WO2025169469A1 - Biological implant and surgical instrument - Google Patents

Abstract

A biological implant according to the present invention comprises an acetabular cup and a liner that has an outer surface in contact with the acetabular cup and is positioned on the inner side of the acetabular cup. The liner has a first tapered surface that is positioned at the peripheral edge of the outer surface and is in contact with the peripheral edge of the inner surface of the acetabular cup. The first tapered surface has a protrusion.

Description

Bioimplants and surgical instruments

This disclosure relates to biological implants and surgical instruments used in hip replacement surgery.

Total hip replacement surgery is known, in which the hip joint is replaced with an artificial joint. Total hip replacement surgery involves placing a cup (shell) in the pelvis and fitting a liner inside the cup. A stem is then inserted into the femur, and a femoral ball (head) that serves as the femoral head is attached to the tip of the stem. The femoral ball is then placed so that it slides within the liner, thereby recreating the ball-and-socket motion of the hip joint.

Also known is an artificial joint called a dual mobility system, which allows for a wider range of motion in ball movement than conventional systems. In a dual mobility system, a bearing is placed between the femoral head ball and the liner, and the bearing slides on the inner surface of the liner, while the femoral head ball slides on the inner surface of the bearing, thereby widening the range of motion in ball movement (Patent Document 1).

Japan Special Table No. 2019-531139

"NOVAE, Dual Mobility Cups, Surgical Technique", [online], [Retrieved February 1, 2024], Internet <URL:https://fischermedical.dk/wp-content/uploads/NOVAE_Surgical-Technique_EN_Ed-4-2018.pdf> "BI-MENTUM, Dual Mobility System, Surgical Technique", [online], [Retrieved February 1, 2024], Internet <https://synthes.vo.llnwd.net/o16/LLNWMB8/INT%20Mobile/Synthes%20International/Product%20Support%20Material/legacy_Synthes_PDF/096052.pdf>

In one aspect of the present disclosure, the biological implant comprises an acetabular cup and a liner positioned inside the acetabular cup, the liner having an outer surface that contacts the acetabular cup, the liner being positioned on the periphery of the outer surface and having a first tapered surface that contacts the periphery of the inner surface of the acetabular cup, the first tapered surface having a protrusion.

1A and 1B are schematic diagrams illustrating an example of a method for attaching a biological implant according to a first embodiment of the present disclosure. FIG. 2 is an exploded perspective view showing an example of the biological implant shown in FIG. 1. 2A and 2B are perspective and cross-sectional views showing an example of the acetabular cup shown in FIG. 1 . 2A and 2B are a perspective view and a cross-sectional view showing an example of the liner shown in FIG. 1 . 2A and 2B are a perspective view and a cross-sectional view showing an example of the bearing shown in FIG. 1 . 2A and 2B are a perspective view and a cross-sectional view showing an example of the femoral head ball shown in FIG. 1 . FIG. 2 is a cross-sectional view showing a state in which the components of the biological implant shown in FIG. 1 are assembled together. FIG. 2 is a schematic diagram illustrating the range of motion of the biological implant shown in FIG. 1 . 2 is a schematic diagram illustrating protrusions formed on the liner shown in FIG. 1 . FIG. 2 is a schematic diagram illustrating a tapered fit between the liner and the acetabular cup shown in FIG. 1 . FIG. FIG. 2 is a schematic diagram illustrating the thickness of the liner shown in FIG. 1 . FIG. 10 is a front view showing an example of a surgical instrument according to a second embodiment of the present disclosure. FIG. 13 is a perspective view of the surgical instrument shown in FIG. 12. FIG. 13 is a schematic diagram illustrating a ratchet structure of the surgical instrument shown in FIG. 12 .

[Embodiment 1]
<Overview>
First, to facilitate understanding of the biological implant 1, an outline of the steps of total hip replacement surgery will be briefly described with reference to Fig. 1. Fig. 1 is a schematic diagram illustrating an example of a method for attaching the biological implant 1 according to the first embodiment of the present disclosure.

As shown in Figure 1, the hip joint 91 is composed of a ball-shaped femoral head (not shown) at the tip of the femur 92 and a dome-shaped recessed acetabulum 94 on the side of the pelvis 93. If the hip joint 91 is damaged due to illness or fracture, total hip joint replacement surgery is performed to replace the damaged hip joint 91 with an artificial hip joint.

The bioimplant 1 according to embodiment 1 of the present disclosure can be used as an artificial hip joint in total hip replacement surgery. The bioimplant 1 is composed of a combination of an acetabular cup 2, a liner 3, a bearing 4, and a femoral head ball 5.

In total hip replacement surgery, first, the acetabulum 94 on the pelvis 93 side is thinned and the acetabular cup 2 is attached. Next, the liner 3 is fitted into the acetabular cup 2. Meanwhile, on the femur 92 side, a stem 90 is inserted into the femur 92 from which the femoral head has been removed, and a femoral head ball 5 fitted into a bearing 4 is attached to the tip 901 of the stem 90. The stem 90 may also be inserted into the femur 92 with the femoral head ball 5 attached to the tip 901 of the stem 90, and the femoral head ball 5 fitted into the bearing 4. By engaging the liner 3 on the pelvis 93 side with the bearing 4 on the femur 92 side, it functions as an artificial hip joint.

<Configuration of biological implant 1>
Fig. 2 is an exploded perspective view showing an example of the bioimplant 1. As shown in Fig. 2, the bioimplant 1 is composed of an acetabular cup 2, a liner 3, a bearing 4, and a femoral head ball 5 in combination.

The biological implant 1 has a so-called dual mobility (double sliding) structure. The outer surface 41 of the bearing 4, which is placed between the liner 3 and the femoral head ball 5, slides against the inner surface 32 of the liner 3, and the inner surface 42 slides against the outer surface 51 of the femoral head ball 5. In this way, the double sliding motion of the biological implant 1 can widen the range of motion of the biological implant 1.

Figure 3 shows perspective views of an example of an acetabular cup 2. The views indicated by reference numerals 300A and 300B are perspective views of the acetabular cup 2, and the view indicated by reference numeral 300C is a cross-sectional view of the acetabular cup 2 taken along line III-III shown in 300A. C2 indicates the central axis of the acetabular cup 2 in the fitting direction.

As shown in Figures 2 and 3, the acetabular cup 2 has an outer surface 21, an inner surface 22, a storage space 23, and an insertion hole 24. The acetabular cup 2 has a dome-like (roughly hemispherical bowl-like) shape. Here, "roughly hemispherical" not only refers to a geometric hemispherical shape, but also includes a shape in which part of the hemisphere is missing, or a shape having an area protruding from part of the hemisphere.

A second tapered surface 221 is located around the entire circumferential direction near the peripheral edge 222 of the inner surface 22. The second tapered surface 221 is shaped so that the diameter of the inner surface 22 increases toward the peripheral edge 222.

The accommodation space 23 is a space for fitting the liner 3. The accommodation space 23 is located inside the acetabular cup 2. The diameter of the accommodation space 23 is slightly larger than the diameter of the liner 3. This allows the liner 3 to be fitted into the accommodation space 23 of the acetabular cup 2, and the liner 3 is fixed to the acetabular cup 2.

The insertion hole 24 is located at the top of the acetabular cup 2. The protrusion 34 of the liner 3, which will be described later, is inserted into the insertion hole 24.

Figure 4 shows perspective views of an example of a liner 3. The view indicated by reference numeral 400A is a perspective view of the liner 3, the view indicated by reference numeral 400B is a front view, and the view indicated by reference numeral 400C is a cross-sectional view taken along line IV-IV shown in 400A. C3 indicates the central axis of the liner 3 in the mating direction.

As shown in Figures 2 and 4, the liner 3 has an outer surface 31, an inner surface 32, a storage space 33, and a protrusion 34. The liner 3 has a dome-like (approximately hemispherical bowl-like) shape.

A first tapered surface 311 is located around the entire circumferential direction near the peripheral edge 312 of the outer surface 31. The diameter of the first tapered surface 311 increases as it approaches the peripheral edge 312.

As described above, the protrusion 34 is inserted into the insertion hole 24 of the acetabular cup 2. By having the protrusion 34, the liner 3 can be easily aligned when inserted into the acetabular cup 2. The liner 3 does not necessarily have to have the protrusion 34.

The accommodation space 33 is a space for fitting the bearing 4. The accommodation space 33 is located inside the liner 3. The diameter of the accommodation space 33 is slightly larger than the diameter of the bearing 4. This allows the bearing 4 to be fitted into the accommodation space 33 of the liner 3. The bearing 4 fitted into the accommodation space 33 is held in the liner 3 so that the outer surface 41 of the bearing 4 and the inner surface 32 of the liner 3 slide against each other.

Figure 5 shows perspective views of an example of a bearing 4. The view indicated by reference numeral 500A is a perspective view of the bearing 4, the view indicated by reference numeral 500B is a front view, and the view indicated by reference numeral 500C is a cross-sectional view taken along the line V-V shown in 500A. C4 indicates the central axis of the bearing 4 in the fitting direction.

As shown in Figures 2 and 5, the bearing 4 has an outer surface 41, an inner surface 42, a storage space 43, and an opening 44. The bearing 4 is made of a resin such as polyethylene.

The accommodation space 43 is a space for fitting the femoral head ball 5 and is formed inside the bearing 4. The diameter of the accommodation space 43 is formed to be slightly larger than the diameter of the femoral head ball 5. This allows the femoral head ball 5 to be fitted into the accommodation space 43 of the bearing 4. The bearing 4 accommodates the femoral head ball 5 within the accommodation space 43 so as to cover most of the outer surface 51 of the femoral head ball 5.

The femoral head ball 5 is fitted into the accommodation space 43 with the inner surface 42 of the bearing 4 and the outer surface 51 of the femoral head ball 5 slidable against each other. The outer surface 41 of the bearing 4 slides against the inner surface 32 of the liner 3, and the inner surface 42 slides against the outer surface 51 of the femoral head ball 5.

The opening 44 has a diameter smaller than the diameter of the femoral head ball 5. As a result, a strong pushing force is required to fit the femoral head ball 5 into the bearing 4, and an engagement instrument 6 (surgical instrument) described below is used.

Figure 6 shows perspective views of an example of a femoral head ball 5. The view indicated by the reference numeral 600A is a perspective view of the femoral head ball 5, the view indicated by the reference numeral 600B is a front view, and the view indicated by the reference numeral 600C is a cross-sectional view taken along the line VI-VI shown in 600A. C5 indicates the central axis of the femoral head ball 5 in the mating direction.

As shown in Figures 2 and 6, the femoral head ball 5 has an outer surface 51 and a recess 53. The femoral head ball 5 is fixed to the stem 90 by inserting the tip 901 of the stem 90 into the recess 53. Furthermore, when attaching the femoral head ball 5 to the fitting instrument 6 (surgical instrument) described below, the femoral head ball support portion 71 of the fitting instrument 6 is inserted into the recess 53.

<Double sliding>
Fig. 7 is a cross-sectional view showing the assembled state of the components of the biological implant 1. Fig. 8 is a schematic diagram illustrating the range of motion of the biological implant 1. As shown in Fig. 7, a liner 3 is placed inside the acetabular cup 2, and a bearing 4 is placed inside the liner 3. The inner surface 32 of the liner 3 and the outer surface 41 of the bearing 4 are in slidable contact with each other. A femoral head ball 5 is housed inside the bearing 4, and the inner surface 42 of the bearing 4 and the outer surface 51 of the femoral head ball 5 are in slidable contact with each other.

As a result, the femoral head ball 5 moves relative to the bearing 4, as shown in 800A in Figure 8, and the bearing 4 moves relative to the liner 3, as shown in 800B in Figure 8. In other words, double sliding is achieved.

<Protrusion>
In total hip replacement surgery, a cup is placed in the acetabulum of the pelvis, and then a liner is fitted into the cup. It is undesirable for the liner to come off the cup, so the fitting force between the cup and the liner should be strong.

Therefore, the liner 3 may have a protrusion 313 arranged on the first tapered surface 311. Figure 9 is a schematic diagram illustrating the protrusion 313 formed on the liner 3. As shown in Figure 9, the protrusion 313 is provided on the outer surface 31 of the liner 3, facing the inner surface 22 of the acetabular cup 2. The tip of the protrusion 313 has an acute angle. The protrusion 313 catches on the inner surface 22 of the acetabular cup 2, strengthening the fit between the acetabular cup 2 and the liner 3.

The protrusions 313 may be formed by arranging grooves in the first tapered surface 311. By forming grooves, the space between the grooves can become the protrusions 313. The grooves may be arranged in a direction different from the line connecting any point on the edge of the liner 3 and the apex of the liner 3, i.e., the protrusion 34 (see Figure 4). This allows the protrusions 313 to be arranged in a direction different from the mating direction between the acetabular cup 2 and the liner 3, thereby strengthening the fit between the acetabular cup 2 and the liner 3. The grooves may be arranged approximately parallel to the edge of the liner 3.

The protrusion 313 may be shaped to protrude from the first tapered surface 311. The protrusion 313 may be shaped to protrude from the first tapered surface 311 toward the acetabular cup 2. The protrusion 313 may protrude in a direction different from a line connecting any point on the edge of the liner 3 and the apex of the liner 3.

The protrusion 313 may have an obtuse tip. For example, the cross section of the protrusion 313 may be triangular, rectangular, or trapezoidal. The protrusion 313 may have a rounded tip. The protrusion 313 may be located on only a portion of the first tapered surface 311. The protrusion 313 may be located around the entire circumference of the liner 3.

The protrusions 313 may be located around the entire circumference of the liner 3, and the tips of the protrusions 313 may be annular in shape. The protrusions 313 may be located around the entire circumference of the liner 3, and the tips of the protrusions 313 may be spiral in shape.

<Tapered fitting>
As described above, the liner 3 has a first tapered surface 311 arranged on the peripheral edge 312 of the surface 31. The first tapered surface 311 fits into the inner surface 22 of the acetabular cup 2, thereby fitting the acetabular cup 2 and the liner 3 together. A second tapered surface 221 may be arranged on the inner surface 22 of the acetabular cup 2, and the first tapered surface 311 of the liner 3 may fit into the second tapered surface 221 of the acetabular cup 2.

10, the first tapered surface 311 may have a biting portion 314 that bites into the second tapered surface 221. The biting portion 314 may be formed by bending the first tapered surface 311 inward at an angle L toward the edge, i.e., toward the center of the circle formed by the edge of the liner 3. In other words, the biting portion 314 may be realized by an edge provided by providing a surface on the first tapered surface 311 whose angle with the mating direction is smaller than the angle of the second tapered surface 221 in a cross section cut along a plane parallel to the mating direction between the acetabular cup 2 and the liner 3. The tip of the biting portion 314 may be either an obtuse angle or an acute angle. When the tip of the biting portion 314 is an acute angle, it bites more firmly into the second tapered surface 221. When the tip of the biting portion 314 is an obtuse angle, the risk of the tip of the liner 3 chipping the inner surface of the acetabular cup 2 is reduced.

Because the first tapered surface 311 has a biting portion 314, when the acetabular cup 2 and the liner 3 are fitted together, the biting portion 314 bites into the inner surface of the acetabular cup 2. This strengthens the fit between the acetabular cup 2 and the liner 3.

<Liner thickness>
11 is a schematic diagram illustrating the thickness of the liner 3. Here, a straight line that passes through the center P0 of the ring formed by the peripheral edge portion 312 of the liner 3 and is parallel to the fitting direction of the acetabular cup 2 and the liner 3 is defined as a central axis C3.

As shown in Figure 11, in a cross section taken along a plane passing through the central axis C3 and parallel to the mating direction, with one side of the central axis C3 designated as the first side and the other side as the second side, the outer shape of the liner 3 has a shape that includes arcs centered on points on the first side and the second side that are approximately symmetrical with respect to the central axis C3, i.e., point P1 on the first side and point P2 on the second side. Here, the arcs do not necessarily refer only to geometric arcs, but also allow for deviations from the geometric arcs due to manufacturing errors, etc.

As a result, the liner 3 has a region where the thickness W1 of the liner 3 in a cross section including the central axis C3 is greater than when the outer shape is formed by an arc centered at P0 on the central axis C3. The liner 3 has a region where the thickness W1 increases from the peripheral edge 312 side toward the convex portion 34 side.

In this way, the outer diameter of the liner 3 can be made larger compared to when the center of the outer diameter is located on the central axis C3. Therefore, if the inner diameter of the liner 3 remains the same as before, the thickness of the liner 3 can be increased, and the strength of the liner 3 can be increased. Furthermore, if the inner diameter of the liner 3 is made larger than before, it becomes possible to place a larger bearing 4 inside the liner 3 than before.

[Embodiment 2]
<Configuration of fitting device 6>
As described above, the bearing 4 has a hollow shape with an opening 44, and the femoral head ball 5 is accommodated in the accommodation space 43, allowing the femoral head ball 5 to slide on the inner surface 42 of the bearing 4. Because the diameter of the opening 44 of the bearing 4 is smaller than the diameter of the femoral head ball 5, a strong pushing force is required to accommodate the femoral head ball 5 in the accommodation space 43 of the bearing 4, and a dedicated tool is used. However, depending on the structure of the tool, the pushing part may be pushed back, making it impossible to accommodate the femoral head ball 5 in the accommodation space 43 of the bearing 4.

The fitting instrument 6 (surgical instrument) according to embodiment 2 of the present disclosure has a ratchet structure. The ratchet structure can restrict the movement direction of the pushing portion 64 only to the direction in which the femoral head ball 5 is accommodated in the bearing 4 (the Y1 direction, first direction, described below). This prevents the pushing portion 64 from being pushed back, allowing the femoral head ball 5 to be accommodated efficiently. Restricting the movement direction of the pushing portion 64 only to the first direction means that a strong force is applied against movement in the direction opposite to the first direction.

The fitting device 6 according to the second embodiment of the present disclosure will be described below. For ease of explanation, components having the same functions as those described in the first embodiment above will be denoted by the same reference numerals, and their description will not be repeated.

Figure 12 is a front view showing an example of a fitting device 6, and Figure 13 is a perspective view. Figure 12 shows the bearing 4 and femoral head ball 5 attached to the fitting device 6 in phantom lines.

As shown in Figures 12 and 13, the fitting device 6 includes a main body 61, a shaft 63, a pushing portion 64, an operating portion 65, a fitting portion 66, and a stopper 67.

The main body 61 includes a femoral head ball support 62 (support portion) that secures the femoral head ball 5. The femoral head ball support 62 has a base 621 and an insertion portion 622 that extends from the base 621. As described above, the femoral head ball 5 can be secured to the fitting device 6 by inserting the insertion portion 622 into the recess 53 of the femoral head ball 5.

The shaft 63 is attached to the main body 61 so as to be movable in the axial direction by being inserted into an insertion hole 611 formed in the main body 61. The shaft 63 has multiple grooves 633 formed in the axial direction. A push-in portion 64 is attached to the first end 631 (first end) of the shaft 63, and a handle portion 68 is attached to the second end 632 (second end).

The push-in portion 64 includes a cup-shaped bearing mounting portion 641. The bearing mounting portion 641 allows the bearing 4 to be mounted with the opening 44 of the bearing 4 facing downward (first direction). The bearing mounting portion 641 can be used for alignment when pressing the bearing 4 toward the femoral head ball 5, reducing the possibility of misalignment between the bearing 4 and the femoral head ball 5. The push-in portion 64 does not necessarily have to include the bearing mounting portion 641.

The bearing mounting portion 641 is positioned to face the femoral head ball support portion 62. By moving the shaft portion 63 in the axial direction and in a direction approaching the femoral head ball support portion 62 (Y1 direction, first direction), the femoral head ball 5 can be pushed into the bearing 4's accommodation space 43 through the bearing 4's opening 44.

The operating unit 65 is a handle-shaped member used to operate the fitting device 6, and includes an operating handle 651 and a fixed handle 652. The operating handle 651 is fixed to the main body 61 so that it can rotate around a fixed part 6511. As will be described in more detail below, the user can move the shaft 63 in the Y1 direction by grasping the operating handle 651 and the fixed handle 652 and rotating the operating handle 651 in a direction approaching the fixed handle 652 (R1 direction).

The operating handle 651 is biased in a direction (R2 direction) away from the fixed handle 652 by a biasing member such as a spring (not shown), and is configured so that when the user loosens their grip, it rotates in the R2 direction and returns to the position it was in before the user gripped it.

The fitting portion 66 has a fitting claw 661 that fits into one of the grooves 633 formed in the shaft portion 63, and is fixed to the operating handle 651 by a fixing portion 662. As the operating handle 651 rotates, the fitting portion 66 moves parallel to the Y1 direction while rotating around the fixing portion 662. As will be described in more detail below, the rotational movement of the fitting portion 66 causes the fitting claw 661 to press the first surface 634a of the groove portion 633 in the Y1 direction, allowing the shaft portion 63 to move in the Y1 direction.

The stopper 67 has a locking claw 671 that fits into one of the grooves 633 formed in the shaft 63, and is fixed to the main body 61 so as to be rotatable around a fixed portion 672. The stopper 67 is biased toward the shaft 63 by a spring 673. When no operation is being performed using the operating unit 65, the locking claw 671 fits into the groove 633, preventing the shaft 63 from being pushed back in the direction opposite the Y1 direction (Y2 direction).

The ratchet structure of the fitting device 6 is mainly composed of a stopper 67 and a fitting portion 66. Details of the stopper 67 and the fitting portion 66 will be described later.

As described above, the handle portion 68 is attached to the second end portion 632 of the shaft portion 63. By turning the handle portion 68, the user can rotate the shaft portion 63 around its axis.

The groove 633 is not formed around the entire circumference of the shaft 63, but only on a portion of the circumference. For example, the groove 633 is formed only in the portion facing the main body 61. Therefore, by turning the handle 68, the user can position the groove 633 on the side opposite the side facing the main body 61. This allows the engagement of the engagement claw 661 and the locking claw 671 that are engaged with the groove 633 to be released.

<Ratchet structure>
14 is a schematic diagram illustrating the ratchet structure of the fitting device 6. As shown in FIG. 14, the groove portion 633 functions as a ratchet tooth 634 and has a first surface 634a perpendicular to the shaft portion 63 and a second surface 634b oblique to the shaft portion 63.

The mating portion 66 is provided with a mating pawl 661 that meshes with one of the ratchet teeth 634. The stopper 67 is provided with a locking pawl 671 that is biased toward the ratchet teeth 634 by a spring 673 and meshes with the other ratchet tooth 634.

When the operating handle 651 is operated and rotated in the R1 direction, the fitting portion 66 fixed to the operating handle 651 rotates in the R1 direction around the fixed portion 6511 in conjunction with the rotation of the operating handle 651. While engaged with the ratchet teeth 634, the fitting pawl 661 presses the first surface 634a in the Y1 direction, moving the shaft portion 63 in the Y1 direction.

The fitting portion 66 is biased by a biasing member in a direction diagonally away from the shaft portion 63, on the Y2 side of the fixed portion 662. As a result, once operation using the operating handle 651 is completed, the operating handle 651 is biased in the R2 direction, the fitting claw 661 is biased in the X1 direction, and the entire fitting portion 66 is biased in the Y2 direction. As a result, the fitting claw 661 slides along the second surface 634b, causing the fitting portion 66 to move in the Y2 direction. Therefore, when the user loosens the operating handle 651, the fitting portion 66 moves in the Y2 direction and returns to its original position.

On the other hand, the locking claw 671 of the stopper 67 locks the first surface 633a of the ratchet tooth 634 that meshes with the locking claw 671, preventing the shaft 63 from being pushed back and moving in the Y2 direction.

By operating the operating handle 651 again, the shaft 63 can be moved further in the Y1 direction. By repeating this operation, the shaft 63 can be moved in the Y1 direction by the desired length.

This restricts the movement direction of the shaft portion 63 to only the Y1 direction, thereby suppressing push-back and allowing the femoral head ball 5 to be efficiently accommodated in the bearing 4.

〔summary〕
A biological implant according to a first aspect of the present disclosure includes an acetabular cup and a liner positioned inside the acetabular cup, the liner having an outer surface that contacts the acetabular cup, the liner having a first tapered surface positioned on the periphery of the outer surface and contacting the periphery of the inner surface of the acetabular cup, the first tapered surface having a protrusion. According to the above configuration, the protrusion on the first tapered surface can increase the strength of the fit compared to when no protrusion is provided. Therefore, the strength of the fit between the acetabular cup and the liner can be increased.

A biological implant according to aspect 2 of the present disclosure is the same as aspect 1, except that it includes a bearing having an outer surface that can slide against the inner surface of the liner. By including the bearing, sliding can be achieved between the outer surface of the bearing and the liner, thereby achieving double sliding, including sliding on the inner surface of the bearing.

The biological implant according to aspect 3 of the present disclosure is the same as that of aspect 1 or 2, except that it includes a femoral head ball that is slidable against the inner surface of the bearing. By including a femoral head ball, sliding can be achieved between the bearing and the femoral head ball.

The bioimplant according to aspect 4 of the present disclosure is the same as the bioimplant according to aspect 3, except that it includes a stem that is inserted into the femoral head ball. By including the stem, the bioimplant can be properly inserted into the femur.

A biological implant according to aspect 5 of the present disclosure is any of aspects 1 to 4, wherein the protrusion is formed by arranging a groove on the first tapered surface, and the groove is arranged in a direction different from a line connecting any point on the edge of the liner to the zenith. The line connecting any point on the edge of the liner to the zenith is parallel to the mating direction between the acetabular cup and the liner. Therefore, with the above configuration, the groove is arranged in a direction different from the mating direction between the acetabular cup and the liner, and the protrusion formed by the groove is also arranged in a direction different from the mating direction between the acetabular cup and the liner. This increases the strength of the fit between the acetabular cup and the liner. For example, the groove may be arranged approximately parallel to the edge of the liner.

A biological implant according to aspect 6 of the present disclosure is any one of aspects 1 to 4, wherein the protrusion has a shape that protrudes from the first tapered surface toward the acetabular cup, and the protrusion protrudes in a direction different from a line connecting any point on the edge of the liner to the zenith apex. This increases the strength of the fit between the acetabular cup and the liner.

A biological implant according to aspect 7 of the present disclosure is any one of aspects 1 to 6, wherein the acetabular cup has a second tapered surface on the periphery of its inner surface, and the first tapered surface and the second tapered surface fit together. With this configuration, tapered surfaces are provided on both the acetabular cup and the liner, making it easy to fit the acetabular cup and the liner together.

A biological implant according to aspect 8 of the present disclosure is any of aspects 1 to 7, wherein the liner has a biting portion located on the peripheral side of the first tapered surface that bites into the second tapered surface. With this configuration, the biting portion increases the resistance force against the liner being removed from the acetabular cup, thereby increasing the strength of the fit between the acetabular cup and the liner. The biting portion may be realized by an edge provided by arranging a surface on the first tapered surface that forms an angle with the fit direction smaller than the angle of the second tapered surface in a cross section taken along a plane parallel to the fit direction between the acetabular cup and the liner.

A biological implant according to aspect 9 of the present disclosure is any of aspects 1 to 8, wherein when a straight line passing through the center of the ring formed by the periphery of the liner and parallel to the direction of engagement between the acetabular cup and the liner is taken as the central axis, the liner has a region with a greater thickness in a cross section including the central axis than when the center of the outer shape is set at the central axis. This configuration allows the wall thickness of the liner to be increased, thereby increasing the strength of the liner. Furthermore, by making the inner diameter of the liner larger than conventional, it becomes possible to place a larger bearing inside the liner than conventional.

A biological implant according to aspect 10 of the present disclosure is any of aspects 1 to 9 described above, wherein a central axis is a straight line passing through the center of the periphery of the liner and parallel to the mating direction between the acetabular cup and the liner, and when a cross section is taken along a plane passing through the central axis and parallel to the mating direction, with one side of the central axis designated as a first side and the other side designated as a second side, the outer shape of the liner, on each of the first side and the second side, has a shape that includes an arc with its center at a point located approximately symmetrically with respect to the central axis. With this configuration, the outer shape of the liner can be made larger than when the center of the outer shape is located on the central axis. Therefore, if the inner diameter of the liner is the same as in conventional liner designs, the thickness of the liner can be increased, thereby increasing the strength of the liner. Furthermore, by making the inner diameter of the liner larger than in conventional liner designs, it is possible to place larger bearings inside the liner than in conventional liner designs.

A biological implant according to aspect 11 of the present disclosure is any of aspects 1 to 10, wherein when a central axis is a straight line passing through the center of a ring formed by the periphery of the liner and parallel to the direction in which the acetabular cup and the liner are fitted together, the liner has a region in which the cross section including the central axis increases in size from the periphery of the liner toward the apex of the liner. This configuration allows the outer shape of the liner to be increased.

A surgical instrument according to aspect 12 of the present disclosure comprises a main body having a support portion that supports a femoral head ball; a pusher portion that pushes the bearing into a hollow bearing having an opening to accommodate the femoral head ball; a shaft portion that connects to the pusher portion at a first end; and an operating portion that connects to the side of the shaft portion and moves the shaft portion in the axial direction relative to the main body portion, and the connection between the shaft portion and the operating portion is structured so that the operating portion can move the shaft portion in the axial direction only in a first direction, which is the direction of the first end. With this configuration, because the shaft portion moves only in the first direction, even when a large force is required to accommodate the femoral head ball inside the bearing, the pushing portion can push the bearing in without being pushed back in the direction opposite to the first direction.

A surgical instrument according to aspect 13 of the present disclosure is the same as aspect 12, except that the connection between the shaft and the operating unit is a ratchet structure that allows the operating unit to move the shaft in the axial direction only in a first direction, which is the first end direction. With this configuration, a ratchet structure can be used to achieve a structure in which the operating unit can move the shaft in the axial direction only in the first direction.

A surgical instrument according to aspect 14 of the present disclosure is the same as aspect 12 or 13, except that the side of the shaft has a plurality of grooves arranged side by side in the axial direction, the grooves being formed by a first surface perpendicular to the shaft and a second surface oblique to the shaft; the operating unit has a fitting portion that fits into one of the plurality of grooves, and moves the shaft in the axial direction by biasing the fitting portion in the axial direction, with the first surface being arranged closer to the first direction than the second surface. This configuration makes it possible to realize a structure in which the operating unit can move the shaft only in the first direction.

A surgical instrument according to aspect 15 of the present disclosure is any one of aspects 12 to 14, in which the main body has a stopper that is biased against the shaft by an elastic body and fits into the groove. This configuration prevents the shaft from being pushed back in the direction opposite the first direction when no operation is being performed by the operating unit.

A surgical instrument according to aspect 16 of the present disclosure is any of aspects 12 to 15, and has a handle portion at a second end of the shank opposite the first end, the handle portion having a diameter larger than the diameter of the shank. This configuration allows the shank to be easily rotated about its axis. The groove in the shank is arranged along a portion of the circumference of the shank, so that by rotating the shank about its axis, the engagement between the operating portion and the groove in the shank, and the engagement between the stopper and the groove in the shank, can be released.

The invention according to the present disclosure has been described above based on various drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope set forth in this disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art would easily be able to make various modifications or corrections based on this disclosure. It should also be noted that these modifications or corrections are included in the scope of this disclosure.

REFERENCE SIGNS LIST 1 Bioimplant 2 Acetabular cup 21 Outer surface 22 Inner surface 221 Second tapered surface 222 Peripheral edge portion 23 Storage space 24 Insertion hole 3 Liner 31 Outer surface 311 First tapered surface 312 Peripheral edge portion 313 Protrusion 314 Biting portion 32 Inner surface 33 Storage space 34 Protrusion 4 Bearing 41 Outer surface 42 Inner surface 43 Storage space 44 Opening 5 Femoral head ball 51 Outer surface 53 Recessed portion 6 Fitting instrument (surgical instrument)
61 Main body portion 62 Femoral head ball support portion (support portion)
63 Shaft portion 64 Push-in portion 65 Operation portion 67 Stopper 68 Handle portion

Claims (16)

an acetabular cup;
a liner positioned inside the acetabular cup and having an outer surface that contacts the acetabular cup;
the liner has a first tapered surface located on a periphery of the outer surface and in contact with a periphery of an inner surface of the acetabular cup;
The biological implant, wherein the first tapered surface has a protrusion. The biological implant of claim 1, comprising a bearing having an outer surface that is slidable against the inner surface of the liner. The biological implant according to claim 2, comprising a femoral head ball that is slidable on the inner surface of the bearing. The biological implant according to claim 3, comprising a stem inserted into the femoral head ball. the protrusion is formed by arranging a groove in the first tapered surface,
The biological implant according to claim 1 , wherein the grooves are arranged in a direction different from a line connecting any point on the edge of the liner to the apex. the protrusion has a shape that protrudes from the first tapered surface toward the acetabular cup,
The biological implant according to claim 1 , wherein the protrusion protrudes in a direction different from a line connecting an arbitrary point on the edge of the liner to the apex. the acetabular cup has a second tapered surface on the periphery of the inner surface;
The biological implant according to claim 1 , wherein the first tapered surface and the second tapered surface mate with each other. The biological implant according to claim 7, wherein the liner is located on the peripheral side of the first tapered surface and has a biting portion that bites into the second tapered surface. When a straight line passing through the center of the ring formed by the periphery of the liner and parallel to the fitting direction of the acetabular cup and the liner is taken as a central axis,
The biological implant according to claim 1 , wherein the liner has a region where the thickness in a cross section including the central axis is greater than when the center of the outer shape is set at the central axis. When a straight line passing through the center of the periphery of the liner and parallel to the fitting direction of the acetabular cup and the liner is defined as a central axis, and when a cross section cut along a plane passing through the central axis and parallel to the fitting direction is defined as a first side and a second side on either side of the central axis,
The biological implant according to claim 1 , wherein the outer shape of the liner is a shape including an arc having a center at a point located approximately symmetrically with respect to the central axis on each of the first side and the second side. When a straight line passing through the center of the ring formed by the periphery of the liner and parallel to the fitting direction of the acetabular cup and the liner is taken as a central axis,
The biological implant according to claim 1 , wherein the liner has a region in which a cross section including the central axis increases in size from the periphery of the liner toward the apex of the liner. a main body portion having a support portion that supports a femoral head ball;
a pusher for pushing the bearing into a hollow bearing having an opening so as to accommodate the femoral head ball;
a shaft portion that connects to the pusher portion at a first end;
an operating unit connected to a side surface of the shaft portion and configured to move the shaft portion in the axial direction relative to the main body portion;
A surgical instrument in which the connection between the shaft portion and the operating portion is structured such that the operating portion can move the shaft portion in the axial direction only in a first direction, which is the first end direction. The surgical instrument according to claim 12, wherein the connection between the shaft and the operating part is a ratchet structure in which the operating part allows the shaft to be moved in the axial direction only in a first direction, i.e., the first end direction. a plurality of grooves are arranged in the axial direction on a side surface of the shaft portion, the grooves being formed by a first surface perpendicular to the shaft and a second surface oblique to the shaft;
the operating portion has a fitting portion that fits into any of the plurality of grooves, and the shaft portion is moved in the axial direction by biasing the fitting portion in the axial direction,
The surgical instrument according to claim 13 , wherein the first surface is disposed on the first direction side of the second surface. The surgical instrument according to claim 14, wherein the main body has a stopper that is biased against the shaft by an elastic body and fits into the groove. The surgical instrument according to claim 12, further comprising a handle portion at a second end of the shaft opposite the first end, the handle portion having a diameter larger than the diameter of the shaft portion.