JP2020028509A - Component for prosthetic hip joint and manufacturing method for the same - Google Patents

Abstract

To provide a component for a prosthetic hip joint capable of suppressing destruction of myeloid cells in the thighbone, and capable of being properly used for artificial joint replacement that enables achieving early regeneration of the myeloid cells after surgery.SOLUTION: A component 10 for a prosthetic hip joint includes a body part 14 for supporting a femoral head ball 12, and an insertion part 16 formed integrally with the body part 14 and having a diameter smaller than the body part 14. In an outer face of the insertion part 16, a fitting surface 17 of a shape substantially matching an inner surface shape of an opposed medullary cavity 60 when inserted into the inside of a thighbone 50 is provided over a circumferential direction. Also, the body part 14 and the insertion part 16 are configured by a porous structure with a lot of cavities in communication with the outside through an opening 32 formed in the tip of the insertion part 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a component for a hip prosthesis used for a femoral artificial joint replacement and a method for manufacturing the same.

  FIG. 7A is a diagram schematically showing a femur. In the figure, 50 is a femur, 52 is a head, 53 is a neck, and 54 is a greater trochanter. The outer surface of the femur 50 is covered with cortical bone 56, and the inside thereof is formed of a spongy body 58 composed of a small hole and a mesh-like trabecular bone on the epiphysial side, and a medullary cavity 60 extends on the diaphysis side. The inside of the medullary cavity 60 is filled with bone marrow cells. In the femur 50, the head 52 fits into the acetabulum of the pelvis (not shown) to support the load from the pelvis.

  Here, when a part of the femur is damaged, an artificial joint replacement operation for replacing a part of the femur with an artificial joint is performed. As a component on the femur side of the artificial joint, a stem inserted and fixed to the femur and a separate head ball that functions as a head are used (for example, see Patent Document 1 below).

  An example of an artificial joint replacement using these stems and a head ball is shown in FIG. 7 (B). In the artificial joint replacement, a part (the part on the epiphysis side including the damaged part) of the femur 50 is excised, and then the central part of the remaining femur 50 is excavated to have a size and shape capable of inserting the stem 62. Is formed. Then, after the stem 62 is inserted into the insertion hole 64, the gap between the stem 62 and the insertion hole 64 is filled with the medical cement 66 to fix the stem 62. In FIG. 7B, reference numeral 63 denotes a head ball that performs the function of a head.

  However, in the above-described artificial joint replacement, since the periphery of the medullary cavity 60 is largely scraped off by excavation for forming the insertion hole 64, the bone marrow cells that existed in the medullary cavity 60 of the femur 50 also Most had been destroyed. Hormones that affect blood pressure and blood sugar level are secreted from the bone marrow cells in the medullary cavity 60, and it has been desired to regenerate bone marrow cells lost by artificial joint replacement at an early stage.

JP-A-7-265341

  The present invention can be suitably used for artificial joint replacement in which the destruction of bone marrow cells in the femur is suppressed, and bone marrow cells can be regenerated early after the operation, in view of the above circumstances. An object of the present invention is to provide an artificial hip joint component and a method of manufacturing the same.

Thus, a component for a hip prosthesis of the present invention includes a main body that supports a head ball formed separately or integrally,
An insertion portion formed integrally with the main body portion and having a smaller diameter than the main body portion,
On the outer surface of the insertion portion, a fitting surface having a shape substantially matching the inner surface shape of the opposing medullary cavity when inserted into the inside of the femur is provided in the circumferential direction,
At least a part of the main body and / or the insertion portion is formed of a porous structure having a large number of voids communicating with the outside through an opening formed at a tip of the insertion portion.

In the artificial hip joint component of the present invention, the outer surface of the insertion portion is provided with a fitting surface having a shape that substantially matches the inner surface shape of the opposing medullary cavity when inserted into the inside of the femur, and is provided in the circumferential direction. Therefore, the component for a hip prosthesis can be fixed in position using the medullary cavity, which is a cavity originally formed inside the femur. For this reason, in the artificial joint replacement using the artificial hip joint component of the present invention, when the artificial hip joint component is inserted into the femur of the patient, the artificial hip joint component is reshaped according to the outer shape of the insertion portion of the artificial hip joint component. The work of excavating the inside can be abolished or minimized, and bone marrow cells in the medullary cavity can be prevented from being destroyed by the excavation work. Therefore, in the artificial joint replacement using the hip component of the present invention, many bone marrow cells can be left.
In addition, in the artificial joint replacement using the hip joint component of the present invention, the operation time for excavating the inside of the femur is substantially eliminated, so that the operation time can be significantly reduced.

  According to the present invention, at least a part of the main body and / or the insertion portion is formed of a porous structure having a large number of voids. By fixing the bone marrow cells that have entered into the porous structure, the bone marrow cells can be regenerated at an early stage. Further, the porous structure having a large number of voids is also effective in reducing the weight of a component for an artificial hip joint.

  Here, in the present invention, a thin skin layer having a plurality of through holes can be formed integrally with the porous structure so as to cover the outer periphery of the porous structure.

Even when a part of the artificial hip joint part is a porous structure, a predetermined strength can be easily ensured by providing the skin layer so as to cover the outer periphery thereof. Further, the manufacturability when the artificial hip joint component is formed by the additive manufacturing method can be improved.
Here, the through-hole formed in the skin layer is used as a discharge hole for discharging unmelted metal powder remaining in the artificial hip joint component to the outside when the artificial hip joint component is formed by the additive manufacturing method. Can be After the hip joint component of the present invention is fixed to the patient's femur, a blood vessel penetrating the epidermis layer in and out through the through hole is formed.

Next, the method for manufacturing a hip prosthesis component according to the present invention provides a method for producing a three-dimensional shape of a femur reproduced by superimposing CT cross-sectional imaging data or MRI cross-sectional imaging data obtained from a femur to be replaced with a hip prosthesis component. Based on, determine the shape of the hip joint component,
The component for an artificial hip joint is formed by an additive manufacturing method using a metal powder material.

  According to the manufacturing method of the present invention, it is possible to provide an artificial hip joint component having an optimal shape for each patient based on the three-dimensional shape of the femur reproduced by superimposing CT slice data or MRI slice data. Can be. According to such a manufacturing method, an artificial hip joint part having the features of the present invention, that is, an artificial hip joint having a fitting surface having a shape substantially matching the inner surface shape of the medullary cavity of the patient is provided on the outer surface of the insertion portion. The hip joint component can be easily manufactured. Further, according to the additive manufacturing method employed in the manufacturing method of the present invention, a high degree of freedom is obtained in the shape, so that it is possible to cope with a porous structure having a complicated shape.

  ADVANTAGE OF THE INVENTION According to this invention as mentioned above, the artificial hip joint which can suppress the destruction of the bone marrow cell in a femur, and can be used suitably for the artificial joint replacement which can aim at the regeneration of a bone marrow cell early after operation | movement Component and a method for manufacturing the same can be provided.

(A) is a side view showing an artificial hip joint component according to an embodiment of the present invention together with a separate head ball, and (B) is a diagram showing a portion of the artificial hip joint component on the insertion portion side from the bottom surface side. is there. It is a longitudinal cross-sectional view of the component for artificial hip joints of FIG. 2 is a flowchart showing a procedure for manufacturing the hip joint component of FIG. 1. FIG. 2A is an enlarged view of an insertion portion of the artificial hip joint component of FIG. 1, and FIG. 2B is a diagram of a modification in which a fitting surface area of the insertion portion is different. It is explanatory drawing of the artificial joint replacement using the component for artificial hip joints of FIG. FIG. 2 is a diagram for explaining an effect of the hip joint component of FIG. 1. (A) is a diagram schematically showing a femur, and (B) is an explanatory diagram of a conventional artificial joint replacement using a stem.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a diagram showing a hip joint component 10 of the present embodiment together with a separate head ball 12. The hip prosthesis component 10 includes a main body 14 that supports the head ball 12 and an insertion portion 16 that extends downward from the bottom surface of the main body 14.

  The body portion 14 is a portion located above the cut surface 68 of the femur 50 in the artificial joint replacement, and a conical neck portion 18 that becomes thinner toward the distal end is integrally formed at the upper end thereof. Have been. In the main body portion 14, the neck portion 18 is pressed into the connection hole 12 a of the separate head ball 12 to support the head ball 12.

  The insertion portion 16 is a portion that is located below the cut surface 68 of the femur 50 and is inserted into the femur 50 in the artificial joint replacement. The insertion portion 16 has a smaller diameter than the main body 14, that is, a shorter perimeter, and is formed integrally with the main body 14 via the step portion 20. As shown in FIG. 1B, the step portion 20 is formed over the circumferential direction of the insertion portion 16, and when the insertion portion 16 is inserted into the inside of the femur 50, the step portion 20 faces downward. The surface contacts the upper surface (cut surface 68) of the femur 50.

  The insertion portion 16 has a tapered shape whose peripheral length is gradually reduced from the proximal side toward the distal side, and can be inserted into the medullary cavity 60 of the femur 50 of the patient located below the cut surface 68 of the femur 50. It has been. On the outer surface of the insertion portion 16, a fitting surface 17 having a shape that substantially matches the inner surface shape of the medullary cavity 60 that faces when inserted into the inside of the femur 50 is provided in the circumferential direction. Here, the shape that substantially matches means not only that it completely matches the inner surface shape of the opposing medullary cavity 60 but also that it substantially matches. That is, a shape that can be inserted into the medullary cavity 60 and that can fit without rattling after insertion is also included.

  FIG. 2 shows a longitudinal section of the hip joint component 10. In the artificial hip joint component 10, the main body portion 14 includes a porous structure 14a and a skin layer 14b covering the outer periphery thereof, and the insertion portion 16 includes a porous structure 16a and a skin layer 16b covering the outer periphery thereof. I have. In addition, a hollow portion 30 is formed in the center of the main body portion 14 and the insertion portion 16 and is surrounded by the porous structures 14a and 16a. The cavity 30 is configured to communicate with the outside of the hip prosthesis component 10 through an opening 32 formed at the distal end of the insertion portion 16 and facing downward in the drawing.

In the porous structures 14a and 16a, as shown in the partially enlarged view of FIG. 2, a plurality of rod-shaped or plate-shaped small pieces 26 are joined to each other, and a void 28 is formed in a portion other than the small pieces 26. By providing such porous structures 14a and 16a, it is possible to reduce the weight of the hip joint component. The bone marrow cells that have entered the artificial hip joint component 10 through the opening 32 formed at the distal end of the insertion portion 16 are settled in the voids 28 of the porous structures 14a and 16a, and the small pieces 26 therearound are used as a scaffold. Can grow into
The specific shapes of the porous structures 14a and 16a can be appropriately determined in consideration of manufacturability and strength.

  The skin layers 14b and 16b are thinner than the porous structures 14a and 16a, and are formed so as to cover the porous structures 14a and 16a. The skin layers 14b, 16b are integrally joined to the radially outward ends of the small pieces 26 located near the outer surfaces of the porous structures 14a, 16a, so that the strength of the hip joint component 10 can be increased. In addition, by providing the skin layers 14b and 16b so as to cover the porous structures 14a and 16a, manufacturability in the case where the artificial hip joint component 10 is formed using the additive manufacturing method can be improved.

  As shown in FIG. 1, a plurality of through holes 34 penetrating in the thickness direction are formed in the skin layers 14b and 16b of the present example. The through hole 34 has a function as a discharge hole for discharging unmelted metal powder remaining in the artificial hip joint component 10 to the outside when the artificial hip joint component 10 is manufactured by the additive manufacturing method.

The component 10 for a hip joint prosthesis of the present embodiment is formed by a layered manufacturing method using a powder of a titanium alloy such as Ti-6Al-4V having excellent biocompatibility.
FIG. 3 is a flow chart showing the procedure for manufacturing the hip joint component 10.

  First, a femur 50 of a patient to which the hip joint component 10 is attached is sequentially photographed at a predetermined interval such as 100 μm by a non-destructive cross-section photographing apparatus 40 such as a CT apparatus or an MRI apparatus. Is obtained (step S101). Then, the obtained imaging data of each section is output in DICOM (Digital Imaging and Communications in Medicine) format that can be transmitted to the workstation (step S102).

  Next, at the workstation 42, the above-mentioned section data in DICOM format is converted into STL (Standard Trianglation language) format (step S103), and then read by three-dimensional CAD software installed on the workstation 42. The three-dimensional shape of the femur 50 is reproduced by superimposing these data (step S104).

  Next, based on the obtained three-dimensional shape of the femur 50, the shape of the artificial hip joint component 10 is determined (step S105). Specifically, based on the three-dimensional shape of the femur 50 reproduced on the three-dimensional CAD software, the medullary cavity 60 of the femur 50 located below the position 36 at which the osteotomy is to be performed (see FIG. 5A). Of the fitting surface 17 provided on the outer surface of the insertion portion 16 of the artificial hip joint component 10. The fitting surface 17 may be provided in the entire region of the insertion portion 16 in the axial direction as shown by a hatched line in FIG. 4A, or may be provided as shown in FIG. It is also possible to provide only a limited area in the axial direction.

  In addition, the outer shape of the femur 50 located above the cut surface 68 is extracted, and the extracted shape is used as the outer shape of the main body 14 of the hip joint component 10. The thicknesses of the skin layers 14b, 16b and the porous structures 14a, 16a constituting the outer shells of the main body 14 and the insertion portion 16, the specific shapes of the porous structures 14a, 16a, and the axial direction of the insertion portion 16 The length and the like are appropriately determined in consideration of the density of the cortical bone 56 obtained from the cross-sectional imaging data, the stress distribution obtained using structural analysis software, and the like.

  Next, using a predetermined metal powder material (here, Ti-6Al-4V alloy powder), the part 10 for artificial hip joint is formed by the 3D printer 44 capable of layering and forming (step S106). The 3D printer 44 scans a laser beam on a powder layer in which metal powder is spread to a predetermined thickness based on slice data of the artificial hip joint component 10 created by three-dimensional CAD software, and is located at a predetermined position. The metal powder is melted and solidified. This operation is repeated for each section (one slice data) to obtain a structure having a predetermined shape.

  After the additive manufacturing, an unnecessary portion is cut out, and then sterilized to obtain a hip joint component 10 having a predetermined shape (step S107).

The artificial hip joint component 10 thus obtained is inserted into the cavity in the medullary cavity 60 opening at the cut surface 68 of the osteotomized femur 50 during artificial joint replacement (see FIG. 5 ( B)). At this time, the downward surface of the stepped portion 20 of the artificial hip joint component 10 abuts on the cut surface 68 of the femur 50, and the fitting surface 17 of the insertion portion 16 has a substantial clearance inside the medullary cavity 60 of the femur 50. They are fitted without being fixed in position. Medical cement as an adhesive for fixing the position of the hip joint component 10 is unnecessary. In some cases, a fixing pin (not shown) may be provided to penetrate the cortical bone 56 of the femur 50 and the insertion portion 16 of the artificial hip joint component 10 in the radial direction to increase the fixing force in the axial direction. It is.
Then, the artificial hip joint component 10 made of a titanium alloy having excellent biocompatibility is integrated with the bone tissue when a certain period of time has elapsed after being inserted into the patient's femur.

  In the artificial joint replacement, an artificial acetabular cup (not shown) that fits with the head ball 12 is fixed to the pelvis side, and in addition to the artificial hip joint component 10 in this example, the head head ball 12 and the acetabular cup. The artificial hip joint is constituted by such components.

As described above, the artificial hip joint component 10 according to the present embodiment has a fitting surface on the outer surface of the insertion portion 16 having a shape substantially matching the inner surface shape of the medullary cavity 60 facing when inserted into the inside of the femur 50. Since the portion 17 is provided in the circumferential direction, the position of the hip joint component 10 can be fixed using the medullary cavity 60, which is a cavity originally formed inside the femur 50. .
For this reason, in the artificial joint replacement using the artificial hip joint component 10 of the present embodiment, when the artificial hip joint component 10 is inserted into the femur 50 of the patient, the outer shape of the insertion portion 16 of the artificial hip joint component 10 is renewed. Accordingly, the operation of excavating the inside of the femur 50 can be abolished or minimized, and bone marrow cells in the medullary cavity 60 can be prevented from being destroyed by the excavation operation. Therefore, in the artificial joint replacement using the artificial hip joint component 10 of the present embodiment, many bone marrow cells can be left, and bone marrow cells can be regenerated at an early stage after the operation. In addition, in the artificial joint replacement using the artificial hip joint component 10 of the present embodiment, the operation for excavating the inside of the femur 50 is substantially eliminated, so that the operation time can be significantly reduced.

  In addition, in the artificial hip joint component 10 of the present embodiment, the main body portion 14 and the insertion portion 16 are formed of the porous structures 14a and 16a, respectively, so that the weight of the artificial hip joint component can be reduced. The porous structures 14a and 16a have a large number of voids 28 communicating with the outside of the artificial hip joint component 10 through an opening 32 formed at the distal end of the insertion portion 16, and the artificial hip joint component 10 of the present embodiment is used for a patient. After being fixed to the femur, as shown in FIG. 6, the bone marrow cells that have entered the artificial hip joint component 10 through the opening 32 formed at the distal end of the insertion portion 16 are fixed to the porous structures 14a and 16a. Thus, bone marrow cells can be regenerated at an early stage.

  Further, in the artificial hip joint component 10 of the present embodiment, since the thin skin layers 14b and 16b are formed so as to cover the outer periphery of the porous structures 14a and 16a, a part of the artificial hip joint component is formed in a porous structure. Even in the case of a body, it is easy to secure a predetermined strength by the skin layers 14b and 16b. In addition, by providing the skin layers 14b and 16b, manufacturability when the artificial hip joint component 10 having the porous structure is formed by the additive manufacturing method can be improved.

  Further, a plurality of through holes 34 are formed in the skin layers 14b and 16b, and when the artificial hip joint component 10 is formed by a lamination molding method, the through holes 34 are formed of unmelted metal remaining in the artificial hip joint component. Functions as a powder discharge hole. After the hip joint component 10 of this embodiment is fixed to the femur 50 of the patient, blood vessels penetrating the skin layers 14b and 16b in and out through the through holes 34 are formed.

  The hip prosthesis component 10 of the present embodiment is based on the three-dimensional shape of the femur 50 reproduced by superimposing CT cross-sectional imaging data or MRI cross-section imaging data obtained from the femur 50 to be replaced with the hip prosthesis component. Then, the shape is determined, and modeling is performed by a layered manufacturing method using a metal powder material.

  According to such a manufacturing method, the hip joint component 10 having an optimal shape for each patient is provided based on the three-dimensional shape of the femur 50 reproduced by superimposing the CT slice imaging data or the MRI slice imaging data. can do. Accordingly, it is possible to easily manufacture the hip prosthesis component 10 in which the outer surface of the insertion portion 16 is provided with the fitting surface 17 having a shape substantially matching the inner surface shape of the medullary cavity 60 of the patient. According to the additive manufacturing method, a high degree of freedom is obtained in the shape, so that it is possible to cope with the porous structures 14a and 16a having a complicated shape.

  The embodiments of the present invention have been described above in detail, but these are merely examples. In the above-described embodiment, the example in which the head ball and the component for the artificial hip joint are configured separately is shown. However, it is also possible to manufacture a component for the artificial hip joint integrally including the head ball by laminate manufacturing. The present invention does not depart from the gist of the present invention. For example, it is possible to employ a configuration in which the hollow portion 30 inside the artificial hip joint component 10 is reduced or abolished, and the area of the porous structures 14a and 16a is further expanded. It can be configured in a form in which various changes are made in the range.

DESCRIPTION OF SYMBOLS 10 Artificial hip joint part 12 Head ball 14 Main part 14a, 16a Porous structure 14b, 16b Skin layer 16 Insertion part 17 Fitting surface 28 Air gap 32 Opening 34 Through-hole 50 Femur 60 Medullary cavity

Claims (3)

A main body that supports the head ball formed separately or integrally,
An insertion portion formed integrally with the main body portion and having a smaller diameter than the main body portion,
On the outer surface of the insertion portion, a fitting surface having a shape substantially matching the inner surface shape of the opposing medullary cavity when inserted into the inside of the femur is provided in the circumferential direction,
At least a part of the main body and / or the insertion portion is formed of a porous structure having a large number of voids communicating with the outside through an opening formed at a tip of the insertion portion. parts.   The component for artificial hip joint according to claim 1, wherein a thin skin layer having a plurality of through holes is formed integrally with the porous structure so as to cover an outer periphery of the porous structure. . It is a manufacturing method of the component for artificial hip joints according to any one of claims 1 and 2,
The shape of the hip prosthesis component is determined based on the three-dimensional shape of the femur reproduced by superimposing CT cross-sectional imaging data or MRI cross-section imaging data obtained from the femur to be replaced with the hip prosthesis component. And
A method of manufacturing a component for an artificial hip joint, wherein the component for an artificial hip joint is formed by a layered manufacturing method using a metal powder material.

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