JP2005329179A - Medical implant, its manufacturing method, and method and device for forming groove in device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medical implant having grooves for ensuring their sufficient growth of bones of human beings or animals on its surface to be in contact with the bones, or a medical implant capable of firmly bonding with them, and its manufacturing method. <P>SOLUTION: In this medical implant, having a surface portion to be in close contact with bones to be fixed, the surface portion is provided with a plurality of grooves stretching in a prescribed direction. The ratio D/W of the space D between each of the above-mentioned grooves in the intersecting direction at right angles to the prescribed direction to the groove width W is 3 to 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a prosthetic joint component and a dental implant used for a hip joint, a knee joint, a shoulder joint, an ankle joint, an elbow joint, a wrist joint, and the like, and a medical implant including a part to be transplanted into a human body or an animal, a manufacturing method and a manufacturing method thereof. Relates to the device.

  FIG. 32 shows a general artificial joint (artificial hip joint) 1001 in the hip joint. The artificial hip joint shown in the figure includes a acetabular part 1004 installed on the lower side of the hipbone 1006 and a bone head (ball part) 1008 that engages with the acetabular part 1004 via a buffer part 1007 formed of polyethylene or the like. And a stem (handle) portion 1010 that extends in the longitudinal direction and is inserted and joined to the shaft portion of the femur 1012. All of the artificial joint 1001 (artificial acetabulum, bone head, and stem) are made of a hard material, for example, a biomedical metal. The biomedical metal means a metal having affinity for a living body, particularly bone tissue, and not harmful (including an alloy), that is, a metal having biocompatibility. For example, pure titanium, titanium alloy, Co-Cr Etc. are included.

  Such an artificial joint 1001 is sufficient for a joint between a medical implant and a bone, for example, a joint between a stem 1010 and a femur 1012 or a joint between an outer surface of an artificial acetabulum 1004 and a hipbone 1006. Ensuring adhesion was a major issue. Therefore, conventionally, a technique for joining a medical implant to bone using bone cement has been generally adopted. In this joining technique, bone cement containing methyl methacrylate as a main component is thinly applied to the joint portion, and a joint state in which the medical implant and the bone are in close contact with each other is formed through this bone cement. However, this technique has been pointed out as a drawback that loosening gradually occurs between the bone cement and the biomedical metal over time, and that reoperation is difficult.

  As another bonding technique, plasma spray coating is proposed in which fine particles made of the same biomedical metal as the medical implant are spray-coated on the surface of the medical implant, and then the fine particles are heat-treated and partially melted to adhere to the surface of the medical implant. ing. This spray coating forms irregularities that allow bone tissue to grow and enter the surface of the medical implant. Therefore, as expected, if the bone tissue enters the unevenness formed on the surface of the medical implant and “roots”, the bonding strength is considered to be very large. However, the degree of unevenness (size) formed by this plasma spray coating varies considerably. For this reason, an ideal bond strength between the medical implant and the bone is hardly obtained. In addition, in medical implants using this plasma spray coating, there is a phenomenon in which fine particles that are not sufficiently melted are peeled off over time, and the necessary adhesion, adhesion, and bonding strength are obtained. I can't.

  As another technique, there is a technique in which a mesh-like biomedical metal film is wound around a medical implant surface part that comes into contact with bone, heat-treated and partially melted, and the metal film is fixed to the stem part. However, this technique has a problem that a sufficient strength cannot be obtained at a portion where the mesh-like film is wound in several layers because the metal film is stuck in several layers.

  In recent years, as a new technique that replaces these techniques, a technique has been developed in which a medical implant surface formed of a biomedical metal or the like is processed with a laser so as to closely bond the medical implant and the bone. Specifically, in Patent Document 1 and Patent Document 2, a medical implant having a high bone affinity is formed by irradiating a surface of a titanium alloy or the like with a laser beam to form a recess having a minute diameter (for example, a diameter of 150 to 400 μm). Techniques for manufacturing the are disclosed. Patent Document 3 discloses a technique for creating a medical implant with high bone affinity by melting a surface of a titanium alloy or the like with a laser to form a protrusion or a needle-like portion there. However, none of the laser processing techniques is sufficient to ensure a sufficient fixing strength at the joint portion. Further, Patent Documents 4 and 5 disclose techniques for processing the surface of a medical implant with a laser. However, the technique disclosed in Patent Document 4 is not used for joining a bone and a medical implant, but relates to the formation of a sliding surface of a joint. The technique disclosed in Patent Document 5 relates to a technique for forming a reticulated stent that serves as a support for a blood vessel wall from a bioabsorbable material such as polyhydroxybutyric acid (PHB). is not.

Japanese Patent Laid-Open No. Sho 63-160662 U.S. Pat. No. 5,222,983 International Patent Application WO00 / 62831 International Patent Application WO90 / 14447 US Pat. No. 6,160,240

  It is an object of the present invention to provide a medical implant provided with a groove that can sufficiently and reliably grow human and animal bones on a surface in contact with the bone, or a medical implant that adheres firmly to the bone, and a method for manufacturing the same. And Another object of the present invention is to provide a medical implant that realizes highly reliable bonding properties and a method for manufacturing the medical implant.

  In order to achieve these objects, the present invention provides a medical implant having a surface portion fixed in close contact with bone, wherein the surface portion has a plurality of grooves extending in a predetermined direction and is orthogonal to the predetermined direction. A ratio D / W between the groove interval D and the groove width W in the transverse direction is 3 to 30.

  According to another aspect of the present invention, in the medical implant having a surface portion fixed in close contact with the bone, the surface portion has a plurality of grooves extending in a predetermined direction, and the center lines of the two adjacent grooves are The ratio A2 / A1 between the area A1 occupied by the groove per unit length in the predetermined direction and the area A2 of the convex portion located between the two grooves is 1 to 5 It is characterized by that.

  According to another aspect of the present invention, in the medical implant having a surface portion that is fixed in close contact with the bone, the surface portion intersects the first direction with a plurality of first grooves extending in the first direction. In a region having a plurality of second grooves extending in the second direction and sandwiched between the center lines of the two adjacent first grooves and the two adjacent center lines of the second grooves, The ratio A2 / A1 between the area A1 occupied by one groove and the second groove and the area A2 of the convex portion surrounded by the first groove and the second groove is 1 to 5.

  According to another aspect of the present invention, in the medical implant having a surface portion that is fixed in close contact with the bone, the surface portion has a plurality of grooves extending in a predetermined direction, and the groove is a predetermined portion of the surface portion. The sum Ly of the component lengths in the first direction of one or more grooves included in the area and the sum Lx of the component lengths in the second direction orthogonal to the first direction are expressed as Ly / Lx = 1/4. It is characterized by having a ratio of ˜4.

  Another aspect of the present invention is a method for manufacturing a medical implant, in which a biomedical metal is formed into a predetermined outer shape to form an intermediate material for implanting before forming a groove, and then a groove is formed in the intermediate material. From the position corresponding to one end of the groove in the direction perpendicular to the longitudinal direction of the groove to be formed (transverse direction) to the position corresponding to the other end of the groove A first step of moving to form a first groove portion, and moving the irradiation position in a transverse direction of the groove from a position corresponding to the other end of the groove to a position corresponding to one end of the groove. The second step of forming the second groove portion connected to the first groove portion, between the first step and the second step, or in parallel with the first step, or In parallel with the second step, the irradiation position is set in the longitudinal direction of the groove. Characterized in that it comprises a moving step of moving the.

  Another aspect of the present invention is a method for manufacturing a medical implant in which a biomedical metal is formed into a predetermined outer shape to form a medical implant intermediate material before groove formation, and then a groove is formed in the intermediate material. Fixing a medical implant intermediate material to be formed on a base with a groove-formed portion directed in a laser irradiation direction, and reflecting and reflecting a laser beam emitted from a laser generator The laser beam emitted from the laser generator is reflected by the mirror while operating the mirror capable of changing the optical path of the beam in the first direction, and the laser beam is irradiated onto the surface of the intermediate material for medical implant and the laser The beam irradiation position is moved from a position corresponding to one end in the transverse direction of the groove to a position corresponding to the other end in the transverse direction of the groove to form a first groove portion. A laser beam emitted from the laser generator while the mirror is operated in a second direction opposite to the first direction, and is reflected by the mirror, The surface of the material is irradiated with the laser beam and the irradiation position of the laser beam is moved from a position corresponding to the other end in the transverse direction of the groove to a position corresponding to one end in the transverse direction of the groove. Between the second laser irradiation step for forming the second groove portion connected to the first groove portion formed in the laser irradiation step, and between the first laser irradiation step and the second laser irradiation step, Alternatively, in parallel with the first laser irradiation step, or in parallel with the second laser irradiation step, a medical step comprising moving the irradiation position in the longitudinal direction of the groove is included. Method of manufacturing plant.

  Another aspect of the present invention is a medical implant manufacturing apparatus for forming a groove in the intermediate material after forming a biomedical metal in a predetermined outer shape to form a medical implant intermediate material before groove formation. A base for fixing the intermediate material, a first moving device for moving the base, a laser generator, a laser beam emitted from the laser generator, and an optical path of the reflected laser beam is changed. And a control device for controlling the first moving device, the laser generator and the second actuator, the control device comprising: The laser beam emitted from the laser generator is reflected by the mirror while the mirror is operated by the second actuator in a direction, and the laser is reflected on the surface of the medical implant intermediate material. And the laser beam irradiation position is moved from a position corresponding to one end portion in the transverse direction of the groove to a position corresponding to the other end portion in the transverse direction of the groove to form a part of the groove. After the execution of the first control means and the first control means, the laser beam is emitted from the laser generator while the mirror is operated by the second actuator in a second direction opposite to the first direction. The reflected laser beam is reflected by the mirror, and the surface of the intermediate material for medical implant is irradiated with the laser beam, and the irradiation position of the laser beam is shifted from the position corresponding to the other end of the groove to one end in the transverse direction of the groove. A second control unit that moves to a position corresponding to the part and forms a part of another groove following a part of the groove formed in the first laser irradiation step; and The second above after execution Before the execution of the control means, or in parallel with the execution of the first control means, or in parallel with the execution of the second control means, a third moving the base in the longitudinal direction of the groove Control means is provided.

  Another aspect of the present invention is characterized in that the medical implant is a prosthetic joint used for a hip joint, a knee joint, a shoulder joint, an ankle joint, an elbow joint, or a wrist joint.

  In another aspect of the present invention, the medical implant is a acetabular portion, and the groove is formed in a surface portion in contact with the bone.

  According to the medical implant of the present invention and the medical implant manufactured by the medical implant manufacturing method and manufacturing apparatus of the present invention, bone tissue grows inside the groove of the surface portion of the medical implant to be joined to the bone, and the medical implant and the bone Sufficient adhesion strength can be obtained during this period. In addition, the medical implant of the present invention can sufficiently withstand the large repetitive stress acting on the joint with bone.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the embodiment, for easy understanding, terms representing directions (for example, “longitudinal direction”, “transverse direction”, “X direction”, “Y direction”, etc.) are used as appropriate. This is for explanation, and the technical scope of the present invention is not limited by these terms.

  An artificial joint 1 shown in FIG. 1 is a prosthetic joint for a hip joint, and has a plurality of medical implants, that is, a stem portion 2 and a acetabular portion 3. The stem portion 2 has an upper ball portion 4 and an elongated lower stem portion 5 extending downward from the ball portion 4, and the lower stem portion 5 is attached and fixed to a hole 7 formed in the femur 6. The ball part 4 and the lower stem part 5 may be formed integrally or may be formed separately and connected by appropriate connecting means (for example, welding, mechanical connection mechanism). On the other hand, the acetabular part 3 has a cup shape having a hemispherical inner surface and an outer surface, and is mounted and fixed in a cup-shaped depression formed in the hipbone 8. Therefore, it is preferable that the stem portion 2 and the acetabular portion 3 that are in contact with the bone are formed of a biocompatible metal such as a Co—Cr alloy and a Ti alloy. The stem portion 2 and the acetabular portion 3 fixed to the bone in this way are formed by placing the ball portion 4 of the stem portion 2 on the cup-shaped buffer portion 9 made of a material such as polyethylene disposed on the inner spherical surface of the acetabular portion 3. It is accommodated and connected.

The lower stem portion 5 in contact with the femur 6 and the acetabular portion 3 in contact with the hipbone 8 are formed with a plurality of grooves in the portion in contact with the bone in order to increase the adhesive force with the bone. The groove does not have to be formed in all the regions in contact with the bones of the lower stem portion 5 and the acetabular portion 3, and may be formed in a part. In particular, the lower stem portion 5 may be provided only in the upper half of the region in contact with the bone.
The medical implant according to the present invention grows bone in the groove formed as described above by directly contacting the outer surface of the medical implant and the bone without using an adhesive such as bone cement, thereby fixing the both. It is intended. Further, in the medical implant according to the present invention, the intermediate material for medical implant before the groove is formed on the surface may be formed by a conventional technique (for example, cutting or molding).

  FIG. 2 is an enlarged view of the surface portion where the groove of the lower stem portion 5 is formed. As shown in the drawing, the surface portion has a left lower direction (first direction) with respect to a main surface direction defined on a surface in which the lower stem portion 5 is attached to the lower stem portion 5 and in contact with the bone. ) And a plurality of parallel grooves 14 extending obliquely downward to the right (second direction).

  Stem portion 2 with respect to the bone in a main surface direction and a circumferential direction perpendicular thereto (subsurface direction: a direction defined on a surface extending in a direction perpendicular to the main surface direction and lower stem portion 5 in contact with the bone) In order to prevent displacement, the grooves 14 and 16 have a main surface direction component length Ly with respect to the main surface direction and a sub surface direction component length Lx with respect to the sub surface direction orthogonal to the main surface direction Ly / Lx = 1/4 to 4-4. It is preferable to form it in such a direction as to have a ratio of Specifically, as shown in FIG. 3, the ratio Ly / Lx of the sum of the component lengths in the main surface and sub-surface directions of the plurality of grooves 14 formed per unit area region is 1/4 to 4. It is preferable that the groove 14 is formed. In addition, in the groove 14 formed on the surface of the lower stem portion 5 of the artificial hip joint, in order to improve the breaking strength and prevent the occurrence of loosening, the longitudinal component Ly of the lower stem portion 5 and its transverse More preferably, the ratio Ly / Lx of the component Lx is 2-4.

  Also, the transverse width (first and second directions) of the grooves 14 and 16 to promote the growth of bone tissue within the grooves 14 and 16 and increase the adhesion between the bone and the medical implant surface. ) W and pitch D are values in which the ratio D / W is 3 to 30 [specifically, any integer value between 3 and 30 (3,4, 5, 6... 27, 28, 29, 30)].

As shown in FIG. 4, the ratio A2 / A1 between the area A1 of the groove at the predetermined distance L in the predetermined direction and the area A2 of the convex portion sandwiched between two adjacent grooves is 1 to 5 [specifically, Is preferably an arbitrary integer value (1, 2, 3, 4, 5)] between 1 and 5.
Similarly, the width W and the pitch D in the transverse direction of the grooves 14 and 16 extending in different directions are such that the first groove 16 is in the region sandwiched by the center lines 18 ′ of the two adjacent first grooves 16. The ratio A2 / A1 between the area A1 occupied by the area A2 and the area A2 of the convex portion 19 located between the two first grooves is 1 to 5 [specifically, any integer value between 1 and 5 (1 , 2, 3, 4, 5)] is preferable (FIG. 5).

  As shown in the figure, when the grooves 16 in the first direction and the grooves 14 in the second direction are provided, the grooves and the pitches are set to the two second grooves adjacent to the center line 18 ′ of the two adjacent first grooves 16. In the rhombus region surrounded by the center line 18 of the second groove 14, the area A <b> 1 occupied by the first groove 16 and the second groove 14 and the convex portion 19 surrounded by the first groove 16 and the second groove 14. It is preferable that the ratio A2 / A1 with the area A2 is 1 to 5 (specifically, any integer value (1, 2, 3, 4, 5) between 1 and 5).

  Specifically, the pitch D of the grooves 14 and 16 of the stem portion 2 is about 1 mm to about 5 mm, more preferably about 2 mm to about 4 mm, and most preferably about 3 mm. The width W of the grooves 14 and 16 is about 100 μm to about 1000 μm, preferably about 300 μm to about 700 μm, and most preferably about 500 μm. In a specific design, the width and pitch of the groove are determined so as to satisfy the above relationship within these ranges.

  Of course, it is also preferable that the depth of the groove is determined so as to promote the growth of bone tissue inside the grooves 14 and 16 to increase the adhesion between the bone and the surface of the medical implant. Specifically, the depth of each of the grooves 14 and 16 is about 200 μm to about 1000 μm, preferably about 400 μm to about 600 μm, and most preferably about 500 μm.

  Further, stress is concentrated on the bone tissue portion attached to the start and end portions of the grooves 14 and 16 formed in the stem portion 2 while being fixed to the bone. Therefore, it is preferable that the depth gradually becomes shallower at the start and end sides of the groove. For the same reason, it is preferable that the depth of both end portions of the groove in the cross-sectional shape gradually becomes shallower.

  In the above explanation, the stem portion 2 is formed with the two grooves 14 and 16 extending in the first direction and the second direction oblique to the main surface direction. Only the grooves in the second direction may be formed. Further, only a plurality of parallel grooves extending in the main surface direction may be formed, or only grooves in a direction (subsurface direction) orthogonal to the main surface direction may be formed, or grooves in these main surface directions may be formed. And a groove in the sub surface direction may be formed. However, it is natural that the width, depth, and pitch of the grooves formed in the main surface direction and the sub surface direction are preferably designed in the above-described ranges.

  The width, depth, and pitch of the grooves formed on the outer surface of the acetabular part 3 are preferably set to the same conditions as the grooves described for the stem part 2. However, in the case of the acetabular part 3, since the surface in contact with the bone is a hemispherical surface, as shown in FIG. 6, the acetabular part 3 extends in the direction in which the acetabular part 3 is attached to the bone, and the acetabular part 3 The principal surface direction defined on the surface in contact with the bone is on the hemispherical surface and extends from the lower edge to the center of the hemispherical surface, extends in a direction perpendicular to the principal surface direction, and the acetabular portion 3 is bone. The sub-surface direction defined on the surface in contact with is a circumferential direction centered on the central axis on the hemispherical surface.

  The groove pattern formed on the outer spherical surface of the acetabular part 3 is more diverse than the groove pattern formed on the stem part 2. For example, FIG. 7 shows a plurality of parallel grooves 21 extending in the first direction and a plurality of parallel grooves 22 extending in a second direction oblique to the first direction on the outer spherical surface of the acetabular part 3. An example in which is formed is shown. FIG. 8 shows an example in which only the plurality of parallel grooves 23 extending in the first direction are formed on the outer spherical surface of the acetabular part 3. FIG. 9 shows an example in which a plurality of annular grooves 24 extending in the circumferential direction around the central axis are formed concentrically on the outer spherical surface of the acetabular part 3. FIG. 10 shows an example in which a plurality of different-sized annular grooves 25 extending in the circumferential direction around the central axis and a plurality of grooves 26 extending in the radial direction (main surface direction) from the central axis are formed. FIG. 11 shows an example in which a plurality of grooves 28 extending along a plurality of lines connecting two points separated by 180 degrees in the circumferential direction in the vicinity of the lower edge of the hemispherical surface are formed.

  A closed loop groove having an arbitrary shape may be arranged in an arbitrary pattern on the outer spherical surface of the acetabular part 3. The shape of the closed loop groove may be circular (see FIGS. 12 and 13), hexagon (see FIG. 14), or oval (see FIGS. 15 and 16). Application of these closed loop grooves is not limited to the acetabular part 3, and similar closed loop grooves may be formed in the stem part 2 in an arbitrary pattern.

  As shown in FIGS. 17 to 19, curved grooves 30 and linear grooves 31 may be arranged in the acetabular part 3 and the stem part 2 in an arbitrary pattern. And the curve shape is arbitrary, and as shown in FIG. 20, you may form a groove | channel in a spiral shape centering on a central axis. Further, as shown in FIG. 21, the acetabular part 3 and the stem part 2 extend in a second direction different from the plurality of first grooves 31 extending in the first direction and are adjacent to each other. A plurality of second grooves 31 ′ disposed between the grooves 31.

  The grooves formed in the acetabular part 3 and the stem part 2 may have a corrugated pattern or a zigzag pattern, as shown in FIGS.

  As described above, various groove shapes and groove arrangements have been shown. However, since stress tends to concentrate at the points where the grooves intersect, it is preferable to select a pattern having as few points as possible where the grooves intersect. However, if the number of points where the grooves intersect is not more than a certain limited number (for example, 10), there is substantially no problem in strength.

  The cross-sectional shape of the groove is arbitrary, and as shown in FIG. 25, any of a rectangular cross-section, a trapezoidal cross-section, a cross-section having a circular arc or semicircular bottom, or a V-shaped cross-section may be adopted. Moreover, it is preferable in view of breaking strength that the groove side end portion is smoothly continuous. Therefore, a shape as shown in FIG. 26B may be adopted as the cross-sectional shape of the groove. Similarly, as shown in FIG. 26 (a), it is preferable from the viewpoint of breaking strength that the grooves are smoothly continuous at the start and end sides of the groove in the longitudinal direction.

  In addition, although the example which applied this invention medical implant utilized for a hip joint above was shown, this invention is applicable similarly to other joints (for example, a knee joint, a shoulder joint, a leg joint, an elbow joint). However, it is not limited to a joint at a specific site. For example, FIG. 27 shows an artificial knee joint 35. In the case of this artificial knee joint 35, the grooves described above can be formed on the surfaces of the stem portion 36 and the receiving portion 37 under the above-described conditions.

  As described above, according to the medical implant according to the present invention, the bone cells of the patient can be grown inside the groove after the transplantation is completed, so that a sufficient bonding strength can be ensured between the bone and the medical implant. Specifically, according to animal experiments conducted by the present inventors, it was confirmed that bone cells grew inside each groove after transplantation, and the bone cell growth rate in the groove exceeded 90%. It was. Also, compared to the shear strength (2.25 Pa) measured after a predetermined period of time after implanting a medical implant using conventional plasma spray coating technology, the shear strength when using the artificial joint of the present invention Has been verified to exceed 6 MPa.

  FIG. 28 shows a medical implant manufacturing apparatus. This apparatus has a table (base) 42 for fixing a medical implant material 41 having an unprocessed groove. The table 42 is connected to a table moving device 46 that moves the table 42 in first, second, and third axial directions (43, 44, 45) orthogonal to each other. Above the table 42, a laser generator 47 and a mirror (galvanomirror) 49 that reflects the laser beam 48 emitted from the laser generator 47 and reflects it toward the table 42 are arranged. The mirror 49 is connected to the mirror rotation device 50 in order to scan the laser beam 48 reflected by the mirror 49 in the first direction, the second direction, or another third direction intersecting therewith. . The table moving device 46, the laser generating device 47, and the mirror rotating device 50 are connected to a control device 52. According to a program incorporated in the control device 52, the medical implant material 41 is irradiated with a laser beam 48 to obtain a predetermined value. A groove is formed.

  When a medical implant is manufactured using an apparatus having such a configuration, the medical implant material 41 is fixed to the table 42. The control device 52 controls the table moving device 46 and the mirror rotating device 50 in accordance with the shape of the groove to be formed and the type of the medical implant material 41, and the laser beam 48 emitted from the laser generator 47 is irradiated onto the medical implant material. The target position is changed, and a target groove is formed in the medical implant material. Since the surface of the medical implant material 41 is generally formed with a curved surface, the control device 46 stores the surface shape (three-dimensional shape) of the medical implant material 41 in advance as shape data. Then, the table moving device 46 is driven to move the medical implant 41 in the optical axis direction of the laser beam 48 so that the imaging position of the laser beam 48 coincides with the surface of the medical implant material.

  More specifically, the control device 52 activates the laser generator 47 to emit the laser beam 48, drives the mirror rotating device 50 to rotate the mirror 49 in one direction, and emits the laser beam from the laser generator 47. The laser beam 48 thus scanned is scanned on the surface of the medical implant material 41 in the first direction, the second direction, or the third direction (hereinafter, this direction is referred to as “main scanning direction”), and the groove is substantially omitted. A part of the groove extending from a position corresponding to one end of the groove toward a position corresponding to the other end is formed in the orthogonal transverse direction (first step, FIG. 29). Next, the control device 52 drives the table moving device 46 to move the medical implant material 41 by a minute amount in the sub-scanning direction orthogonal to the main scanning direction (second step, FIG. 30). The amount of minute movement is preferably in the range of 10% to 100%, preferably 20% to 90%, more preferably 30% to 80% of the laser diameter irradiated onto the artificial joint surface. The laser diameter is a distance between two points that is 1 / e (= 0.3679) of the optical power in the cross section of the laser beam at the irradiation position. Next, the control device 52 switches the mirror rotation direction by the mirror rotation device 50 in the reverse direction, and separates the groove extending from the position corresponding to the other end of the groove to the position corresponding to one end in the main scanning direction. Is formed (third step). A part of the groove formed at this time is connected to a part of the previously formed groove because the movement amount of the medical implant material 41 in the sub-scanning direction is controlled to a minute amount as described above. . Next, again, the control device 52 drives the table moving device 46 to move the medical implant material 41 by a minute amount in the sub-scanning direction orthogonal to the main scanning direction (fourth step, FIG. 30). Then, the control device 52 repeats the four steps described above to extend the groove in the sub-scanning direction.

  The step of moving the medical implant material 41 in the sub-scanning direction need not be provided between the first step and the third step of moving the irradiation position of the laser beam 48 in the main scanning direction, and at the same time as the first step. It may be performed in parallel, may be performed concurrently with the third step, or may be performed concurrently with the first and third steps (FIG. 31).

  The means for moving the optical path of the laser beam 48 in the main scanning direction is not limited to rotating the mirror, and the irradiation position of the laser beam 48 reflected by the mirror 49 on the surface of the medical implant material 41 is changed. Various means that can be moved are available. For example, as a means for operating such a mirror, a moving mechanism for moving (vibrating) the mirror 49 in a direction including a direction component parallel to the optical axis direction of the optical path of the laser beam 48 is included. At this time, it is preferable to move the irradiation point of the medical implant material 41 in small steps and at high speed. The means for operating the mirror as described above includes a means for rotating the mirror and a means for translating (vibrating) the mirror.

  Furthermore, the rotational speed or moving speed of the mirror 49 need not be constant, and can be varied according to the cross-sectional shape of the groove to be formed.

  In addition, the surface of the medical implant material 41 is usually not flat. Therefore, the table moving device 46 preferably has a rotation mechanism that rotates the table 42 in the circumferential direction around the central axes of the first, second, and third axial directions 43, 44, and 45.

  When the groove formed on the surface of the medical implant material 41 manufactured as described above was examined closely, a thermal crack peculiar to the groove formed on the surface of the biometal by normal laser processing was manufactured by the conventional technique. The present inventors confirmed that it was significantly reduced as compared with. Further, it is verified that the generation of thermal cracks is suppressed when the wavelength of the laser beam 48 is shortened using a wavelength converter (for example, 532 nm to 193 nm) and grooves are formed on the surface of the medical implant material 41. It was done. The same effect can be obtained by using an ultraviolet laser such as an excimer laser. Further, compared with a general laser beam having a pulse width of typically 10 nanoseconds, the surface of the medical implant material 41 is applied using a shortened laser beam (for example, 30 femtoseconds or more and 100 picoseconds or less). It was confirmed that the formation of the grooves was also effective in suppressing the formation of thermal cracks.

  In the above description, the laser beam 48 is mainly used as a means for forming a groove on the surface of the medical implant material 41. However, the groove can be formed in the medical implant material 41 by any other method. For example, among the medical implants, in particular, when manufacturing an artificial acetabular part, grooves are formed on the surface of the medical implant material 41 using various processing techniques such as a machining technique, an electric discharge machining technique, and an optical shaping technique. be able to.

It is a perspective view of an artificial joint (artificial hip joint) which is a preferred embodiment according to the present invention. It is the elements on larger scale of the artificial hip joint shown in FIG. It is the elements on larger scale of the artificial hip joint shown in FIG. It is the elements on larger scale of the artificial hip joint shown in FIG. It is the elements on larger scale of the artificial hip joint shown in FIG. It is a perspective view of the artificial acetabulum part shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a top view of the artificial acetabulum part of the artificial joint shown in FIG. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a figure which shows the pattern of the groove | channel formed in the surface of a medical implant. It is a cross-sectional view of the groove | channel formed in the surface of a medical implant. It is the cross-sectional view of the longitudinal direction and the cross direction of the groove | channel formed in the surface of a medical implant. It is a perspective view of an artificial joint (artificial knee joint) which is a preferred embodiment according to the present invention. It is a schematic block diagram of the manufacturing apparatus of the medical implant of suitable embodiment which concerns on this invention. It is the schematic which shows the relationship between a laser beam, the artificial joint surface, and a galvanometer mirror. It is the schematic which shows the relationship between the groove | channel of a medical implant, a laser beam scanning locus | trajectory, and the moving amount | distance of a table. It is the schematic which shows the relationship between the groove | channel of a medical implant, a laser beam scanning locus | trajectory, and the moving amount | distance of a table. The front view of the conventional artificial joint (artificial hip joint).

Explanation of symbols

1 artificial joint, 2 stem part, 3 acetabulum part, 4 ball part, 5 lower stem part, 6 femur, 8 hipbone, 9 buffer part, 14, 16 groove, 18, 18 'center line, 19 convex part, 35 Artificial knee joint, 36 Stem portion, 37 Receiving portion, 41 Medical implant material, 42 Table (base), 46 Table moving device, 47 Laser generator, 48 Laser beam, 49 Mirror (galvano mirror), 50 Mirror rotating device 52 Control device.

Claims (16)

In a medical implant with a surface part that is fixed in close contact with the bone,
The surface portion has a plurality of grooves extending in a predetermined direction,
A medical implant, wherein a ratio D / W between the inter-groove distance D and the groove width W in a transverse direction orthogonal to the predetermined direction is 3 to 30. In a medical implant with a surface part that is fixed in close contact with the bone,
The surface portion has a plurality of grooves extending in a predetermined direction;
The ratio between the area A1 occupied by the groove per unit length in the predetermined direction and the area A2 of the convex portion located between the two grooves in a region sandwiched by the center lines of the two adjacent grooves A medical implant, wherein A2 / A1 is 1-5. In a medical implant with a surface part that is fixed in close contact with the bone,
The surface portion has a plurality of first grooves extending in a first direction and a plurality of second grooves extending in a second direction intersecting the first direction;
The area A1 occupied by the first groove and the second groove in the region sandwiched between the center lines of the two adjacent first grooves and the center lines of the two second grooves adjacent to each other, and the first A medical implant, wherein a ratio A2 / A1 between the groove A and the area A2 of the convex portion surrounded by the second groove is 1 to 5. In a medical implant with a surface part that is fixed in close contact with the bone,
The surface portion has a plurality of grooves extending in a predetermined direction;
The groove has a component length in a second direction perpendicular to the first direction and a sum Ly of component lengths in a first direction of one or a plurality of grooves included in a predetermined area of the surface portion. A medical implant characterized by having a sum Lx of Ly / Lx = 1/4 to 4. A method for producing a medical implant in which a biomedical metal is formed into a predetermined outer shape and used as an intermediate material for an implant before groove formation, and then a groove is formed in the intermediate material,
The irradiation position at which the laser is applied to the medical implant intermediate material corresponds to the other end portion of the groove from a position corresponding to one end portion of the groove in a direction (transverse direction) perpendicular to the longitudinal direction of the groove to be formed. A first step of moving to a position to form a first groove portion;
The irradiation position is moved in a transverse direction of the groove from a position corresponding to the other end portion of the groove to a position corresponding to one end portion of the groove to form a second groove portion connected to the first groove portion. A second step;
Movement for moving the irradiation position in the longitudinal direction of the groove between the first step and the second step, in parallel with the first step, or in parallel with the second step The manufacturing method of the medical implant characterized by including the process. After forming a biomedical metal in a predetermined outer shape to form a medical implant intermediate material before groove formation, a method for manufacturing a medical implant that forms a groove in the intermediate material,
Fixing the medical implant intermediate material to be grooved on the base with the portion where the groove is formed facing the direction of laser irradiation;
Reflecting the laser beam emitted from the laser generator while reflecting the laser beam emitted from the laser generator and operating the mirror capable of changing the optical path of the reflected laser beam in the first direction, The surface of the intermediate material for medical implant is irradiated with the laser beam, and the irradiation position of the laser beam is moved from a position corresponding to one end in the transverse direction of the groove to a position corresponding to the other end in the transverse direction of the groove. A first laser irradiation step for forming a first groove portion;
The laser beam emitted from the laser generator is reflected by the mirror while operating the mirror in the second direction opposite to the first direction, and the surface of the medical implant intermediate material is irradiated with the laser beam. The laser beam irradiation position is moved from a position corresponding to the other end in the transverse direction of the groove to a position corresponding to the one end in the transverse direction of the groove, and the first laser irradiation step formed in the first laser irradiation step is performed. A second laser irradiation step for forming a second groove portion connected to the first groove portion;
The irradiation position is set between the first laser irradiation step and the second laser irradiation step, in parallel with the first laser irradiation step, or in parallel with the second laser irradiation step. The manufacturing method of the medical implant characterized by including the movement process moved to the longitudinal direction of a groove | channel.   The method of manufacturing a medical implant according to claim 6, wherein the operation of the mirror in the first laser irradiation step or the second laser irradiation step includes rotation of the mirror.   7. The method of manufacturing a medical implant according to claim 6, wherein the operation of the mirror in the first laser irradiation step or the second laser irradiation step includes translational movement of the mirror.   The distance by which the irradiation position is moved in the longitudinal direction of the groove in the moving step is 10% to 100% of the laser diameter at the irradiation position. A method for manufacturing a medical implant.   A medical implant manufactured by the manufacturing method according to any one of claims 5 to 9. An apparatus for manufacturing a medical implant that forms a groove in the intermediate material after forming a biomedical metal in a predetermined outer shape to form a medical implant intermediate material before groove formation,
A base for fixing the intermediate material for medical implant;
A first moving device for moving the base;
A laser generator;
A mirror that reflects the laser beam emitted from the laser generator and can change the optical path of the reflected laser beam;
A second actuator for operating the mirror;
A control device for controlling the first moving device, the laser generator and the second operating device;
The control device
While the mirror is operated by the second actuator in the first direction, the laser beam emitted from the laser generator is reflected by the mirror to irradiate the surface of the medical implant intermediate material with the laser beam. First control means for forming a part of the groove by moving the irradiation position of the laser beam from a position corresponding to one end in the transverse direction of the groove to a position corresponding to the other end in the transverse direction of the groove;
After the execution of the first control means, the laser beam emitted from the laser generator is moved while the mirror is operated by the second operating device in a second direction opposite to the first direction. Reflecting with a mirror, irradiating the surface of the intermediate material of the medical implant with the laser beam and the irradiation position of the laser beam from a position corresponding to the other end of the groove to a position corresponding to one end in the transverse direction of the groove Second control means for moving and forming a part of another groove following the part of the groove formed in the first laser irradiation step;
After the execution of the first control means, before the execution of the second control means, in parallel with the execution of the first control means, or in parallel with the execution of the second control means, An apparatus comprising third control means for moving the base in the longitudinal direction of the groove.   The method of manufacturing a medical implant according to claim 11, wherein the operation of the mirror executed by the second actuator includes rotation of the mirror.   12. The method of manufacturing a medical implant according to claim 11, wherein the operation of the mirror performed by the second actuating device includes translational movement of the mirror.   A medical implant manufactured by the manufacturing method according to any one of claims 11 to 13.   15. The medical implant according to claim 1, wherein the medical implant is a prosthetic joint used for a hip joint, a knee joint, a shoulder joint, an ankle joint, an elbow joint, or a wrist joint. Implant. The medical implant according to any one of claims 1 to 4, 10, and 14, wherein the medical implant is a acetabular part, and the groove is formed in a surface portion in contact with a bone.

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