Radial pressure sensing pedicle screw for internal fixation of spine

Abstract

According to the radial pressure sensing pedicle screw for internal fixation of the spine, a sensitive film pressure sensing structure and the internal space of the pedicle screw are integrated, and the radial pressure of the side wall of the screw can be monitored in real time on the premise that the mechanical property of the screw is not remarkably weakened. The structure has the advantages of being compact in structure, clear in force transmission path, sensitive in response, good in repeatability, suitable for miniaturized integration and the like, a new technical path can be provided for intelligent sensing of intelligent pedicle screws and orthopedic internal fixation instruments, and good clinical application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of medical implantation device technology, specifically to a radial pressure-sensing pedicle screw for spinal fixation. Background Technology

[0002] Pedicle screws are widely used in spinal internal fixation surgery, and their stability directly affects postoperative fusion outcomes. Current clinical practice relies primarily on intraoperative tactile feedback and postoperative imaging to assess the contact state between the screw and bone tissue, lacking real-time, quantitative mechanical feedback methods. Existing screw mechanical monitoring solutions often employ axial tension / compression or torque monitoring, which struggles to effectively reflect the radial contact pressure between the screw and the pedicle bone wall. Furthermore, the sensors are bulky, hindering integration within the limited space of the screw. Existing MEMS pressure sensors are mostly designed for planar loading or cavity pressure environments; when directly applied inside the screw, they suffer from issues such as mismatched force directions, susceptibility to overload damage, and packaging difficulties. Therefore, there is an urgent need for a pressure sensing solution suitable for the interior of pedicle screws, capable of sensing radial pressure, with a compact structure and strong overload resistance. Summary of the Invention

[0003] To address the shortcomings of existing pedicle screw technologies that lack real-time monitoring of the contact state between the screw and bone tissue, this invention provides a radial pressure-sensing pedicle screw for spinal internal fixation. By integrating a miniature sensitive membrane pressure-sensing chip inside the pedicle screw and combining it with a modular carrier of a specific structure, the radial pressure on the screw sidewall is effectively transmitted to the sensitive membrane. This allows the sensitive membrane to undergo detectable deformation under radial load, thereby enabling real-time sensing of the contact pressure at the screw-bone tissue interface. This provides a technical basis for intraoperative and postoperative screw stability assessment and intelligent orthopedic internal fixation.

[0004] The technical solution adopted in this invention is: a radial pressure sensing pedicle screw for spinal internal fixation, comprising a screw body, wherein a hollow cavity is provided within the screw body, and a module carrier is disposed within the hollow cavity. The module carrier includes a first cylindrical structure and a second cylindrical structure, which are arranged in a cross shape and interconnected. A lateral through hole is provided on the side wall of the screw body. The two ends of the first cylindrical structure and the second cylindrical structure of the module carrier are respectively disposed at the lateral through hole on the side wall. Sensitive membrane components are provided at both ends of the first cylindrical structure and the second cylindrical structure.

[0005] Furthermore, the sensitive membrane assembly includes a sensitive membrane body and a varistor disposed on the sensitive membrane body. The varistor is arranged in the high strain region of the sensitive membrane body and extends along the tangential direction of the membrane of the sensitive membrane body.

[0006] Furthermore, each of the aforementioned sensitive membrane bodies has four piezoresistors, which together form a Wheatstone bridge structure to convert the diaphragm deformation caused by radial pressure into an electrical signal output.

[0007] Furthermore, the module carrier also includes a carrier support, wherein the carrier support is fixed in a cross-shaped arrangement and interconnected with a first cylindrical structure and a second cylindrical structure.

[0008] Furthermore, the sensitive membrane body adopts an SOI silicon-based structure, which includes a top silicon layer, a buried oxide layer, and a bottom silicon layer, wherein the top silicon layer is a deformable membrane structure.

[0009] Furthermore, the outer side of the sensitive membrane assembly is also provided with a biocompatible sealing layer to prevent the entry of bodily fluids.

[0010] Furthermore, the module carrier is also equipped with a signal transmission unit, and the sensitive membrane assembly is electrically connected to the signal transmission unit through conductive leads.

[0011] Preferably, the hollow cavity has a diameter of 2 mm and the radial hole has a diameter of 1 mm, so as to achieve effective radial pressure transmission while ensuring the overall mechanical strength of the screw.

[0012] Preferably, the module carrier is composed of two intersecting cylindrical structures with a length of 6.2 mm and a diameter of 1 mm. The intersecting structure is used to improve the stability and repeatability of the radial load transmission to the sensitive membrane body.

[0013] Preferably, the sensitive membrane body has a diameter of 400μm and the varistor size is 65×13μm, so as to balance sensitivity and structural reliability within a limited space.

[0014] Preferably, the biocompatible sealing layer includes a biocompatible encapsulating adhesive or an elastic filler material, used to fill the gap between the module carrier and the internal cavity of the screw, while fixing and sealing the sensitive membrane assembly and electrical connection structure to prevent the intrusion of body fluids and reduce the impact of external impacts on sensing performance.

[0015] The beneficial effects of this invention are as follows: This invention provides a radial pressure-sensing pedicle screw for spinal internal fixation, integrating a sensitive membrane pressure sensing structure with the internal space of the pedicle screw. This enables real-time monitoring of radial pressure on the screw's sidewall without significantly weakening the screw's mechanical properties. This structure has advantages such as compact design, clear force transmission path, sensitive response, good repeatability, and suitability for miniaturization integration. It can provide a new technical path for intelligent sensing in smart pedicle screws and orthopedic internal fixation devices, and has good prospects for clinical application. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the pedicle screw structure of the present invention.

[0017] Figure 2 This is a schematic diagram of the module carrier structure.

[0018] Figure 3 This is a schematic diagram showing the installation of the pressure sensing module inside the screw.

[0019] Figure 4 This is a schematic diagram of a pressure sensor operating under radial pressure.

[0020] In the figure: 1-Screw body; 2-Module carrier; 3-Sensitive membrane assembly; 11-Hollow cavity; 21-First cylindrical structure; 22-Second cylindrical structure; 23-Carrier support; 31-Sensitive membrane body; 32-Varistor. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present invention.

[0022] A radial pressure-sensing pedicle screw for spinal fixation includes a screw body 1 with a hollow cavity 11. A module carrier 2 is disposed within the hollow cavity 11. The module carrier 2 includes a first cylindrical structure 21 and a second cylindrical structure 22, which are arranged in a cross shape and interconnected to concentrate and guide the radial pressure on the screw's sidewall. Lateral through holes are formed on the sidewall of the screw body 1. The two ends of the first cylindrical structure 21 and the second cylindrical structure 22 of the module carrier 2 are respectively positioned at the lateral through holes on the sidewall. Sensitive membrane components 3 are provided at both ends of the first cylindrical structure 21 and the second cylindrical structure 22 for sensing the radial pressure experienced by the screw after implantation into bone tissue.

[0023] The sensitive membrane assembly 3 includes a sensitive membrane body 31 and piezoresistors 32 disposed on the sensitive membrane body 31. The piezoresistors 32 are arranged in the high-strain region of the sensitive membrane body 31 and extend along the tangential direction of the membrane of the sensitive membrane body 31. Each sensitive membrane body 31 has four piezoresistors 32, which form a Wheatstone bridge structure to convert the membrane deformation caused by radial pressure into an electrical signal output. The module carrier 2 also includes a carrier support 23, which is fixed in a cross-shaped arrangement and interconnected with a first cylindrical structure 21 and a second cylindrical structure 22.

[0024] The sensitive membrane body 31 adopts an SOI silicon-based structure, which includes a top silicon layer, a buried oxide layer, and a bottom silicon layer, wherein the top silicon layer is a deformable membrane structure. The outer side of the sensitive membrane assembly 3 is also provided with a biocompatible sealing layer to prevent the ingress of bodily fluids.

[0025] The module carrier 2 is also equipped with a signal transmission unit, and the sensitive membrane assembly 3 is electrically connected to the signal transmission unit through conductive leads.

[0026] like Figure 4 As shown, under anesthesia, the pedicle screw is implanted into the target location of the vertebral body of a mouse, so that the screw body 1 forms a fixed connection with the bone tissue. After implantation, the sidewall of the screw body 1 contacts the bone tissue, and the bone tissue exerts a radial constraint force on the screw. When the screw is subjected to radial pressure applied by the bone tissue, the radial pressure is transmitted to the module carrier 2 through the sidewall of the screw body 1. The module carrier 2 applies the pressure to the sensitive membrane assembly 3, causing the sensitive membrane to undergo slight deformation. The piezoresistor set on the sensitive membrane generates a resistance change under the action of membrane deformation, and the Wheatstone bridge composed of multiple piezoresistors converts the resistance change into an electrical signal output. The electrical signal output by the sensitive membrane assembly 3 is transmitted to an external signal acquisition device through an electrical connection structure for monitoring the radial force state of the screw during or after implantation. As can be seen from the above embodiments and the accompanying drawings, the built-in sensitive membrane pedicle screw provided by the present invention can effectively sense the radial pressure of the screw in an animal model, verifying the feasibility of this structure in vivo.

[0027] The specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding its defined scope. Although the invention has been detailed and described in the accompanying drawings and foregoing description, such descriptions are considered illustrative or exemplary rather than restrictive. It should be understood that changes and modifications can be made by those skilled in the art within the scope of the following claims.

Claims

1. A radial pressure-sensing pedicle screw for spinal internal fixation, comprising a screw body (1), characterized in that, The screw body (1) has a hollow cavity (11) inside, and a module carrier (2) is provided inside the hollow cavity (11). The module carrier (2) includes a first cylindrical structure (21) and a second cylindrical structure (22). The first cylindrical structure (21) and the second cylindrical structure (22) are arranged in a cross shape and are interconnected. A lateral through hole is provided on the side wall of the screw body (1). The two ends of the first cylindrical structure (21) and the second cylindrical structure (22) of the module carrier (2) are respectively provided at the lateral through hole of the side wall. A sensitive membrane assembly (3) is provided at both ends of the first cylindrical structure (21) and the second cylindrical structure (22).

2. The radial pressure-sensing pedicle screw for spinal internal fixation according to claim 1, characterized in that, The sensitive membrane assembly (3) includes a sensitive membrane body (31) and a varistor (32) disposed on the sensitive membrane body (31). The varistor (32) is arranged in the high strain region of the sensitive membrane body (31) and extends along the tangential direction of the membrane of the sensitive membrane body (31).

3. A radial pressure-sensing pedicle screw for spinal internal fixation according to claim 2, characterized in that, The number of piezoresistors (32) on each of the aforementioned sensitive membrane bodies (31) is four, and the four piezoresistors (32) constitute a Wheatstone bridge structure for converting the diaphragm deformation caused by radial pressure into an electrical signal output.

4. A radial pressure-sensing pedicle screw for spinal internal fixation according to claim 1, characterized in that, The module carrier (2) also includes a carrier support (23), which is fixed in a cross-shaped arrangement and interconnected with a first cylindrical structure (21) and a second cylindrical structure (22).

5. A radial pressure-sensing pedicle screw for spinal internal fixation according to claim 2, characterized in that, The sensitive membrane body (31) adopts an SOI silicon-based structure, which includes a top silicon layer, a buried oxide layer and a bottom silicon layer, wherein the top silicon layer is a deformable membrane structure.

6. A radial pressure-sensing pedicle screw for spinal internal fixation according to claim 5, characterized in that, The outer side of the sensitive membrane assembly (3) is also provided with a biocompatible sealing layer to prevent the entry of body fluids.

7. A radial pressure-sensing pedicle screw for spinal internal fixation according to claim 1, characterized in that, The module carrier (2) is also provided with a signal transmission unit, and the sensitive membrane assembly (3) is electrically connected to the signal transmission unit through conductive leads.

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