Implant insertion system
The wide acetabular cup design with peripheral engagement holes and a radially actuating insertion tool facilitates precise positioning and manipulation of ceramic cups, addressing the challenges of existing methods by maintaining structural integrity and performance.
Patent Information
- Application Number
- JP2025504034
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-28
- Filing Date
- 2023-07-27
- Publication Date
- 2025-07-25
AI Technical Summary
Existing acetabular cup insertion methods face challenges in properly positioning and manipulating ceramic cups due to the difficulty in creating tool engagement holes without compromising structural integrity and avoiding damage to the highly polished articular surfaces, and existing tools lack sufficient control for rotation and tilting.
A wide acetabular cup design with a smooth central bearing zone and peripheral bearing zone featuring insertion tool engagement holes, combined with a radially actuating insertion tool that engages these holes to allow for precise positioning and manipulation without degrading the central bearing surface.
Enables accurate placement and adjustment of the acetabular cup, preserving the structural integrity and performance of the ceramic cup by minimizing contact with the central bearing zone, allowing for rotation and tilting without damaging the smooth surface.
Smart Images
Figure 2025524052000001_ABST
Abstract
Description
Technical Field
[0001] The present invention generally relates to devices and techniques for placing and positioning an acetabular cup.
Background Art
[0002] An acetabular cup is inserted into a prepared acetabulum and directly receives a femoral head component or receives an articular component via a liner for a dual mobility hip prosthesis.
[0003] An acetabular cup is typically pushed into the acetabulum using an insertion tool having a rounded head at the distal end of a rod to avoid damage to the smooth bearing surface of the acetabular cup.
[0004] However, once the acetabular cup is placed in the acetabulum, it is difficult to properly position the acetabular cup. For example, using the aforementioned insertion tool, it is not possible to rotate or tilt the acetabular cup axially, and misalignment may occur.
[0005] Metal cups may have intricate tool engagement holes such as threaded holes on their rims to engage corresponding threads of a special engagement tool, but it is difficult to create such tool engagement holes in ceramic acetabular cups without compromising their structural integrity and / or damaging their articular surfaces that can be highly polished.
[0006] As such, one type of conventional acetabular cup engagement tool involves a plate that seals across the rim of the acetabular cup and is coupled to a vacuum to create a suction force for holding the acetabular cup to the engagement tool. However, this suction force is generally insufficient, especially for removing the acetabular cup, and cannot be used to twist the acetabular cup.
[0007] The present invention seeks to provide a method that overcomes at least some of the drawbacks of the prior art, or substantially improves it, or at least provides an alternative.
[0008] It should be understood that where prior art information is referred to in this specification, such reference does not constitute an admission that such information forms part of the common general knowledge in the art in Australia or any other country.
Summary of the Invention
[0009] An implant system is provided herein that includes a wide acetabular cup defining an internal bearing surface. The internal bearing surface defines a central bearing zone that is generally smooth overall and a peripheral bearing zone surrounding the central bearing zone.
[0010] The internal bearing surface has a plurality of insertion tool engagement holes located only within the peripheral bearing zone.
[0011] The system involves the use of an insertion tool that includes a rod and a plurality of radially actuating interlocks at the distal end of the rod.
[0012] The interlocks are configurable between a disengaged configuration where the interlocks retract towards the rod and fit within the peripheral bearing zone, and an engaged configuration where the interlocks extend from the rod and engage respective insertion tool engagement holes to attach the wide acetabular cup to the insertion tool.
[0013] Preferably, a central bearing zone located within 150° from the center of gravity of the joint movement supports the main forces during joint movement. This central bearing zone is smooth and has no holes or depressions to withstand these main forces. On the other hand, the peripheral bearing zone experiences little or rarely any force even under extreme rotation.
[0014] The engagement holes are located only within the peripheral bearing zone and have little impact on the performance of the internal bearing surface.
[0015] As such, once the cup is implanted, the system enables the insertion and manipulation of the acetabular cup using an insertion tool without significantly degrading the performance of the bearing surface.
[0016] Furthermore, the protrusions avoid contact with the central bearing zone, thereby avoiding damage to its smooth surface, which can be highly polished.
[0017] The system is particularly suitable for ceramic acetabular cups and can form engagement holes in the ceramic without substantially affecting the structural integrity of the acetabular cup.
[0018] Other aspects of the invention are also disclosed.
[0019] Although any other form may fall within the scope of the present invention, the preferred embodiments of the present disclosure will now be described by way of example only, with reference to the accompanying drawings.
Brief Description of the Drawings
[0020]
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
[0021] Referring to FIG. 10, implant system 100 includes a wide acetabular cup 101.
[0022] FIG. 1 shows wide acetabular cup 101 engaging dual mobility liner 102, which engages head 103 of the femoral component of a dual mobility implant. However, in an alternative embodiment, wide acetabular cup 101 engages directly with head 103 of the femoral component.
[0023] Wide acetabular cup 101 defines an inner bearing surface 104. Inner bearing surface 104 defines a central bearing zone 105 that is smooth overall (i.e., without any holes, depressions, etc.). Inner bearing surface 104 can be highly polished.
[0024] Wide acetabular cup 101 defines a center of gravity 106 of joint movement, about which head 103 of the femoral component rotates according to the geometry of wide acetabular cup 101. Preferably, central bearing zone 105 is within 150° of center of gravity 106 of joint movement. In other words, referring to FIG. 1, interior angle 107 with respect to center of gravity 106, defined by edge 109 of central bearing zone 105, is preferably less than 150°.
[0025] The inner bearing surface 104 further defines a peripheral bearing zone 108 that surrounds a central bearing zone 105. FIG. 2 shows an imaginary line 109 that separates the central bearing zone 105 from the peripheral bearing zone 108.
[0026] The peripheral bearing zone 108 includes a plurality of insertion tool engagement holes 110. The central bearing zone 105 does not include any tool engagement holes 110, and the tool engagement holes 110 are located only within the peripheral bearing zone 108.
[0027] Referring to FIG. 10, the system 100 further includes an insertion tool 111. The insertion tool includes a rod 112 and a plurality of radially actuating interlocks 113 at the distal end of the rod 112.
[0028] The interlock 113 can be configured in a non-engaged configuration where the interlock 113 retracts towards the rod 112 and fits within the peripheral bearing zone 108.
[0029] FIGS. 10-12 show that the interlock 113 can further be configured in an engaged configuration where the interlock 113 extends from the rod 112 and engages respective insertion tool engagement holes 110, such that by attaching the acetabular cup 101 to the insertion tool 111, it is possible to position the acetabular cup 111 with the insertion tool 111.
[0030] Referring to FIG. 12, the interlock 113 can have a distal arm 116 and a central arm 115 that is hingedly coupled at an angle between the distal arm 116 and the rod 112. The distal arm 116 can define an insertion portion 117 that is shaped to fit within the engagement hole 111 with a small tolerance.
[0031] Referring to FIG. 5, the engagement hole 111 can be elongated and define straight upper and lower edges 118 parallel to the rim 119 of the acetabular cup 101. In this regard, the insertion portion 117 can be planar so as to fit flat against respective edges 118 and disperse the insertion force along the edges 118.
[0032] The insertion portion 117 may have a rounded edge 120 (i.e., in a plane perpendicular to the elongated axis defined by the rod 112) such that the interlock 113 can rotate within the peripheral bearing zone 108 and reach the engagement hole 110. However, the distal arm 116 preferably has a side portion 120 that engages irreversibly with the corresponding side portion of the engagement hole 110 such that once the distal arm 116 reaches each engagement hole 110, the distal arm 116 cannot be twisted out of the engagement hole 110. Thereby, the rod 112 can be twisted to rotate the acetabular cup 101. In the embodiment shown in FIG. 10, the side portion 120 of the distal arm 116 is planar.
[0033] As shown in FIG. 5, each tool engagement hole 101 may be approximately 12.5 mm in length and approximately 3 mm in width. Further, the ends of the tool engagement hole 101 may have a radius of approximately 1.5 mm.
[0034] As further shown in FIG. 4, the inner edge of the engagement hole 110 may be chamfered to avoid a sharp edge hitting the head 103 of the femoral component or the dual mobility liner 102.
[0035] The insertion tool 111 may include a manual operating mechanism for configuring the interlock 113 between engaged and disengaged configurations.
[0036] In one embodiment, the insertion tool 111 includes a sleeve (not shown) that slides along the rod 110 and interrupts between the interlocks 113. Further, the interlock 113 may be biased towards the disengaged configuration.
[0037] As such, when engaging the acetabular cup 111, the sleeve is pushed towards the distal end of the rod 112, whereby the interlocks 113 are forced outwards into their respective engagement holes 113 and the interlocks 113 can be held in the engagement holes 113 until the sleeve retracts.
[0038] The acetabular cup 101 is typically implanted directly into the native acetabulum of the hip bone that has been processed / prepared with a hip reamer. In this regard, the outer surface 114 of the acetabular cup 101 may be coated with an osseointegration coating such as a roughened titanium coating. Alternatively, the acetabular cup 101 may be fixed to the prepared acetabulum with cement.
[0039] By engaging the interlock 113 within each engagement hole 110, it becomes possible to adjust the insertion angle and / or rotation of the acetabular cup 101 with the insertion tool 111.
[0040] Once the acetabular cup 101 is properly positioned within the acetabulum, the interlock 113 retracts to a disengaged configuration, releasing the engagement hole 112 and allowing the insertion tool 113 to be removed from the acetabular cup 101. The acetabular cup 101 then remains implanted while the insertion tool 113 is withdrawn from the wound.
[0041] The insertion tool 113 can also be used during re - surgery to change or remove the position of the acetabular cup 110.
[0042] The central bearing zone 105 (preferably within 150° from the center of joint movement 106) supports the main forces during joint movement and is smooth overall (i.e., without holes, depressions, etc.) to withstand these main forces.
[0043] However, the peripheral bearing zone 108 can withstand only small or rare forces during extreme rotation. The engagement holes 110 are present only within the peripheral bearing zone 108, and thus, even if there is any effect, it has a negligible impact on the performance of the inner bearing surface 104. In other words, since the engagement holes 110 are present only within the peripheral bearing zone 108 and the central bearing zone 105 is smooth overall, it is possible to insert the acetabular cup 101 using the insertion tool 111, and once the acetabular cup 101 is implanted, the performance of the bearing surface 104 will not be significantly degraded (even if it is reduced).
[0044] Preferably, the lower edge 118B of the tool engagement hole 110 defines an interior angle 107 greater than 165° with respect to the center of gravity 106.
[0045] In some embodiments, the upper edge 118A of the tool engagement hole 118 defines an interior angle less than 180° to enable an unconstrained wide acetabular cup 101.
[0046] In a preferred embodiment, the wide acetabular cup 113 is ceramic. As suggested above, the outer surface 114 of the wide acetabular cup 111 may be coated with an osseointegration coating.
[0047] FIG. 8 shows a preferred embodiment of the wide acetabular cup 101 in which the engagement hole 110 is a through-hole. Finite element analysis suggests that the through-hole can reduce the structural stress of the ceramic wide acetabular cup 101, especially during sintering. However, FIG. 6 shows an alternative embodiment in which the engagement hole 110 is a blind hole. In other words, the blind hole 110 is a depression in the inner bearing surface 104 and does not cross to the outer surface 114.
[0048] FIGS. 6 and 8 show that the engagement hole 110 has straight upper and lower edges 118. However, the embodiment of FIG. 7 shows an embodiment in which the cross-section of the engagement hole 110 is oval and its upper and lower edges 118 have curvature.
[0049] FIG. 9 shows an embodiment of the wide acetabular cup 101 in which the wide acetabular cup 101 has a single engagement hole 110 in the form of a channel that extends around the entire circumference of the peripheral bearing zone 108. However, this embodiment is not very preferred because it may make it difficult to rotate the wide acetabular cup 101.
[0050] In some embodiments, the insertion tool may comprise an impact plate (not shown), which is located above the interlock 113 and configured to be placed flat in contact with the rim 119 of the acetabular cup 101. Further, the offset of the interlock 113 from the impact plate may be configured such that when the impact plate is placed in contact with the rim 119, the interlock 113 is properly offset to reach the engagement hole 110.
[0051] The impact plate can be used to disperse the impact force around the rim 119 of the acetabular cup 101. As such, the impact plate allows the acetabular cup 101 to be pushed into the acetabulum by hitting or tapping the rod 112 without applying a load to the interlock 113.
[0052] In a preferred embodiment as shown in FIG. 3, the acetabular cup 101 comprises three engagement holes 108. The three engagement holes 110 represent the minimum number of holes 110 (i.e., with the least impact on the inner bearing surface 104) that allow the acetabular cup 101 to be manipulated along three axes with the insertion tool 101.
[0053] As further shown in FIG. 3, the engagement holes 100 may be arranged at equal intervals (i.e., at 120° intervals).
[0054] In the foregoing description, for purposes of explanation, a specific nomenclature has been used to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that specific details are not required to practice the present invention. Accordingly, the foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations will be apparent in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The following claims and their equivalents are intended to define the scope of the present invention.
Claims
**Claim 1** An implant system, a wide acetabular cup, an inner bearing surface, wherein the inner bearing surface has a central bearing zone that is smooth as a whole, a peripheral bearing zone surrounding the central bearing zone, and a plurality of insertion tool engagement holes located only within the peripheral bearing zone, defining the inner bearing surface defining the wide acetabular cup, an insertion tool, a rod, a plurality of radially operating interlocks at the distal end of the rod, wherein the interlocks have a non-engagement configuration in which the interlocks are retracted toward the rod and fit within the peripheral bearing zone, and an engagement configuration in which, for positioning the wide acetabular cup by the insertion tool, the interlocks extend from the rod and engage respective insertion tool engagement holes to attach the wide acetabular cup to the insertion tool, the interlocks being configurable to, comprising the insertion tool, comprising the system. **Claim 2** The system according to claim 1, wherein the central bearing zone is within 150° as a whole from the center of gravity of the articular movement of the inner bearing surface. **Claim 3** The system according to claim 1, wherein the lower edge of the tool engagement hole defines an inner angle greater than 165° with respect to the center of gravity. **Claim 4** The system according to claim 1, wherein the upper edge of the tool engagement hole defines an inner angle less than 180° with respect to the center of gravity. **Claim 5** The system according to claim 1, wherein the peripheral bearing zone comprises three tool engagement holes. **Claim 6** The system according to claim 5, wherein the tool engagement holes are arranged at equal intervals. **Claim 7** The system according to claim 1, wherein the wide acetabular cup is ceramic. **Claim 8** The system according to claim 1, wherein the wide acetabular cup has a roughened osteointegration outer surface. **Claim 9** The system according to claim 1, wherein each interlock has a distal arm and a central arm that is hingedly coupled at an angle between the distal arm and the rod. **Claim 10** The system according to claim 1, wherein each interlock defines an insertion portion shaped to fit within the engagement hole with little tolerance. **Claim 11** The system according to claim 10, wherein the engagement hole is elongated and defines straight upper and lower edges parallel to the rim of the wide acetabular cup, and the insertion portion is planar. **Claim 12** The system of claim 10, wherein the insertion portion has a rounded edge in a plane perpendicular to the elongated axis defined by the rod. **Claim 13** The system of claim 10, wherein the insertion portion has a side that irreversibly engages a corresponding side of the engagement hole when the insertion tool is twisted relative to the acetabular cup. **Claim 14** The system of claim 1, wherein each engagement hole has a length exceeding 10 mm. **Claim 15** The system of claim 1, wherein each engagement hole has a width of less than 5 mm. **Claim 16** The system of claim 1, wherein the inner edge of each engagement hole is chamfered. **Claim 17** The system of claim 1, wherein the insertion tool comprises a manual operating mechanism for configuring the interlock between an engaged and a disengaged configuration. **Claim 18** The system of claim 17, wherein the insertion tool comprises a sleeve that slides along the rod to interrupt between the interlocks, forces the interlocks outwardly into respective engagement holes, and holds the interlocks in the respective engagement holes. **Claim 19** The system of claim 18, wherein the interlock is biased into the disengaged configuration. **Claim 20** The system of claim 1, wherein the insertion tool engagement holes are through holes. **Claim 21** The system of claim 1, wherein the insertion tool comprises an impact plate configured to be disposed flat in contact with the rim of the acetabular cup. **Claim 22** The system of claim 21, wherein the offset of the interlock from the impact plate is configured such that when the impact plate is disposed in contact with the rim, the interlock is properly offset to reach the engagement hole. **Claim 23** A method of using the system of claim 1, the method comprising: configuring the interlock in the disengaged configuration; inserting the interlock into the peripheral bearing zone; configuring the interlock in the engaged configuration such that the interlock extends from the rod and engages respective insertion tool engagement holes to attach the acetabular cup to the insertion tool; positioning the acetabular cup using the insertion tool. **Claim 24** An acetabular cup defining an inner bearing surface, the inner bearing surface A central bearing zone that is smooth as a whole, and A peripheral bearing zone surrounding the central bearing zone, and A plurality of insertion tool engagement holes located only within the peripheral bearing zone, and A wide acetabular cup that defines them.