A prosthesis for defects after partial atlas resection
By designing a porous outer frame and a bioactive coating for the repair of atlantoaxial defects, the problem of atlantoaxial prosthesis filling was solved, achieving stable fixation and bone fusion after partial atlantoaxial resection, reducing postoperative recovery time and trauma risk, and maintaining the stability and physiological function of the upper cervical spine.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- THE SECOND AFFILIATED HOSPITAL OF NAVAL MEDICAL UNIVERSITY PLA
- Filing Date
- 2025-05-23
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies lack specialized implants for filling the atlas prosthesis. Autologous bone grafting results in a long postoperative recovery time, and titanium mesh implantation cannot be effectively fixed, posing risks of displacement and internal fixation failure.
A prosthesis for defects after partial atlas resection is designed, employing a porous tubular or columnar outer frame filled with autologous or allogeneic bone, a support unit, and a bioactive coating. It is precisely matched to the patient's anatomical structure using 3D printing technology and fixed with bone screws. The outer frame is matched with the occipital condyle and the facet joint of the axis to provide stability and space for bone growth.
It achieves stable fixation of the posterior atlas prosthesis, reduces postoperative recovery time, promotes bone fusion, reduces the risk of trauma, maintains the stability and physiological function of the upper cervical spine structure, has good biocompatibility, and reduces the impact of the implant on the nerves in the spinal canal.
Smart Images
Figure CN224421245U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of orthopedic implant technology, and in particular to a defect repair body for partial atlas resection. Background Technology
[0002] The atlantoaxial joint is responsible for the main cervical rotation function in normal individuals, and its stability is provided by the ligamentous complex of the lateral joints and the atlanto-odontoid joint. Tumors of the atlantoaxial joint will cause local bone tissue destruction, leading to symptoms such as neck pain, limited mobility, weakness in the limbs, and abnormal sensations, which seriously affect the patient's quality of life and may even threaten the patient's life.
[0003] Surgical treatment is currently the most effective treatment for patients with atlas tumors. The goal of surgery is to relieve nerve compression and restore the stability of the upper cervical spine. Surgical approaches include combined anterior and posterior approaches, purely anterior approaches, and purely posterior approaches. Among these, posterior partial atlas resection and spinal fusion is an effective treatment for vertebral tissue destruction caused by atlas tumors. This technique involves partial resection of the lateral mass of the atlas via a purely posterior approach, followed by bone grafting and fusion between the occipital condyle and the facet joint of the axis. Theoretically, this can reduce surgical trauma, achieve a good rate of bony fusion, and improve the long-term efficacy of the surgery.
[0004] Chinese patent document 202011180516.0 discloses an artificial axis prosthesis, which relates to the field of medical devices. The artificial axis prosthesis includes a main body, a locking plate, and a limiting plate. The main body connects the inferior articular surface of the atlas lateral mass and the bone surface of the upper endplate of C3, and has a connecting and load-bearing function. The bone contact surface is a rough surface with an internal porous structure, which is conducive to establishing immediate stability and promoting bone ingrowth. The main body is designed with screw channels on both sides, which can be screwed in to firmly connect with the atlas lateral mass. The locking plate has screw holes, which can firmly connect with the C3 vertebral body. The limiting plate is locked in front of and behind the anterior tubercle of the atlas, which can limit the implant from moving forward or backward.
[0005] However, the above-mentioned approach has at least the following technical problems: Currently, there are no commercially available atlas prostheses specifically designed for atlas partial resection and interaxial-occipital fusion. The commonly used methods are autologous bone grafting or titanium mesh implantation. Autologous bone grafting may cause additional trauma to the donor site, leading to prolonged postoperative recovery time, and may also cause problems such as pain, sensory abnormalities, infection, bleeding, or fracture at the bone harvesting site. Titanium mesh implantation carries the risk of ineffective fixation, perioperative mesh displacement, and internal fixation failure. Therefore, there is an urgent need to develop a prosthesis for defects after atlas partial resection. Summary of the Invention
[0006] In view of the above technical problems, this disclosure provides a prosthesis for defects after partial atlas resection, which solves the problems of lack of atlas prosthesis implants, long recovery time after autologous bone grafting, and ineffective fixation of titanium mesh implants in the prior art.
[0007] According to one aspect of this disclosure, a prosthesis for defects after partial atlas resection is provided, comprising a prosthesis that replaces the atlas, the prosthesis having bone screw holes to accommodate bone screw fixation contact areas; the prosthesis including an outer frame, the outer frame being a porous tubular structure or a porous columnar structure, the cavity of the porous tubular structure being filled with autologous bone, allogeneic bone, or artificial bone; the upper and lower ends of the outer frame having curved surfaces matching the facet joints of the occipital condyle and the axis, and a support unit being provided within the outer frame.
[0008] In some embodiments of this disclosure, the shape of the support unit is one or more combinations of a pentahedron, hexahedron, octahedron, decahedron, dodecahedron, tetrahedron, hexahedron, octahedron, icosahedron, icosahedron, ticosahedron, TPMS minimal surface, Thiessen polygon, cylinder, frustum or elliptic.
[0009] In some embodiments of this disclosure, the outer frame is further provided with a support beam, the two ends of which are connected to the curved surfaces at the ends of the outer frame.
[0010] In some embodiments of this disclosure, the pores of the support unit are interconnected but not through each other.
[0011] In some embodiments of this disclosure, the pore area in the porous tubular structure accounts for 60%-90% of the sidewall area.
[0012] In some embodiments of this disclosure, there are 2 to 5 support beams.
[0013] In some embodiments of this disclosure, clamping positions are also provided on the sidewalls of the outer frame.
[0014] In some embodiments of this disclosure, the outer frame is further provided with a filling hole, which penetrates the outer frame and communicates with the lumen.
[0015] In some embodiments of this disclosure, there are two bone screw holes, one of which is inclined upward and the other is inclined downward.
[0016] In some embodiments of this disclosure, the curved surface at the end of the outer frame is covered with a bioactive coating, the coating comprising a composite material of hydroxyapatite and polylactic acid-glycolic acid copolymer, with a thickness of 50-200 μm.
[0017] In some embodiments of this disclosure, the repair body is assembled from an upper non-standard part, a middle standard part, and a lower non-standard part. The inner sides of the upper and lower non-standard parts are respectively provided with grooves, and the middle standard part is provided with a protrusion at the corresponding groove position, so that the middle standard part is snapped between the upper and lower non-standard parts.
[0018] The beneficial effects of this utility model are as follows:
[0019] 1. To address the gap left after partial atlas resection, an atlas defect prosthesis is used to fill the defect area from the posterior cervical approach. At the same time, screws are used to fix the prosthesis between the occipital bone and the axis. The upper and lower end faces of the prosthesis match the occipital condyle and the facet joint of the axis, which can achieve fusion of the occipital bone and the axis and reconstruct the anatomical structure of the upper cervical spine.
[0020] 2. The posterior cervical spine prosthesis is implanted using a zero-notch implantation method. This design allows the implant to be completely integrated into the defect space without protruding from the posterior edge of the vertebral body, without changing the original anatomical structure of the upper cervical spine, while minimizing the impact of the implant on the nerves in the spinal canal.
[0021] 3. Using an atlas defect prosthesis to replace part of the atlas structure (such as the superior articular surface, inferior articular process, transverse process, etc.) can preserve the anterior arch, healthy transverse process, articular surface, posterior arch, lateral mass, etc. of the atlas to the greatest extent, thus preserving the stability of the upper cervical spine structure to the greatest extent.
[0022] 4. Based on 3D printing technology, the integrated molding reduces the difficulty of processing and assembly. Moreover, the established 3D model can accurately determine the patient's anatomical structure, such as the development of the craniocervical junction bones and the course of the vertebral artery, and reasonably adjust the product parameters to achieve a more stable support effect.
[0023] 5. The porous structure of the outer frame facilitates bone ingrowth and repair, enhances the bonding between the prosthesis and surrounding bone tissue, promotes bone healing, and ensures good biocompatibility and bone integration. The well-proportioned pore area ensures sufficient space for bone growth while maintaining the structural strength of the prosthesis. The support unit provides internal support to the outer frame, resisting external impacts and reducing the risk of deformation. Its diverse shape options allow for optimized layout to enhance local strength and ensure high structural stability. The curved design of the upper and lower ends of the outer frame perfectly conforms to the occipital condyle and the facet joints of the axis, ensuring the stability and physiological function recovery of the prosthesis after implantation and precisely adapting to the anatomical structure. The inclined placement of the bone screw holes allows the bone screws to firmly anchor the prosthesis from different angles, enhancing fixation reliability and facilitating installation. Clamping positions on the sidewalls of the outer frame facilitate grasping and fixation during surgery, while filling holes facilitate the filling of the lumen with bone material, further promoting bone growth and repair. The bioactive coating covering the curved surfaces at the ends of the outer frame promotes bone tissue growth and repair. The coating material gradually degrades in vivo and is replaced by new bone tissue, exhibiting no long-term toxicity. The coating thickness is appropriately sized to ensure bioactivity without affecting the contact and integration between the prosthesis and bone tissue. Multiple shape combinations of the support units can meet different anatomical locations and mechanical requirements, optimizing the mechanical properties and biocompatibility of the prosthesis. The modular structure allows for individualized printing for different patients; identical areas use the same dimensions, while different areas are printed independently without affecting assembly. This allows for the assembly of both standard and non-standard components. Standard components reduce costs, while non-standard components improve individual comfort. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of a prosthesis structure used for partial atlas resection.
[0025] Figure 2 This is a schematic diagram of a prosthesis used for defects after partial atlas resection, taken from another perspective.
[0026] Figure 3 A schematic diagram of the structure of a prosthesis used for defects after partial atlas resection;
[0027] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of this application;
[0028] Figure 5 for Figure 4 Top view;
[0029] Figure 6 for Figure 5 Sectional view of plane AA;
[0030] The components in the diagram are named as follows: 1. Outer frame, 11. Bone screw hole, 12. Side wall, 13. Clamping position, 2. Support beam. Detailed Implementation
[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1
[0032] This example discloses a prosthesis for defects after partial atlas resection. See [link to relevant documentation]. Figures 1 to 6 ;
[0033] The prosthesis includes a replacement for the atlas, with bone screw holes 11 provided to accommodate the bone screw fixation contact area; the prosthesis includes an outer frame 1, which is a porous tubular structure or a porous columnar structure, and the cavity of the porous tubular structure is filled with autologous bone, allogeneic bone or artificial bone; the upper and lower ends of the outer frame 1 are provided with curved surfaces that match the facet joints of the occipital condyle and the axis, and a support unit is provided inside the outer frame 1.
[0034] The shape of the support unit is one or more of the following: pentahedron, hexahedron, octahedron, decahedron, dodecahedron, tetrahedron, hexahedron, octahedron, icosahedron, icosahedron, ticosahedron, TPMS minimal surface, Thiessen polygon, cylinder, frustum or elliptic.
[0035] The outer frame 1 is also provided with a support beam 2, and the two ends of the support beam 2 are connected to the curved surfaces at the ends of the outer frame 1.
[0036] The pores of the support unit are interconnected but not through each other.
[0037] In porous tubular structures, the pore area accounts for 60%-90% of the sidewall area.
[0038] There are 2 to 5 support beams.
[0039] A clamping position 13 is also provided on the side wall 12 of the outer frame 1.
[0040] The outer frame 1 is also provided with a filling hole, which penetrates the outer frame 1 and connects to the cavity.
[0041] There are two bone screw holes 11, one of which is set at an upward angle and the other at a downward angle.
[0042] The curved surface at one end of the outer frame is covered with a bioactive coating, which is a composite material of hydroxyapatite and polylactic acid-glycolic acid copolymer with a thickness of 50-200 μm.
[0043] The prosthesis is used to replace the partially removed atlas. It is usually implanted into the defect site through the posterior cervical approach and fixed to the superior articular facet of the occipital bone and axis vertebral body using bone screws. With the help of 3D printing technology, the shape is matched with the corresponding segment and the resected site, thereby replacing the resected segment, promoting the fusion of the atlantoaxial segment, and helping to restore the physiological function of the upper cervical spine.
[0044] The prosthesis includes an outer frame 1 and supporting beams. The outer frame 1 is a tubular structure with a tubular cavity for filling with fillers such as autologous bone. The sidewalls 12 of the outer frame 1 are connected to the outside, fully utilizing the bone-growth-promoting effect of the filler and facilitating subsequent bone tissue ingrowth, thus forming a more stable connection. The sidewalls 12 of the outer frame 1 are also provided with clamping positions 13. The shape of the clamping positions 13 is the same as that of existing clamps, facilitating intraoperative gripping.
[0045] The structure connecting the outer wall to the outside is achieved using a porous structure. The porous structure is a three-dimensional mesh structure formed by interconnecting several internal support units. This structure has a low porosity, similar to the trabecular structure of native bone, which is conducive to bone tissue ingrowth and joint load-bearing. It also maintains the integrity of the side of the external support and avoids the detachment of the filler implanted in the external support.
[0046] The ends of the outer frame 1 are smooth, continuous curved surfaces whose shape matches their contact surfaces. The solid structure of this curved surface increases the contact area. Through 3D printing, the sidewalls are tightly integrated with the end curved surfaces. The combination of porous and curved structures optimizes the stress distribution, overcomes the problem of mismatch between the mechanical properties of metal structures and bone tissue, especially the elastic modulus, and avoids stress shielding.
[0047] The outer frame 1 is also equipped with support beams, whose two ends are connected to continuous curved surfaces at the ends. The support beams are solid structures that serve to strengthen the support. Of course, the number and position of the support beams can be adjusted based on the patient's resection situation.
[0048] This application achieves fixation to the affected area using bone screws. The threaded holes in this application are inclined, and the openings of the threaded holes on the side wall surface are close to each other, which facilitates operation during surgery. At the same time, the outward inclined setting allows the bone screws to be embedded in the threaded holes without protruding from the side wall, thereby achieving a zero-notch effect. Example 2
[0049] The principle of this example is the same as that of Example 1, the specific difference being: see [link / reference] Figures 4 to 6 ;
[0050] The repair body is assembled from an upper non-standard part 3, a middle standard part 4, and a lower non-standard part 5. Grooves 6 are respectively provided on the inner sides of the upper non-standard part 3 and the lower non-standard part 5. A protrusion 7 is provided on the middle standard part 4 at the position corresponding to the groove 6, so that the middle standard part 4 can be snapped between the upper non-standard part 3 and the lower non-standard part 5.
[0051] Although some preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.
[0052] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this utility model also intends to include these modifications and variations.
Claims
1. A prosthesis for defects after partial atlas resection, characterized in that: The prosthesis includes a replacement for the atlas, wherein the prosthesis has bone screw holes to accommodate bone screw fixation contact points; the prosthesis includes an outer frame, which is a porous tubular structure or a porous columnar structure, wherein the cavity of the porous tubular structure is filled with autologous bone, allogeneic bone, or artificial bone; the upper and lower ends of the outer frame are provided with curved surfaces that match the facet joints of the occipital condyle and the axis, and a support unit is provided within the outer frame.
2. The defect repair body for partial atlas resection as described in claim 1, characterized in that: The shape of the support unit is one or more of the following: pentahedron, hexahedron, octahedron, decahedron, dodecahedron, tetrahedron, hexahedron, octahedron, icosahedron, icosahedron, ticosahedron, TPMS minimal surface, Thiessen polygon, cylinder, frustum or elliptic.
3. The defect repair body for partial atlas resection as described in claim 2, characterized in that: The pores of the support unit are interconnected but not through each other.
4. The defect repair body for partial atlas resection as described in claim 1, characterized in that: The pore area in the porous tubular structure accounts for 60%-90% of the sidewall area.
5. The defect repair body for partial atlas resection as described in claim 1, characterized in that: The outer frame is also provided with support beams, the two ends of which are connected to the curved surfaces at the ends of the outer frame; there are 2 to 5 support beams.
6. The defect repair body for partial atlas resection as described in claim 1, characterized in that: The outer frame is also provided with a filling hole, which penetrates the outer frame and communicates with the cavity.
7. The defect repair body for partial atlas resection as described in claim 1, characterized in that: The curved surface at the end of the outer frame is covered with a bioactive coating, which is a composite material of hydroxyapatite and polylactic acid-glycolic acid copolymer, with a thickness of 50-200 μm.
8. A detachable prosthesis for defects after partial atlas resection, characterized in that: The invention includes a defect repair body assembled from a detachable structure. The detachable structure comprises an upper non-standard component, a middle standard component, and a lower non-standard component that can be assembled. Grooves are provided on the inner sides of the upper and lower non-standard components, and a protrusion is provided on the middle standard component at the corresponding groove position to allow the middle standard component to be snapped between the upper and lower non-standard components. The defect repair body includes a repair body that can replace the atlas. The repair body has bone screw holes to accommodate bone screw fixation contact points. The repair body includes an outer frame, which is a porous tubular or porous columnar structure. The cavity of the porous tubular structure is filled with autologous bone, allogeneic bone, or artificial bone. The upper and lower ends of the outer frame are provided with curved surfaces that match the facet joints of the occipital condyle and axis. Support units are provided within the outer frame.