95 results about "Medullary cavity" patented technology

This invention relates to an ultrasonic bone scalpel and an ultrasonic cutting device, belonging to the field of medical device technology. The ultrasonic bone scalpel is used to cut bone tissue from within the medullary cavity, and includes an ultrasonic scalpel body and a retaining assembly. The ultrasonic scalpel body includes a handle and a cutting head mounted on one end of the handle. The retaining assembly includes a pressure bladder mounted on the handle, with the pressure bladder and cutting head arranged radially opposite each other along the handle. The pressure bladder is capable of expanding or contracting. The ultrasonic bone scalpel provided by this invention utilizes the expansion of the pressure bladder to provide continuous cutting pressure based on the cutting action of the ultrasonic scalpel body, reducing the cutting wound on soft tissue, thereby protecting soft tissue while satisfying bone tissue cutting requirements. Furthermore, because this ultrasonic bone scalpel cuts from the inside out of the medullary cavity, it avoids external damage to soft tissue, thus reducing the cutting wound on soft tissue and further protecting it. Therefore, when the cutting wound on soft tissue is reduced, the risk of intraoperative infection is correspondingly reduced, and the healing time is shortened.

The invention relates to a tibial plateau prosthesis. The tibial plateau prosthesis mainly comprises a tibial spacer, a tibial plateau and a sleeve. The tibia gasket is provided with a first fixing block and three arc-shaped holes, and movable second fixing blocks are arranged in the holes. The tibial plateau comprises a plateau support with open holes and a shell, and the open holes are formed in the side portion and the bottom of the shell. The screw penetrates through the gasket and the platform support to be inserted into the shell, and outer threads of the screw are meshed with inner threads of the sleeve. The sleeve moves upwards and extends out of the side hole of the shell through a hinged connecting rod system to penetrate into the medullary cavity to enhance fixation. A spring is arranged in the screw to drive the first pushing part and can be matched with the sleeve to prevent downward movement; and meanwhile, the second pushing part in the screw can extend into the medullary cavity from the bottom through threads. The design realizes multidirectional fixation and improves the stability of the prosthesis.

The invention discloses a three-section thighbone retrograde intramedullary nail, relates to the field of medical instruments, and provides a detachable and assembled three-section thighbone retrograde intramedullary nail aiming at the problems that an existing thighbone medial condyle retrograde intramedullary nail is poor in adaptability and insufficient in fixing strength. A main nail body of the intramedullary nail is composed of a head section, a middle section and a tail section, original spiral nested structures are adopted at the joints of the sections, and the three sections are tightly connected to form the complete and high-strength intramedullary nail by matching with the hollow interior design and penetrating a titanium cable into a medullary cavity for tightening and automatically rotating and matching the head section and the middle section of the main nail body. And medullary cavity structures and fracture types of different patients can be accurately matched. Compared with a traditional intramedullary nail, the intramedullary nail has the advantages that mounting convenience and structural stability are remarkably improved, intraoperative adjustment time can be shortened, the risk of injury to a medullary cavity of a patient is reduced, and an innovative solution is provided for personalized treatment of distal femur fractures.

The invention provides a femoral stem prosthesis. The femoral stem prosthesis comprises a femoral stem, an expansion component and a sleeve. The femoral stem is composed of an upper stem body and a replaceable lower stem body, and threads are arranged in the femoral stem. The expansion part is located in the upper handle body and comprises a screw, a rotating disc and a multi-layer pushing structure. The screws are connected with the upper and lower handle bodies through threads; and the turntable is in threaded engagement with the screw and can drive the first pushing part along the first guide rail during rotation. Ratchets are arranged in the rail component and meshed with the pawls of the second pushing part, and an open hole is formed in the side of the second pushing part. And the sleeve is linked with the expansion component through the fifth pushing part, the fourth pushing part and the third pushing part. During implantation, the second pushing part outwards pushes the sleeve to be attached to the wall of the medullary cavity, the internal pushing structure acts successively under the counter-acting force, and finally the first pushing part is separated from the second pushing part. Then bone cement is injected through a sleeve micropore, and the stability of the prosthesis is enhanced. By means of the design, intraoperative adaptation and stable filling are achieved.

The invention provides a multi-column integrated biological fixation partial femoral head replacement device, and relates to the field of medical instruments. The device comprises a bone nail, an auxiliary fixing piece and a joint prosthesis, the bone nail is provided with a first end part and a second end part nailed into a femoral neck medullary cavity, and the first end part, the auxiliary fixing piece and the joint prosthesis are integrally formed; the auxiliary fixture has a first surface and a second surface in contact with the conical osteotomy femoral head to prevent sinking and lateral rotation. The joint prosthesis only replaces the cut part of the necrotic femoral head, more normal sclerotin can be reserved, trauma is small, femoral head supporting and bearing are not affected or changed, long-term stability of the joint prosthesis is guaranteed, and meanwhile future rebuilding is facilitated. In addition, the first end part, the auxiliary fixing piece and the joint prosthesis are integrally formed, so that joint prosthesis failure caused by looseness or corrosion among the first end part, the auxiliary fixing piece and the joint prosthesis can be avoided.

The invention discloses a bionic type tibia intramedullary nail and a matched instrument thereof, and relates to the technical field of medical instruments, and the bionic type tibia intramedullary nail comprises an intramedullary nail body; the intramedullary nail body comprises an intramedullary nail near end, an intramedullary nail middle section and an intramedullary nail far end, the intramedullary nail middle section is inserted into the intramedullary nail near end in a threaded mode, and the intramedullary nail far end is inserted into the intramedullary nail middle section in a threaded mode; according to the intramedullary nail, through the sectional type thread inserting design of the intramedullary nail near end, the intramedullary nail middle section and the intramedullary nail far end and the matching of the variable pitch gradient structures of the near end thread, the middle section thread and the far end thread, precise adaptation of the intramedullary nail and the anatomical form of the tibia marrow cavity is achieved, and a gradient mechanical buffering system is formed by the near end thread, the middle section thread and the far end thread; the problem of stress shielding caused by the fact that rigidity of a traditional intramedullary nail is not matched with a skeleton is effectively solved, meanwhile, the variable-pitch threads and the thread depth gradual change design are adopted, damage to an endosteum during nail placement is reduced, uniform stress conduction is achieved, local stress concentration is avoided, and the risks of osteoporosis, delayed fracture healing and secondary fracture are reduced.

The application provides a controllable self-expanding intramedullary nail internal fixation system for long bone fracture, belonging to the technical field of orthopedic medical instruments, and comprising a self-expanding intramedullary nail, a visible controllable self-expanding platform and a locking nail; the self-expanding intramedullary nail comprises a locking hole and an expandable support; the locking hole is arranged at the proximal end of the self-expanding intramedullary nail and is matched with the locking nail to fix the proximal end of the self-expanding intramedullary nail; the expandable support is arranged at the distal end of the self-expanding intramedullary nail after expansion to fix the distal end of the self-expanding intramedullary nail. The visible controllable self-expanding platform is in communication with the expandable support and can display the expansion size, and the self-expanding intramedullary nail can be prevented from being expanded too large to affect the medullary cavity by precalculating the expansion size.

The application provides a femoral stem prosthesis and a hip joint prosthesis with the same, wherein the femoral stem prosthesis comprises: a mounting block comprising a first block body and a second block body, the second block body being arranged on the side of the first block body, and the first block body and the second block body being capable of relative movement; a guide structure arranged between the first block body and the second block body, the guide structure extending along the axial direction of the first block body; a locking assembly arranged between the first block body and the second block body to fix the first block body and the second block body; a support column swingably arranged on the second block body, and an acetabular component arranged on the support column; and a fixing mechanism arranged below the first block body and capable of being inserted into the medullary cavity. The technical scheme of the application effectively solves the problem that the relative position of the neck stem of the femoral stem and the stem body cannot be adjusted in the related art.

Bone harvesting system including methods and devices for obtaining and / or removing osseous debris from a bone using an auger having a flexible, helical fin projecting from a shaft. In an exemplary method, a leading end region of the auger is placed into a reamed portion of a bone's medullary cavity via an entry site extending into the bone. Osseous debris is driven toward the entry site with the auger. At least a portion of the osseous debris that has passed through the entry site is collected outside the bone. In some embodiments, the leading end region of the auger is deformed by contact between the helical fin and a wall of the medullary cavity, to conform the helical fin in the leading end region to a portion of the medullary cavity.

Provided herein are methods and systems for stabilizing a joint, such as the elbow. The system may include an intramedullary rod configured to be placed in a medullary canal of a bone, a pin, a linking member defining an aperture for receiving the pin, and a connector defining a first aperture and a second aperture, the first aperture configured to receive the linking member. The system may further include a screw extending through the second aperture of the connector and the aperture of the intramedullary rod. The system may be configured to be implanted into a patient.

The invention relates to the field of medical instruments, and provides a conicity-locked osseointegration prosthesis. The osseointegration prosthesis comprises an implantation prosthesis, a percutaneous device and an abutment screw, a plurality of fixing ridges are arranged on the periphery of the implantation prosthesis, intraosseous fixation is achieved in a press-fit mode, a taper locking structure is combined to prevent the implantation prosthesis from sinking, and it is ensured that the position of the implantation prosthesis is fixed after implantation; a flushing hole communicated with the internal flushing cavity is further formed in the periphery of the implant prosthesis, and the implant prosthesis can be used for injecting medicine into the medullary cavity, implanting bone materials and the like or used for follow-up flushing treatment for intramedullary infection possibly occurring in the later period. The percutaneous device and the implanted prosthesis are connected through the anti-rotation structure and the taper locking structure, the percutaneous section has the surface state formed through surface treatment, stimulation to surrounding soft tissue is reduced, the anti-infection capacity is improved, and the percutaneous sealing effect is improved. By optimizing the implantation structure and the percutaneous interface design, the intraoperative operation difficulty is reduced, the intraoperative time is shortened, meanwhile, the percutaneous stoma is reduced, and the infection risk is reduced.

The application discloses a guiding locking device and a fracture fixation system thereof, and relates to the technical field of medical devices. The guiding locking device comprises a guiding locking pipe and a locking piece, at least one strip-shaped slot is arranged on the pipe wall of the guiding locking pipe and communicates with the pipe cavity of the guiding locking pipe, the strip-shaped slot penetrates through the locking end, and the locking piece can drive the pipe wall of the locking end to contract. The fracture fixation system comprises a bone plate, a bone needle and the guiding locking device, a fixing through hole is arranged on the bone plate, the connecting end of the guiding locking pipe is fixedly connected with the fixing through hole, the guiding locking pipe is arranged perpendicularly to the bone plate, the bone needle is arranged in the pipe cavity of the guiding locking pipe, and the locking piece can drive the pipe wall of the locking end to contract and clamp the bone needle. The application reduces the risk of fracture displacement when the bone needle is used to fix the fracture; avoids the influence of the bone needle on the placement of the bone plate; shortens the length of the bone needle entering the medullary cavity, so that the application scene of the temporary fracture fixation technology of the bone needle is not limited in the treatment of the fracture by the intramedullary nail; and the stability is better than that of the multiple bone needles used to fix the fracture.

Systems and methods for reaming an intramedullary canal of a long bone comprise a trial stem configured to extend into the long bone along an insertion axis and a guide device comprising an adapter configured to couple to the trial stem and a reaming guidepost extending from the adapter along a guide axis, wherein the guide axis and the insertion axis are non-aligned. A method of reaming an intramedullary canal of a long bone to form a complex shaped socket can comprise inserting a stem into the intramedullary canal along an insertion axis, connecting a guide device to the stem, the guide device comprising a guidepost extending along a guide axis and guiding a cannulated reamer along the guidepost to remove bone from the intramedullary canal to form the complex shaped socket, wherein the guide axis and the insertion axis are non-aligned.

The utility model discloses a far-end precise locking intramedullary nail system which comprises an intramedullary nail, an intramedullary nail locking device, an intramedullary nail locking device, an intramedullary nail locking device and an intramedullary nail locking device. The far-end hole is formed in the intramedullary nail; the far-end hole is matched with the lock nail, and the bone substance is provided with a screw-in hole upper part and a screw-in hole lower part through which the lock nail penetrates; the thickened part is arranged at the end, away from the intramedullary nail, of the lock nail, external threads are arranged on the peripheral face of the lock nail, and internal threads matched with the external threads are arranged in the lower portion of the far-end hole and the lower portion of the screwing-in hole. The inner diameter of the upper portion of the bone screwing-in hole is slightly larger than the outer diameter of the lock nail, the outer diameter of the thickened portion is gradually increased in the direction away from the intramedullary nail, when the lock nail is screwed in, the lock nail completely penetrates through the upper portion of the screwing-in hole and the far-end hole and partially extends into the lower portion of the screwing-in hole, and the thickened portion of the lock nail is embedded into the upper portion of the screwing-in hole. At the moment, the intramedullary nail can be fixed to the bone through the lock nail, displacement is avoided, and precise locking of the intramedullary nail is achieved.

The application relates to a medical orthopedic quick drill bit, which comprises a drill bit body composed of a drill bit part and a drill rod part, wherein the drill bit part is provided with circularly arranged cutting edges for bone positioning and hole forming, and the drill rod part is designed as a light rod; a connecting piece is connected with the drill bit body at one end and fixed with a driving piece at the other end, and the two are quickly separated through a split device containing a clamping piece and a disengaging piece, so that safe disconnection is ensured when the pressure of the medullary cavity or cancellous bone is abnormal. The application has the technical effects of improving the operation efficiency, enhancing the safety and reducing accidental injuries.

The utility model discloses a metal 3D printing porous bone induction structure tibial prosthesis, which comprises a diaphysis prosthesis, a bone fracture plate and an intramedullary nail, the diaphysis prosthesis is designed according to the anatomical form of the focus part of a patient, the diaphysis prosthesis comprises a solid framework and a porous structure, and a cavity is arranged in the diaphysis prosthesis; the at least two bone fracture plates are connected to the two ends of the diaphysis prosthesis in the tibia direction respectively, and the at least two bone fracture plates are connected with the tibia near end and the tibia far end through screws respectively. The tibia near end comprises a first medullary cavity, the tibia far end comprises a second medullary cavity, the intramedullary nail penetrates through the first medullary cavity, the cavity and the second medullary cavity, and the two ends of the intramedullary nail are connected with the tibia near end and the tibia far end through screws respectively. The utility model can solve the problems of incapability of realizing rapid healing, poor initial stability and poor long-term stability in the existing bone defect reconstruction.

An intramedullary implant (1) for connection to a prosthetic device (E), comprising a main stem (2) having a proximal end (3) for insertion into a medullary cavity of a bone stump (B) and a distal end (4) for engagement with the prosthetic device (E). The main stem (2) comprises a medullar section (5) extending from the proximal end (3) in distal direction (D), and a coupling section (6) extending from the distal end (4) in proximal direction (P). The medullar section (5) and coupling section (6) meet at an insertion point (S) along the main stem (2) between the proximal end (3) and the distal end (4), wherein the insertion point (S) designates a maximum insertion depth (Di) into the medullar cavity. The coupling section (6) has a constant coupling diameter (d1) extending from the insertion point (S) to the distal end (4).

This invention provides an aiming device, including a loading mechanism, an aiming base, and a locking mechanism. The loading mechanism is used to load a target object. The aiming base has an aiming channel for the loading mechanism to pass through. The locking mechanism is disposed on the aiming base and selectively engages or disengages from the loading mechanism. The aiming device is configured such that when the loading mechanism is partially inserted into the aiming channel and is in a predetermined position, the locking mechanism engages with the loading mechanism and locks it on the aiming base, preventing movement of the loading mechanism relative to the aiming base. When the locking mechanism disengages from the loading mechanism, movement of the loading mechanism relative to the aiming base is permitted. This aiming device allows the fourth screw hole of the lag screw in the intramedullary nail assembly to be coaxial with the first screw hole of the main nail after insertion into the medullary cavity, thereby enabling rapid insertion of the locking screw.

The utility model provides a hemostasis device for a femoral medullary cavity. The hemostasis device comprises a guider, a first bag body, a second bag body, an overflow hole, a first injection port, a second injection port and a sealing piece. A first bag body is wrapped outside the guider, a pressurizing bag cavity is arranged between the guider and the first bag body, a second bag body is wrapped outside the first bag body, a liquid storage bag cavity is arranged between the first bag body and the second bag body, and a group of liquid overflow holes communicated with the liquid storage bag cavity are further formed in the second bag body. A pressurizing medium is injected into the pressurizing bag cavity through the first injection port, so that the first bag body expands outwards until the blood stopping medium in the liquid storage bag cavity overflows from the liquid overflowing hole, the blood stopping medium enters a medullary cavity, the blood stopping medium is injected into the pressurizing bag cavity through the second injection port, and the blood stopping medium in the liquid storage bag cavity flows out from the liquid overflowing hole. Meanwhile, the second capsule body is attached to the inner surface of the medullary cavity, the wound surface in the medullary cavity is pressurized, and the dual hemostasis effect is achieved.

The modular intramedullary fixation device is a multi-piece bone fixation device for insertion into the medullary cavity of a bone. In one embodiment, the modular intramedullary fixation device is formed from a plurality of substantially Z-shaped modular elements, which are assembled together to a desired length and width. In additional embodiments, the modular intramedullary fixation device includes a proximal portion, a distal portion, and a connector for connecting the two portions to each other. The connector may be provided in a wide variety of configurations, including an adjustable connector for adjusting the length of the modular intramedullary fixation device. Each of the proximal and distal portions may further have an adjustable length.

The utility model relates to the technical field of orthopedic medical instruments, and discloses a tibial prosthesis structure. Comprising a tibia prosthesis and a medullary cavity insertion section which are detachably connected, a first groove is formed in the outer side wall of the tibia prosthesis, a third groove is formed in the outer side wall of the medullary cavity insertion section, and the first groove and the third groove are sequentially communicated to form a long groove used for placing an implanted bone. The long groove is a bone grafting space extending in the length direction of the tibia prosthesis structure, the bone grafting material is contained in the long groove, on one hand, the bone grafting part can be prevented from protruding after an operation, and the occurrence rate of wound complications is reduced; on the other hand, healing of the patellar ligament and the bone grafting part is facilitated, the patellar ligament fracture risk is reduced, and the knee joint function of a patient is improved.

The invention discloses a distal humerus prosthesis for the small head of the humerus, and relates to the technical field of medical instruments. The distal humerus prosthesis for the capitulum humerus comprises a humerus main body group which is used for being fixed at the resection position of the capitulum humerus; one end of the humerus handle group is used for being inserted into a humerus marrow cavity, and the other end of the humerus handle group is detachably connected with the humerus main body; the humerus side plate is fixed to the side face of the humerus through the steel plate nails, and the humerus side plate is fixedly connected with the humerus handle through the steel plate nails. In order to enhance the fixing effect between the prosthesis and the humerus, a steel plate nail originally needing to be hit between the humerus side plate and the humerus is arranged on the humerus handle in the humerus marrow cavity in a penetrating mode, so that the fixing enhancing effect is achieved, in the operation, more damage cannot be caused to the bone of a patient, and the fixing effect is improved. When the distal humerus prosthesis is used, a user only needs to form a hole in the humerus handle before an operation, so that the time required by the operation is not prolonged, and the stability of fixation between the distal humerus prosthesis and the bone of a patient can be improved by the distal humerus prosthesis.

The application relates to the technical field of femoral head necrosis treatment, in particular to a bionic artificial balloon type half hip joint, which comprises a sleeve, a femoral neck, a fixing screw and a femoral neck limiting nut, the sleeve is fixed on a femur through the fixing screw, the femoral neck is slidingly connected in the sleeve, a balloon is fixed on the outer periphery of the top section of the femoral neck, the inside of the femoral neck is hollow, and a side hole is arranged at the top end of the femoral neck and communicates with the balloon, and the femoral neck limiting nut is used for being fixed in the sleeve to position the femoral neck. The balloon type femoral head is compared with the metal and ceramic femoral heads, the balloon type femoral head is more matched with the shape of the acetabulum in terms of shape, the elastic modulus of the balloon type femoral head is equivalent to that of the bone cartilage of the acetabulum, the balloon type femoral head is beneficial to cartilage nutrition, and the wear of the bone cartilage of the acetabulum is small; the balloon is in a shriveled state when no filler is filled in the balloon, the balloon can be placed in the femur along the sleeve, the joint capsule and the medullary cavity do not need to be opened, the trauma is small, the risk of subsequent infection and dislocation is small, meanwhile, the prosthesis wear can be replaced through the sleeve, and the replacement is convenient and fast and can be completed under local anesthesia.

A portable device is configured to connect directly to an intraosseous (IO) catheter and provide a clinician with actionable information to determine whether the catheter is placed correctly, such as whether the catheter is placed in the medullary cavity of bone. The device provides this information leveraging the presence or absence of arterial pressure waveforms. A method for assessing placement of an intraosseous catheter includes coupling a pressure transducer to an IO catheter placed in tissue, obtaining a continuous pressure waveform from a pressure signal provided by the pressure transducer, and assessing placement of the catheter based on the continuous pressure waveform.

Disclosed herein are medical device systems and methods thereof for automatic detection of entry into a medullary cavity. Embodiments include an intraosseous access system having a sensing obturator configured to detect a change in a modality at its distal tip, such as pressure, oxygen saturation, electrical impedance, etc. The signal can be transmitted to control logic that can responsively modify activation of the driver. The signal can be transmitted by way of wired or wireless communication. In embodiments, the signal can be transmitted through a conductive polymeric material that forms the obturator and allows the obturator to be sufficiently flexible to mitigate accidental needle stick injuries.

A femoral intramedullary device is capable of treating a variety of femoral bone fractures. The device includes an intramedullary nail capable of antegrade or retrograde insertion into the femur and having a shank long enough to extend into the shaft of the long bone and reach the corresponding distal area or proximal area and sockets located intermediate the ends of the shank for receiving anchoring pins or screws extended transversely or radially from the shaft of the long bone. The intramedullary nail is placed in the intramedullary canal of a portion of the bone and the screws are fixed in the radial sockets or receivers at the level of the femoral neck to provide mechanical support across the bone. Transverse screws are placed through the transverse sockets to provide additional support and secure the nail within the femur.

The application discloses a kind of bone fracture fixation devices, the bone fracture fixation device includes internal fixation and external fixation, internal fixation is suitable for being matched in medullary cavity, internal fixation includes body, body has the cavity through body along the extension direction of medullary cavity, body includes first support section and second support section oppositely arranged and can be enclosed cavity, and first support section and / or second support section have elasticity, one end of first support section is connected with one end of second support section, the other end of first support section is spaced apart from the other end of second support section to form elastic groove, external fixation is suitable for being matched in medullary cavity outside and be connected with internal fixation by connecting piece.The internal fixation of the bone fracture fixation device of the application can automatically abut against the inner wall of medullary cavity after being implanted in medullary cavity, to form support to bone wall, solve the difficult reduction during operation, postoperative bone wall collapse and overturning problem caused by bone defect in the bone quality of comminuted fracture or osteoporosis patient.

The invention provides a femoral intramedullary nail system, which comprises a medullary cavity registration modeling unit used for performing three-dimensional reconstruction based on a patient preoperative CT or MRI image, automatically extracting femoral medullary cavity boundary, curvature radius and neck-shaft angle parameters, and generating an individualized medullary cavity geometric model; the intramedullary nail customization design unit is used for automatically matching the diameter, curvature and front rake angle of the intramedullary nail according to the medullary cavity model, ensuring that the gap between the outer diameter of the intramedullary nail and the inner diameter of the medullary cavity is less than or equal to 0.2 mm, and designing a radial limiting rib at the near end of the intramedullary nail to form multi-point contact support; according to the anti-swing matching structure, the head of the intramedullary nail adopts a double-spherical-surface-conical composite matching interface; according to the technical scheme, the intramedullary nail structure customization and surface hydroxyapatite gradient coating deposition are achieved through the metal 3D printing technology, continuous elastic modulus transition is formed at the near end and the far end of the intramedullary nail, and the fixing stability is remarkably improved, and the pendulum effect is restrained.

The application provides a tibial prosthesis, comprising: a platform part, comprising a platform body, a first porous structure and a medullary cavity rod, the medullary cavity rod being connected to a first side of the platform body, the first porous structure being arranged on the first side of the platform body and located at the outer periphery of the medullary cavity rod, the first porous structure comprising a first porous layer and a second porous layer, the first porous layer being arranged closer to the platform body than the second porous layer, the first porous layer having a first porosity, the second porous layer having a second porosity, the first porosity being smaller than the second porosity; and a spacer part arranged on a second side of the platform body. The technical scheme of the application can effectively solve the problem of poor prosthesis adaptability and stability in the related art.

The invention discloses a dental medullary cavity retention crown surface composite coating and a preparation method, and belongs to the technical field of medullary cavity retention crowns. The dental medullary cavity retention crown surface composite coating is characterized by comprising the following components in parts by weight: a moisture curing layer, a middle layer and a mineralized polypeptide layer, the moisture curing layer is prepared from 75 parts of a polyurethane prepolymer, 12 to 24 parts of modified nano hydroxyapatite, 4 parts of p-toluenesulfonyl isocyanate, 0.2 part of stannous octoate and 0.6 part of fumed silica; according to the composite coating, it is guaranteed that the medullary cavity retention crown with the root canal internal extending retention achieves high-strength bonding in the deep portion of the root canal, the stability of the bonding interface of the retention crown in long-term use is avoided through a multiple defense mechanism, the durability of the bonding effect is effectively guaranteed, and effective retention can be maintained for a longer time.