Joint implant system for a ball joint

Abstract

Joint implant system (22) for a roller joint (43) or a ball joint (7) with a first bony joint component, a joint head (2), and a second bony joint component, a joint socket (3), characterized in that the joint implant system (22) comprises an intermediate body (24) which is designed for bilaterally movable arrangement between the first bony joint component, the joint head (2), and the second bony joint component, the joint socket (3), wherein a joint head-side contact surface (30) and a joint socket-side contact surface (32) of the intermediate body (24) have the same radius of curvature (R) in certain areas. k , R p exhibit.

Description

[0001] The present invention relates to a joint implant system for a roller joint or a ball joint, in particular for a socket joint. In particular, the invention relates to a joint implant system for a hip joint.

[0002] True joints (diarthroses or synovial joints) exhibit a discontinuity (joint space) between the bones involved in the joint. The joint space separates the articular surfaces (contact surfaces of the joint), which in a healthy joint are covered with articular cartilage. Externally, the joint is surrounded by a tight joint capsule. This capsule may have reinforcements in some areas, known as ligaments or capsular ligaments.

[0003] The joint capsule defines a joint cavity, which corresponds to a completely enclosed space and is filled with a viscous fluid (synovia).

[0004] The invention relates in particular to hinge joints as a subtype of the roller joint. The hinge joint consists of a roller-shaped joint head that rests in a joint socket corresponding to a segment of a hollow cylinder. It is usually additionally stabilized by strong collateral ligaments and may also have guide ridges or grooves in the articular cartilage.

[0005] A hinge joint has one axis of movement, or one degree of freedom, and allows simple flexion and extension movements. Examples of hinge joints are the joints between the bones of the finger joints, also known as interphalangeal joints (articulationes interphalangeales).

[0006] A ball and socket joint is a variant of a true joint in which the joint partners are an approximately spherical joint head and a corresponding joint socket.

[0007] In a ball-and-socket joint, the center of the joint head is the pivot point of the joint. A ball-and-socket joint can perform any type of movement along three axes in space. It therefore possesses three degrees of freedom, enabling movement in all three planes of space. The mobility of the ball-and-socket joint is limited by the surrounding joint capsule and ligaments, which provide guidance.

[0008] Examples of ball-and-socket joints are the human hip joint (a nut joint, which will be explained in more detail later) and the human shoulder joint.

[0009] A ball joint is a special type of ball joint in which the socket of the joint extends beyond the equator of the joint head.

[0010] In a ball-and-socket joint, the range of motion is restricted earlier by the acetabular rims than in a less tightly fitted ball-and-socket joint. The hip joint is an example of a ball-and-socket joint.

[0011] The invention relates to roller or ball joints designed as single-chamber joints, in which the bones involved or the cartilage tissue present in a healthy state are in direct contact with each other and move against each other.

[0012] The hip joint is the articulated connection between the pelvis and the thigh bone, which enables movement of the leg and thus walking while simultaneously stabilizing the body.

[0013] The hip joint consists of the acetabulum (hip socket) and the femoral head (caput femoris). The acetabulum is formed by portions of the ilium, pubis, and ischium, which connect via a Y-shaped joint in the region of the acetabulum. The upper rim of the socket is reinforced by a cartilaginous rim, the acetabular rim. The femoral head is an approximately spherical end of the femur (thigh bone) that presses into the acetabulum, thus connecting the leg to the torso. As already explained, the hip joint is therefore a ball-and-socket joint.

[0014] As already mentioned, the shoulder joint is also an example of a ball-and-socket joint, and it is the most mobile ball-and-socket joint in the human body. In the shoulder joint, the head of the humerus (caput humeri) articulates with the articular surface (cavitas glenoidalis) of the scapula. The spherical head of the humerus articulates with the elongated oval-shaped glenoid cavity. Compared to the humeral head, the glenoid cavity is small and therefore does not completely enclose the humeral head (unlike in the hip joint).

[0015] In conventional implant systems of the type mentioned above, the joint head or part of the joint head and the glenoid cavity or part of the glenoid cavity are usually removed and replaced by appropriate implants that are in direct contact with each other in the final state.

[0016] For example, in a classic hip replacement, the femoral neck is first cut and the femoral head removed. Then, a cavity is milled into the diseased acetabulum, and an artificial acetabular cup is anchored. The artificial acetabular cup can be a single piece or a two-piece device. In a two-piece acetabular cup, a shell-like first element is typically connected to the bony structure, and then a second shell-like element, called an inlay, is rigidly and immovably connected to the first element. On the femoral side, an elongated stem (prosthetic stem) is then inserted into the femur at the site of the previously removed femoral head (usually by hammering). Depending on the condition of the femur, this is done with or without the use of bone cement.Next, an artificial joint head, the prosthetic head, is attached to the prosthetic stem. The prosthetic head is then inserted into the artificial hip socket.

[0017] Conventional hip implants have the disadvantage that the stem, inserted into the femur, must be hammered into the bone and only maintains a secure position for a limited time. Over time, the connection between the stem and the femur loosens, and the implant must be replaced.

[0018] DE 41 40 838 C1, DE 10 2005 028 523 A1, DE 20 2017 101 341 U1, US 2014 / 0031948, AU 1996 068 882 A1 disclose devices and methods for replacing a joint. DE 41 40 838 C1 has features of the preamble of claim 1.

[0019] To explain the present invention, the following text refers in part to a first bony joint component and a second bony joint component. The bony joint components are the bony structures that are movable relative to each other by means of the articulated connection. The first bony joint component can, in particular, be a joint head, and the second bony joint component can, in particular, be a joint socket.

[0020] The object of the present invention is to provide a particularly gentle and durable implant.

[0021] This problem is solved according to the invention by the joint implant system comprising an intermediate body. The intermediate body is inserted into the joint between the first and second bony joint components, i.e., between the articular head and the articular fossa. It is possible to preserve the original bony joint components, the original damaged articular head, or the original damaged articular fossa. However, it is also possible to provide implants on both sides. These implants can, for example, be only superficially designed. In their extent, they can essentially correspond to the original cartilage layer.

[0022] The implant system according to the invention is thus designed such that a double-chamber joint is created by inserting the intermediate body. The implant system is designed such that the intermediate body slides on both sides, namely against the first bony joint component and against the second bony joint component, or against the articular head-side and articular acetabular counterparts (articular head and articular acetabulum or corresponding implants).

[0023] A joint implant is typically needed when the cartilage layer of both gliding surfaces—in this case, the articular head or acetabulum and the glenoid cavity—is worn away. The patient suffers from pain due to bone-on-bone contact. The bone surfaces in direct contact are not smooth but have a certain roughness that prevents smooth gliding against each other. In a healthy joint, the smooth gliding properties are ensured by the presence of cartilage. Inserting the implant prevents the two rough bone surfaces from rubbing against each other and becoming locked, for example. Instead, the bones are in contact with the smooth implant. This allows for pain-free or reduced-pain gliding.

[0024] Typically, the contact surfaces of the intermediate body are designed to be polished (i.e., the contact surfaces facing the joint head and the contact surface of the intermediate body facing the joint socket) in order to achieve the smoothest possible surface.

[0025] As previously explained, the joint implant system can comprise a joint head implant or a joint augmentation implant. The joint head implant is specifically designed to replace the contact surface of the joint head and to contact the joint head-side contact surface of the intermediate body. Accordingly, the contact surface of the joint head implant and the joint head-side contact surface of the intermediate body are complementary to each other. The contact surface of the intermediate body on the joint head side is typically concave and preferably in the form of a hollow spherical segment. The contact surface of the joint head implant, therefore, has a convex and typically spherical segment-shaped form that closely resembles the shape of a healthy joint head.

[0026] The joint implant system can also include a socket implant. The socket implant is specifically designed to replace the contact surface of the glenoid cavity and to contact the socket-side contact surface of the intermediate body. Accordingly, the contact surface of the socket implant and the socket-side contact surface of the intermediate body are complementary to each other. The contact surface of the intermediate body on the glenoid side is typically convex and preferably in the form of a spherical segment. The contact surface of the socket implant is then correspondingly concave and typically hollow-spherical segment-shaped, closely resembling the shape of a healthy glenoid cavity.

[0027] The femoral head implant, or joint augmentation implant, can be designed in a shell-like shape. This means the implant is essentially fitted over the remaining stump of the femoral head, or attached to it. Unlike conventional implants, such as those used in the hip, the entire femoral head is not removed and a stem inserted into the remaining bone structure for anchorage. Instead, the femoral head implant is placed onto the remaining bone structure. If necessary, the shape of the remaining bone structure of the femoral head is adjusted beforehand.

[0028] The contact surfaces on the articular head implant and the articular acetabular implant are typically polished.

[0029] The intermediate body, the femoral head implant, and / or the acetabular cup implant may comprise a ceramic material, in particular zirconium oxide. It is also provided for in the invention that the intermediate body, the femoral head implant, and / or the acetabular cup implant consist of a ceramic material, in particular zirconium oxide.

[0030] The contact surface on the ball head side and the contact surface on the socket side of the intermediate body are designed with the same radii of curvature in certain areas, in accordance with the invention.

[0031] The intermediate body can therefore have a radius of curvature on the articular head side that is identical to the radius of curvature on the articular fossa side. Such a design of the intermediate body can be suitable, for example, in cases where an implant is provided on both the articular fossa and the articular head side, and their radii of curvature are correspondingly shaped.

[0032] Such a design of the intermediate body can also be suitable in cases where essentially intact bone structures are present on both the glenoid and articular head sides, and only the cartilage tissue is insufficiently present. Accordingly, the radius of curvature on the articular head side is adapted to the articular head, and the radius of curvature on the articular acetabulum side to the articular acetabulum. Since, in its original state, the articular head has a radius matching the articular acetabulum, the intermediate body exhibits locally identical radii of curvature on both sides.

[0033] It is also conceivable to provide an intermediate body with a radius of curvature on the condylar side that is smaller than the radius of curvature on the acetabulum side. In particular, it can be provided that the intermediate body has a wall thickness that remains essentially constant along its entire length and that the radius of curvature on the condylar side plus the wall thickness corresponds to the radius of curvature on the acetabulum side. Thus, both curvature surfaces or contact surfaces have, so to speak, the same center of rotation, or rather, they rotate about the same point.

[0034] The intermediate body can be formed in one piece. According to the invention, the intermediate body can comprise a shell-shaped contact surface on the joint head side and a ball-segment-shaped contact surface on the joint socket side.

[0035] According to the invention, the intermediate body may comprise a shell-shaped first contact surface and a shell-shaped second contact surface arranged opposite the first contact surface. Such a so-called double-shell-shaped intermediate body may, for example, be arranged in the knee joint between the femur and tibia, or be intended for such arrangement. Such a construction is generally suitable for use in a roller joint. Such an intermediate body may be formed in one piece, but it may also be formed in multiple parts. In particular, the intermediate body may comprise at least two components that are pivotable relative to each other. The intermediate body may, in particular, comprise a first shell-shaped contact surface and a second shell-shaped contact surface that are pivotable relative to each other.are arranged on mutually pivotable sub-components of the intermediate body.

[0036] The intermediate body can generally be multi-part and comprise at least two components that can pivot relative to each other.

[0037] The present invention also relates to a treatment method in which an implant system of the type described in this application is inserted into a joint with damaged cartilage layer and additionally cartilage tissue is transplanted to the joint head or the joint elevation and / or to the joint socket.

[0038] In the first step, a cartilage graft is transplanted onto the femoral head and / or the glenoid cavity (autologous or allogeneic cartilage tissue can be used for this). In the second step, the intermediate body is then placed within the joint. The intermediate body is positioned so that the cartilage graft is located in a corresponding recess between the bone structure and the intermediate body. This prevents the graft from being crushed between the two frictional surfaces when the femoral head moves relative to the intermediate body or vice versa. The joint capsule is then closed. The recess is created because the bone structure deviates from its ideal shape (e.g., spherical segment) due to the damage to the cartilage tissue being treated.

[0039] Dura mater, periosteum, or similar tissues can also be transplanted over the cartilage tissue.

[0040] Further details and advantageous embodiments can be found in the following description, which provides a more detailed description and explanation of exemplary embodiments of the invention.

[0041] They show: Fig. 1. A schematic view of a hip joint; Fig. 2 a conventional implant system for a hip joint; Fig. 3 an implant system according to the invention for a hip joint in a sectional view; Fig. 4 a further embodiment of an implant system according to the invention for a hip joint in a sectional view; Fig. 5 a further embodiment of an implant system according to the invention for a hip joint in a sectional view; Fig. 6 a further embodiment of an implant system according to the invention for a hip joint in a sectional view; Fig. 7 a further embodiment of an implant system according to the invention for a roller joint in a sectional view; Fig. 8 a further embodiment of an implant system according to the invention for a roller joint in a sectional view; and Fig. 9 of an implant system according to the invention for a roller joint in a sectional view.

[0042] Fig. Figure 1 shows a schematic view of a human hip joint. The hip joint is formed by a femoral head (caput femoris) and an acetabulum. The femoral head is part of the femur, and the acetabulum is part of the pelvis.

[0043] The acetabulum (3) is cup-shaped or bowl-like. It is located in the lateral pelvic region and serves to hold the femoral head (2).

[0044] The femoral head 2 has an approximately spherical shape. A femoral neck 6 (collum femoris) is attached to the femoral head 2. The hip joint 1 is an example of a ball-and-socket joint 7. Another example is a human shoulder joint (not shown).

[0045] The human hip joint 1 is further an example of a ball-and-socket joint 8. The ball-and-socket joint 8 is a special form of the ball-and-socket joint 7, in which the socket 3 surrounds the joint head 2 beyond its equator.

[0046] In a healthy state, the surface of the femoral head (2) and the acetabulum (3) is covered with cartilage (9) and is smooth. If the cartilage tissue is damaged, the bony structures of the femoral head (2) and the acetabulum (3) come into contact, which is associated with sometimes severe pain for the patient and can, in the long term, lead to inflammation and ultimately to stiffness of the hip joint (1).

[0047] With increasing symptoms, a conventional hip implant system 10 is currently used, as described in Fig. 2 is illustrated.

[0048] In conventional implant systems 10, the femoral head 2 and the acetabulum 3 are typically removed and replaced with appropriate implants. For this purpose, the femoral neck 6 is cut and the femoral head 2 is removed. Subsequently, a cavity is milled into the diseased acetabulum 3, and an artificial acetabulum 12 is anchored. The artificial acetabulum 12 can therefore be a single piece or a two-piece implant. In a two-piece acetabulum 12, a shell-like first element 16 is typically connected to the bony structure, and then a second shell-like element 14, a so-called inlay 14, is rigidly and immovably connected to the first element 16. On the femoral side 4, an elongated stem 18 (prosthetic stem) is then inserted into the femoral head 4 at the site of the previously removed femoral head 2.Depending on the condition of the femur 4, this is performed with or without the use of bone cement. Subsequently, an artificial joint head 20, the prosthetic head 20, is attached to the prosthetic stem 18. The prosthetic head 20 is then inserted into the artificial acetabulum 12.

[0049] Fig. Figure 3 now shows an implant system 22 according to the invention. The implant system 22 according to the invention comprises in the present case an intermediate body 24 as well as a joint socket implant 26 and a joint head implant 28.

[0050] The intermediate body 24 has a condylar-head contact surface 30 and a glenoid-head contact surface 32, which face the condylar-head implant 28 and the glenoid-head implant 26, respectively. Similarly, the condylar-head implant 28 has a contact surface 34 facing the intermediate body 24, and the glenoid-head implant 26 has a contact surface 36 also facing the intermediate body 24. The contact surfaces 30, 32, 34, and 36 are each polished smooth to facilitate optimal sliding against one another. Sliding movement occurs between the intermediate body 24 and the glenoid-head implant 26, as well as between the intermediate body 24 and the condylar-head implant 28.

[0051] The joint head implant 28 is designed in a shell-like form. The joint head implant 28 is thus essentially "placed" over, or attached to, a remaining stump 38 of the joint head 2, in a shell-like manner. In contrast to conventional implants used in the hip region, the entire joint head 2 is therefore not removed.

[0052] In the present invention, the intermediate body 24, the acetabular implant 26, and the articular head implant 28 are made of a ceramic material, in particular zirconium oxide. The use of other materials for the manufacture of the implants is equally within the scope of the present invention.

[0053] In Fig. Figure 4 shows an implant system 22 according to the invention, in which a recess 40 is shown on the articular head side between intermediate body 24 and articular head 2, since the articular head 2 has a deviation from its ideal shape or healthy shape in its corresponding contact surface 34.

[0054] In Fig. Figure 5 shows an implant system 22 according to the invention, in which a recess 42 is shown on the acetabular side between the intermediate body 24 and the acetabular cup 3, since the acetabular cup 3 has a deviation from its ideal shape or healthy shape in its corresponding contact surface 36.

[0055] During the insertion of the implant system, cartilage material or a cartilage graft 48, 50 can be transplanted into the recesses 40 and 42, respectively, onto the worn or damaged articular head 2 or the articular fossa 3. The recesses 40 and 42 then provide sufficient space to protect the transplanted cartilage material 48, 50 from being compressed, for example, between the worn articular head 2 and the intermediate body 24. The transplanted cartilage material 48, 50 can then integrate and improve the condition of joint 1.

[0056] If sufficient regeneration of the cartilage structure occurs, it may be possible to remove the intermediate body 24 again.

[0057] According to the invention, the implant system 22 can be used as follows: In a first step, a cartilage graft 48, 50 is transplanted onto the articular head 2 and / or the articular acetabulum 3.

[0058] In a second step, the intermediate body 24 is then placed in the joint (in this case, hip joint 1).

[0059] The intermediate body 24 is positioned in such a way that the cartilage graft 48, 50 is located in the area of ​​a corresponding recess 40, 42 between the intermediate body 24 and the bone structure, so that it is not ground between the two frictional surfaces when the articular head 2 moves relative to the intermediate body 24 or the intermediate body 24 moves relative to the articular fossa 3. The joint capsule is then closed again.

[0060] In Fig. Figures 4 and 5 further illustrate that the acetabular implant 26 and the articular head implant 28 can be shell-shaped, with the inner and outer radii of the curvature corresponding to the desired curvature of the joint components, so that if the cartilage structure on the opposite side (opposite bone structure) successfully grows, the respective implant can be removed and the remaining bone structure has a shape suitable for the function of the joint.

[0061] Fig. Figure 6 shows a sectional view of an intermediate body 24 of an implant system 22 according to the invention. It can be seen that the intermediate body 24 has a radius of curvature R on the condylar side. k exhibits a radius of curvature R that is identical in this case to the acetabular side of the joint socket. p.Such a design of the intermediate body 24 may be suitable in cases where an implant is provided on the side of the acetabulum 3 as well as on the side of the articular head 2 and their radii of curvature are designed accordingly.

[0062] Such a design of the intermediate body 24 can also be suitable in cases where essentially intact bone structures are present on both the acetabulum 3 and the articular head 2, and only the cartilage tissue is insufficiently present. Accordingly, the radius of curvature R on the articular head side is k adapted to the joint head 2 and the acetabular side radius of curvature R p of the articular acetabulum 3. Since in the original state the articular head 2 has a suitable radius for the articular acetabulum 3, the intermediate body 24 has locally the same radii of curvature on both sides.

[0063] Such a design of the intermediate body 24 may be suitable in cases where an implant is provided on the side of the acetabulum 3 as well as on the side of the articular head 2 and their radii of curvature are designed accordingly.

[0064] It is also conceivable to provide an intermediate body 24 which has a radius of curvature R on the articular head side. k exhibits a radius of curvature R that is smaller than the acetabular side radius of curvature. p It may be provided, in particular, that the intermediate body 24 has a wall thickness that is essentially constant over its length and that the radius of curvature R on the joint head side k plus the wall thickness and the radius of curvature R on the acetabular side p This corresponds to the following: Both curvature surfaces or contact surfaces thus have, so to speak, the same pivot center or pivot around the same point.

[0065] Fig. Figure 7 shows a further embodiment of an implant system 22 according to the invention. The implant system 22 is intended for use in a ball joint 43 and is shown in a sectional view. The implant system 22 comprises an intermediate body 24 and a socket implant 26. The implant system 22 is shown arranged in a knee joint 43 between a femur 44 and a tibia 46. The socket implant 26 is rigidly connected to the tibia 46 by means of corresponding fixing screws 48. A cavity 50 is arranged between the socket implant 26 and the tibia 46 or the remaining bone structure. Cartilage tissue can be placed in this cavity 50 with the aim of allowing the original cartilage tissue structure to regenerate and potentially even enabling the removal of the socket implant 26.

[0066] The intermediate body 24 is similarly spaced locally from the remaining bone structure of the femur 44, so that a cavity 52 is also arranged between the bone structure of the femur 44 and the intermediate body 24. The intermediate body 24 is cup-shaped on its side facing the femur 44 and is pivotally movable relative to the femur 44 in the joint 43, as indicated by the double arrows 54 and 56 on the intermediate body 24 and the femur 44, respectively. The intermediate body 24 is segment-shaped on its side facing the tibia 46 and is pivotally movable relative to the tibia 46 or the acetabular implant 26 in the joint 43.

[0067] In Fig. Figure 8 shows a further embodiment of an implant system 22 according to the invention for a roller joint 43 in a sectional view. This implant system 22 also comprises an intermediate body 24. In this example, the intermediate body 24 is formed in one piece. The intermediate body 24 is furthermore shell-shaped on both its side facing the femur 44 and its side facing the tibia 46, with a cavity 50, 52 on both sides, which serves to receive cartilage tissue or to promote the further formation or regeneration of cartilage tissue.

[0068] In Fig. Figure 9 shows a further embodiment of an implant system 22 according to the invention for a roller joint 43. This implant system 22 comprises an intermediate body 24, which is designed in two parts. The intermediate body 24 comprises two sub-bodies 58 and 60, which are pivotably mounted relative to each other. The sub-bodies 58 and 60 each have a shell-like design on their side facing the bone structure (femur 44 and tibia 46, respectively). The femoral sub-body 58 has a spherical segment-shaped side 62 facing away from the bone. Correspondingly, the tibia-side sub-body 60 has a cup- or shell-like side 64 facing away from the bone, in which the spherical segment-shaped, bone-facing side 62 of the femoral sub-body 58 is pivotably mounted. Otherwise, the intermediate body resembles the Fig. 9 the Fig.8 in that here too the intermediate body 24 is formed in such a way that the corresponding cavities 50, 52 are formed towards the bone structure.

Claims

[1] Joint implant system (22) for a roller joint (43) or a ball joint (7) comprising a first bony joint component, a joint head (2), and a second bony joint component, a joint socket (3), characterized by , that the joint implant system (22) comprises an intermediate body (24) which is designed for bilaterally movable arrangement between the first bony joint component, the joint head (2), and the second bony joint component, the joint socket (3), wherein a joint head-side contact surface (30) and a joint socket-side contact surface (32) of the intermediate body (24) have the same radius of curvature (R) in certain areas k , R p exhibit. [2] Joint implant system (22) according to claim 1, characterized by, that the joint implant system (22) comprises a joint head implant (28) which is designed to replace the contact surface (34) of the joint head (2) and to contact the joint head-side contact surface (30) of the intermediate body (24), wherein the contact surface (34) of the joint head implant (28) and the joint head-side contact surface (30) of the intermediate body (24) are designed to be complementary to each other. [3] Joint implant system (22) according to any one of the preceding claims, characterized by , that the joint implant system (22) comprises a socket implant (26) which is designed to replace the contact surface (36) of the socket (3) and to contact the socket-side contact surface (32) of the intermediate body (24), wherein the contact surface (36) of the socket (3) and the socket-side contact surface (32) of the intermediate body (24) are designed to be complementary to each other. [4] Joint implant system (22) according to any one of the preceding claims, characterized by , that the articular head implant (28) is shell-shaped. [5] Joint implant system (22) according to any one of the preceding claims, characterized by , that the intermediate body (24), the articular head implant (28) and / or the articular acetabular implant (26) comprise a ceramic material, in particular zirconium oxide, or in particular consist of a ceramic material, in particular zirconium oxide. [6] Joint implant system (22) according to any one of the preceding claims, characterized by , that the intermediate body (24) is formed in one piece. [7] Joint implant system (22) according to any one of the preceding claims, characterized by , that the joint implant system (22) is a hip joint implant system. [8] Joint implant system (22) according to any one of the preceding claims 1 to 6, characterized by, that the intermediate body (24) comprises a shell-shaped contact surface (30) on the articular head side and a shell-shaped contact surface (32) on the articular acetabulum side. [9] Joint implant system (22) according to any one of the preceding claims 1 to 5 or 8, characterized by , that the intermediate body (24) is designed in multiple parts and comprises at least two components which are pivotable relative to each other.

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