Spacers for tibial bone defects

Abstract

The present invention relates to a pad for tibial bone defects, which belongs to the field of bone implantation technology. The pad comprises a main body that is pressed into the bone defect area on the inner posterior side of the tibial plateau, one side of the main body is an arcuate surface, the main body is fixedly connected to the tibial tray, the main body is a porous structure, the porosity of the main body along the length direction of the tibia increases gradually from the tibial tray to the bone bed, and the porosity of the main body along the radial direction of the tibia increases gradually from the cortical bone to the medullary cavity; the present invention utilizes the arcuate surface on the main body to match the morphology of the bone defect on the inner posterior side of the tibial plateau, so as to avoid cutting off too much normal bone, the porosity of the main body with a porous structure increases gradually from the proximal end to the distal end of the tibia along the length direction of the tibia, and the porosity along the radial direction of the tibia increases gradually from the bone cortex to the medullary cavity, the pad fits the elastic modulus of the surrounding bone tissue, effectively reduces stress shielding, can effectively support the tibial tray, and avoids various complications such as prosthesis loosening and displacement after surgery.

Description

Technical Field

[0001] The invention belongs to the technical field of bone implantation, and in particular relates to a spacer for tibial bone defects. Background Art

[0002] Knee replacement surgery is one of the treatment options for end-stage knee osteoarthritis. It uses an artificial joint (prosthesis) to replace the diseased knee joint tissue to help patients restore normal knee joint mobility. Knee replacement surgery often faces the thorny problem of bone defects, and bone loss can lead to insufficient bone support, reduce the stability of the prosthesis, and easily increase the risk of prosthesis loosening. Depending on the extent of the bone defect, different reconstruction plans can be used to fill the defect between the tibial tray and the tibial bone bed. When the defect is small, bone cement filling, bone cement combined with screw implants, structural bone grafting and other methods can be used to fill it. When the defect is large, pads, conical patches or sleeve structures can be used to fill it.

[0003] Patients with varus knee deformity often have bone defects of varying depths in the medial and posterior regions of the tibial plateau. When the bone defect is large, metal pads are primarily used to fill and repair the bone defect in that area. Existing metal pads are mostly rectangular or wedge-shaped, while the bone defects in the medial and posterior regions of the tibial plateau are often spherical or ellipsoidal in shape. Before surgical implantation of the metal pad, the bone defect area needs to be trimmed to match the metal pad with the bone defect area. This will result in the removal of an excessive amount of normal bone, leading to a further reduction in the bone mass around the proximal tibia metal pad implant area.

[0004] At the same time, research has found that the elastic modulus of a normal tibia gradually decreases from the cortical bone toward the medullary cavity, and also from the proximal end of the tibia to the distal end. However, the elastic modulus of current metal pads is uniform, and there is a significant difference between the elastic modulus of metal pads and that of normal bone tissue. After implantation, the metal pads become the primary load-bearing component, resulting in reduced stress on the bone tissue surrounding the metal pads and causing stress shielding. According to Wolf's law, bone grows where it is needed and absorbs where it is not. Stress shielding can cause the already small amount of bone around the metal pads to absorb and collapse, which can easily lead to various complications such as prosthetic loosening and displacement after surgery. Summary of the Invention

[0005] In view of this, the present invention provides a pad for tibial bone defects to address the deficiencies in the prior art. The present invention can avoid cutting off too much normal bone, effectively alleviate stress shielding, effectively support the tibial tray, and avoid various complications such as prosthesis loosening and displacement after surgery.

[0006] The technical solution of the present invention is: a pad for tibial bone defects, configured and connected to the tibial platform to support and fix the tibial tray on the tibial platform, including a main body, pressed into the bone defect area on the inner posterior side of the tibial platform, one side of the main body is an arcuate surface, the arcuate surface abuts the bone bed of the tibia, the main body is flush with the tibial platform, the tibial tray abuts the tibial platform, the main body is fixedly connected to the tibial tray, the main body is a porous structure, the porosity of the main body along the length direction of the tibia increases gradually from the tibial tray to the bone bed, and the porosity of the main body along the radial direction of the tibia increases gradually from the cortical bone to the medullary cavity.

[0007] Preferably, the porosity of the main body ranges from 30% to 85%.

[0008] Preferably, the material of the main body is titanium alloy or tantalum metal. When the material of the main body is titanium alloy, the pore size range is 0.1mm to 0.4mm; when the material of the main body is tantalum metal, the pore size range is 0.4mm to 0.6mm.

[0009] Preferably, the main body is a cancellous bone trabecular structure imitating a cancellous bone trabecular structure, and the cancellous bone trabecular structure is constructed into a porous structure by periodically arranging cubic unit cells.

[0010] Preferably, the outer contour of the main body is smoothly connected to the natural bone surface of the human body.

[0011] Preferably, a through hole is provided on the main body along its center line direction and is perpendicular to the tibial tray. A support column is passed through the through hole and is fixedly connected to the tibial tray. The support column is a solid structure, and one end of the support column abuts the tibial tray. A threaded hole is provided on the support column along its center line direction so that a threaded fastener is threadedly connected to the threaded hole. The threaded fastener passes through the threaded hole and is threadedly fixed to the tibial tray.

[0012] Preferably, the outer contour of the longitudinal section of the support column is stepped, and the outer diameter of one end of the support column close to the tibial tray is larger than the outer diameter of the other end.

[0013] Preferably, a countersunk hole is coaxially formed on the side of the main body located away from the tibial tray at the through hole, and one end of the support column away from the tibial tray is flush with the bottom surface of the countersunk hole.

[0014] Preferably, the surface of the main body in contact with the tibial bone bed is provided with an osteoinductive growth factor coating, an antibacterial coating and an angiogenic growth factor coating.

[0015] Compared with the prior art, the present invention provides a pad for tibial bone defects, which fills the bone defect area on the inner and posterior side of the tibial plateau through the main body, and uses the curved surface on the main body to match the shape of the bone defect on the inner and posterior side of the tibial plateau, so as to avoid cutting off too much normal bone and retain more bone around the metal pad. At the same time, the porosity of the main body of the porous structure along the length direction of the tibia increases gradually from the proximal end to the distal end of the tibia, and the porosity along the radial direction of the tibia increases gradually from the cortical bone to the medullary cavity, so that the bidirectional gradient distribution of the porosity of the pad realizes elastic modulus adaptation, and the pad fits the elastic modulus of the surrounding bone tissue, effectively reducing stress shielding, and can effectively support the tibial tray, avoiding various complications such as prosthesis loosening and displacement after surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the installation of the cushion block of the present invention;

[0017] Figure 2 It is a schematic diagram of the internal structure of the cushion block of the present invention;

[0018] Figure 3 is a top view of the spacer block of the present invention;

[0019] Figure 4 It is a bottom view of the cushion block of the present invention. DETAILED DESCRIPTION

[0020] The present invention provides a spacer for tibial bone defect, Figures 1 to 4 The present invention is described with reference to a structural schematic diagram of FIG.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] Patients with varus knee deformity often have bone defects of varying depths in the medial and posterior regions of the tibial plateau. When the bone defect is large, metal pads are primarily used to fill and repair the bone defect in that area. Existing metal pads are mostly rectangular or wedge-shaped, while the bone defects in the medial and posterior regions of the tibial plateau are often spherical or ellipsoidal in shape. Before surgical implantation of the metal pad, the bone defect area needs to be trimmed to match the metal pad with the bone defect area. This will result in the removal of an excessive amount of normal bone, leading to a further reduction in the bone mass around the proximal tibia metal pad implant area.

[0023] At the same time, research has found that the elastic modulus of a normal tibia gradually decreases from the cortical bone toward the medullary cavity, and also from the proximal end of the tibia to the distal end. However, the elastic modulus of current metal pads is uniform, and there is a significant difference between the elastic modulus of metal pads and that of normal bone tissue. After implantation, the metal pads become the primary load-bearing component, resulting in reduced stress on the bone tissue surrounding the metal pads and causing stress shielding. According to Wolf's law, bone grows where it is needed and absorbs where it is not. Stress shielding can cause the already small amount of bone around the metal pads to absorb and collapse, which can easily lead to various complications such as prosthetic loosening and displacement after surgery.

[0024] Based on the above problems, an embodiment of the present invention provides a pad for tibial bone defects, which fills the bone defect area on the inner and posterior side of the tibial plateau through the main body, and uses the curved surface on the main body to match the shape of the bone defect on the inner and posterior side of the tibial plateau, so as to avoid cutting off too much normal bone and retain more bone around the metal pad. At the same time, the porosity of the main body of the porous structure along the length direction of the tibia increases gradually from the proximal end to the distal end of the tibia, and the porosity along the radial direction of the tibia increases gradually from the cortical bone to the medullary cavity, so that the bidirectional gradient distribution of the porosity of the pad realizes elastic modulus adaptation, and the pad fits the elastic modulus of the surrounding bone tissue, effectively reducing stress shielding, and can effectively support the tibial tray, avoiding various complications such as prosthesis loosening and displacement after surgery.

[0025] Reference Figure 1 The figure shows the installation diagram of the pad block of the present embodiment, which is a pad block for tibial bone defects, configured to be connected to the tibial platform to support and fix the tibial tray 1 on the tibial platform, including a main body 2, which is pressed into the bone defect area 33 on the inner posterior side of the tibial platform. The bone defect area is essentially spherical and socket-shaped. One side of the main body 2 is an arcuate surface, which abuts the bone bed of the tibia 3. The main body 2 is flush with the tibial platform, the tibial tray 1 abuts the tibial platform, and the main body 2 is fixedly connected to the tibial tray 1. The main body 2 is a porous structure, and the porosity of the main body 2 along the length direction of the tibia 3 increases gradually from the tibial tray 1 to the bone bed, and the porosity of the main body 2 along the radial direction of the tibia 3 increases gradually from the cortical bone to the medullary cavity.

[0026] The pad for tibial bone defect disclosed in this embodiment mainly fills the bone defect area on the inner and posterior side of the tibial plateau. The bone defect area is essentially spherical and socket-shaped. When the main body 2 is implanted, a press-fit fixation method is adopted to press the main body 2 into the spherical socket to achieve a stable combination of the pad and the bone tissue. The curved surface (or partial spherical shape) of the main body 2 is used to match the bone defect contour, which greatly reduces the amount of bone resection and retains more bone around the metal pad. At the same time, the porous structure has a bidirectional gradient porosity design, and the elastic modulus adapts to the surrounding bone tissue, which improves the mechanical environment after the pad is implanted, effectively alleviates the stress shielding effect, and avoids the absorption and collapse of the bone around the pad. It can effectively support the tibial tray and avoid various complications such as prosthesis loosening and displacement after surgery.

[0027] The pad in this embodiment is perpendicular to the stress direction of the surrounding bone tissue and is mostly spherical or ellipsoidal in shape. This avoids the longitudinal shear stress of conventional pads. The compressive stress of the spherical pad can improve the mechanical environment after the pad is implanted, avoid excessive tangential displacement caused by shear stress, and optimize biomechanical properties. The arc design can avoid stress concentration at the right-angle edge. The bone bed mainly bears the compressive load perpendicular to the spherical surface, reducing the displacement caused by tangential shear action and the potential risk of tibial fracture caused by intraoperative osteotomy and postoperative fatigue stress.

[0028] In this embodiment, the main body 2 is a porous structure, and the surface of the main body 2 has a certain degree of roughness (the porous structure itself uses holes to achieve a certain degree of roughness), which further enhances the effect of bone tissue adhesion.

[0029] At the same time, the pad for tibial bone defects disclosed in this embodiment minimizes the patient's application cost through serialized product design, and designs spherical structure pads of different diameters and thicknesses for different bone defect ranges to provide patients with the greatest matching degree and reduce the amount of bone resection.

[0030] As a further optimization solution, the porosity range of the main body 2 in this embodiment is 30% to 85%. The porosity value and distribution are designed based on the variation law of natural knee bone density and biomechanical analysis, and are selected during surgery based on the patient's bone density and bone defect condition to improve mechanical properties and reduce the impact of stress shielding.

[0031] The porosity range of the main body 2 disclosed in this embodiment is 30% to 85%, which can enable the porosity change of the pad with bidirectional gradient porosity to be designed according to the distribution law of bone density in the lower limbs of the human body, thereby realizing a porous structure with adaptive elastic modulus. The bidirectional gradient porosity design of the porous structure has a smaller porosity on the side close to the proximal end 31 of the tibia to ensure the strength of the connection with the tibial prosthesis, and a larger porosity on the side close to the distal end 32 of the tibia in contact with the bone to promote bone integration. The porosity of the area filling the cortical bone is smaller, which plays a supporting role, and the porosity of the area near the medullary cavity is larger, which promotes the growth of surrounding bones.

[0032] The porosity adjustment range of the porous structure of the main body 2 disclosed in this embodiment is 30% to 85%, and its elastic modulus varies in the range of 0.337GPa to 6GPa, which is between cancellous bone (0.1GPa to 0.5GPa) and cortical bone (12GPa to 18GPa), further making the elastic modulus of the pad close to that of normal bone tissue, thereby alleviating the stress shielding effect.

[0033] As a further optimization solution, the material of the main body 2 in this embodiment is titanium alloy or tantalum metal. When the material of the main body 2 is titanium alloy, the aperture range is 0.1mm~0.4mm, and when the material is tantalum metal, the aperture range is 0.4mm~0.6mm.

[0034] The main body 2 in this embodiment is made of titanium alloy or tantalum metal. Porous tantalum metal has good biocompatibility. The pore size range of titanium alloy is 0.1mm to 0.4mm, and that of tantalum metal is 0.4mm to 0.6mm. The pore size is the optimal size for bone tissue growth.

[0035] As a further optimization solution, the main body 2 in this embodiment is a cancellous bone trabecular structure imitating a cancellous bone trabecular structure, and the cancellous bone trabecular structure is constructed into a porous structure by periodically arranging cubic unit cells.

[0036] The main body 2 in this embodiment is a cancellous bone trabecular structure that can promote the growth of bone tissue and fibrous tissue, provide a structural support for bone ingrowth, facilitate blood vessel regeneration and bone tissue ingrowth, and promote bone tissue regeneration.

[0037] As a further optimization solution, the outer contour of the main body 2 in this embodiment is smoothly connected to the natural bone surface of the human body.

[0038] In this embodiment, the outer curved surface of the main body 2 connecting with the cortical bone is based on the anatomical shape near the natural tibial metaphysis, and adopts a ligament-friendly bionic curve design, which smoothly connects with the natural bone surface of the human body, providing a more friendly biomechanical environment for the knee joint soft tissue sleeve.

[0039] Reference Figure 2The figure shows the internal structure of the pad of this embodiment. As a further optimization scheme, a through hole is provided on the main body 2 along its center line direction, and is perpendicular to the tibial tray 1. A support column 22 is passed through the through hole and is fixedly connected to it. Figure 3 This is a top view of the pad block of this embodiment. The support column 22 is a solid structure. One end of the support column 22 abuts against the tibial tray 1. A threaded hole 23 is provided on the support column 22 along its center line so that the threaded fastener is threadedly connected to the threaded hole 23. The threaded fastener passes through the threaded hole 23 and is threadedly fixed to the tibial tray 1.

[0040] In this embodiment, a support column 22 is set in the through hole on the main body 2, so that the threaded fastener is connected to the tibial tray 1 using the threaded hole 23 on the support column 22. The support column 22 provides sufficient support strength for fixing the threaded fastener, thereby realizing the positioning and fixation of the pad.

[0041] In this embodiment, the support column 22 is made of titanium alloy or tantalum metal material. The main body 2 and the support column 22 are integrally formed by 3D printing, and the threaded hole 23 on the support column 22 is formed by mechanical processing.

[0042] In addition, the outer diameter of the support column 22 is 1.5-3 times the inner diameter of the threaded hole 23. At the same time, the diameter, depth and other parameters of the threaded hole are designed to be consistent with the threaded connection mechanism on the tibial tray. The threaded structure is used to ensure that the pad and the tibial tray are correctly positioned and reliably connected.

[0043] The internal solid structure 1 of the spherical bidirectional gradient porosity pad is located at the center of the pad and is cylindrical or stepped cylindrical structure. The diameter of the cylinder is 1.5-3 times the diameter of the threaded hole, providing the necessary support structure and mechanical strength for the threaded hole connected to the tibial tray.

[0044] Reference Figure 4 This is a bottom view of the pad block of this embodiment. Preferably, the outer contour of the longitudinal section of the support column 22 is stepped, and the outer diameter of one end of the support column 22 close to the tibial tray 1 is larger than the outer diameter of the other end.

[0045] As a further optimization solution, in this embodiment, a countersunk hole 24 is coaxially opened on the side of the main body 2 away from the tibial tray 1 at the through hole, and the end of the support column 22 away from the tibial tray 1 is flush with the bottom surface of the countersunk hole 24.

[0046] This embodiment utilizes the countersunk hole 24 on the main body 2 so that when a screw is used to connect the spacer to the tibial tray prosthesis, the head of the screw is located in the countersunk hole 24, facilitating bone tissue attachment.

[0047] As a further optimization solution, in this embodiment, the surface of the main body 2 that contacts the bone bed of the tibia 4 is provided with an osteoinductive growth factor coating, an antibacterial coating, and an angiogenic growth factor coating.

[0048] In this embodiment, the surface of the main body 2 is treated. The BMP-2 component contained in the bone induction growth factor coating can stimulate the activity of osteoblasts and accelerate the bone conduction process. The silver nanoparticle antibacterial substance in the antibacterial coating can inhibit the attachment and aggregation of bacteria on the implant surface and reduce the risk of infection. The angiogenic growth factor coating can promote the formation of new blood vessels and provide sufficient nutrition for bone tissue regeneration.

[0049] The present invention provides a spacer for tibial bone defects. The installation process includes:

[0050] S1. Collect imaging data of the patient's lower limbs to determine the size and shape of the tibial bone defect;

[0051] S2. Select an appropriate bidirectional gradient porosity spacer based on the size and shape of the bone defect;

[0052] S3. Place the upper surface of the pad in contact with the tibial tray and fix it to the tibial tray prosthesis with screws. The curved surface of the pad is press-fitted and fixed to the bone bed.

[0053] The above disclosure is only a preferred specific embodiment of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A pad for tibial bone defects, configured to be connected to the tibial plateau to support and fix a tibial tray (1) on the tibial plateau, characterized in that: include: The main body (2) is pressed into the bone defect area on the inner posterior side of the tibial plateau, the part of the main body (2) is spherical or ellipsoidal, the spherical or ellipsoidal shape abuts against the bone bed of the tibia (3), the main body (2) is perpendicular to the stress direction of the surrounding bone tissue and is spherical or ellipsoidal. The main body (2) is flush with the tibial plateau, the tibial tray (1) abuts against the tibial plateau, the main body (2) is fixedly connected to the tibial tray (1), the main body (2) is a porous structure, the porosity of the main body (2) along the length direction of the tibia (3) increases gradually from the tibial tray (1) to the bone bed, and the porosity of the main body (2) along the radial direction of the tibia (3) increases gradually from the cortical bone to the medullary cavity; A through hole is provided on the main body (2) along the center line thereof and is perpendicular to the tibial tray (1). A support column (22) is passed through the through hole and is fixedly connected thereto. The support column (22) is a solid structure. One end of the support column (22) abuts against the tibial tray (1). A threaded hole (23) is provided on the support column (22) along the center line thereof so that a threaded fastener is threadedly connected to the threaded hole (23). The threaded fastener passes through the threaded hole (23) and is threadedly fixedly connected to the tibial tray (1). The outer contour of the longitudinal section of the support column (22) is stepped, and the outer diameter of one end of the support column (22) close to the tibial tray (1) is larger than the outer diameter of the other end; The main body (2) is coaxially provided with a countersunk hole (24) on the side of the through hole away from the tibial tray (1), and the end of the support column (22) away from the tibial tray (1) is flush with the bottom surface of the countersunk hole (24).

2. The spacer for tibial bone defect according to claim 1, characterized in that: The porosity of the main body (2) ranges from 30% to 85%.

3. The spacer for tibial bone defect according to claim 1, characterized in that: The material of the main body (2) is titanium alloy or tantalum metal. When the material of the main body (2) is titanium alloy, the aperture range is 0.1 mm to 0.4 mm. When the material of the main body (2) is tantalum metal, the aperture range is 0.4 mm to 0.6 mm.

4. The spacer for tibial bone defect according to claim 1, characterized in that: The main body (2) is a cancellous bone trabecular structure imitating a cancellous bone trabecular structure, and the cancellous bone trabecular structure is constructed by periodically arranging cubic unit cells to form a porous structure.

5. The spacer for tibial bone defect according to claim 1, characterized in that: The outer contour of the main body (2) smoothly connects with the natural bone surface of the human body.

6. The spacer for tibial bone defect according to claim 1, characterized in that: The surface of the main body (2) in contact with the tibia (3) bone bed is provided with an osteoinductive growth factor coating, an antibacterial coating and an angiogenic growth factor coating.

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