibrated with high precision by the vibrator 11.

In the implant 20, the manner of fixing the vibrator can be variously changed. In the implant 20A of the modification shown in FIG. 5, the axis of the columnar vibrator 12 is arranged so as to be parallel to the longitudinal direction of the PS 21. When the vibrator 12 is a magnet and the magnetization direction is a cylindrical height direction, when the vibrator 12 of the implant 20A is irradiated with a magnetic pulse, the PS 21 reciprocally vibrates in its longitudinal direction.
In this way, the installation strength in the depth direction of the implant can be evaluated.

  In the implant 20B of the modified example shown in FIG. 6, one of the two vibrators 12A is attached in parallel with the longitudinal direction of the PS 21, and the other vibrator 12B has its own axis aligned with the longitudinal direction of the PS 21. They are arranged at right angles.

  When the magnetization directions of the vibrators 12A and 12B are the same, in the implant 20B, in the third step, the vibration direction changes depending on which vibrator is irradiated with the magnetic pulse. Therefore, PS21 can be vibrated in a desired direction, and the installation strength in the desired direction can be evaluated.

The bone tissue in which the implant is implanted is usually not uniform in various parameters including bone density. Therefore, there is a possibility that the installation strength has anisotropy, but even in such a case, the use of the implant 20B helps to evaluate the installation strength in a plurality of directions and to make more detailed clinical judgment. It can be.
In any of the above-described implants, if the position of the vibrator is changed by rotating the PS 21 around the axis by a desired rotation angle, the installation strength index in more directions is obtained, and the installation strength is anisotropic in more detail. Sex can be evaluated.

  Another modification of the implant 20 is shown. FIG. 7 is a partially enlarged cross-sectional view showing a modified implant 20C. The PS 31 constituting the implant 20C is configured by connecting a screw portion 32 and a head portion 33 with a known ball joint structure. Thereby, 20 C of implants are comprised so that adjustment of the angle which the screw part 32 and the axis line of the horizontal hole 33a formed in the head 33 make is possible, and adjustment according to the arrangement | positioning aspect of a rod is possible.

  Since the screw part 32 and the head part 33 can be moved relative to each other by the ball joint structure, they do not function as one measuring body as they are. However, the vibrator portion 34 to which the vibrator 11 is attached is screwed into the screw groove 33 b formed on the inner peripheral surface of the head portion 33, so that the ball portion 32 a at the base end of the screw portion 32 is replaced with the head portion 33. When the screw portion 32 is pressed toward the opening 33c from which the screw portion 32 protrudes, the screw portion 32 and the head portion 33 are fixed so as not to move relative to each other. That is, by tightening and fixing the vibrator portion 34 to the PS 31, the PS 31 having the screw portion 32 and the head portion 33 functions as a measurement body that vibrates integrally.

Therefore, when the installation strength evaluation is performed using the implant 20C, the transducer unit 34 is temporarily installed in the measurement hole, and the transducer unit 34 is removed after the installation strength evaluation is acquired, so that the rod is preferably used. Can be attached.
Further, when the transducer unit 34 is configured to have a magnet, the post-operative MRI examination can be performed without any trouble by removing the transducer unit 34 after the installation strength evaluation is completed.

A third embodiment of the present invention will be described with reference to FIGS.
The implant 40 of this embodiment shown in FIG. 8 includes a metal cup (main body, measuring body) 41 that is a rigid body formed of an implant material. The cup 41 is an implant that is implanted into the hipbone to receive a ball-shaped portion on the stem side in hip replacement.

  In the implant 40, the vibrator part 42 including the vibrator 11 is provided so as to protrude from the concave surface 41a that receives the stem. As shown in FIG. 9, the base part (fragile part) 42a of the vibrator part 42 is made weaker and weaker than other parts by, for example, forming a groove so that the operator can fold it by hand. It is configured.

Operation during use of the implant 40 configured as described above will be described.
After forming the prepared hole for embedding the cup 41 in the hipbone, the surgeon brings the convex surface 41b of the cup 41 into contact with the prepared hole toward the hipbone Ac side as the target bone, as shown in FIG. . Then, while holding the implant 40, the impactor 50 is pressed against the implant 40, the impact is applied to the implant 40 with a hammer (not shown) through the impactor 50, and the impactor 50 is driven into the prepared hole. In the impactor 50, since the tip side pressed against the implant 40 is formed in a cylindrical shape, the implant can be driven without interfering with the vibrator portion 42.

  When the above-described evaluation method is executed by vibrating the vibrator 11 when the implant 40 is embedded in an assumed amount or at an arbitrary timing before that, the installation strength index of the implant 40 at that time can be acquired. Based on the acquired installation strength index, the surgeon can determine whether to add or end driving.

  When the driving is finished, the operator applies a force to the base portion 42 a to fold the vibrator portion 42 and remove it from the cup 41. As a result, the cup 41 remains in the hipbone Ac and there is no structure protruding on the concave surface 41a, so that the subsequent procedure can be performed smoothly.

  As described above, also in the implant 40 of the present embodiment, the evaluation method of the present invention can be suitably executed by vibrating the cup 41 as the measurement body by the vibrator 11.

In addition, since the implant 40 can be driven without removing the transducer portion 42 by using the impactor 50 having the tip side formed in a cylindrical shape, the evaluation method can be performed without complicating the replacement technique. Can be executed.
Furthermore, since the vibrator part 42 can be removed from the cup 41 simply by folding the base part 42a, the vibrator can be removed easily.

  As mentioned above, although the aspect of the implant of this invention has been demonstrated, the implant of this invention is not limited to what was mentioned above. For example, the above-described configuration can be applied to an implant that is implanted in a tibia in a knee replacement.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, an orthopedic jig that can be suitably used in the evaluation method of the present invention will be described.

  FIG. 10 shows a probe 60 that is an orthopedic jig of this embodiment. The probe 60 is made of an implant material and includes a metal main body 61 used as a measurement body, a gripping part 62 provided at one end of the main body 61, and a vibrator 63 attached to the main body. As for the main body 61 and the gripping portion 62, various configurations of a known orthopedic probe can be appropriately selected and employed.

  The vibrator 63 has the same configuration as the vibrator 11 described above except that it has a quadrangular prism shape. The quadrangular prism shape is an example, and there is no problem with other shapes.

  Before installing the PS, the probe may be inserted into a pre-formed pilot hole for probing. When the probe 60 of this embodiment provided with a vibrator is used, it is possible to acquire the installation strength index before installing the PS by vibrating the main body 61 of the probe 60 inserted using the prepared hole as a measurement hole. It is. Therefore, it is possible to contribute to selecting an appropriate size PS with reference to the acquired installation strength index.

In addition, when the vibrator is attached to the orthopedic jig, the evaluation method of the present invention can be executed without providing the vibrator on the implant, and therefore, an operation such as removing the vibrator from the implant is not necessary. Furthermore, since it is not necessary to remove the transducer from the orthopedic jig, the evaluation method can be executed more simply.
It is possible to perform optimal installation strength evaluation in various cases by using properly the installation strength index obtained before installation using the orthopedic jig and the installation strength index acquired from the actually installed implant. become.

  In the present invention, the orthopedic jig provided with the vibrator is not limited to the probe described above. For example, as shown in FIG. 11, a vibrator 63 may be provided in a main body 71 formed of an implant material in a tap 70 for forming a screw groove for installing PS in a pilot hole. In this case, after the tap 70 is screwed into the pilot hole to form a screw groove, the main body 71 can be vibrated as it is to obtain the installation strength index.

Further, when the vibrator is provided in the orthopedic jig, a vibration source 66 that vibrates the vibrator 65 may be provided in the main body 61 like a probe 60A of a modified example schematically shown in FIG. In this way, there is no need to externally apply a pulse or the like for vibrating the vibrator 65. For example, the main body 62 installed in the measurement hole is simply driven simply by pressing the switch 66a that operates the vibration source 66. be able to.
Furthermore, as shown in FIG. 12, a storage unit 67 including a storage medium that stores the acquired frequency, an analysis unit 68 including an IC chip that performs resonance frequency analysis on the frequency, and an acquired installation strength index If the configuration is equipped with a display unit 69 including a liquid crystal display or the like for displaying, etc., a series of operations from installation to a measurement hole to acquisition of an installation strength index are performed very easily, and various judgments during the procedure can be made quickly and quickly. It can contribute to doing suitably.
The storage unit, analysis unit, display unit, and the like described above may not be provided directly on the orthopedic jig. For example, the computer and the orthopedic jig may be configured to be able to communicate with each other by wire or wirelessly, and the computer may function as a storage unit, an analysis unit, a display unit, or the like.

  The embodiments of the present invention have been described above. However, the technical scope of the present invention is not limited to the above-described embodiments, and combinations of components or components may be changed without departing from the spirit of the present invention. It is possible to make various changes to or delete them.

For example, in the evaluation method of the present invention, the method of vibrating the measurement body installed in the measurement hole is not limited to the above-described magnetic force. For example, an ultrasonic transducer may be attached to the measurement body, and the measurement body may be vibrated by ultrasonic waves.
In addition, it is possible to vibrate by directly impacting the measurement object, but this method may apply an excessive load to the target bone, so the measurement object is vibrated in a non-contact manner by magnetic force or ultrasonic waves. The method of making it preferable is.

10 Measurement object 11, 12, 12A, 12B, 63, 65 Transducer 20, 20A, 20B, 20C, 40 Orthopedic implant 21, 31 Pedicle screw (main body)
34, 42 Vibrator part 41 Cup (main body)
42a Base (fragile)
60, 60A probe (orthopedic jig)
61 body 70 tap (orthopedic jig)
71 Body 100 Target bone 101 Cortical bone 102 Cancellous bone 110 Measurement hole Ac Hip bone (target bone)

Claims (9)

A first step of forming a measurement hole in the target bone;
A second step of installing a measurement body formed of an implant material in the measurement hole;
Vibrating the measuring body to obtain a frequency, and performing a resonance frequency analysis on the frequency; and
Comprising
A method for evaluating the installation strength of an orthopedic implant.   The orthopedic implant according to claim 1, wherein the measurement hole penetrates the cortical bone to reach the cancellous bone, and the depth dimension of the measurement hole is, for example, greater than 10 millimeters and less than or equal to 80 millimeters. Installation strength evaluation method. A vibrator is provided on the measurement body,
In the third step, the vibrator is vibrated without contact.
The installation strength evaluation method of the orthopedic implant of Claim 1 or 2. A body formed of an implant material;
A vibrator attached to the main body;
An orthopedic implant comprising:   The orthopedic implant according to claim 4, wherein the transducer is detachable from the body.   The shaping according to claim 4, wherein the vibrator is attached to the main body via a vibrator portion having a fragile portion, and the vibrator can be removed from the main body by breaking the fragile portion. Surgical implant.   The orthopedic implant according to any one of claims 4 to 6, wherein the vibrator includes a magnet. A body formed of an implant material;
A vibrator attached to the main body;
Comprising
Orthopedic jig.   The orthopedic jig according to claim 8, wherein the vibrator includes a magnet.

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