Hip Prosthesis

Abstract

The present invention proposes a hip joint prosthesis, which includes: an acetabulum liner, which has an inner wall defining a cavity and an opening and a protrusion protruding from the inner wall, the protrusion having a side surface extending from the opening toward the cavity, the inner wall including a spherical wall in a spherical shape; and a femoral head prosthesis, which has a spherical shape corresponding to the spherical wall and is provided with a mating surface, wherein the side surface extends obliquely relative to the opening and is configured to cooperate with the mating surface so that the femoral head prosthesis is only allowed to enter and exit the cavity along a direction oblique to the opening.

Description

Technical Field

[0001] The present invention relates to the field of orthopedic medicine, and more specifically, to a hip joint prosthesis used in hip replacement surgery. Background Art

[0002] Total hip replacement is an effective method for treating severe hip joint diseases and is increasingly used in clinical treatment. It has the functions of reconstructing joints, relieving pain, correcting deformities, stabilizing and improving joint function. Dislocation of the ball head from the acetabulum is one of the common complications after hip replacement. According to statistics and reports from various aspects at home and abroad, its incidence rate is less than 0.1-10%, and there are even records of dislocation rates as high as 25% after revision surgery. Dislocation of the joint can cause sciatic nerve injury, difficulty in reduction, and even re-dislocation after reduction, etc., which brings great pain to patients. There are many reasons for joint dislocation: such as the patient is too thin or obese, has been bedridden for a long time before surgery and has poor physical fitness, the muscles around the hip joint are atrophied and lack tension, the prosthesis is placed in an improper position and tilt angle, accidents occur during postoperative patient transportation, improper rehabilitation training movements, etc. For total hip replacement, the positions where dislocation is prone to occur are the upper edge and the anterior and posterior edges of the acetabulum liner. For bipolar hemihip replacement, the liner structure restrains the ball head and prevents dislocation. Therefore, exploring the causes of early dislocation of the hip joint after hip replacement and studying artificial hip joint systems that reduce the risk of dislocation are important issues facing designers and manufacturers.

[0003] There are many solutions in the prior art for solving the problem of joint dislocation, but these prior arts either cannot achieve reliable restraint of the ball head, or cannot achieve large-area contact (for example, more than hemisphere) of the ball head and the acetabular liner, or involve more anti-dislocation structural components, resulting in complex structure, complex installation, high price, prolonged operation time and many other problems.

[0004] Therefore, in the art, there is an urgent need for a prosthetic device that can reliably constrain the ball head and ensure a large contact area between the ball head and the acetabulum liner while having a simple structure and convenient installation. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention proposes a hip joint prosthesis, which comprises:

[0006] an acetabular liner having an inner wall defining a cavity and an opening and a projection protruding from the inner wall, the projection having a side surface extending from the opening toward the cavity, the inner wall including a spherical wall having a spherical shape; and

[0007] a femoral head prosthesis having a spherical shape corresponding to the spherical wall and provided with a mating surface,

[0008] Wherein, the side surface extends obliquely relative to the opening and is configured to cooperate with the mating surface so that the femoral head prosthesis is only allowed to enter and exit the cavity along a direction oblique relative to the opening.

[0009] Optionally, the inner wall includes a channel wall extending from the opening to the spherical wall in a direction parallel to the side surface, and the side surface has a shape corresponding to the mating surface so that the femoral head prosthesis is only allowed to enter and exit the cavity in a manner in which the mating surface is aligned with the side surface.

[0010] Optionally, the protrusion has an upper surface located in the cavity and connected to the side surface, and the upper surface is a continuation of the spherical wall.

[0011] Optionally, on a side opposite to the protrusion, a portion of the spherical wall is between an imaginary plane and the opening, and the imaginary plane passes through the center of the spherical wall and is parallel to the opening.

[0012] Optionally, the channel wall is tangent to the spherical wall.

[0013] Optionally, the side surface and the channel wall define a channel as a part of the cavity, and a cross-section of the channel has the same profile as a projection of the femoral head prosthesis along a direction parallel to the mating surface.

[0014] Optionally, a dimension of the femoral head prosthesis measured along a direction perpendicular to the mating surface and passing through its center is greater than a depth of the cavity measured along a direction perpendicular to the opening and passing through the center of the spherical wall.

[0015] Optionally, the protrusion further has a lower surface located at the opening, and the lower surface and the upper surface are spaced apart from each other.

[0016] Optionally, the spherical wall and the opening are spaced apart from each other.

[0017] Optionally, the hip joint prosthesis further comprises a femoral stem prosthesis adapted to be coupled to the femoral head prosthesis.

[0018] The present invention can be embodied as the illustrative embodiments in the accompanying drawings. However, it should be noted that the accompanying drawings are only illustrative, and any changes conceived under the teachings of the present invention should be considered to be included in the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings illustrate exemplary embodiments of the present invention. These drawings should not be interpreted as necessarily limiting the scope of the present invention, wherein:

[0020] Figure 1is a schematic perspective view of a hip joint prosthesis according to an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A schematic cross-sectional view of a hip prosthesis shown in , wherein the femoral head prosthesis is aligned with the channel in the acetabular liner;

[0022] Figure 3 yes Figure 2 A schematic cross-sectional view of a hip prosthesis shown in , wherein a femoral head prosthesis is inserted through a passage into an acetabular liner;

[0023] Figure 4 yes Figure 2 A schematic cross-sectional view of a hip prosthesis shown in , wherein the femoral head prosthesis is rotated to a constrained position in the acetabular liner;

[0024] Figure 5 yes Figure 2 A schematic cross-sectional view of a hip prosthesis shown in , wherein a femoral stem prosthesis is coupled to a femoral head prosthesis;

[0025] Figure 6 yes Figure 5 A schematic cross-sectional view of a hip joint prosthesis shown in , wherein the femoral stem prosthesis is rotated to an extreme position;

[0026] Figure 7 yes Figure 5 A schematic cross-sectional view of a hip joint prosthesis shown in , wherein the femoral stem prosthesis is rotated to another extreme position; and

[0027] Figure 8 yes Figure 1 Schematic perspective view of the acetabular liner of the hip prosthesis shown in . DETAILED DESCRIPTION

[0028] Further features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings. Exemplary embodiments of the present invention are shown in the accompanying drawings, and each of the accompanying drawings is not necessarily drawn to actual scale. However, the present invention can be implemented in many different forms and should not be interpreted as necessarily being limited to the exemplary embodiments disclosed herein. On the contrary, these exemplary embodiments are only provided to illustrate the present invention and to convey the spirit and essence of the present invention to those skilled in the art.

[0029] The hip joint prosthesis according to the present invention is intended to provide an acetabular liner, which can receive and constrain the femoral head prosthesis of the femoral prosthesis to prevent it from detaching from the acetabular liner. Generally, the hip joint prosthesis according to one embodiment of the present invention includes an acetabular liner, which has a cavity and an opening to receive the femoral head prosthesis. The acetabular liner also has a protrusion extending from one side along a portion of the opening to reduce the size of the opening. The hip joint prosthesis also includes a femoral head prosthesis, which has a mating surface, and the mating surface has a shape corresponding to the side surface of the protrusion. In addition, the side surface of the protrusion and the surface of the cavity connected thereto jointly define a channel for guiding the femoral head prosthesis in and out of the cavity, and the channel extends obliquely relative to the opening so that the femoral head prosthesis can only enter and exit the cavity in a direction inclined relative to the opening when its mating surface and the side surface of the protrusion face each other. In a more particular embodiment, the femoral head prosthesis can only enter and exit the cavity along the inclined channel when its mating surface is aligned (fitting, abutting) with the side surface of the protrusion. The femoral head prosthesis and the acetabular liner are assembled together by adjusting the mating surface of the femoral head prosthesis to the side surface facing the protrusion, and then moving the femoral head prosthesis into the cavity in a direction inclined relative to the opening. Then, the femoral head prosthesis is rotated and the femoral stem prosthesis is attached to the femoral head prosthesis. After this, since the femoral stem prosthesis limits the rotation angle of the femoral head prosthesis, the femoral head prosthesis can no longer be rotated to a position where its mating surface is relative to or even aligned with the side surface of the protrusion, which makes it impossible for the femoral head prosthesis to detach from the cavity unless the femoral stem prosthesis is removed in advance. In this way, as long as the femoral head prosthesis is combined with the femoral stem prosthesis, the femoral head prosthesis is constrained in the acetabular liner and cannot be dislocated.

[0030] Consider an embodiment of a hip prosthesis according to the present invention. Figure 1-Figure 5 As shown, there are shown an acetabular liner 100 and a femoral head prosthesis 200 of a hip joint prosthesis according to the present invention, wherein the acetabular liner 100 is suitable for receiving the femoral head prosthesis 200, the femoral head prosthesis 200 is suitable for combining with a femoral stem prosthesis 300, and the femoral head prosthesis 200 and the femoral stem prosthesis 300 form a femoral prosthesis after assembly. More specifically, the acetabular liner 100 is suitable for being implanted in the patient's acetabulum to replace a diseased or damaged acetabular socket, and the acetabular liner 100 is suitable for receiving and retaining the femoral head prosthesis 200. The acetabular liner 100 includes an inner wall 120, which defines a cavity 110 inside the acetabular liner 100 and defines an opening 130 on its surface. Figure 1The cavity 110 mainly includes two parts, namely, a generally spherical inner cavity 111 and a channel 112 leading from an opening 130 to the inner cavity 111. The femoral head prosthesis 200 can pass through the channel 112 to reach the inner cavity 111. The inner cavity 111 is defined by a spherical wall 121 of the channel 120. The channel 112 is defined by a side surface 143 of the protrusion 140 mentioned below and a channel wall 122 of the inner wall 120 extending from the opening 130 to the spherical wall 121. For the sake of clarity, Figure 1 In the embodiment, the channel wall 122 is shown by hatching. The acetabular liner 100 further includes a protrusion 140 protruding from one side of the inner wall 120 toward the other side opposite thereto. Figure 8 As shown more clearly, the protrusion 140 has a lower surface 141 at the opening 130, an upper surface 142 in the cavity 110, and a side surface 143 connecting the lower surface 141 and the upper surface 142. In particular, the lower surface 141 occupies a portion of the opening 130, thereby reducing the size of the opening 130 and defining the opening 130 into a D-shape. Figure 1 As shown in , the channel 112 of the cavity 110 is defined by the side surface 143 of the protrusion 140 and the channel wall 122 of the inner wall 120 extending from the unoccupied portion of the opening 130 to its spherical wall 121 (in other words, the spherical inner cavity 111). In particular, as Figure 2 As shown, the side surface 143 and the channel wall 122 extend parallel to each other.

[0031] like Figure 1 and Figure 2 As shown, the side surface 143 of the protrusion 140 and the channel wall 122 of the inner wall 120 are parallel to each other and extend obliquely relative to the opening 130 until the boundary line DL with the spherical wall 121, and the boundary line DL passes through the spherical center 121C of the spherical wall 121. Thus, the side surface 143 and the channel wall 122 define the channel 112 to extend obliquely relative to the opening 130 and communicate with the inner cavity 111 at the boundary line DL, and the boundary line DL is inclined relative to the opening 130. The channel wall 122 of the inner wall 120 is connected to its spherical wall 121 at the boundary line DL. Preferably, the channel wall 122 of the inner wall 120 is tangent to its spherical wall 121 at the boundary line DL.

[0032] like Figure 2 As shown, the portion of the protrusion 140 between its side surface 143 and the inner wall 120 is a continuation of the spherical inner cavity 111. In other words, the spherical wall 121 of the inner wall 120 extends to the side surface 143 of the protrusion 140, which makes the upper surface 142 ( Figure 8The spherical wall 121 is formed as a continuation of the spherical wall 121 (as shown more clearly in FIG. 1 ) and maintains the same curvature as the rest of the spherical wall 121. In this configuration, the protrusion 140 reduces the size of the opening 130 at the bottom and continues the spherical wall 121 at the top, so that the spherical wall 121 extends beyond the imaginary plane PL passing through the spherical center 121C of the spherical wall 121 (in other words, the spherical inner cavity 111) and parallel to the opening 130 on one side of the protrusion 140. Further, the dividing line DL is below the imaginary plane PL on the side opposite to the protrusion 140, so that the channel wall 122 is connected to the spherical wall 121 below the imaginary plane PL on the side opposite to the protrusion 140 (preferably tangent to it), in other words, a part of the spherical wall 121 is between the imaginary plane PL and the opening 130. In this configuration, the spherical wall 121 also extends beyond the imaginary plane PL on the side opposite to the protrusion 140.

[0033] like Figure 1 and Figure 2 As shown, the femoral head prosthesis 200 is generally spherical in shape corresponding to the spherical wall 121, and includes a mating surface 210, which enables the femoral head prosthesis 200 to enter the cavity 110 of the acetabular liner 100, more specifically, to pass through the channel 112 into the spherical inner cavity 111, so that the spherical surface of the femoral head prosthesis 200 fits together with the spherical wall 121 of the inner wall 120. The mating surface 210 can be flat, such as Figures 1 to 5 As shown, or may have other shapes corresponding to the side surface 143 of the protrusion 140. Figure 2 As shown, the mating surface 210 is positioned on the femoral head prosthesis 200 so that the dimension S2 of the femoral head prosthesis 200 measured along a direction perpendicular to the mating surface 210 and passing through the spherical center 200C of the femoral head prosthesis 200 is slightly less than or equal to the dimension S1 of the channel 112, wherein the dimension S1 of the channel 112 can be understood as the distance between the side surface 143 of the protrusion 140 and the channel wall 122 on the other side. Under this configuration, the femoral head prosthesis 200 is allowed to be inserted into the channel 112 and further slid along the channel 112 until it contacts the spherical wall 121 by adjusting the femoral head prosthesis 200 so that the mating surface 210 faces or is aligned with the side surface 143 of the protrusion 140, as shown in FIG. Figure 3 More specifically, this configuration only allows the femoral head prosthesis 200 to enter and exit the cavity 110 in a manner where the mating surface 210 faces or is aligned with the side surface 143 .

[0034] like Figure 3 and Figure 4 As shown, after the femoral head prosthesis 200 completely enters the cavity 110 of the acetabular liner 100, the femoral head prosthesis 200 is rotated so that the femoral head prosthesis 200 is retained in the cavity 110. Figure 4 As shown, after the femoral head prosthesis 200 is rotated, the femoral head prosthesis 200 cannot be removed from the cavity 110 because the diameter D2 ( Figure 2 ) is larger than the dimension S1 of the passage 112, so that as long as the mating surface 210 is not facing or aligned with the side surface 143, the femoral head prosthesis 200 cannot enter the passage 112, and also cannot leave the cavity 110 from the passage 112. In addition, as described above, the spherical wall 121 extends beyond the imaginary plane PL on one side of the protrusion 140 and the opposite side, which makes it possible for the femoral head prosthesis 200 to enter the passage 112 and leave the cavity 110 from the passage 112. Figure 4 As shown, the spherical wall 121 can constrain the femoral head prosthesis 200 substantially along the whole circumference below the imaginary plane PL, which can more effectively and reliably prevent the femoral head prosthesis 200 from coming out of the cavity 110 compared with the prior art that can only constrain the sphere from one side. In addition, as shown in the figure, since the femoral head prosthesis 200 has a sphere that exceeds hemisphere, the spherical wall 121 can make contact with the femoral head prosthesis 200 that exceeds hemisphere from the vertex of the spherical shape to the bottom of the imaginary plane PL, and compared with the prior art that is difficult to achieve contact that exceeds hemisphere, this contact that exceeds hemisphere minimizes the phenomenon of stress concentration between the femoral head prosthesis 200 and the spherical wall 121, which enables the femoral head prosthesis 200 to stably rotate in the cavity 110, and can effectively slow down the wear of the femoral head prosthesis 200 and the spherical wall 121.

[0035] Then, if Figure 5-Figure 7 As shown, the femoral stem prosthesis 300 is coupled to the femoral head prosthesis 200, thereby preventing the mating surface 210 from facing or aligning with the side surface 143 of the protrusion 140, so as to constrain the femoral head prosthesis 200 in the acetabular liner 100. Figure 6 and Figure 7 As shown, once the femoral stem prosthesis 300 has been coupled to the femoral head prosthesis 200, the femoral head prosthesis 200 cannot be removed from the acetabular liner 100 until the femoral stem prosthesis 300 is removed because the femoral stem prosthesis 300 prevents the femoral head prosthesis 200 from being rotated to a position where the mating surface 210 faces or is aligned with the side surface 143.

[0036] like Figure 1-Figure 7 As shown, the femoral head prosthesis 200 has a hole 220, which is suitable for receiving the femoral stem prosthesis 300 and is generally cylindrical. In an alternative embodiment, the hole 220 can be conical, cubic or any other suitable shape. In other alternative embodiments, the hole 220 can include a thread, a barb, a snap ring or any other suitable mechanical connector, so that the femoral head prosthesis 200 is combined with the femoral stem prosthesis 300. In another embodiment, adhesive or bone cement can be used to combine the femoral head prosthesis 200 with the femoral stem prosthesis 300.

[0037] In one embodiment, the orifice 221 of the hole 220 of the femoral head prosthesis 200 is positioned on the mating surface 210. In this embodiment, the orifice 221 is positioned to be only when the femoral head prosthesis 200 is rotated to a position where the orifice 221 is exposed (e.g. Figure 4 After receiving the femoral stem prosthesis 300 (as shown) Figure 5 As shown in Figure 6 and Figure 7 As shown, the combination of the femoral stem prosthesis 300 and the femoral head prosthesis 200 prevents the femoral head prosthesis 200 from rotating to a position where the mating surface 210 faces or aligns with the side surface 143, thereby preventing the femoral head prosthesis 200 from being separated from the cavity 110 of the acetabular liner 100. More specifically, after the femoral stem prosthesis 300 has been coupled to the femoral head prosthesis 200, the femoral stem prosthesis 300 will be blocked by the edge of the opening 130, thereby preventing the femoral head prosthesis 200 from further rotating. Therefore, the opening 130 limits the range of motion of the femoral stem prosthesis 300 (that is, the femoral head prosthesis 200). In other embodiments, the orifice 221 can be positioned at the femoral head prosthesis 200 in addition to the mating surface 210, for example, the orifice 221 can be adjacent to the mating surface 210 or be located at other positions.

[0038] like Figure 4 As shown, after the femoral head prosthesis 200 rotates, on one side of the protrusion 140, the femoral head prosthesis 200 is mainly constrained by the upper surface 142 of the protrusion 140. Since the upper surface 142 is a continuation of the spherical wall 121, the upper surface 142 can constrain the femoral head prosthesis 200 to prevent it from dislocating, but at the same time will not interfere with the rotation of the femoral head prosthesis 200 in the cavity 110. In one embodiment, the lower surface 141 and the upper surface 142 of the protrusion 140 are spaced apart from each other, as shown in FIG. Figure 1 and Figure 8 As shown. Under this configuration, the protrusion 140 has more material for supporting / constraining the femoral head prosthesis 200, so the femoral head prosthesis 200 can be more reliably prevented from dislocating. More specifically, the spherical wall 121 is spaced apart from the opening 130. As mentioned above, what prevents the femoral head prosthesis 200 from detaching from the spherical wall 121 is actually the material between the spherical wall 121 and the opening 130. By spacing the spherical wall 121 apart from the opening 130, more material for preventing the femoral head prosthesis 200 from dislocating can be obtained, thereby more reliably preventing the femoral head prosthesis 200 from dislocating.

[0039] In one embodiment, the dimension S2 of the femoral head prosthesis 200 is greater than the depth D1 of the cavity 110, wherein the depth D1 can be understood as the depth of the cavity 110 measured along a direction perpendicular to the opening 130 and passing through the center 111C of the spherical inner cavity 111. In this configuration, Figure 4 As shown, after the femoral head prosthesis 200 enters the cavity 110, a portion of the femoral head prosthesis 200 will protrude beyond the opening 130 to the outside of the cavity 110. As mentioned above, after the femoral stem prosthesis 300 is combined with the femoral head prosthesis 200, the range of motion of the femoral stem prosthesis 300 is limited by the opening 130. Therefore, a portion of the femoral head prosthesis 200 protruding beyond the opening 130 to the outside of the cavity 110 will give the femoral stem prosthesis 300 a larger range of motion.

[0040] In one embodiment, the side surface 143 and the channel wall 122 extend parallel to each other and define the channel 112 so that the cross-section of the channel 112 has the same profile as the projection of the femoral head prosthesis 200 along a direction parallel to the mating surface 210. In this configuration, the femoral head prosthesis 200 can only enter and exit the channel 112 in a manner in which the mating surface 210 is aligned with the side surface 143, which makes it possible to more reliably constrain the femoral head prosthesis 200 to prevent it from dislocating.

[0041] The optional but non-limiting embodiments of the hip prosthesis according to the present invention are described in detail above with the aid of the accompanying drawings. For those of ordinary skill in the art, modifications and supplements to the technology and structure and the re-combination of the features in each embodiment should obviously be considered to be included within the scope of the present invention without departing from the spirit and essence of the present disclosure. Therefore, these modifications and supplements that can be conceived under the teachings of the present invention should be considered as part of the present invention. The scope of the present invention includes equivalent technologies known at the filing date of the present invention and equivalent technologies that have not yet been foreseen.

Claims

1. A hip joint prosthesis comprising: An acetabular liner (100) having an inner wall (120) defining a cavity (110) and an opening (130) and a projection (140) projecting from the inner wall (120), the projection (140) having a side surface (143) extending from the opening (130) toward the cavity (110), the inner wall (120) including a spherical wall (121) having a spherical shape; and A femoral head prosthesis (200) having a spherical shape corresponding to the spherical wall (121) and provided with a mating surface (210), The side surface (143) extends obliquely relative to the opening (130) and is configured to cooperate with the mating surface (210) so that the femoral head prosthesis (200) is only allowed to enter and exit the cavity (110) along a direction oblique to the opening (130). The inner wall (120) comprises a channel wall (122), wherein the channel wall (122) extends from the opening (130) to the spherical wall (121) along a direction parallel to the side surface (143), and the side surface (143) has a shape corresponding to the mating surface (210), so that the femoral head prosthesis (200) is only allowed to enter and exit the cavity (110) in a manner in which the mating surface (210) is aligned with the side surface (143). The protrusion (140) has an upper surface (142) located in the cavity (110) and connected to the side surface (143), and the upper surface (142) is a continuation of the spherical wall (121), and Wherein, the spherical wall (121) and the opening (130) are spaced apart from each other.

2. The hip joint prosthesis according to claim 1, wherein: On the side opposite to the protrusion (140), a portion of the spherical wall (121) is between an imaginary plane (PL) and the opening (130), and the imaginary plane (PL) passes through the center of the spherical wall (121) and is parallel to the opening (130).

3. The hip joint prosthesis according to claim 1, wherein: The channel wall (122) is tangent to the spherical wall (121).

4. The hip joint prosthesis according to claim 3, wherein: The side surface (143) and the channel wall (122) define a channel (112) which is a part of the cavity (110), and the cross-section of the channel (112) has the same profile as the projection of the femoral head prosthesis (200) along a direction parallel to the mating surface (210).

5. The hip joint prosthesis according to claim 1, wherein: The dimension (S2) of the femoral head prosthesis (200) measured along a direction perpendicular to the mating surface (210) and passing through its center is greater than the depth (D1) of the cavity (110) measured along a direction perpendicular to the opening (130) and passing through the center of the spherical wall (121).

6. The hip joint prosthesis according to claim 1, wherein: The protrusion (140) further has a lower surface (141) located at the opening (130), and the lower surface (141) and the upper surface (142) are spaced apart from each other.

7. The hip joint prosthesis according to any one of claims 1 to 6, wherein: The hip joint prosthesis further comprises a femoral stem prosthesis (300) adapted to be coupled to the femoral head prosthesis (200).

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