Adjustable intraosseous fixation guide and method of use

Abstract

The application discloses a jaw internal fixation guiding device with adjustable and a using method thereof, relates to the technical field of surgical operation instruments, and comprises a base plate, a deflectable guiding sleeve, a contralateral auxiliary arm, an elastic antiskid touch foot and a rigidity switching assembly. Compared with the prior art, the application has the beneficial effects that the universal adjustment of the axial direction of the sleeve body in a very compact space is realized through the cooperation of the inner concave spherical surface of the rotary positioning piece and the arc-shaped protrusion on the outer surface of the base plate; the rotary positioning piece is buckled on the arc-shaped protrusion and can freely rotate in any direction, the maximum deflection angle of the rotary positioning piece is naturally limited by the contact between the arc-shaped section of the rotary positioning piece itself and the outer surface of the base plate, the rotary positioning piece is designed as a one-third spherical surface, the occupied space in the thickness direction is greatly reduced while the universal rotation function of the complete sphere is reserved, and the deflectable guiding sleeve can be installed on the outer surface of the base plate without affecting the adhesion between the inner surface of the base plate and the bone surface.

Description

Technical Field

[0001] This invention belongs to the field of surgical instrument technology, specifically relating to an adjustable jawbone internal fixation guide device and its usage method. Background Technology

[0002] In the field of oral and maxillofacial surgery, fractures of the mandibular ramus and condylar neck are common types of maxillofacial injuries. Internal fixation surgery for these fractures typically employs a small intraoral incision approach, through which a miniature titanium plate is inserted and fixed to the bone surfaces on both sides of the fracture line using screws to restore the continuity and function of the mandible. Precise drilling is a crucial step in ensuring accurate screw placement and stable fixation of the titanium plate. Currently, various designs exist for drilling guides for mandibular internal fixation, and personalized 3D-printed guides can be developed based on patient CT scans. While the guide plates are designed to fit the bone surface, they are mostly rigid structures that cannot flexibly adjust the drill direction at bone surface transitions. Some guide plates use a ball joint structure to adjust the drilling angle, but this structure usually requires a large installation space and is difficult to arrange compactly in the narrow surgical area of ​​the oral cavity. In addition, existing guide plates generally lack an effective protection mechanism against initial drill slippage. The moment the drill bit first contacts the bone surface and has not yet formed a stable drilling channel is the most dangerous moment for slippage, and existing guide plates lack a dedicated structure to deal with this.

[0003] Therefore, there is an urgent need for an adjustable jawbone fixation guide device that can achieve flexible angle adjustment within the narrow space of the oral cavity and has a drill bit initial slippage protection function to solve the above-mentioned problems in the existing technology. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an adjustable jawbone internal fixation guide device, which aims to solve the following technical problems: the inability of existing guide plates to flexibly adjust the drill bit direction at bone surface transitions and to prevent the drill bit from slipping at the moment of contact with the bone surface.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an adjustable jawbone internal fixation guide device, comprising a base plate, a deflectable guide sleeve, a contralateral auxiliary arm, an elastic anti-slip contact foot, and a stiffness switching assembly, wherein: The substrate is an arc-shaped plate-like component with an inner surface and an outer surface. The inner surface faces the bone surface, and the outer surface faces the soft tissue surface. The inner surface of the substrate forms a unique contact with the distal bone surface of the fracture. The deflectable guide sleeve is mounted on the outer surface of the substrate and includes a sleeve body, a rotating positioning component, and a positioning locking structure. The inner hole of the sleeve body is a drill bit channel. The rotating positioning component is one-third spherical and has a concave spherical surface and a convex spherical surface. The concave spherical surface engages with an arc-shaped protrusion on the outer surface of the substrate. The rotating positioning component can rotate freely in any direction on the arc-shaped protrusion to adjust the axial direction of the sleeve body. The positioning locking structure is used to lock the rotating positioning component. The substrate is positioned at any rotation angle. The elastic anti-slip foot consists of several conical spring components installed on the inner surface of the substrate. During the procedure, the conical tip is embedded in a pre-drilled shallow pit on the bone surface, providing axial pre-tightening force to press the substrate against the bone surface and prevent initial slippage of the drill bit. The stiffness switching component is located at the interface between the inner surface of the substrate and the bone surface, and has two working states: flexible fitting mode and rigid locking mode. In the flexible fitting mode, the stiffness switching component is in a low stiffness state, and a flexible contact is formed between the inner surface of the substrate and the bone surface, which can adaptively fit with the slight undulations of the bone surface. After switching to the rigid locking mode, the stiffness switching component becomes a high stiffness state, rigidly locking the substrate and the bone surface, providing a stable guiding reference for subsequent drilling.

[0006] In one feasible embodiment, the positioning and locking structure includes an annular boss and a locking member. The annular boss is disposed on the outer surface of the substrate and constrains the rotary positioning member on the arc-shaped protrusion to prevent it from coming off. The inner wall of the annular boss is provided with an internal thread. The locking member is located inside the annular boss and is an annular member with an external thread, the external thread of which engages with the internal thread of the annular boss. The lower surface of the locking member is an arc surface, and the radius of curvature of the arc surface matches the radius of the outer convex spherical surface of the rotary positioning member.

[0007] In one feasible implementation, a tapered through hole is provided on the inner surface of the substrate corresponding to the center position of the arc-shaped protrusion. The diameter of the tapered through hole is smaller than the diameter of the arc-shaped protrusion. The tapered barrel passes through the through hole at the center of the tapered through hole, allowing the sleeve body to pass through.

[0008] In one feasible implementation, the elastic anti-slip foot is three conical spring members arranged in a ring array around the periphery of the conical through hole, and the elastic anti-slip foot is located within the projection of the arc-shaped protrusion. Each elastic anti-slip foot includes a helical spring segment and a conical tip segment, the conical tip segment extending toward the bone surface and higher than the inner surface of the substrate.

[0009] In one feasible implementation, the stiffness switching component includes a magnetorheological elastomer annular pad, a micro coil, and an electromagnetic drive module; an annular groove is formed on the inner surface of the substrate, the magnetorheological elastomer annular pad is embedded in the annular groove, a coil slot is also provided in the annular groove, the micro coil is embedded in the coil slot, and a wiring slot is also provided inside the substrate, the wiring slot is connected to the coil slot, and the two ends of the micro coil are led out and connected to the electromagnetic drive module through the wiring slot.

[0010] In one feasible implementation, the stiffness switching component includes a shape memory polymer annular pad and a micro resistance wire; the shape memory polymer annular pad is embedded in an annular groove opened on the inner surface of the substrate, and is in a rigid state when the temperature is below the glass transition temperature and in a flexible state when the temperature is above the glass transition temperature; the micro resistance wire is embedded in a resistance wire groove inside the substrate, and the shape memory polymer annular pad is changed from a rigid state to a flexible state by heating it with electricity.

[0011] In one feasible implementation, the contralateral auxiliary arm is connected to the lower edge of the substrate and includes a flexible metal arm and a stop pad. The flexible metal arm passes around the lower edge of the mandible during the operation, and the stop pad abuts against the lingual bone surface.

[0012] In one feasible implementation, the flexible metal arm is a medical-grade TiNi shape memory alloy wire, which allows manual bending into any curve shape during the operation and maintains the bent shape without rebounding after bending. It will not undergo plastic deformation when the bending radius is not less than 5mm.

[0013] In one feasible implementation, the method of using the adjustable jawbone internal fixation guide device is as follows: S1. Obtain the patient's mandibular CT scan data, extract the curved surface data of the distal bone surface after three-dimensional reconstruction, and customize the inner surface curvature of the substrate based on the curved surface data so that the inner surface of the substrate and the distal bone surface of the fracture form a unique fit relationship. S2, attach the inner surface of the substrate to the outer bone surface of the distal end of the fracture, pre-drill several shallow pits around the target drilling point on the bone surface, so that the conical tip of the elastic anti-slip foot is embedded in the corresponding shallow pit. S3, the stiffness switching component is placed in a low stiffness state, and the inner surface of the substrate adapts to the slight undulations of the bone surface through the elastic deformation of the stiffness switching component to achieve adaptive fitting, and the flexible metal arm of the opposite auxiliary arm is wrapped around the lower edge of the mandible, with the end abutting pad pressing against the lingual bone surface. S4, switch the stiffness switching component to a high stiffness state, rigidly lock the substrate and the bone surface, manually rotate the sleeve body to adjust the drilling axis direction, lock the rotating positioning member at a predetermined angle through the positioning and locking structure, and insert the drill bit into the drill bit channel of the sleeve body for drilling. S5, release the locking structure from the rotating positioning component, restore the stiffness switching component to a low stiffness state, remove the substrate, and complete the subsequent internal fixing operation.

[0014] (III) Beneficial Effects Compared with the prior art, the beneficial effects of the present invention are: 1. By engaging the concave spherical surface of the rotating positioning component with the arc-shaped protrusion on the outer surface of the substrate, universal adjustment of the sleeve body axis is achieved within an extremely compact space. The rotating positioning component is fastened to the arc-shaped protrusion and can rotate freely in any direction. Its maximum deflection angle is naturally limited by the contact between the arc-shaped cross section of the rotating positioning component and the outer surface of the substrate, eliminating the need for additional limiting steps. The structure is more compact. The rotating positioning component is designed as a one-third spherical shape, which, while retaining the universal rotation function of the complete sphere, significantly reduces the space occupied in the thickness direction, allowing the entire deflectable guide sleeve to be installed on the outer surface of the substrate without affecting the fit between the inner surface of the substrate and the bone surface.

[0015] 2. By embedding elastic anti-slip feet into pre-drilled shallow pits on the bone surface and providing dynamic counter-thrust, the problem of initial slippage of the drill bit on the inclined bone surface is solved; several conical spring components are evenly distributed around the sleeve outlet end. During the operation, the conical tip is embedded in the pre-drilled shallow pit on the bone surface. After the spring is compressed, it generates a pre-tightening force pointing in the direction of the bone surface, making the inner surface of the substrate and the bone surface fit more tightly. When the drill bit starts to rotate and drills a hole on the bone surface, the elastic anti-slip feet offset the vibration force through the dual mechanism of pre-tightening force and mechanical interlocking of the shallow pit. At the same time, the elasticity of the spring allows for a slight buffer displacement at the peak of the vibration force. After absorbing the vibration energy, it returns to its original shape, preventing irreversible positional displacement of the substrate due to vibration accumulation during the drilling process.

[0016] 3. A dual-mode switching system, enabling flexible bonding and rigid locking, is achieved through a stiffness switching component. This solves the problem that existing guide plates cannot simultaneously meet the dual requirements of "flexible bonding to adapt to the bone surface" and "rigid locking for precise drilling." In flexible bonding mode, the stiffness switching component operates at low stiffness, creating flexible contact between the inner surface of the substrate and the bone surface. This allows for adaptive bonding to minute undulations of the bone surface, achieving precise substrate positioning. Switching to rigid locking mode, the stiffness switching component becomes high-stiffness, rigidly locking the substrate to the bone surface and providing an absolutely stable guiding reference for subsequent drilling.

[0017] 4. The circumferential rotation tendency during drilling is eliminated by the contralateral auxiliary arm; the flexible metal arm goes around the lower edge of the mandible during the operation, and the end pad is pressed against the lingual bone surface. The frictional torque between the silicone material and the moist bone surface is sufficient to counteract the rotation tendency generated by the drilling torque, forming a spatially complementary constraint system with the axial preload provided by the elastic anti-slip foot. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the exploded structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the positioning and locking structure of the present invention.

[0020] Figure 3 This is a schematic diagram of the stiffness switching component of the present invention.

[0021] Figure 4 This is a schematic diagram of the rotating positioning component of the present invention.

[0022] Figure 5 This is a schematic cross-sectional view of the assembled structure of the present invention.

[0023] Figure 6 for Figure 5 Enlarged schematic diagram of the structure of section A in the middle.

[0024] Figure 7 This is a schematic diagram of the connection relationship of the stiffness switching component of the present invention.

[0025] Figure 8 This is a schematic diagram of the preoperative preparation stage when using this invention.

[0026] Figure 9 This is a schematic diagram of the installation process during the use of this invention.

[0027] Figure 10 This is a schematic diagram of the flexible bonding stage process when using the present invention.

[0028] Figure 11 This is a schematic diagram of the rigid locking stage and drilling stage when using this invention.

[0029] Figure 12 This is a schematic diagram of the final stage of the process when using this invention.

[0030] Figure Labels 1-Substrate; 11-Arc-shaped protrusion; 12-Conical through hole; 14-Annular boss; 15-Annular groove; 16-Coil groove; 17-Wire routing groove; 18-Blind hole; 21-Sleeve body; 22-Rotating positioning component; 24-Locking component; 25-Operating handle; 31-Flexible metal arm; 32-Stopping pad; 4-Elastic anti-slip contact foot; 51-Magnetorheological elastomer annular liner; 52-Miniature coil; 53-Electromagnetic drive module. Detailed Implementation

[0031] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Due to the unique anatomical complexity of the mandibular ramus and condylar region, which is tightly surrounded by the parotid gland, facial nerve branches, and masticatory muscle attachments, the surgical space is extremely limited. Furthermore, the bone surface in this area exhibits a complex three-dimensional curved shape, especially at the ridge transition, where the surface is not a flat plane but rather shows significant slope changes. Traditional straight or slightly curved positioning guides cannot achieve precise fit and stable positioning on such complex surfaces. This leads to a rare but serious intraoperative risk: when the fracture line is located precisely at the ridge transition, the drill bit is highly susceptible to slipping along the slope on the inclined bone surface. This slippage often points directly towards the inferior alveolar nerve and vascular bundle deep posteriorly. The inferior alveolar nerve is an important sensory nerve within the mandible; damage during drilling can result in permanent numbness of the lower lip postoperatively, severely impacting the patient's quality of life.

[0033] This invention uses a base plate 1 to fit and position itself against the distal bone surface of a fracture. A deflectable guide sleeve is used to adjust the drilling axis on an arc-shaped convex surface via a rotating positioning component 22, and is locked in place by a ring boss 14 and a locking component 24. An auxiliary arm on the opposite side passes around the lower edge of the mandible to abut against the lingual bone surface with a stop pad 32 to eliminate the rotational tendency. An elastic anti-slip foot 4 is embedded in a pre-drilled shallow pit on the bone surface to provide dynamic counter-thrust. A stiffness switching component enables dual-mode switching between a flexible fitting mode and a rigid locking mode. The above structures work together to achieve precise control of the drilling path and reliable protection of the nerve structure at complex three-dimensional bone surface transitions.

[0034] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0035] Example 1

[0036] Please see Figures 1 to 8 This embodiment provides an adjustable jawbone internal fixation guide device, including a base plate 1, a deflectable guide sleeve, an auxiliary arm on the opposite side, an elastic anti-slip contact foot 4, and a stiffness switching component.

[0037] Substrate 1 is made of medical-grade Ti6Al4V titanium alloy sheet, with an average thickness of 2.0 mm, a width of 6 mm to 12 mm, and a length of 15 mm to 25 mm, customized within this range according to the fracture location and bone surface morphology. Substrate 1 has an inner surface and an outer surface, with the inner surface facing the bone surface and the outer surface facing the soft tissue surface. The curvature of the inner surface of substrate 1 is customized based on the morphology of the mandibular lateral surface extracted after three-dimensional reconstruction of the patient's preoperative jawbone CT scan data. The customization process involves obtaining the patient's jawbone CBCT scan data with a slice thickness of no more than 0.5 mm, importing the DICOM format data into three-dimensional modeling software for bone tissue threshold segmentation and three-dimensional surface reconstruction, and extracting the fracture. The surface data of the distal lateral bone surface within a 20mm radius around the fracture line is imported into computer-aided design software as a reference for the bonding surface of the inner surface of the base plate 1. A uniform gap of 0.2mm is added to the bonding surface reference to accommodate trace amounts of blood and exudate between the bone surface and the base plate 1 during surgery, generating three-dimensional model data of the base plate 1. A unique bonding relationship is formed between the inner surface of the base plate 1 and the distal bone surface of the fracture. After the base plate 1 is placed on the distal bone surface of the fracture, the surface bonding area between its inner surface and the bone surface is not less than 80% of the total area of ​​the inner surface of the base plate 1. Furthermore, if the base plate 1 slides more than 0.5mm in any direction on the bone surface, the bonding surface will separate, thus ensuring the accuracy of the bonding between the base plate 1 and the bone surface.

[0038] An arc-shaped protrusion 11 is provided on the outer surface of the substrate 1. The arc-shaped protrusion 11 is a spherical cap surface. A tapered through hole 12 is provided on the inner surface of the substrate 1 corresponding to the center position of the arc-shaped protrusion 11. The diameter of the tapered through hole 12 is smaller than the diameter of the arc-shaped protrusion 11. A through hole is opened at the center of the arc-shaped protrusion 11, penetrating the center of the tapered through hole 12. The diameter of the through hole is larger than the outer diameter of the sleeve body 21.

[0039] The deflectable guide sleeve includes a sleeve body 21, a rotating positioning component 22, an annular boss 14, and a locking component 24. The sleeve body 21 is a cylindrical component made of stainless steel. One end of the sleeve body 21 is the inlet end, and the other end is the outlet end. The inner hole of the sleeve body 21 is the drill bit channel. The inner hole of the sleeve body 21 and the matching micro drill bit form a clearance fit. This clearance value can ensure that the drill bit can rotate freely and feed axially in the channel, and can limit the radial deviation of the drill bit to within 0.05mm. For example, if the outer diameter of the drill bit is 2mm, then the inner diameter of the sleeve body 21 is 2.1mm.

[0040] The rotating positioning member 22 is one-third spherical in shape, having a concave spherical surface and a convex spherical surface. The concave spherical surface is used to engage with the arc-shaped protrusion 11 on the outer surface of the substrate 1, and the convex spherical surface of the rotating positioning member 22 is connected to the sleeve body 21. The rotating positioning member 22 is located on the side near the outlet end of the sleeve body 21. The rotating positioning member 22 is fastened to the arc-shaped protrusion 11 on the outer surface of the substrate 1, and the rotating positioning member 22 can rotate freely in any direction on the arc-shaped protrusion 11. After the rotating positioning member 22 is fastened to the arc-shaped protrusion 11, the sleeve body 2... 1. The through hole in the center of the arc-shaped protrusion 11 extends towards the inner surface of the substrate 1, and the outlet end of the sleeve body 21 faces the bone surface. The drill bit is inserted from the inlet end of the sleeve body 21, passes through the rotating positioning member 22 along the drill bit channel, and extends out from the outlet end of the sleeve body 21 and aligns with the bone surface to drill a hole. A 1mm axial working gap is reserved between the outlet end face of the sleeve body 21 and the bone surface. When the substrate 1 is attached to the bone surface, the outlet end face of the sleeve floats 1mm above the bone surface. After the drill bit extends out from the inner hole of the sleeve, it passes through this gap to contact the bone surface and begins to drill.

[0041] A positioning and locking structure is also provided on the outer surface of the substrate 1. The positioning and locking structure includes an annular boss 14 and a locking member 24. The annular boss 14 is located at the connection between the arc-shaped protrusion 11 and the substrate 1, thereby constraining the rotating positioning member 22 on the arc-shaped protrusion 11 so that it will not fall out. The inner wall of the annular boss 14 is machined with internal threads. The locking member 24 is located inside the annular boss 14. The locking member 24 is an annular member with external threads, and its external threads are engaged with the internal threads of the annular boss 14. The lower surface of the locking member 24 is an arc surface, and the radius of curvature of the arc surface is... The radius of the convex spherical surface of the rotating positioning member 22 is matched; the upper end of the locking member 24 is provided with an operating handle 25. When the operating handle 25 is rotated to move the locking member 24 downward, the lower surface of the arc surface of the locking member 24 contacts the convex spherical surface of the rotating positioning member 22 and applies downward pressing force, pressing the rotating positioning member 22 against the arc protrusion 11 of the substrate 1. The friction between the spherical surfaces is used to lock the rotating positioning member 22 at any rotation angle position; when the operating handle 25 is rotated to move the locking member 24 upward, the lower surface of the arc surface of the locking member 24 is released from contact with the rotating positioning member 22, and the rotating positioning member 22 returns to the free rotation state.

[0042] The elastic anti-slip contact 4 consists of three conical spring components, arranged in a ring array around the periphery of the conical through hole 12. Each elastic anti-slip contact 4 includes a helical spring segment and a conical tip segment. The helical spring segment is made of stainless steel spring wire, with both ends tightly coiled and ground flat. The conical tip segment is integrally formed with the helical spring segment and is the end extension of the helical spring segment. A blind hole 18 is provided on the base plate 1, and a shallow pit is drilled on the bone surface. The end of the helical spring segment is placed in the blind hole 18, and the end of the conical tip segment is placed in the shallow pit. The blind hole 18 is located on the inner surface of the base plate 1 surrounding the conical through hole 12. The holes 18 are arranged in a ring around the arc-shaped concave surface, and the opening positions of the blind holes 18 are all within the projection range of the arc-shaped protrusions 11 on the inner surface of the substrate 1. That is, the blind holes 18 extend from the inner surface of the substrate 1 into the interior of the substrate 1, and their bottom ends in the thickness area increased by the arc-shaped protrusions 11. The arc-shaped protrusions 11 can provide the blind holes 18 with an additional accommodating depth beyond the thickness of the substrate 1 body. The spring end is double-fixed in the blind hole 18 by press-fit and medical-grade cyanoacrylate adhesive. The tapered tip extends towards the bone surface, and the height of the protrusion of the inner surface of the substrate 1 in the non-compression state is between 4.5 mm and 5.5 mm.

[0043] The working principle of the elastic anti-slip foot 4 is as follows: During the operation, at the position corresponding to the bone surface and the three conical tips, when the base plate 1 is attached to the bone surface, the three conical tips are pressed into the corresponding blind holes 18, so that the elastic anti-slip foot 4 generates a counter-pushing force. This counter-pushing force applies a pre-tightening force perpendicular to the bone surface and pointing towards the bone surface to the base plate 1, making the fit between the inner surface of the base plate 1 and the bone surface tighter. When the drill bit starts to rotate and drills a hole in the bone surface, the elastic anti-slip foot 4 counteracts the vibration force through the dual mechanism of pre-tightening force and the mechanical interlocking of the shallow pit. At the same time, the elasticity of the spring allows for a slight buffer displacement at the peak of the vibration force, and returns to its original shape after absorbing the vibration energy.

[0044] The contralateral auxiliary arm includes a flexible metal arm 31 and a stop pad 32. The flexible metal arm 31 is a medical-grade TiNi shape memory alloy wire with a diameter of 1.2 mm. One end is connected to the substrate 1. The connection method can be welding, mechanical connection or bonding. The connection point is located on the outer side of the lower edge of the substrate 1. The flexible metal arm 31 extends outward from the connection point and has a total length between 30 mm and 50 mm. The TiNi shape memory alloy wire is in the austenitic phase at room temperature and has superelasticity, allowing it to be manually bent into any curve shape during the operation and maintaining the bent shape without rebounding after bending. It will not undergo plastic deformation when the bending radius is not less than 5 mm. The stop pad 32 is a circular soft silicone pad with a diameter of 5 mm, a thickness of 2 mm and a Shore hardness of A50. It is embedded at the end of the flexible metal arm 31 and is used to provide frictional force for contact with the lingual bone surface. The static friction coefficient between the silicone material and the moist bone surface is not less than 0.6. When the substrate 1 is subjected to drilling torque, the frictional torque between the stop pad 32 and the lingual bone surface is sufficient to counteract the rotational tendency generated by the drilling torque.

[0045] The stiffness switching assembly includes a magnetorheological elastomer annular pad 51, a micro coil 52, and an electromagnetic drive module 53. An annular groove 15 with a depth of 1.5 mm is formed on the inner surface of the substrate 1, and the groove 15 is located around the blind hole 18 of the elastic anti-slip contact 4. The magnetorheological elastomer annular pad 51 is embedded in the annular groove 15. The magnetorheological elastomer annular pad 51 is made of polyurethane matrix doped with micron-sized carbonyl iron powder particles, the average particle size of which is 3 μm to 5 μm and the particle mass fraction is 35%. Under zero magnetic field conditions, the initial elastic modulus of the magnetorheological elastomer is approximately 0.5 MPa, corresponding to… Flexible bonding mode; under saturated magnetic field conditions, the elastic modulus can increase to about 12MPa, corresponding to a modulus increase of about 24 times in rigid locking mode; a coil groove 16 is also provided directly below the annular groove 15, the depth of the coil groove 16 is 1.0mm, the coil groove 16 penetrates the substrate 1 and enters the annular boss 14, the micro coil 52 is embedded in the coil groove 16, the micro coil 52 is made of enameled copper wire, a wiring groove 17 is provided inside the substrate 1, the wiring groove 17 is connected to the coil groove 16, the starting end lead and the ending end lead of the micro coil 52 converge and are arranged in the wiring groove 17, together from the edge of the substrate 1 The cable tray 17 leads out and connects to the electromagnetic drive module 53. The electromagnetic drive module 53 is an adjustable constant current source. During the operation, the output current is continuously adjusted within the range of 0 to 1.5A via a foot switch, corresponding to a continuous adjustment of the magnetic field strength within the range of 0 to 0.3T. This controls the continuous variation of the elastic modulus of the magnetorheological elastomer annular liner 51 between 0.5MPa and 12MPa. When the magnetorheological elastomer is at 0.5MPa, it is in a flexible fitting mode. At this time, a flexible contact is formed between the inner surface of the substrate 1 and the bone surface, which can adaptively fit with the slight undulations of the bone surface. Even if there are irregular bends in the bone surface, the substrate 1 can still fit. The rigid guide plate fits tightly without stress concentration, avoiding micro-slippage or warping at the steep slope of the bone surface, thus achieving precise positioning. When the magnetorheological elastomer is at 12MPa, it is in rigid locking mode. At this time, the stiffness switching component becomes high-stiffness, rigidly locking the substrate 1 to the bone surface, providing an absolutely stable guiding reference for subsequent drilling, and completely eliminating micro-movement caused by drill bit vibration. This dual-mode mechanism of "flexible positioning and rigid locking" takes into account both the adaptive requirements of the bonding stage and the stability requirements of the drilling stage, and solves the contradiction that traditional rigid guide plates cannot achieve dual optimization at complex three-dimensional bone surface transitions.

[0046] The usage method of this embodiment is divided into the preoperative preparation stage, the intraoperative installation stage, the flexible fitting stage, the rigid locking stage, the drilling stage, and the finishing stage.

[0047] Preoperative preparation stage: Obtain CBCT scan data of the patient's mandible with a slice thickness not exceeding 0.5mm. Import the DICOM format data into 3D modeling software for bone tissue threshold segmentation and extract the 3D bone surface model of the mandibular ramus and condylar process region. Mark the fracture line position and determine the distal bone surface region of the fracture in the 3D bone surface model. Extract the curved surface data within a 20mm range around the fracture line from the distal bone surface of the fracture. Import this curved surface data into computer-aided design software as a reference for the mating surface of the inner surface of substrate 1. Add a uniform gap of 0.2mm on the mating surface reference and generate the 3D model data of substrate 1. Design the specific positions and dimensions of the arc-shaped protrusion 11, tapered through hole 12, positioning and locking structure, elastic anti-slip contact foot 4 mounting blind hole 18, magnetorheological elastomer annular groove 15, and coil groove 16 in the substrate 1 model. Import the substrate 1 model data into the programming software of a five-axis CNC milling machining center and generate a CNC machining program. Select Ti6Al4V. Titanium alloy sheet is processed and formed; after processing, the inner surface of the substrate 1 is sandblasted and the surface roughness Ra value after sandblasting is 3.2μm. The arc-shaped protrusion 11 is precision ground and the surface roughness Ra value of the arc-shaped protrusion 11 after grinding is not greater than 0.4μm. Three elastic anti-slip feet 4 are pressed into three blind holes 18 on the inner surface of the substrate 1 and a small amount of medical grade cyanoacrylate adhesive is injected for curing and fixing. The micro coil 52 is embedded in the coil groove 16 and sealed and fixed with medical grade epoxy resin. The magnetorheological elastomer annular liner 51 is embedded in the annular groove 15 on the inner surface of the substrate 1. The rotating positioning member 22 is fastened to the arc-shaped protrusion 11 on the outer surface of the substrate 1. The locking member 24 is screwed into the annular boss 14. The flexible metal arm 31 of the opposite auxiliary arm is connected to the outer side of the lower edge of the substrate 1 and the end of the flexible metal arm 31 is installed with a stop pad 32. The coil lead is connected to the electromagnetic drive module 53 and the current output and coil magnetic field response of the electromagnetic drive module 53 are tested.

[0048] Intraoperative installation stage: The patient is placed in a supine position and general anesthesia is administered via nasal intubation. Routine disinfection and draping are performed. An incision of approximately 25 mm is made along the anterior margin of the mandibular ramus intraorally, cutting through the mucosa and periosteum. A periosteal elevator is used to dissect the periosteum, exposing the fracture area and fracture line on the lateral surface of the mandibular ramus. The fracture ends are temporarily fixed with fracture reduction forceps, and the anatomical alignment after fracture reduction is verified. Using a 0.5 mm diameter micro-drill, three conical shallow pits with a depth of 2 mm-3 mm are pre-drilled around the target drilling point on the bone surface, corresponding to the positions of the three elastic anti-slip tentacles 4. The three shallow pits are evenly distributed around the circumference and within the range of 3, with a depth deviation of no more than ±0.05 mm. The inner surface of the base plate 1 is attached to the lateral bone surface of the distal fracture end. The base plate 1 is naturally positioned in the predetermined location, and the conical tips of the three elastic anti-slip tentacles 4 are embedded in the three shallow pits respectively.

[0049] Flexible fitting stage: The electromagnetic drive module 53 is in the off state and the coil current is 0. The magnetorheological elastomer annular pad 51 is in a low stiffness state and the elastic modulus is about 0.5MPa. The inner surface of the substrate 1 adapts to the slight undulations of the bone surface through the elastic deformation of the magnetorheological elastomer to achieve adaptive fitting. After the surgeon confirms that the substrate 1 is in place, the flexible metal arm 31 of the contralateral auxiliary arm is bent down from the lower edge of the substrate 1 and then inward to bypass the lower edge of the mandible. The end abutment pad 32 is placed against the lingual bone surface of the mandible. The surgeon manually adjusts the degree of bending of the flexible metal arm 31 to make the abutment pad 32 fit tightly against the lingual bone surface.

[0050] Rigid locking stage and drilling stage: The surgeon activates the electromagnetic drive module 53, gradually increasing the output current to 1.5A via a switch. The micro coil 52 generates a magnetic field of approximately 0.3T. Under the influence of the magnetic field, the elastic modulus of the magnetorheological elastomer annular pad 51 rapidly increases from 0.5MPa to approximately 12MPa, and the interface between the inner surface of the substrate 1 and the bone surface instantly switches from flexible contact to rigid locking. The surgeon manually rotates the sleeve body 21, adjusting the axial direction of the sleeve body 21 by rotating the positioning component 22 on the arc-shaped protrusion 11, so that the axis of the sleeve body 21 is perpendicular to the bone surface section at the target drilling point. After confirming that the adjustment is in place, the surgeon rotates the operating handle 25 of the locking component 24. The rotating positioning component 22 is locked at a predetermined angle; the micro drill bit is inserted into the drill bit channel of the sleeve body 21, and the micro drill bit is started at a speed of 1200 rpm with a stable and uniform axial force to advance the drill bit; under the constraint of the sleeve body 21, the drill bit drills into the bone surface along the predetermined axis direction. The counter-thrust provided by the elastic anti-slip foot 4 presses the base plate 1 against the bone surface and counteracts the vibration force generated by the rotation of the drill bit. The frictional torque between the stop pad 32 of the opposite auxiliary arm and the lingual bone surface counteracts the circumferential rotation tendency generated by the drill bit torque. The rigid locking of the magnetorheological elastomer annular liner 51 eliminates any possible small gaps between the base plate 1 and the bone surface; after the drill bit penetrates the opposite bone cortex, the drilling stops and the drill bit is withdrawn.

[0051] Final stage: Rotate the operating handle 25 of the locking member 24 to move the locking member 24 upward and release the locking of the rotating positioning member 22; cut off the current of the electromagnetic drive module 53, the elastic modulus of the magnetorheological elastomer annular pad 51 is restored to 0.5MPa, and the rigid lock between the base plate 1 and the bone surface is released; remove the contralateral auxiliary arm from the lingual bone surface and remove the base plate 1, rinse the drilled hole and surrounding bone surface with saline and remove bone debris; subsequently, follow the routine jawbone internal fixation surgery steps, select a micro titanium plate of appropriate size and place it at both ends of the fracture line to bridge the fracture, align the screw holes on the titanium plate with the drilled bone holes and screw in the micro titanium nails to fix the titanium plate, and suture the periosteum and mucosa layer by layer to complete the surgery.

[0052] Example 2

[0053] The main difference between this embodiment and Embodiment 1 is that the flexible metal arm 31 of the contralateral auxiliary arm is replaced with a telescopic adjustable structure to adapt to the personalized needs of different mandibular bone thicknesses and shapes.

[0054] The telescopic adjustable structure includes an outer tube and an inner rod. The outer tube is a thin stainless steel tube, and its outer end is connected to the lower edge of the base plate 1 via a hinge seat. The hinge seat includes a U-shaped bracket fixed to the lower edge of the base plate 1 and a hinge pin that passes through the outer end of the outer tube. The outer tube can swing around the hinge pin in a direction parallel to the plane of the base plate 1 with a swing angle range of 30°. After swinging to the desired position, it is tightened and fixed by a locking nut on the side of the hinge seat. The inner rod is made of TiNi alloy wire and can slide axially inside the outer tube to adjust the overall length with an adjustment range of 10mm to 25mm. The outer tube has radial locking screws on its sidewall to fix the inner rod, and the end of the inner rod has a stop pad 32. The surgeon adjusts the extension length of the inner rod and the swing angle of the outer tube according to the thickness of the patient's mandible so that the stop pad 32 reaches the lingual bone surface at the optimal angle and length.

[0055] The other structures in this embodiment are the same as in Embodiment 1, and will not be described again here.

[0056] Example 3

[0057] The main difference between this embodiment and Embodiment 1 is that the stiffness switching component uses a shape memory polymer annular pad instead of a magnetorheological elastomer annular pad 51 and uses a micro resistance wire instead of a micro coil 52.

[0058] The shape memory polymer annular pad is made of polyurethane-based shape memory polymer with a glass transition temperature of approximately 55°C. It is rigid with an elastic modulus of approximately 800 MPa below the glass transition temperature and flexible with an elastic modulus of approximately 5 MPa above the glass transition temperature. The micro-resistance wire is made of NiCr alloy wire with a diameter of 0.3 mm and a resistance of approximately 5 Ω. It is embedded in the resistance wire groove directly below the shape memory polymer annular groove 15 inside the substrate 1. During the flexible bonding stage, the surgeon connects the power supply to the micro-resistance wire. A 3A DC current is applied, and the resistance wire heats the shape memory polymer annular pad to 60°C to 65°C within 30 seconds, exceeding its glass transition temperature. The shape memory polymer changes from a rigid state to a flexible state, and the surgeon attaches the substrate 1 to the bone surface. During the rigid locking phase, the surgeon cuts off the power supply to the resistance wire, and the shape memory polymer annular pad gradually cools to 37°C at body temperature. When the temperature drops below the glass transition temperature, the shape memory polymer returns to a rigid state, and the elastic modulus increases from 5MPa to 800MPa, thus rigidly locking the substrate 1 to the bone surface.

[0059] The other structures in this embodiment are the same as in Embodiment 1, and will not be described again here.

[0060] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0061] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0063] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An adjustable jawbone internal fixation guide device, characterized in that, Includes a base plate (1), a deflectable guide sleeve, an auxiliary arm on the opposite side, an elastic anti-slip contact foot (4), and a stiffness switching assembly, wherein: The substrate (1) is an arc-shaped plate-shaped component with an inner surface and an outer surface. The inner surface faces the bone surface, and the outer surface faces the soft tissue surface. The inner surface of the substrate (1) forms a unique fit with the distal bone surface of the fracture. The deflectable guide sleeve is installed on the outer surface of the substrate (1) and includes a sleeve body (21), a rotating positioning member (22), and a positioning locking structure. The inner hole of the sleeve body (21) is a drill bit channel. The rotating positioning member (22) is one-third spherical and has an inner concave spherical surface and an outer convex spherical surface. The inner concave spherical surface cooperates with the arc-shaped protrusion (11) provided on the outer surface of the substrate (1). The rotating positioning member (22) can rotate freely in any direction on the arc-shaped protrusion (11) to adjust the axial direction of the sleeve body (21). The positioning locking structure is used to lock the rotating positioning member (22) at any rotation angle position. The elastic anti-slip foot (4) consists of several conical spring components installed on the inner surface of the substrate (1). During the operation, the conical tip is embedded in a pre-drilled shallow pit on the bone surface to provide an axial pre-tightening force that presses the substrate (1) against the bone surface. The stiffness switching component is located at the interface between the inner surface of the substrate (1) and the bone surface, and has two working states: flexible bonding mode and rigid locking mode. In the flexible bonding mode, the stiffness switching component is in a low stiffness state, and the inner surface of the substrate (1) and the bone surface form a flexible contact, which can adaptively bond with the slight undulations of the bone surface. After switching to the rigid locking mode, the stiffness switching component becomes a high stiffness state, and the substrate (1) is rigidly locked to the bone surface.

2. The adjustable jawbone internal fixation guide device according to claim 1, characterized in that, The positioning and locking structure includes an annular boss (14) and a locking member (24). The annular boss (14) is disposed on the outer surface of the substrate (1). The annular boss (14) constrains the rotating positioning member (22) on the arc-shaped protrusion (11) so that it will not come out. The inner wall of the annular boss (14) is provided with an internal thread. The locking member (24) is located inside the annular boss (14). The locking member (24) is an annular member with an external thread, and its external thread is engaged with the internal thread of the annular boss (14). The lower surface of the locking member (24) is an arc surface, and the radius of curvature of the arc surface matches the radius of the convex spherical surface of the rotating positioning member (22).

3. The adjustable jawbone internal fixation guide device according to claim 1, characterized in that, A tapered through hole (12) is provided on the inner surface of the substrate (1) corresponding to the center position of the arc protrusion (11). The diameter of the tapered through hole (12) is smaller than the diameter of the arc protrusion (11). The tapered barrel passes through the through hole in the center of the tapered through hole (12) so that the sleeve body (21) can pass through.

4. The adjustable jawbone internal fixation guide device according to claim 3, characterized in that, The elastic anti-slip foot (4) consists of three conical spring components. The elastic anti-slip foot (4) is arranged in a ring array around the periphery of the conical through hole (12), and the elastic anti-slip foot (4) is located within the projection of the arc-shaped protrusion (11). Each elastic anti-slip foot (4) includes a helical spring segment and a conical tip segment. The conical tip segment extends toward the bone surface and is higher than the inner surface of the substrate (1).

5. The adjustable jawbone internal fixation guide device according to claim 1, characterized in that, The stiffness switching component includes a magnetorheological elastomer annular pad (51), a micro coil (52), and an electromagnetic drive module (53). An annular groove (15) is formed on the inner surface of the substrate (1). The magnetorheological elastomer annular pad (51) is embedded in the annular groove (15). A coil groove (16) is also provided in the annular groove (15). The micro coil (52) is embedded in the coil groove (16). A wiring groove (17) is also provided inside the substrate (1). The wiring groove (17) is connected to the coil groove (16). The two ends of the micro coil (52) are led out and connected to the electromagnetic drive module (53) through the wiring groove (17).

6. The adjustable jawbone internal fixation guide device according to claim 1, characterized in that, The stiffness switching component includes a shape memory polymer annular pad and a micro resistance wire; the shape memory polymer annular pad is embedded in an annular groove (15) opened on the inner surface of the substrate (1), and is in a rigid state when the temperature is below the glass transition temperature and in a flexible state when the temperature is above the glass transition temperature; the micro resistance wire is embedded in the resistance wire groove inside the substrate (1), and the shape memory polymer annular pad is changed from a rigid state to a flexible state by heating it with electricity.

7. The adjustable jawbone internal fixation guide device according to claim 1, characterized in that, The contralateral auxiliary arm is connected to the lower edge of the base plate (1) and includes a flexible metal arm (31) and a stop pad (32). The flexible metal arm (31) passes around the lower edge of the mandible during the operation, and the stop pad (32) presses against the lingual bone surface.

8. The adjustable jawbone internal fixation guide device according to claim 7, characterized in that, The flexible metal arm (31) is a medical-grade TiNi memory alloy wire, which allows manual bending into any curve shape during the operation and maintains the bent shape without rebounding after bending. When the bending radius is not less than 5mm, no plastic deformation will occur.

9. The adjustable jawbone internal fixation guide device according to claim 7, characterized in that, The flexible metal arm (31) is replaced by a telescopic adjustable structure, which includes an outer tube and an inner rod. The outer end of the outer tube is connected to the lower edge of the base plate (1) through a hinge seat. The inner rod can slide axially inside the outer tube to adjust the overall length and adapt to different mandibular thicknesses.

10. The method of using the adjustable jawbone internal fixation guide device according to any one of claims 1 to 9, characterized in that: S1, acquire the patient's mandibular CT scan data, extract the fracture distal bone surface curvature data after three-dimensional reconstruction, and customize the inner surface curvature of the substrate (1) based on the curvature data so that the inner surface of the substrate (1) and the fracture distal bone surface form a unique fit relationship. S2, attach the inner surface of the substrate (1) to the outer bone surface of the distal end of the fracture, pre-drill several shallow pits around the target drilling point on the bone surface, so that the conical tip of the elastic anti-slip foot (4) is embedded in the corresponding shallow pit; S3, the stiffness switching component is in a low stiffness state, the inner surface of the substrate (1) adapts to the small undulations of the bone surface through the elastic deformation of the stiffness switching component to achieve adaptive fitting, the flexible metal arm (31) of the opposite auxiliary arm is wrapped around the lower edge of the mandible, and the end stop pad (32) is pressed against the lingual bone surface. S4, switch the stiffness switching component to a high stiffness state, lock the substrate (1) and the bone surface rigidly, manually rotate the sleeve body (21) to adjust the drilling axis direction, lock the rotating positioning member (22) at a predetermined angle through the positioning locking structure, and insert the drill bit into the drill bit channel of the sleeve body (21) for drilling. S5, release the locking structure from the rotating positioning member (22), restore the stiffness switching component to a low stiffness state, remove the substrate (1), and complete the subsequent internal fixing operation.

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