JP2012165879A - Artificial skull valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology improving attachability to a skull and strength of an artificial skull valve.SOLUTION: The artificial skull valve 10 is used for covering a fracture part 21 of the skull 20. A plurality of through-holes 11 to insert a holding member 30 to hold the artificial skull valve 10 within the fracture part 21 are arranged along a peripheral end of the artificial skull valve 10. A groove part 12 to extend toward the peripheral end from each of the plurality of the through-holes 11 and to guide the holding member 30 is provided on a first surface S1 to be outside when covering the fracture part 21 is also provided on the artificial skull valve 10.

Description

  The present invention relates to an artificial skull flap used for filling a defect in a skull.

  After external decompression or surgery for the treatment of trauma or bone injuries in human heads, the skull defect site after cutting and removing a part of the skull (hereinafter referred to as “bone defect site”) In general, an artificial skull flap is used. Generally, when an artificial skull flap is attached and fixed to a bone defect site of the skull, it is held between the artificial skull flap and the skull (also called “autologous bone” or “living bone”). A member is used. In order to make it possible to attach such a holding member, the artificial skull valve is provided with a through-hole or the like for attaching the holding member (the following Patent Document 1 or the like).

Japanese Patent No. 3571232

  By the way, it is desirable that the artificial skull flap is easily and quickly attached to the defect site of the skull, and it is desirable that the displacement of the artificial skull valve is suppressed after being attached to the skull defect site. Therefore, in the artificial skull valve, further improvement in the fixing property of the holding member to the artificial skull valve and further improvement in attachment property of the artificial skull valve to the skull are required. Further, in the artificial skull flap, it is desirable that sufficient strength is ensured even when a through hole or the like for attaching the holding member is provided. Therefore, further contrivance is required for improving the strength of the artificial skull flap. An object of this invention is to provide the technique which improves the attachment property, fixation property, and intensity | strength to the skull of an artificial skull valve.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
An artificial skull valve used for filling a bone defect portion of a skull, wherein a plurality of through holes for inserting a holding member for holding the artificial skull valve in the bone defect portion are provided on an outer periphery of the artificial skull valve. In the artificial skull flap that is arranged along the edge,
A first groove that extends from each of the plurality of through-holes toward an outer peripheral end of the artificial skull flap and that is outside when a groove for arranging a part of the holding member is compensated for the bone defect. An artificial skull flap on the surface side.
According to this artificial skull valve, the attachment of the holding member to the artificial skull valve is improved because the holding member can be easily guided to the attachment position of the groove when attaching the artificial skull valve. Furthermore, after the holding member is attached to the artificial skull flap, the groove portion suppresses the positional deviation of the holding member, so that the fixability of the position of the holding member is improved. Therefore, the attachment property and fixation property of the artificial skull valve to the skull can be improved.

[Application Example 2]
The artificial skull valve according to Application Example 1,
The second surface opposite to the first surface is provided with a raised portion having a thickness greater than that of the other part,
The protuberance is an artificial skull flap that is provided at least in a region overlapping with the groove when the artificial skull flap is viewed in the thickness direction.
According to this artificial skull valve, even when the groove is provided, the thickness of the artificial skull valve is secured by the raised portion, and the strength of the artificial skull valve can be secured.

[Application Example 3]
An artificial skull flap according to Application Example 2,
The artificial skull flap, wherein the thickness of the portion where the groove portion and the raised portion overlap when viewed along the thickness direction of the artificial skull flap is substantially the same as the thickness of the other portion.
According to this artificial skull valve, the thickness of the artificial skull valve is more reliably ensured by the raised portion, so that the strength of the artificial skull valve can be more reliably ensured.

[Application Example 4]
The artificial skull valve according to any one of Application Examples 1 to 3,
Each of the plurality of through holes has a horizontally long shape having a long side in the direction along the outer periphery of the artificial skull flap,
The holding member includes a first part extending along the first surface from an outer periphery of the artificial skull flap, a second part bent from the first part and inserted into the through hole, Including a plate-like member having a tip extending from the through hole along the second surface opposite to the first surface;
The second surface is provided with holes for accommodating and holding at least a part of the tip of the holding member corresponding to each of the plurality of through holes,
The holding member has a thickness of 1 mm or less,
The thickness of the artificial skull flap is 5-7 mm,
Each of the plurality of through holes is an artificial skull flap having a width in the short side direction of 2 mm ± 0.5 mm.
According to this artificial skull valve, when the artificial skull valve is held on the skull by the holding member obtained by bending the plate-like member, the attachment / retention property of the artificial skull valve is improved and the through hole is provided. This prevents a decrease in strength of the artificial skull flap.

  Note that the present invention can be realized in various forms, for example, in the form of an artificial skull valve, a method for attaching the artificial skull valve, and the like.

The schematic front view of an artificial skull valve. The schematic sectional drawing of an artificial skull flap. The schematic perspective view which shows the structure of a holding member. Schematic which shows the attachment process to the skull of the artificial skull valve using a holding member in order of a process. Schematic which shows the structure of the artificial skull valve as 2nd Embodiment. The schematic diagram which shows the sample body in a 1st experiment example, and explanatory drawing which shows the table | surface which put together the factor verified in the 1st experiment example, and the parameter set for each factor. Explanatory drawing which shows the table | surface which put together the example of a structure of the sample body which combined the 1st and 2nd level of each factor. The schematic diagram which shows the measuring method of the intensity | strength of the sample body in a 1st experiment example. Explanatory drawing which shows the measurement result of the intensity | strength for each sample group. The factor effect figure for analyzing the influence which each factor has on intensity. Explanatory drawing which shows the estimated value plot which plotted the estimated value of the intensity | strength of a sample body. The schematic diagram which shows the sample body which imitated the artificial skull flap used in the 2nd experiment example, and explanatory drawing which shows the table | surface which put together the parameter verified for the factor verified in the 2nd experiment example, and each factor. Schematic for demonstrating the other arrangement structure of the through-hole in a sample body. Explanatory drawing which shows the table | surface which put together the example of a structure of 8 types of sample bodies which combined the 1st and 2nd level of each factor. The schematic diagram which shows the measuring method of the intensity | strength of the sample body in a 2nd experiment example. Explanatory drawing which shows the measurement result of the intensity | strength for each sample group. The factor effect figure for analyzing the influence which each factor has on intensity. Explanatory drawing which shows the estimated value plot about factor AxC and factor BxC.

Next, embodiments and examples of the present invention will be described in the following order.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
C1. First experimental example:
C2. Second experimental example:
D. Variations:

A. First embodiment:
1 and 2 are schematic views showing the configuration of an artificial skull valve 10 as an embodiment of the present invention. 1A is a schematic front view of the artificial skull valve 10, and FIG. 1B is an enlarged schematic view showing a region A surrounded by a two-dot chain line in FIG. 1A. FIG. 2 is a schematic cross-sectional view of the artificial skull valve 10 taken along the line BB shown in FIG.

  The artificial skull valve 10 is used to compensate for a bone defect 21 that is a hole formed by excising a part of a skull 20 (illustrated by a two-dot chain line in FIG. 2) that is a living bone in a surgical operation or the like. It is used. The artificial skull flap 10 is a substantially plate-like member curved toward one side, and is composed of a composite ceramic of hydroxyapatite and tricalcium phosphate. The artificial skull valve 10 is preferably formed with a thickness of about 5 to 7 mm in order to balance the thickness of the skull 20 and ensure its strength.

  In the present specification, in the artificial skull valve 10, the convex side that becomes the outside when the artificial skull valve 10 is compensated (attached) to the bone defect portion 21 of the skull 20 is referred to as “first surface S1”. The concave surface on the opposite side is referred to as “second surface S2”. FIG. 1 shows the first surface S1 side of the artificial skull valve 10.

  Here, the artificial skull valve 10 has an outer peripheral end surface 15 configured as a tapered inclined surface having an inclination angle as described below, so that attachment to the skull 20 is improved. Specifically, the angle θ between the outer peripheral end surface 15 of the artificial skull valve 10 and the virtual plane VP virtually extending from the outer peripheral end of the second surface S2 is in the range of 50 to 70 °. It is configured as follows.

  In this way, by tilting the outer peripheral end face 15 so that the angle θ is 70 ° or less, the artificial skull valve 10 is prevented from falling into the skull 20 when or after the artificial skull valve 10 is attached. can do. In addition, by inclining the outer peripheral end surface 15 so that the angle θ is 50 ° or more, it is possible to suppress the strength of the end portion on the first surface S1 side from being significantly reduced, and the artificial skull valve 10 The defect | deletion of the outer peripheral edge part can be suppressed.

  The artificial skull valve 10 is provided with a plurality of laterally extending through holes 11 arranged along the outer peripheral edge of the artificial skull valve 10. More specifically, each through hole 11 is provided such that its long side is adjacent to the outer peripheral end of the artificial skull flap 10. The through-hole 11 is for inserting the holding member 30 (described later) into the artificial skull valve 10. In addition, it is preferable that each through-hole 11 is formed in the position disperse | distributed along the outer periphery of the artificial skull flap 10 without bias. Thereby, the retention property and the fixation property when attached to the skull 20 are improved.

  On the second surface S <b> 2 side of the artificial skull valve 10, two substantially circular bottomed holes 13 are provided so as to correspond to the respective through holes 11. The two bottomed holes 13 are arranged along the long side of the through hole 11 on the central side of the artificial skull flap 10 from the corresponding through hole 11. These bottomed holes 13 are for inserting a pin 34 (described later) provided at the tip of the holding member 30 inserted through the through-hole 11 to fix the mounting position of the holding member 30. The depth of the bottomed hole 13 may be, for example, about 2/3 of the thickness of the artificial skull valve 10.

  On the first surface S1 side of the artificial skull valve 10, a groove portion 12 extending from each through hole 11 toward the outer peripheral end of the artificial skull valve 10 is formed. The groove portion 12 has a width approximately equal to the width of the long side of each through-hole 11 and is linearly formed at a depth of about 1 mm from the long side of each through-hole 11 to the outer peripheral end of the artificial skull flap 10. Has been. The groove 12 functions as a guide for fixing the mounting position of the holding member 30. Further, the groove portion 12 prevents the holding member 30 from protruding from the first surface S <b> 1 of the artificial skull valve 10 when the holding member 30 is attached to the artificial skull valve 10.

  FIG. 3 is a schematic perspective view showing a configuration of a holding member 30 for holding the artificial skull valve 10 on the bone defect portion 21 of the skull 20. The holding member 30 is a member configured by bending a front end portion of a substantially rectangular plate-like member substantially at a right angle so that the cross section is substantially L-shaped. In addition, the holding member 30 is good also as what is comprised with titanium or a titanium alloy, and thickness is about 0.5-0.8 mm.

  Here, among the parts of the holding member 30, the long part with the fold of the bent part as the boundary is called “main body part 31”, and the short part is called “tip part 32”. A screw hole 33 is provided on the end of the main body 31 opposite to the tip 32. Further, two pins 34 are provided on the surface of the distal end portion 32 on the main body portion 31 side. Each of the two pins 34 extends in the extending direction of the main body 31 at two corners in the vicinity of the end face of the distal end portion 32.

  FIGS. 4A to 4C are schematic views showing the process of attaching the artificial skull valve 10 to the skull 20 using the holding member 30 in the order of steps. First, the holding member 30 is attached to each through hole 11 of the artificial skull valve 10. Specifically, the main body 31 of the holding member 30 is inserted through the through hole 11 from the second surface S2 side of the artificial skull valve 10 (FIG. 4A). Then, by inserting the two pins 34 into the two bottomed holes 13 of the artificial skull valve 10, respectively, the surface of the distal end portion 32 of the holding member 30 and the second surface S2 of the artificial skull valve 10 are formed. Make contact.

  Next, the part which protruded from the through-hole 11 of the holding member 30 to the 1st surface S1 side is bent along the bottom face of the groove part 12 of the artificial skull flap 10 (FIG. 4 (B)). Of the main body portion 31 of the holding member 30 at this time, a portion along the first surface S1 is also referred to as a “first main body portion 31a”, and a portion inserted through the through hole 11 is referred to as a “second main body portion. 31b ".

  Then, the artificial skull flap 10 in which the holding member 30 is attached to each through-hole 11 is disposed on the bone defect portion 21 of the skull 20 with the first surface S1 side as the upper side (FIG. 4C). Thereafter, the holding member 30 is fixed to the skull 20 by attaching the fixing screw 35 to the skull 20 through the screw hole 33 of the holding member 30.

  Thus, according to the artificial skull valve 10 of this embodiment, when attaching the holding member 30 to the artificial skull valve 10, the groove 12 functions as a guide for the holding member 30, and the attachment position of the holding member 30 is desired. Deviation from the position can be suppressed. Therefore, the artificial skull valve 10 can be quickly and reliably attached to the skull 20.

  Further, according to the artificial skull valve 10 of the present embodiment, even after the artificial skull valve 10 is attached to the skull 20, the positional deviation of the holding member 30 is suppressed by the groove portion 12. Furthermore, in the case of the artificial skull valve 10 of the present embodiment, since the main body portion 31 of the holding member 30 is fitted into the groove portion 12, the holding member 30 extends in the thickness direction from the first surface S1 of the artificial skull valve 10. It can suppress protruding to.

  As described above, according to the artificial skull valve 10 of the present embodiment, by having the groove portion 12, it is possible to suppress the displacement of the holding member 30 and improve the attachment property to the skull 20. Further, according to the artificial skull valve 10 of the present embodiment, by having the outer peripheral end surface 15 having a predetermined inclination angle, the attachment property and strength to the skull 20 are ensured.

B. Second embodiment:
5A and 5B are schematic views showing the configuration of an artificial skull valve 10A as a second embodiment of the present invention. FIG. 5A is a schematic front view showing the first surface S1 side of the artificial skull flap 10A, and a two-dot chain line showing the region of the raised portion 14 formed on the second surface S2 side is added. Except for this point, it is the same as FIG. FIG. 5B is a schematic cross-sectional view of the artificial skull valve 10A taken along the line BB shown in FIG. 5A, except that the raised portion 14 is provided on the second surface S2 side. 2 is almost the same.

  In the artificial skull valve 10A of the second embodiment, a raised portion 14 having a thickness greater than that of the other portion is provided on the second surface S2 opposite to the first surface S1 provided with the groove 12. . The raised portions 14 are provided corresponding to the respective groove portions 12 and are formed in regions overlapping with the respective groove portions 12 when the artificial skull flap 10A is viewed along the thickness direction. More specifically, the raised portion 14 is formed so that the through hole 11, the groove portion 12, and the two bottomed holes 13 are included in the formation region.

  By forming each raised portion 14 corresponding to each groove portion 12, a decrease in strength of the artificial skull valve 10 </ b> A due to the provision of each groove portion 12 is suppressed. In addition, since the through hole 11 and the two bottomed holes 13 are included in the formation region of the raised portion 14, a decrease in strength of the artificial skull valve 10A due to the provision of the through hole 11 and the two bottomed holes 13 is suppressed. Is done.

  Here, it is preferable that the height h of the raised portion 14 at the position where the groove portion 12 is formed is substantially the same as the depth dp of the groove portion 12. That is, when the artificial skull flap 10A is viewed along the thickness direction, the thickness where the groove 12 and the raised portion 14 overlap is substantially the same as the thickness of the other portion where the raised portion 14 is not formed. Is preferred. As a result, the strength of the artificial skull valve 10A can be ensured more reliably.

  Thus, according to the artificial skull valve 10A of the second embodiment, the bulging portion 14 provided on the second surface S2 side suppresses a decrease in strength at the outer peripheral edge portion. More specifically, when the protuberance 14 is provided, the artificial skull flap 10 is thin (for example, with a thickness of 5 mm or less), or the groove 12 is deep (for example, with a depth of 1.5 mm or more). ) Even when configured, it is possible to ensure the strength of the artificial skull valve 10A.

C. Third embodiment:
The configuration of the artificial skull valve in the third embodiment is the same as that of the artificial skull valve 10, 10A described in the first embodiment or the second embodiment except for the points described below (FIG. 1, FIG. 1). 2 and 5). Further, the artificial skull valve of the third embodiment is fixed to the bone defect portion 21 of the skull 20 by the holding member 30 in the same manner as the artificial skull valves 10 and 10A described in the first embodiment or the second embodiment. (FIGS. 3 and 4). In the artificial skull valve according to the third embodiment, the groove 12 in the artificial skull valves 10 and 10A may be omitted.

  In the artificial skull flap in the third embodiment, the thickness of the holding member 30 is about 0.5 to 0.8 mm, and the width ws of the short side of the through hole 11 is set to about 1 to 2 mm. It is more preferable that the width ws of the short side of the through hole 11 is approximately 2 mm (2 ± 0.5 mm may be considered in consideration of an error of about ± 25%). Further, the thickness ts of the artificial skull flap in the third embodiment is set to about 5 to 7 mm. The thickness ts is more preferably 7 mm (which may be 7 ± 1.4 mm in consideration of an error of about ± 20%).

  In the artificial skull valve according to the third embodiment, the distance between the long side of the through hole 11 and the outer peripheral end of the artificial skull valve may be set to about 8 to 12 mm. When the thickness of the artificial skull valve is about 5 mm, the distance between the long side of the through-hole 11 and the outer peripheral end of the artificial skull valve is about 8 mm (8% considering an error of about ± 20%). It may be ± 1.6 mm).

  FIGS. 6-18 is explanatory drawing for demonstrating the experiment and the experimental result which the inventor of this invention conducted regarding the artificial skull valve as 3rd Embodiment of this invention. The inventors of the present invention conducted the first and second experimental examples described below based on the experimental design method in order to verify the constituent elements of the artificial skull valve that affect the strength of the artificial skull valve. .

  Here, the first experimental example is an experiment assuming a case where a load is applied to the outer peripheral end portion of the artificial skull valve when the artificial skull valve is attached to the skull. On the other hand, the second experimental example is an experiment assuming a case where a load is applied to the central part of the artificial skull valve when or after the artificial skull valve is attached to the skull.

C1. First experimental example:
6A and 6B are schematic views showing a sample body 40 simulating a part of the configuration of the artificial skull valve used in the first experimental example. 6A is a schematic front view showing one surface side of the sample body 40, and FIG. 6B is a schematic cross-sectional view of the sample body 40 taken along the line BB shown in FIG. 6A. is there.

  The sample body 40 is a substantially rectangular plate-shaped member having a long side of 55 mm and a short side of 37 mm, and is made of the same material as that of the artificial skull valves 10 and 10A described in the above embodiment. The sample body 40 has a substantially rectangular through hole 41, a groove 42 extending from the through hole 41 toward the outer peripheral end, and the vicinity of the through hole 41 so as to correspond to the configuration of the artificial skull valve 10 of the first embodiment. And two bottomed holes 43 provided in.

  FIG. 6C is an explanatory diagram showing a table that summarizes the factors A to F to be verified in the first experimental example and the parameters set as the first and second levels for each factor A to F. is there. The inventor of the present invention sets factors A to F described below as factors that may affect the strength among the constituent elements of the sample body 40, and as specific parameters of the factors A to F, respectively. The first and second levels were set as follows.

  Factors A and B are elements related to the formation position of the through hole 41. Factor A is a distance ds between the short side of the sample body 40 and the through hole 41. As the parameter of the factor A, 8 mm was set as the first level, and 15 mm was set as the second level. The factor B is the position of the center CP of the through hole 41 in the short side direction of the sample body 40. The parameter of the factor B was set by the offset amount between the center line CL (shown by a one-dot chain line) in the short side direction of the sample body 40 and the center CP of the through hole 41. Specifically, the first level of factor B has an offset amount of 0 mm (no offset), and the second level has an offset amount of 3 mm.

  Factors C and D are elements related to the shape of the through hole 41. The factor C is the width wl of the long side of the through hole 41, and the factor D is the width ws of the short side of the through hole 41. Note that the width wl of the long side of the through hole 41 corresponds to the width of the groove 12. As the parameter of the factor C, 8 mm was set as the first level, and 12 mm was set as the second level. As the parameter of the factor D, 1 mm was set as the first level, and 2 mm was set as the second level.

  The factor E is the thickness ts of the sample body. As the parameter of the factor E, 5 mm was set as the first level, and 7 mm was set as the second level. The factor F is an element regarding the presence or absence of the groove 12. The factor F was defined as the first level when the groove 12 was omitted, and the second level when the groove 12 was provided. In addition, the depth of the groove part 12 in the sample body 40 was 1 mm. In the first experimental example, a plurality of types of sample bodies 40 having a configuration in which the combinations of the first and second levels of the factors A to F are changed were created.

  FIG. 7 is an explanatory diagram showing a table in which configuration examples of 16 kinds of sample bodies 40 in which the first and second levels of the factors A to F are combined are summarized. The inventor of the present invention sets 16 configurations combining the first and second levels of each factor A to F using a two-level orthogonal table L16 (not shown), and samples each configuration. Five bodies 40 were created. Then, the strength of each sample body 40 was measured for each group of 16 types of sample bodies 40 having different configurations (hereinafter referred to as “sample groups S01 to S16”).

  FIGS. 8A and 8B are schematic views showing a method for measuring the strength of the sample body 40 in the first experimental example. FIG. 8A is a diagram schematically showing an apparatus for measuring the strength, and is a diagram when viewed from the side surface direction of the sample body 40. FIG. 8B is a schematic diagram showing a place where a load is applied to the sample body 40 in the measurement of strength, and this place is shown by a broken line LC.

  In the first experimental example, the sample body 40 was sandwiched and fixed by the support members 51 and 52 (FIG. 8A). At this time, the sample body 40 was protruded by 30 mm from the outer peripheral end so that the through hole 41, the groove portion 42, and the two bottomed holes 43 were exposed to the outside. And the intensity | strength of the sample body 40 was measured by pressing the outer peripheral edge part (part 2 mm from the end) of the sample body 40 by the crosshead 55 in the gravity direction. Here, as the cross head 55, a head capable of making line contact with the sample body 40 over a width of about 8 mm was used. The crosshead 55 pressed the outer peripheral end portion along the through hole 41 of the sample body 40 over a width of 8 mm (broken line LC in FIG. 8B). The driving speed of the cross head 55 at the time of measurement was 0.5 mm / min.

  FIG. 9 is an explanatory diagram showing the measurement results of the intensity for each of the sample groups S01 to S16. FIG. 9A is a table summarizing measured values (kgf) of the strengths of five sample bodies 40 and average values (kgf) of the five measured values for each sample group S01 to S16. . FIG. 9B is a graph in which the measured values and average values of FIG. 9A are plotted, with the vertical axis representing strength (kgf) and the horizontal axis representing the group numbers of the sample groups S01 to S16. In the graph of FIG. 9B, the measured values are plotted with black circles (●), and the average values are plotted with horizontal bars (−).

  FIG. 10 is a factor effect diagram for analyzing the influence of the factors A to F on the strength. In this factor effect diagram, the first and second levels are shown for each factor A to F or for each factor that combines two factors that may have an interaction, with the vertical axis representing strength (kgf). The mean intensity values for each of the are plotted. Specifically, the average intensity value for the first level is plotted with black circles (●), and the average intensity value for the second level is plotted with crosses (x).

  In FIG. 10, the factors obtained by combining the two factors are displayed as follows. That is, for example, a factor combining factor A and factor B is displayed as “A × B”. Further, the intensity value “15.72” in the figure is an average value of all measured values, and the intensity values “24.48” and “6.95” are average values ± standard deviation values, respectively. .

  In this factor effect diagram, factors E and D having a large difference in value for each of the first and second levels correspond to the load on the portion outside the through hole 41 of the sample body 40, that is, the outer peripheral edge. It was shown that the strength (hereinafter also referred to as “outer peripheral edge strength”) is greatly affected. That is, from this result, it was found that the sample body 40 has a larger outer peripheral edge strength when the thickness ts is thicker, and the outer peripheral edge strength is improved when the width ws of the short side of the through hole 41 is wider. .

  FIG. 11 is an explanatory diagram showing an estimated value plot obtained by plotting estimated values of the strength of the sample body 40 when the combinations of the first and second levels of the factors E and D are changed. The estimated value plot shows the range of 95% confidence interval for each plotted point. Thus, in the configuration in which the thickness ts of the sample body 40 is 7 mm and the width ws of the short side of the through-hole 41 is 2 mm, the estimated value of the highest strength is obtained.

  As described above, in the first experimental example, it was possible to improve the strength of the outer peripheral edge of the sample body 40 by configuring the width of the short side of the through hole 41 wider. That is, in order to improve the strength of the outer peripheral edge of the artificial skull flap, it is preferable to configure the width of the short side of the through-hole 11 of the artificial skull valve wider. However, in the artificial skull flap, if the width of the short side of the through-hole 11 is made too wide with respect to the thickness of the holding member 30, the fixability / retainability of the second main body portion 31 b of the holding member 30 in the through-hole 11 is increased. There is a possibility of lowering. Therefore, when the thickness of the holding member 30 is about 0.5 to 0.8 mm, the width of the short side of the through hole 11 is preferably about 1 to 2 mm, and is almost 2 mm (about ± 25%). More preferably, it may be 2 ± 0.5 mm in consideration of errors.

  Further, the strength of the outer peripheral edge of the sample body 40 could be improved by increasing the thickness of the sample body 40. That is, in order to improve the strength of the outer peripheral edge of the artificial skull flap, it is preferable to make the thickness thicker. However, since the thickness of the artificial skull flap is preferably balanced with the thickness of the skull 20, it is preferably about 5 to 7 mm, and is at most about 7 mm (in consideration of an error of about + 20%, 7.0 to 8). More preferably, the thickness may be 4 mm.

  Here, it can be seen from the estimated value plot shown in FIG. 11 that when the thickness of the artificial skull flap is relatively thin, about 5 mm, the width of the short side of the through hole 11 is preferably about 2 mm. . By configuring in this way, the strength of the outer peripheral edge can be ensured as compared with the case where the width of the short side of the through hole 11 is 1 mm. In addition, when the thickness of the artificial skull flap is about 7 mm, if the width of the short side of the through hole 11 is 2 mm, the strength of the outer peripheral edge of the artificial skull valve can be further improved.

  By the way, in the first experimental example, it was shown that the strength of the sample body 40 is not greatly affected by the presence or absence of the groove portion 42. This is presumably because the sample body 40 had a thickness of 5 mm or 7 mm, and if the groove portion 42 had a depth of about 1 mm, the strength could be ensured regardless of the presence or absence thereof. Further, when a load is applied to the outside of the through hole 41 as in the first experimental example, it is considered that the thickness of the sample body 40 in the formation region of the groove 42 has a small influence on the fracture progress distance. .

  That is, if the artificial skull flap is configured to have the above-mentioned thickness and the width of the short side of the through-hole 11, it is possible to ensure strength against the load on the outer peripheral end regardless of the presence or absence of the groove 12. is there. However, if the groove 12 is provided in the artificial skull flap and the thickness in the formation region of the groove 12 is smaller than 5 mm, the strength in the formation region of the groove 12 may be reduced. Therefore, in such a case, it is preferable to provide the raised portion 14 as described in the second embodiment so as to correspond to the groove portion 12.

C2. Second experimental example:
FIGS. 12A and 12B are schematic views showing a sample body 40a simulating an artificial skull flap used in the second experimental example. 12A is a schematic front view showing one surface side of the sample body 40a, and FIG. 12B is a schematic cross-sectional view of the sample body 40a in the BB cut shown in FIG. 12A. is there.

  The sample body 40a is a substantially circular disk member having a diameter of about 100 mm, and is made of the same material as the artificial skull flaps 10 and 10A described in the above embodiment. The sample body 40a is provided with three substantially rectangular through holes 41 corresponding to the through holes 11 described in the above embodiment. Each through hole 41 was formed such that a virtual straight line VL (shown by a one-dot chain line) passing through the center CP and the center CS of the sample body 40 was orthogonal to the long side direction of the through hole 41. Moreover, each through-hole 41 was arranged in a substantially annular shape along the outer periphery of the sample body 40a.

  Furthermore, two bottomed holes 43 corresponding to the bottomed holes 13 described in the above embodiment are provided in the sample body 40 a in the vicinity of each through hole 41. Here, in this second experimental example, as the sample body 40a, the thickness and the position and size of the through hole 41 are changed according to the first and second levels of the factors A to D described below. Created multiple types.

  FIG. 12C is an explanatory diagram showing a table in which the factors A to D to be verified in the second experimental example and the parameters set as the first and second levels for each factor A to D are summarized. . The inventor of the present invention sets factors A to D described below as those that may affect the strength among the constituent elements of the sample body 40a, and as specific parameters for the factors A to D, respectively. The first and second levels were set as follows.

  The factor A is an element related to the formation position of the through hole 41, and is the shortest distance ds between the outer peripheral end of the sample body 40 a and the long side of the through hole 41. As the parameter of the factor A, 8 mm was set as the first level, and 15 mm was set as the second level. The factor B is the width ws of the short side of the through hole 41. As the parameter of the factor B, 1 mm was set as the first level, and 2 mm was set as the second level. The factor C is the thickness ts of the sample body 40a. As the parameter of the factor C, 5 mm was set as the first level, and 7 mm was set as the second level.

  The factor D is an element regarding the arrangement of the through holes 41. Here, three central angles α of the sample body 40a formed by a virtual straight line VL passing through the center CP of each through hole 41 and the center CS of the sample body 40a are assumed. The first level of the factor D is an arrangement configuration of the through holes 41 in which the three central angles α are all about 120 °, and the configuration shown in FIG. That is, at the first level of the factor D, the through holes 41 are arranged at substantially equal intervals along the outer periphery of the sample body 40a.

  FIG. 13 is a schematic diagram for explaining an arrangement configuration of the through holes 41 in the second level of the factor D. FIG. FIG. 13 is substantially the same as FIG. 12A except that the arrangement positions of the through holes 41 are different. In the second level of the factor D, the arrangement of the through holes 41 is such that two of the three central angles α are approximately 90 ° and the remaining one is approximately 180 °. That is, in the second level of the factor D, the through holes 41 are arranged at unequal intervals, and are arranged biased to one side of the sample body 40a.

  FIG. 14 is an explanatory diagram showing a table in which configuration examples of eight sample bodies 40a in which the first and second levels of the factors A to D are combined are summarized. The inventor of the present invention uses the two-level orthogonal table L16 (not shown) to set eight configurations combining the first and second levels of the factors A to D, and samples each configuration. Five bodies 40a were created. Then, the strength of each sample body 40a was measured for each group of eight types of sample bodies 40a having different configurations (hereinafter referred to as “sample groups S21 to S28”).

  FIG. 15 is a schematic diagram showing a method for measuring the strength of the sample body 40a in the second experimental example. In the second experimental example, each sample body 40a is fixedly held on a support base 53 that is a base having a substantially circular recess 531 capable of accommodating the sample body 40a at the center, An intensity measurement of 40a was performed. Specifically, each sample body 40 a was held on the support base 53 by attaching the holding member 30 to each through hole 41. Each holding member 30 was fixed to the support base 53 with three fixing screws 35. The strength measurement is performed by placing a nylon cushioning material 56 having a diameter of 30 mm and a height of 20 mm in the center of each sample body 40a and pressing the sample body 40a with a crosshead (not shown) until it breaks. It went by. The crosshead drive speed during measurement was 5 mm / min.

  FIG. 16 is an explanatory diagram showing the measurement results of the intensity for each of the sample groups S21 to S28. FIG. 16A is a table summarizing measured values (kgf) of the strength of five sample bodies 40a and average values (kgf) of the five measured values for each sample group S21 to S28. . FIG. 16B is a graph in which the measured values and average values of FIG. 16A are plotted with the vertical axis as the strength (kgf) and the horizontal axis as the group numbers of the sample groups S21 to S28. In the graph of FIG. 16B, the measured values are plotted with black circles (●), and the average values are plotted with horizontal bars (−).

  FIG. 17 is a factor effect diagram for analyzing the influence of the factors A to D on the strength. In this factor effect diagram, the vertical axis is strength (kgf), and each of the first and second levels for each factor or for each factor that combines two factors that may have an interaction. The mean intensity values for are plotted. Specifically, the average value of intensity for the first level is plotted with black circles (●), and the average value of intensity for the second level is plotted with crosses (x).

  In FIG. 17, factors that combine two factors are shown in the same display method as in FIG. 10. The intensity value “23.1” in the figure is an average value of all measured values, and the intensity values “37.8” and “8.5” are average values ± standard deviation values, respectively. . This factor effect diagram shows that the factors B and C having a large difference in values for the first and second levels and the combination factor B × C greatly affect the strength of the sample body 40a. ing.

  From the factor-effect diagram of FIG. 17 and the test results by analysis of variance, each factor A to D is in the order of factor B, factor C, factor D, factor A, the strength against the load on the central part of the sample body 40a (hereinafter, It was found to affect the "center strength"). That is, the width of the short side of the through hole 41 most affects the strength of the central portion of the sample body 40a, and it is preferable that the width is large. Next, it is preferable that the thickness of the sample body 40a affects the strength of the central portion of the sample body 40a, and the thickness is larger. Next, it is preferable that the arrangement configuration of the through holes 41 is such that the thickness of the sample body 40a affects the strength of the central portion of the sample body 40a, and the through holes 41 are arranged at substantially equal intervals. The factor having the least influence on the strength of the central portion of the sample body 40a is the distance between the through hole 41 and the long side of the outer peripheral end of the sample body 40a, but the through hole 41 is close to the outer peripheral end of the sample body 40a. The central portion strength is improved by being formed at the position.

  By the way, in the factor effect diagram of FIG. 17 and the test result by analysis of variance, the factors A and C and the factors B and C further have an interaction, and the factors A × C and B × C combining them are the sample body 40a. It was shown that it greatly affects the strength of the central part. Therefore, the optimum combination of the setting conditions for the factors A and C and the factors B and C showing the interaction was examined by the estimated value plot described below.

FIG. 18 is an explanatory diagram showing estimated value plots for the factor A × C and the factor B × C. In this estimated value plot, the estimated values of the intensity when the first and second level settings are combined for the factor A × C are plotted on the left side of the page. Specifically, for the combination of the first or second level of factor A and the first level of factor C (indicated as “A ₁ C ₁ ” or “A ₂ C ₁ ” in the figure), Plotted with black circles (●). On the other hand, the combination of the first or second level of factor A and the second level of factor C (shown as “A ₁ C ₂ ” or “A ₂ C ₂ ” in the figure) is indicated by a cross ( X) is plotted.

Also, on the right side of the page, the estimated values of the intensity when the settings of the first and second levels are combined for the factor B × C are plotted. Specifically, for the combination of the first or second level of factor B and the first level of factor C (indicated as “B ₁ C ₁ ” or “B ₂ C ₁ ” in the figure), Plotted with black circles (●). On the other hand, the combination of the first or second level of factor B and the second level of factor C (indicated as “B ₁ C ₂ ” or “B ₂ C ₂ ” in the figure) is a cross ( X) is plotted.

The estimated value plot shown on the left side of the page shows the following. That is, for the combination of factors A and C, it is preferable to secure the strength by combining the first level of factor A and the second level of factor C (A ₁ C ₂ ). In addition, when the factor C is at the second level, the intensity does not change significantly regardless of whether the factor A is at the first or second level (A ₁ C ₂ , A ₂ C ₂ ). On the other hand, when the factor C is at the first level, the factor A is at the second level (A ₂ C ₁ ) when the factor A is at the first level (A ₁ C ₁ ). ) More improved strength.

  From this, the inventors of the present invention have found the following. That is, the closer the formation position of the through hole 41 is to the outer peripheral end of the sample body 40a and the greater the thickness of the sample body 40a, the more the central portion strength of the sample body 40a is improved. Further, if the thickness of the sample body 40a is increased, the influence of the distance between the through hole 41 and the outer peripheral end of the sample body 40a on the central portion strength is relatively small. Conversely, when the thickness of the sample body 40a is relatively thin, the strength of the central portion is improved as the distance between the through hole 41 and the outer peripheral end of the sample body 40a is reduced.

Moreover, the estimated value plot shown on the right side of the drawing shows the following. That is, for the combination of the factors B and C, it is preferable to combine the second level of the factor B and the second level of the factor C (B ₂ C ₂ ) in order to secure the central portion strength. In this combination, remarkably high strength can be obtained as compared with the conditions in which other factors A and C and factors B and C are combined. Further, when the factor C is the second level, the factor C is changed to the first level when the factor B is changed from the first level to the second level (B ₁ C ₂ → B ₂ C ₂ ). When the factor B is changed from the first level to the second level (B ₁ C ₁ → B ₂ C ₁ ), the degree of improvement in strength is greater.

  From this, the inventors of the present invention have found the following. That is, by appropriately setting the width of the short side of the through hole 41 and the thickness of the sample body 40a, the strength of the central portion of the sample body 40a can be further improved. More specifically, the strength of the central portion of the sample body 40a can be improved by increasing the width of the short side of the through hole 41 and increasing the thickness of the sample body 40a. Further, the thicker the sample body 40a, the higher the degree of improvement in the central portion strength when the width of the short side of the through hole 41 is increased.

  Thus, in the second experimental example, the central portion strength of the sample body 40a could be improved by configuring the width of the short side of the through hole 41 to be wide. Therefore, also in the artificial skull flap, by configuring the width of the short side of the through hole 11 wider, the central portion strength, which is the strength against the load applied to the center side from the through hole 11, can be improved. However, as described above, if the width of the short side of the through-hole 11 is made too large with respect to the thickness of the holding member 30, there is a possibility that the fixing / holding property of the holding member 30 by the through-hole 11 is lowered. is there. Therefore, when the thickness of the holding member 30 is about 0.5 to 0.8 mm, the width of the short side of the through hole 11 is preferably about 1 mm to 2 mm, and is almost 2 mm (about ± 25%). More preferably, it may be 2 ± 0.5 mm in consideration of errors.

  Moreover, the sample body 40a was able to improve the center part intensity | strength by thickening the thickness. Therefore, even in the artificial skull flap, the central portion strength can be improved by configuring the artificial skull valve to be thicker. However, since the thickness of the artificial skull flap is preferably balanced with the thickness of the skull 20 as described above, it is preferably 5 to 7 mm, and at most 7 mm (7.0 considering an error of about + 20%). It is desirable that the thickness is ˜8.4 mm.

  In the second experimental example, when the thickness of the sample body 40a is about 5 mm, the distance between the long side of the through hole 41 and the outer peripheral end of the sample body 40a is 8 mm, compared to 15 mm. The strength of the central part of the sample body 40a was improved when Therefore, when the artificial skull flap is configured to be relatively thin, by reducing the distance between the long side of the through hole 11 and the outer peripheral end of the artificial skull valve, the strength of the central portion can be reduced. It is possible to suppress. However, if the distance between the long side of the through-hole 11 and the outer peripheral end portion of the artificial skull valve is too short, the retainability of the artificial skull valve by the holding member 30 may be lowered. Therefore, the distance between the long side of the through hole 11 and the outer peripheral end of the artificial skull flap is preferably about 8 to 12 mm. When the thickness of the artificial skull valve is about 5 mm, the distance between the long side of the through-hole 11 and the outer peripheral end of the artificial skull valve is 8 mm (8 ± 1. 6 mm may be preferable).

  Further, in the second experimental example, when the thickness of the sample body 40a is 7 mm and the width of the short side of the through hole 41 is 2 mm, the strength of the central portion of the sample body 40a shows the highest value. Therefore, even in the artificial skull flap, the thickness is set to about 7 mm, and the width of the short side of the through hole 11 is set to 2 mm (2 ± 0.5 mm may be considered in consideration of an error of about ± 25%). The central portion strength can be further improved.

  In the second experimental example, the strength of the central portion is improved when the through holes 41 of the sample body 40a are arranged at almost equal intervals than when the through holes 41 are arranged at a biased position. It was. Therefore, also in the artificial skull valve, it is preferable that the plurality of through holes 11 are arranged in a well-balanced manner so as to be substantially equally spaced along the outer periphery of the artificial skull valve.

  By the way, the sample body 40a in the second experimental example was not provided with a groove corresponding to the groove 12 described in the first embodiment. However, in the second experimental example, when the sample body 40a receives a load at a position inside the through hole 41, the inventor of the present invention presses the long side outside the through hole 41 by the holding member 30. I observed that. That is, when the groove portion corresponding to the groove portion 12 is provided in the sample body 40a, the holding member 30 presses the formation portion of the groove portion that is thinned and has reduced strength, so that the breakage of the sample body 40a is promoted, and the central portion The strength may decrease. Therefore, when providing a groove part in the sample body 40a, it is preferable to ensure sufficient thickness in the formation part of a groove part, and to ensure the intensity | strength of the said area | region.

  That is, when the groove 12 is formed in the artificial skull flap, it is preferable that at least the region where the groove 12 is formed has the above thickness value. Thereby, even if it is a case where the groove part 12 is formed, the fall of the intensity | strength of an artificial skull flap can be suppressed. Further, if the raised portion 14 described in the second embodiment is provided corresponding to the groove portion 12, even if the thickness in the formation region of the groove portion 12 is the above-described thickness value, the region other than the formation region of the groove portion 12 is used. It is possible to comprise in thickness with the thickness of about 5-7 mm. Therefore, an increase in the thickness of the artificial skull flap in a region other than the region where the groove 12 is formed can be suppressed, and an increase in the weight of the artificial skull valve can be suppressed.

  Thus, according to the artificial skull flap of 3rd Embodiment, center part intensity | strength and outer periphery part intensity | strength can be improved by setting the thickness and the width | variety of the short side of the through-hole 11 appropriately. Therefore, damage at the time of attachment to the skull 20 or after attachment can be suppressed. Further, according to the artificial skull valve of the third embodiment, even when the thickness is configured to be relatively thin, by forming the position of the through hole 11 closer to the outer periphery of the artificial skull valve, the outer periphery portion Strength can be improved. Therefore, damage to the artificial skull valve during attachment to the skull 20 can be suppressed.

D. Variations:
The present invention is not limited to the above-described embodiments and examples, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
In the above embodiment, when attaching the artificial skull flaps 10 and 10A to the bone defect portion 21 of the skull 20, the holding member 30 obtained by deforming a rectangular plate is used. However, the artificial skull flaps 10, 10 </ b> A may be attached to and held by the bone defect part 21 of the skull 20 by another member instead of the holding member 30. Specifically, for example, the artificial skull flaps 10, 10 </ b> A may be attached to and held by the bone defect 21 of the skull 20 by inserting a thread-like member through the through hole 11. In this case, the through hole 11 and the groove portion 12 only need to be configured in a shape and size through which a thread can be inserted.

D2. Modification 2:
In the artificial skull valves 10, 10 </ b> A of the above-described embodiment, in order to improve the fixing property of the holding member 30, two pins 34 are used as holes that receive and hold at least a part of the distal end portion of the holding member 30. Two bottomed holes 13 for inserting the holes are provided corresponding to the through holes 11. However, the hole for holding at least a part of the tip of the holding member 30 may not be the two bottomed holes 13, and differs from the two bottomed holes 13 depending on the configuration of the holding member 30. A hole having a configuration may be formed. For example, instead of the two bottomed holes 13, a through hole into which two pins 34 can be inserted may be provided. Further, instead of the two bottomed holes 13, a rectangular hole portion capable of accommodating a distal end bent portion obtained by bending the distal end portion of the holding member 30 may be formed. Further, in the artificial skull valves 10 and 10A, the hole portion that accommodates and holds at least a part of the distal end portion of the holding member 30 as described above may be omitted. In this case, the holding member 30 is fixed to the bone defect portion 21 of the skull 20 by pre-adhering the distal end portion thereof to the second surface S2 of the artificial skull valve 10, 10A. It is good also as what is attached to.

D3. Modification 3:
In the second embodiment, the raised portion 14 of the artificial skull flap 10A has a through hole 11, a groove portion 12, and two bottomed holes in the formation region when the artificial skull flap 10A is viewed along the thickness direction. 13 was included. However, the bulging part 14 should just be formed in the thickness direction lower part of the groove part 12 so that the thickness in the formation area of the groove part 12 may be compensated. However, when the artificial skull flap 10A is viewed in the thickness direction, if the through hole 11 and the two bottomed holes 13 are included in the formation region of the raised portion 14, the through hole 11 and the two bottomed holes It is possible to ensure the strength at the site where the hole 13 is formed. Further, since the raised portion 14 is desirably formed gently so as to gradually increase the height in order to protect the dura mater, it is formed in a relatively wide region with respect to the region where the groove portion 12 is formed. It is preferable.

DESCRIPTION OF SYMBOLS 10 ... Artificial skull valve 10A ... Artificial skull valve 11 ... Through-hole 12 ... Groove part 13 ... Bottom hole 14 ... Raised part 15 ... Outer peripheral end surface 20 ... Skull 21 ... Bone defect part 30 ... Holding member 31 ... Main-body part 31a ... 1st Main body part 31b ... Second main body part 32 ... Tip part 33 ... Screw hole 34 ... Pin 35 ... Fixing screw 40 ... Sample body 40a ... Sample body 41 ... Through hole 42 ... Groove part 43 ... Bottomed holes 51, 52 ... Supporting member 53 ... Support base 531 ... Recessed portion 55 ... Cross head 56 ... Buffer material S1 ... First surface S2 ... Second surface

Claims (4)

An artificial skull valve used for filling a bone defect portion of a skull, wherein a plurality of through holes for inserting a holding member for holding the artificial skull valve in the bone defect portion are provided on an outer periphery of the artificial skull valve. In the artificial skull flap that is arranged along the edge,
A first groove that extends from each of the plurality of through-holes toward an outer peripheral end of the artificial skull flap and that is outside when a groove for arranging a part of the holding member is compensated for the bone defect. An artificial skull flap on the surface side. The artificial skull valve according to claim 1, further comprising:
The second surface opposite to the first surface is provided with a raised portion having a thickness greater than that of the other part,
The protuberance is an artificial skull flap that is provided at least in a region overlapping with the groove when the artificial skull flap is viewed in the thickness direction. The artificial skull valve according to claim 2,
The artificial skull flap, wherein the thickness of the portion where the groove portion and the raised portion overlap when viewed along the thickness direction of the artificial skull flap is substantially the same as the thickness of the other portion. The artificial skull valve according to any one of claims 1 to 3,
Each of the plurality of through holes has a horizontally long shape having a long side in the direction along the outer periphery of the artificial skull flap,
The holding member includes a first part extending along the first surface from an outer periphery of the artificial skull flap, a second part bent from the first part and inserted into the through hole, Including a plate-like member having a tip extending from the through hole along the second surface opposite to the first surface;
The second surface is provided with holes for accommodating and holding at least a part of the tip of the holding member corresponding to each of the plurality of through holes,
The holding member has a thickness of 1 mm or less,
The thickness of the artificial skull flap is 5-7 mm,
Each of the plurality of through holes is an artificial skull flap having a width in the short side direction of 2 mm ± 0.5 mm.

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