CN-121987391-A - Vertebral body prosthesis

CN121987391ACN 121987391 ACN121987391 ACN 121987391ACN-121987391-A

Abstract

The application provides a vertebral body prosthesis which comprises an upper vertebral plate and a lower vertebral plate, a wave spring, a bearing plate, an aspheric core and a limiting cylinder, wherein the wave spring is formed by a plurality of sheets twisted in parallel and is arranged between the upper vertebral plate and the lower vertebral plate, the bearing plate is positioned in the middle of the wave spring and is in a circular ring shape, a circular track is arranged in the bearing plate, a limiting ring groove is formed in the outer edge of the bearing plate, the aspheric core is in an ellipsoid shape, a rotating surface of the aspheric core is tightly adhered between an arc surface of the upper vertebral plate at the bottom of the upper vertebral plate and an arc surface of the lower vertebral plate at the top of the lower vertebral plate, the limiting cylinder is arranged at the periphery of the aspheric core, a sliding groove is formed between the limiting cylinders, and the end points of the aspheric core are movably arranged in the sliding groove. The application solves the technical problem that the prosthesis can reasonably recover or partially recover the physiological activity of the resected segment on the premise of ensuring enough supporting strength and anti-displacement capability.

Inventors

HU BIN
DING BO
SHAO JIAWEI
HUA XIN
ZHANG SHUAI

Assignees

北京爱康宜诚医疗器材有限公司
益阳市中心医院

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (9)

1. The vertebral body prosthesis is characterized by comprising an upper vertebral plate and a lower vertebral plate, wherein an upper vertebral plate cambered surface and a lower vertebral plate cambered surface are respectively arranged at the bottom of the upper vertebral plate and the top of the lower vertebral plate; The wave spring is composed of a plurality of sheets twisted in parallel and arranged between the upper vertebral plate and the lower vertebral plate, and an accommodating cavity is formed between the upper vertebral plate and the lower vertebral plate in the wave spring; The bearing plate is positioned in the middle of the wave spring, is annular, is internally provided with a circular track, and is provided with a limit ring groove along the outer edge; The aspheric core is in an ellipsoid shape, a rotating surface of the aspheric core is tightly adhered between an upper vertebral plate cambered surface at the bottom of the upper vertebral plate and a lower vertebral plate cambered surface at the top of the lower vertebral plate, and the end point of the aspheric core is rotatably arranged in a limit ring groove of the bearing plate; The limiting cylinders are symmetrically designed, the limiting cylinders are arranged on the periphery of the aspheric core, sliding grooves are formed between the limiting cylinders, and endpoints of the aspheric core are movably placed in the sliding grooves.
2. The vertebral body prosthesis of claim 1, wherein the interiors of the upper and lower vertebral plates are provided with upper and lower stepped grooves, respectively, which are formed of a plurality of hollow rectangular solids having lengths that increase at once from inside to outside.
3. The vertebral body prosthesis of claim 1, wherein the wave spring is divided into an upper wave spring and a lower wave spring, both of which are fixedly disposed at the outer edge of the bearing plate, the upper wave spring and the lower wave spring being provided with different elastic coefficients.
4. A vertebral body prosthesis according to claim 3, wherein the upper and lower wave springs are further connected in series by a load-bearing post having a length less than the overall length of the wave spring, the load-bearing post being rotatably disposed in a retaining groove in the load-bearing plate.
5. The vertebral body prosthesis of claim 4, wherein the upper wave spring has a lower wave spring having a lower spring constant and wherein the wave spring has a longitudinal cross-section that exhibits a nested configuration with multiple layers of wave peaks aligned.
6. The vertebral body prosthesis of claim 1, wherein the surfaces of the upper and lower vertebral plates that contact the autologous bone are provided with surface structures that are comprised of a fixation cone that is disposed on the outer surfaces of the upper and lower vertebral plates, a sliding ball that connects the fixation cones inside the upper and lower vertebral plates, and a wave slide rail on which the sliding ball is slidably disposed.
7. The vertebral prosthesis of claim 1, wherein the radius of curvature of the aspheric core decreases non-linearly from center to edge and the radius of curvature of the upper and lower lamina arches is greater than the radius of curvature of the aspheric core.
8. The vertebral prosthesis of claim 1, wherein the inner wall of the sliding groove of the limiting cylinder is provided with a flexible buffer gasket, and the flexible buffer gasket is made of medical polymer materials.
9. The vertebral prosthesis of claim 1, wherein the thickness of the bearing plate is less than the height of the aspheric core and the bearing plate is made of ultra high molecular weight polyethylene or bioceramic material having self-lubricating properties.

Description

Vertebral body prosthesis Technical Field The invention relates to the field of orthopedic implants, in particular to a vertebral body prosthesis. Background The vertebral body prosthesis is the mainstream implant for bone defect reconstruction after vertebrotomy. The variety of the vertebral prosthesis used clinically is various and mainly comprises titanium alloy prosthesis, stainless steel prosthesis, polyether ether ketone (PEEK) prosthesis and porous tantalum or cobalt chromium molybdenum alloy prosthesis which appear in recent years according to materials. The device is divided according to structural design and comprises a single-height fixed prosthesis, a height-adjustable expansion type or spiral type prosthesis and a fixed prosthesis with an end plate screw or anchoring structure. Regardless of the specific form, the existing cone prosthesis has high consistency in design concept, namely, the maximum static mechanical strength is pursued, reliable supporting rigidity is provided, and the implant is prevented from sinking, breaking or shifting. For this purpose, these prostheses are generally manufactured as a one-piece, unitary rigid structure with upper and lower surfaces in intimate contact with the adjacent vertebral bodies, either directly or through endplates, with the assistance of screws, locking devices, or interbody press-fit to achieve secure fixation. However, the most fundamental problem is that such prostheses completely ignore the nature of the spine as a moving organ. Under normal physiological conditions, the laminectomy segment would otherwise comprise one or more motion segments, each having a non-zero range of motion, e.g., about 2-6 for the thoracic segment and about 8-12 for the lumbar segment. When the integrated rigid prosthesis is implanted, the prosthesis itself does not have any deformation or relative movement possibility, and forms a stiff whole with the adjacent vertebral bodies, thereby thoroughly eliminating the whole movement property of the resected segment. From a biomechanical point of view, this rigid fixation effect can have a number of adverse consequences. First, loss of surgical segment mobility results in compensatory increases in motion of adjacent segments, with significant changes in stress distribution. During flexion and extension movements of the spinal column, the lamina (or adjacent vertebral bodies) at the upper and lower ends of the rigid prosthesis cannot produce normal relative angular displacements, resulting in significant increases in shear and tensile stresses in the adjacent disc. In the long term, the incidence and the progression rate of adjacent segment degeneration are obviously increased, which is manifested by the loss of intervertebral disc height, the stenosis of intervertebral space, the degeneration of facet joints and even the slipping of vertebral bodies, and is clinically called as 'adjacent segment degeneration'. A number of retrospective studies have demonstrated that patients receiving rigid-cone prosthetic replacement have a proportion of imaging degeneration of adjacent segments up to 30% -50% within 3-5 years after surgery, with some patients requiring a re-surgery to fix the adjacent segments together. Second, the rigid prosthesis alters the normal load transmission path of the spine. In the physiological state, the vertebral bodies distribute the load through the intervertebral discs to the upper and lower endplates, which are then conducted through cancellous and cortical bone. The elastic modulus of the rigid prosthesis is far higher than that of the natural vertebral body and the intervertebral disc, so that a stress shielding effect is generated, and the bone tissue around the prosthesis cannot obtain normal mechanical stimulation, so that osteoporosis and the stability of a bone-implant interface are possibly reduced. Again, from a functional recovery perspective, loss of spinal motion segments can significantly reduce the patient's mobility. The rigid fusion of lumbar or cervical spine segments can cause the patient to feel stiff and clumsy when performing daily activities such as bending, twisting, turning, etc., and may cause compensatory posture abnormalities and muscle strain, severely affecting post-operative quality of life. In summary, the existing vertebral prostheses generally adopt a rigid integrated structure, which, although capable of providing a reliable initial stability, has the fundamental drawback of damaging the functional movement unit of the spinal column at the expense of the intrinsic movement properties between the vertebral bodies. This results in a series of problems of accelerated degeneration of adjacent segments, abnormal stress distribution, reduced patient mobility, etc. Therefore, there is a need for a new vertebral prosthesis that reasonably restores or partially restores the physiological activity of the resected segment while guaranteeing sufficient support strength and resistanc