An external bone fixation auxiliary retention system

Abstract

The present invention discloses an external bone fixation auxiliary retention system, which includes two relatively arranged fixing rings. A bone pin mounting structure is provided on the fixing rings. A plurality of support arms are also hingedly arranged between the two fixing rings. It is characterized in that a variable stiffness joint capable of adjusting the axial stiffness of the support arms is further installed on each support arm. The present invention has the advantages of being able to better meet the requirements of different periods of growth and healing of the fracture site and being more conducive to the rehabilitation and growth of the fracture site.

Description

Technical Field

[0001] The present invention relates to the field of orthopedic external fixation and fracture rehabilitation assistance devices, and particularly to an external bone fixation assistance maintaining system. Background Art

[0002] During the medical fixation of fractures, it is usually necessary to set up an external fixation bracket or fixing device outside the patient's body to avoid secondary injuries and better facilitate the normal healing of the fracture site. When medical technology was not developed enough in the early days, splints were usually tied or plaster templates were poured to fix the fracture site. This kind of fixation method is too rigid and not conducive to the later growth and rehabilitation of the fracture site.

[0003] In foreign patents such as US6030386, US8439914, and WO2011163406, as well as the Chinese patent CN201810623485.8, a type of six-axis parallel bone external fixation device has been proposed. This kind of device consists of six struts (support arms) with exactly the same topological structure and two fixing rings. Doctors use metal bone pins (Kirschner wires) to fixedly connect the two fixing rings to the bone blocks at both ends of the patient's fracture respectively; the six struts are connected to the two fixing rings through hinges at both ends. By regularly adjusting the lengths of the six struts, a six-degree-of-freedom relative movement of the two fixing rings can be generated, which can accurately correct the spatial deformity of the fracture and achieve fracture reduction; after fracture reduction, by maintaining the lengths of the struts, the six-axis parallel bone external fixation device can maintain the relative stability of the fracture ends. Therefore, this kind of six-axis parallel bone external fixation device has both the functions of reducing and fixing the fracture ends and has broad application prospects.

[0004] However, for this existing six-axis parallel bone external fixation device, the adjustment method of the struts is still a rigid adjustment, that is, the struts are in a rigid state before and after adjustment. But in fact, during the fracture healing process, the bone growth conditions, bone mass density, etc. will change in the early and later stages, resulting in different requirements for the rigidity and flexibility of the fixed support. Therefore, the existing six-axis parallel bone external fixation devices still cannot better meet the needs of the growth and healing of the fracture site and are not conducive to the rehabilitation of the fracture site. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: how to provide an external bone fixation assistance maintaining system that can better meet the requirements of different periods of the growth and healing of the fracture site and is more conducive to the rehabilitation growth of the fracture site.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An external bone fixation assistance maintaining system, comprising two oppositely arranged fixing rings, wherein a plurality of mounting holes are provided on the fixing rings to form a bone pin mounting structure, and a plurality of support arms are hingedly arranged between the two fixing rings. It is characterized in that a variable stiffness joint capable of adjusting the axial stiffness of the support arms is further mounted on each support arm.

[0008] In this way, when the device of this solution is used, the two fixing rings are respectively fixed at both ends of the human fracture position, the needle seat of the bone pin (Kirschner wire) is fixed to the fixing ring through the bone pin mounting structure, and then the two fixing rings are respectively fixedly connected to the bone blocks at both ends of the patient's fracture through the bone pins, so that the fixing and supporting of both ends of the fracture position can be realized by relying on the support arms, avoiding secondary injuries during the healing process. In this solution, a variable stiffness joint capable of adjusting the axial stiffness of the support arms is further mounted on the support arms. Therefore, during the use process, the axial stiffness of the support arms can be adjusted to different values at different stages of the fracture healing. It can be adjusted to maintain a relatively large stiffness in the early stage, so that the two ends of the fracture are fixed and grow rapidly; in the later stage, the stiffness can be adjusted to be reduced and the flexibility can be increased, so that the bracket will not absorb all the energy during the rehabilitation training and cause stress shielding, and the newly grown bone can have a relatively large activity space, so as to better promote the healing of the bone and be more conducive to its healthy growth. Therefore, this solution can better meet the requirements of different periods of the growth and healing of the fracture site and is more conducive to the rehabilitation growth of the fracture site. Among them, a plurality of mounting holes are provided on the fixing ring to form a bone pin mounting structure. In this way, the outer end of the bone pin can be fixed to a bone pin mounting seat, and the bone pin mounting seat can be fixed to the fixing ring by bolts passing through the mounting holes. The structure is simple, the installation is convenient, and the installation position of the fracture can be conveniently adjusted.

[0009] Furthermore, an axial length adjustment structure is further provided on the support arm.

[0010] In this way, the length of each support arm can be adjusted according to needs during the fixation process of the device and during the rehabilitation process of the fracture site, so that it can better keep both ends of the fracture in the correct attitude position.

[0011] Furthermore, there are 6 support arms, and the support arms are obliquely and staggeredly distributed so that one end of each adjacent two support arms approaches and the other end separates to form a V-shaped or inverted V-shaped arrangement, and the connection positions of every two support arms on the fixing ring are evenly distributed along the circumferential direction.

[0012] In this way, the 6 support arms form 6 branch chains, which can together with the two fixing rings form a spatial parallel external fixation bracket with three rotational degrees of freedom and three translational degrees of freedom. In this way, it is convenient to realize three rotational degrees of freedom and three translational degrees of freedom by adjusting the axial length of each support arm, and further realize the spatial angle adjustment of any position of the fixing ring. During implementation, the spatial angle adjustment process can be assisted by computer calculation, which is the prior art and will not be elaborated here.

[0013] Further, the fixing ring is integrally circular and has three outwardly protruding connecting parts evenly distributed around the perimeter. The ends of each adjacent pair of support arms are connected to the connecting parts, and the connecting parts of the two fixing rings are arranged with a 60-degree offset.

[0014] In this way, the connection and installation of the support arms will not affect the area and structure for the installation of the bone pins.

[0015] Further, both ends of the support arm are respectively hinged to the fixing ring through a Hooke's hinge.

[0016] In this way, the Hooke's hinge can achieve hinged rotation in two directions, which is convenient for adjustment and reliable.

[0017] Further, the axial length adjustment structure includes two halves that are axially butted to form the main body of the support arm. One half is the force-applying end half, and the other half is the force-receiving end half. At the axial center of the end of the force-applying end half, a lead screw extends axially outward. The rear end of the lead screw is rotatably installed on the force-applying end half and is connected to an axial adjustment motor on the force-applying end half. The front end of the lead screw is threadedly engaged and passes through an adjustment nut fixed at the end of the force-receiving end half and is located in a lead screw holding cavity within the force-receiving end half.

[0018] In this way, the axial adjustment motor can drive the lead screw to rotate. Due to the threaded fit between the adjustment nut and the lead screw, and at the same time the adjustment nut is fixed on the force-receiving end half and is restricted from circumferential rotation by the Hooke's hinge at the end, a lead screw-nut transmission pair can be formed to drive the force-receiving end half to achieve axial telescopic adjustment. It has the characteristics of simple structure, stable and reliable adjustment.

[0019] Further, the lead screw holding cavity has a section of inner cavity that is in close contact with the outer circumference of the lead screw.

[0020] In this way, the circumferential limit of the lead screw can be better maintained, avoiding shaking and affecting the fracture fixation effect; and better ensuring the stability and reliability of the detection value of the pressure sensor.

[0021] Further, the outer end of the lead screw holding cavity also has a pre-tightening chamber located on the outer circumference of the lead screw. The outer shell of the pre-tightening chamber is rigidly connected to the adjustment nut. The pre-tightening chamber has a spiral pre-tightening spring that is movably sleeved on the lead screw. One end of the pre-tightening spring abuts against a convex platform protruding from the circumference of the lead screw, and the other end abuts against one end of the inner cavity of the pre-tightening chamber.

[0022] In this way, an axial pre-tightening force can be applied to the lead screw and the nut by the pre-tightening spring, avoiding axial shaking caused by thread clearance and affecting the fracture fixation effect; and at the same time better ensuring the stability and reliability of the detection value of the pressure sensor.

[0023] Further, the convex platform on the lead screw is formed by a pre-tightening nut located within the pre-tightening chamber and threadedly screwed onto the lead screw.

[0024] This not only facilitates the setting and installation of the boss, but also can further change the magnitude of the pre-tightening force by adjusting the position of the pre-tightening nut on the lead screw, so that it has a good pre-tightening effect without affecting the transmission of the lead screw nut itself.

[0025] Furthermore, the outer shell of the pre-tightening chamber is obtained as a cylindrical member fixedly installed on the force-bearing end half body, and the outer end of the cylindrical member fixes the adjusting nut.

[0026] This makes the installation and setting of the structure more convenient.

[0027] Furthermore, a pressure sensor for detecting its axial force is also installed on the support arm.

[0028] In this way, it is convenient to detect the axial force condition of the support arm, which serves as the information basis for adjusting feedback control.

[0029] Furthermore, the pressure sensor is installed between the end of the force-bearing end half body and the corresponding Hooke's hinge, making it convenient to install.

[0030] Furthermore, it also includes a computer. One end of the computer is connected to the pressure sensor, and the other end is connected to the axial adjustment motor. In this way, with the computer system for auxiliary calculation control, the calculation difficulty of manual operation is greatly reduced, and the convenience of equipment use is improved.

[0031] Further, a fracture graphic simulation module, a control center, and an adjustment output control module are sequentially connected in the computer. The control center includes an adjustment parameter calculation module. The computer also has a man-machine operation graphic interface respectively connected to the fracture graphic simulation module, the adjustment parameter calculation module, and the adjustment output control module. The fracture graphic simulation module can calculate and simulate the bone structure graphic of the fractured part (the calculation and simulation method is the prior art and will not be elaborated here) by importing multi-angle X-ray films of the fractured part, and obtain bone deformity parameters. The adjustment parameter calculation module can calculate the installation attitude graphic situation of the device according to the obtained bone structure graphic of the fractured part and the bone deformity parameters (including the deformation amount of the fractured part of the bone), combined with data and / or manual judgment. The adjustment parameter calculation module can also obtain the parameter situation to be adjusted according to the bone structure graphic of the fractured part, the bone deformity parameters, and the detection feedback signal of the pressure sensor after the device is installed. The adjustment output control module is used to convert the parameter situation to be adjusted into an output control signal and send it to the axial adjustment motor. The man-machine operation graphic interface is used to input operation instructions and display the obtained graphics and the output instructions. In this way, it is convenient to realize automatic detection calculation and adjustment calculation through computer assistance, and better assist in realizing the fixation and orthopedic operation of the device. During the use of the device, the computer can detect the data feedback of the pressure sensor in real time to judge whether it is necessary to adjust the axial length of the support arm to ensure the healing effect of the fracture site.

[0032] Further, the control center of the computer further includes a support arm stiffness timing adjustment module. The support arm stiffness timing adjustment module is respectively connected to the pressure sensor, the man-machine operation graphic interface, and the adjustment output control module. The adjustment output control module is connected to the variable stiffness joint. The support arm stiffness timing adjustment module can generate a variable stiffness joint adjustment signal through the (time and stiffness) adjustment parameter instruction input by the man-machine operation graphic interface and the signal detected by the pressure sensor, and output the signal to the variable stiffness joint through the adjustment output control module to achieve control and adjustment. In this way, the computer system can be better utilized to assist in the calculation and control of the support arm stiffness adjustment operation in the device.

[0033] Further, the process of the support arm stiffness timing adjustment module to realize detection, control, and adjustment can be as follows: After the initial formation of callus at the fracture site (3 - 4 weeks), after the two fixing rings of the external bone fixation assistance maintenance system are respectively fixed at both ends of the human fracture position, first output an instruction to control the movement of the axial adjustment motor, so that the two ends of the fractured bone are axially displaced by a certain distance. This distance is the axial deformation amount of the callus part of the bone, denoted as dx. At this time, the control center reads the values f1 - f6 of the sensor, and fits the force condition at the callus through a mathematical method, denoted as Obtain the load-deformation relationship Record the ratio of this value to the allowable load-deformation relationship I δ as and use this as an index to divide fracture rehabilitation into two stages; in the first stage, when K < K δ (K δ : the critical ratio of the treatment stage), set the variable stiffness joint to be rigid (at this time, the fractured part of the bone is not under any load, and no relative displacement can occur at the fracture ends, preventing the patient from causing malunion or secondary fracture); in the second stage, K > K δ , set the variable stiffness joint to be flexible (at this time, the patient enters the rehabilitation training stage, and the bone can already bear a certain load. First, according to the stiffness of the bone fracture ends, adjust the variable stiffness joints in the rods so that the support will not absorb all the energy during rehabilitation training, avoid causing stress shielding, and promote bone healing). The specific numerical ranges of the rigidity and flexibility of the variable stiffness joint can be obtained through calculations, experiments, and doctors' experience.

[0034] In this way, it is possible to better adjust the stiffness of the support arm, better avoid secondary injuries during the rehabilitation process of the fracture site, and be more conducive to the recovery of the fracture site.

[0035] As an option, the variable stiffness joint includes a first cylinder and a second cylinder. The open end of the first cylinder is slidably inserted into the open end of the second cylinder and cooperates to form a closed chamber (the other ends of the first sleeve and the second sleeve are respectively installed on a part of the support arm, so that the two parts of the support arm are connected as a whole by the first cylinder and the second sleeve). The outer side wall of the first cylinder and the inner side wall of the second cylinder are fitted and a dynamic sealing structure is provided between them. The first half of the open end of the first cylinder is axially provided with a relief groove, and the relief groove is located in the closed chamber. A plurality of partitions arranged at intervals along the axial direction are also radially provided in the closed chamber. Some partitions are fixedly arranged on the inner side wall of the first cylinder, and the other part of the partitions pass through the relief groove and are fixed on the inner side wall of the second cylinder. The partitions fixed to the first cylinder and the partitions fixed to the second cylinder are staggered and arranged at intervals. The closed chamber is also filled with magnetorheological fluid, and a magnetic field generating and controlling device is also provided near the closed chamber inside the first cylinder and the second cylinder.

[0036] In this way, when the variable stiffness joint of this structure is used, the magnetic field generating and controlling device is connected to the computer. The computer can control and adjust the magnitude of the magnetic field by controlling the magnetic field generating and controlling device according to the preset program and instructions, and change the viscosity and hardness of the magnetorheological fluid. Furthermore, the axial stiffness between the first cylinder and the second sleeve can be adjusted and controlled. The variable stiffness joint of this solution has the advantages of simple structure and convenient control and adjustment, but the defect is that it is necessary to keep the magnetic field generated by the magnetic field generating and controlling device in a stable state for a long time, consuming a large amount of electric energy, and it is easy to cause control instability due to reasons such as power fluctuations.

[0037] As another option, the variable stiffness joint includes a first connecting plate and a second connecting plate that are coaxially arranged opposite to each other, a connecting shaft is axially arranged at one end of the first connecting plate facing the second connecting plate, a plurality of spiral abutment springs are evenly distributed circumferentially at the outer end of the connecting shaft, the abutment springs are arranged along the diameter direction and the inner end abuts against the connecting shaft, and the outer end is connected to the second connecting plate through a force adjustment mechanism.

[0038] In this way, the first connection plate and the second connection plate in the variable stiffness joint are respectively installed on a part of the support arm, so that the two parts of the support arm are connected as a whole by the first connection plate and the second connection plate. When in use, the force adjustment mechanism applies force to the abutment spring to adjust the abutment force of the abutment spring on the connection shaft, thereby adjusting the axial stiffness. In this way, there is no need to maintain power supply for a long time, the structure is simple and the cost is low.

[0039] Furthermore, the outer peripheral surface of the connecting shaft facing the abutment spring position has an outward mounting protrusion, the outer end of the mounting protrusion is correspondingly provided with a spring mounting groove, and the inner end of the abutment spring abuts against the inner end of the spring mounting groove.

[0040] In this way, the stability and reliability of the spring installation can be better guaranteed, the direction of the spring force application can be guaranteed to be directly opposite to the axis center line, and the stability and reliability of the stiffness adjustment can be guaranteed.

[0041] Furthermore, the axial center position of the first connecting disk is fixedly connected and installed with the connecting shaft through a connecting shaft fixing bolt.

[0042] This makes it easier to set up the structure and install and disassemble components.

[0043] Furthermore, the force adjustment mechanism includes a nut sleeve, and the two ends of the inner ring of the nut sleeve are respectively provided with a section of symmetrical internal thread and are respectively matched with an adjustment ring arranged at a circumferential interval. The outer surface of the adjustment ring has an external thread and the internal thread of the nut is matched. The second connecting disk is also provided with an adjustment ring anti-rotation structure for preventing the adjustment ring from rotating. The force adjustment mechanism also includes a spring seat arranged at the outer end of the abutting spring, and the upper and lower sides of the outer end of the spring seat are each slidably abutted with an obliquely arranged adjustment baffle, the outer ends of the two adjustment baffles are close to each other and the inner ends are opened in a horizontal figure eight shape, the inner ends of the two adjustment baffles are rotatably connected to the adjustment rings corresponding to the upper and lower ends, and the outer end of the adjustment baffle is rotatably connected to a retaining frame relatively fixed on the second connecting disk.

[0044] In this way, during use, only the nut sleeve needs to be rotated to drive the two adjusting rings to move linearly in the same or opposite directions, thereby driving the inner end of the adjusting baffle to move axially along the joint, changing the inclination angle of the adjusting baffle, and then squeezing or relaxing the abutting spring, so that the radial pressure of the abutting spring on the connecting shaft increases or decreases, realizing the adjustment of the axially movable performance of the connecting shaft, that is, realizing the adjustment of the axial stiffness of the joint. By using this method, the adjustment of the spring pressing force is realized through the screw-nut transmission and then combined with the inclined plate extrusion and cooperation transmission, and then the adjustment of the axial stiffness is realized, which has the following advantages. First, the overall structure is compact, and the force transmission is stable and reliable. The force application is converted from the circumferential rotational motion through multiple force transmissions and conversions before being converted into the radial motion force application, making the device have good self-locking performance and not easily losing stability. Second, through multiple force transmissions and conversions (especially the inclined plane of the inclined plate for converting and transmitting the force application direction), the transmission ratio of the adjustment is very large, and a large stiffness adjustment effect can be obtained with a small input, so that the adjustable range of the axial stiffness will be very large. In addition, the initial inclination angle of the adjusting baffle can be pre-adjusted and set, and it is very convenient to realize the control adjustment of the conversion of the adjustment accuracy requirements. When the inclination angle of the adjusting baffle is smaller, a smaller adjustment distance can be used to realize a larger stiffness change adjustment. Finally, and very importantly, in this structure, the axial stiffness adjustment is realized by relying on the radial pressing of the spring on the connecting shaft. Therefore, when the axial bearing force of the connecting disk changes during the adjustment process, it basically does not affect the change in the magnitude of the radial pressing force of the spring. Therefore, it can have good stability and reliability. Therefore, the force application adjustment mechanism can adjust and realize a large range of continuously controllable stiffness changes, realize a large range of stiffness adjustment with small energy loss, and is extremely stable and reliable.

[0045] Further, a roller is arranged at the outer end of the spring seat along the axial direction of the joint. The axial center line direction of the roller is perpendicular to the axial center line direction of the abutting spring, and the circumferential outer side of the roller is in abutting and cooperating setting with the adjusting baffle.

[0046] In this way, the force transmission between the obliquely arranged adjusting baffle and the abutting spring can be better realized by the rolling cooperation of the roller, ensuring better reliability.

[0047] Further, a threaded adjustment hole is arranged at the middle position of the outer end of the spring seat opposite to the spring. An adjustment bolt is installed in the threaded adjustment hole, and the front end of the adjustment bolt abuts against the end of the abutting spring.

[0048] In this way, when needed, the pre-tightening force of the adjusting spring can be conveniently changed by the adjustment bolt.

[0049] Further, a bearing sleeve is formed by the inner end of the spring seat extending forward. The outer end of the abutting spring is located inside the bearing sleeve, and the bearing sleeve has a mating section that is slidably inserted into the spring installation groove on the connecting shaft.

[0050] In this way, the front section of the bearing sleeve in the structure is inserted into the spring installation groove, and a small gap is formed between the outer wall of the matching section and the inner wall of the spring installation groove, which can produce a very important effect. That is, if a large axial force is suddenly generated between the first connecting plate and the second connecting plate due to an accident (such as falling or collision), the first connecting plate and the second connecting plate will produce a large axial movement, which will enable the spring installation groove to directly drive the spring seat as a whole to move in the same direction through the cooperation with the matching section of the bearing sleeve, thereby pressing the outer end of the spring seat and the adjustment baffle on the corresponding side, and the adjustment baffle on this side can compress the spring seat inward, thereby causing the spring to squeeze the connecting shaft to clamp it, correspondingly increasing the axial stiffness, so that it can withstand or offset part of the axial force generated by the accident. The adaptive emergency protection effect of the device is achieved, reducing or avoiding safety risks caused by accidents. Furthermore, the thread between the nut sleeve and the adjustment ring is a self-locking thread. The above-mentioned adaptive emergency protection effect is better guaranteed.

[0051] Furthermore, the retaining frame is cylindrical as a whole and is coaxially spaced on the inner side of the nut sleeve. An adjusting baffle installation window is provided in the middle of the retaining frame, and the outer end of the adjusting baffle can be rotatably installed on the adjusting baffle installation window; both ends of the outer circumferential surface of the retaining frame have a circle of inwardly concave limiting grooves, and both ends of the inner cavity of the nut sleeve are respectively fixed inward with a threaded ring, and the internal threads at both ends of the nut sleeve are provided on the inner ring surface of the threaded ring, and the threaded ring can be rotatably clamped and limited in the limiting groove, and a plurality of clearance windows are also provided in the limiting groove of the retaining frame, and a plurality of outward mounting protrusions are evenly distributed on the outer surface of the adjusting ring, and the external threads on the adjusting ring are provided on the outer end surface of the mounting protrusion, and the mounting protrusion passes through the clearance window and cooperates with the outer end thread of the threaded ring, and the two sides of the mounting protrusion and the two sides of the clearance window are attached to form the adjusting ring anti-rotation structure.

[0052] In this way, the entire structure is ingenious, compact, stable and reliable, avoiding mutual interference of movements and ensuring the stability of movement and force transmission.

[0053] As an option, the outer surface of the nut sleeve is evenly distributed with vertical grooves and rotation scales along the axial direction, so that it is convenient to manually apply force to rotate the nut sleeve to adjust the rigidity.

[0054] As another option, a nut adjusting motor is also installed on the second connecting plate, and the nut adjusting motor is drivingly connected to the nut sleeve.

[0055] In this way, it is convenient to realize electric control and adjustment of stiffness by controlling the nut adjustment motor. During implementation, the nut adjustment motor is connected to a computer, and automatic control can be realized according to preset programs and instructions.

[0056] In summary, the present invention has the advantages of being able to better meet the requirements of different growth and healing periods of the fracture site, and being more conducive to the rehabilitation and growth of the fracture site. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 FIG. is a schematic structural diagram of the external bone fixation assistance and retention system in an embodiment of the present invention.

[0058] Figure 2 FIG. Figure 1 is a schematic structural diagram in the use state.

[0059] Figure 3 FIG. Figure 1 is a schematic structural diagram of a single support arm in FIG..

[0060] Figure 4 FIG. Figure 3 is a cross-sectional view of FIG..

[0061] Figure 5 FIG. Figure 3 is a schematic structural diagram of a single variable stiffness joint in FIG..

[0062] Figure 6 FIG. Figure 5 is a cross-sectional view of FIG..

[0063] Figure 7 FIG. Figure 5 is a schematic diagram after removing the nut sleeve in FIG..

[0064] Figure 8 FIG. Figure 5 is a schematic structural diagram after removing the cage, the upper half of the first connection disk, and the second connection disk in FIG..

[0065] Figure 9 FIG. Figure 8 is a three-dimensional structural diagram of FIG..

[0066] Figure 10 FIG. Figure 8 is a schematic structural diagram of a single connecting shaft and a spring seat in FIG..

[0067] Figure 11 FIG. Figure 10 is a cross-sectional view of FIG..

[0068] Figure 12 FIG. is a schematic structural diagram of a second variable stiffness joint.

[0069] Figure 13 FIG. Figure 12 is a schematic structural diagram of a single first cylinder in FIG..

[0070] Figure 14 FIG. Figure 12 is a schematic structural diagram of a single second cylinder in FIG.. DETAILED DESCRIPTION OF THE INVENTION

[0071] The present invention will be further described in detail below in conjunction with specific embodiments.

[0072] During specific implementation, refer to Figures 1-11 : An external bone fixation assistance and retention system (refer to Figures 1-4 ) includes two relatively arranged fixing rings 4. A plurality of mounting holes are provided on the fixing rings 4 to form a bone pin mounting structure. A plurality of support arms 2 are also hingedly arranged between the two fixing rings. Among them, a variable stiffness joint 5 capable of adjusting the axial stiffness of the support arm is further installed on each support arm 2.

[0073] In this way, when the device of this solution is used, refer to Figure 2 , fix the two fixing rings at both ends of the human fracture position 1 respectively. Fix the needle seat of the bone pin (Kirschner wire) to the fixing ring through the bone pin mounting structure. Then, the two fixing rings are respectively fixedly connected to the bone blocks at both ends of the patient's fracture through the bone pins, and the fixing and support of both ends of the fracture position can be realized by relying on the support arms, avoiding secondary injuries during the healing process. In this solution, a variable stiffness joint capable of adjusting the axial stiffness of the support arm is further installed on the support arm. Therefore, during the use process, the axial stiffness of the support arm can be adjusted to different values at different stages of the fracture healing. It can be adjusted to maintain a relatively large stiffness in the early stage, so that the two ends of the fracture are fixed and grow rapidly; in the later stage, the stiffness can be adjusted to decrease and the flexibility can be increased, so that the bracket will not absorb all the energy during rehabilitation training and cause stress shielding, and the newly grown bone can have a relatively large activity space, so as to better promote bone healing and be more beneficial to its healthy growth. Therefore, this solution can better meet the requirements of different periods of fracture growth and healing, and is more conducive to the rehabilitation growth of the fracture. Among them, a plurality of mounting holes are provided on the fixing ring to form a bone pin mounting structure. In this way, the outer end of the bone pin can be fixed to a bone pin mounting seat, and the bone pin mounting seat can be fixed to the fixing ring by bolts passing through the mounting holes. The structure is simple, the installation is convenient, and the installation position of the fracture can be adjusted conveniently.

[0074] Among them, an axial length adjustment structure is further provided on the support arm 2.

[0075] In this way, the length of each support arm can be adjusted as needed during the fixing process of the device and during the rehabilitation process of the fracture, so that it can better keep both ends of the fracture in the correct attitude position.

[0076] Among them, there are 6 support arms 2. The support arms are obliquely and staggeredly distributed so that one end of each adjacent two support arms approaches and the other end separates, showing a V-shaped or inverted V-shaped arrangement. The connection positions of every two support arms on the fixing ring are evenly distributed along the circumferential direction.

[0077] In this way, the six branch chains formed by the six support arms, together with the two fixed rings, can jointly form a spatial parallel external fixation bracket with three rotational degrees of freedom and three translational degrees of freedom. Thus, it is convenient to adjust the axial lengths of the support arms to achieve three rotational degrees of freedom and three translational degrees of freedom, and further achieve the adjustment of the spatial angle of any position of the fixed ring. During implementation, the spatial angle adjustment process can be assisted by computer calculation, which is the prior art and will not be elaborated here.

[0078] Among them, the fixed ring 4 is integrally circular and is evenly distributed with three outwardly convex connecting parts 6 on the periphery. The ends of every two adjacent groups of support arms 2 are connected to the connecting parts 6, and the connecting parts 6 of the two fixed rings 4 are arranged with a 60-degree offset.

[0079] This enables the connection and installation of the support arms not to affect the area and structure for bone pin installation.

[0080] Among them, both ends of the support arm 2 are respectively hinged to the fixed ring through a Hooke's joint 3.

[0081] In this way, the Hooke's joint can achieve articulated rotation in two directions, facilitating reliable adjustment.

[0082] Among them, the axial length adjustment structure includes two half-bodies that are axially butted to form the main body of the support arm. One half-body is the force-applying end half-body 7, and the other half-body is the force-receiving end half-body 8. An axial lead screw 9 extends axially outward from the axial center of the end of the force-applying end half-body 7. The rear end of the lead screw 9 is rotatably installed on the force-applying end half-body 7 and is connected to the axial adjustment motor 10 on the force-applying end half-body. The front end of the lead screw 9 is threadedly engaged and passes through an adjustment nut 11 fixed to the end of the force-receiving end half-body and is located in a lead screw holding cavity 12 inside the force-receiving end half-body 8.

[0083] In this way, the axial adjustment motor can drive the lead screw to rotate. Due to the threaded fit between the adjustment nut and the lead screw, and at the same time, the adjustment nut is fixed to the force-receiving end half-body and is restricted from circumferential rotation by the Hooke's joint at the end, a lead screw-nut transmission pair can be formed to drive the force-receiving end half-body to achieve axial telescopic adjustment. It has the characteristics of simple structure and stable and reliable adjustment.

[0084] Among them, the lead screw holding cavity 12 has a section of inner cavity that is in close contact with the outer periphery of the lead screw 9.

[0085] In this way, the circumferential limit of the lead screw can be better maintained, avoiding shaking and affecting the fracture fixation effect; and better ensuring the stability and reliability of the detection value of the pressure sensor.

[0086] Wherein, an outer end of the lead screw holding cavity 12 further has a pre-tightening chamber located on the outer periphery of the lead screw. The outer shell 13 of the pre-tightening chamber is rigidly connected to the adjusting nut. A spiral pre-tightening spring 14 sleeved on the lead screw movably is arranged in the pre-tightening chamber. One end of the pre-tightening spring 14 abuts against a boss protruding outwards from the circumference of the lead screw, and the other end abuts against one end of the inner cavity of the pre-tightening chamber.

[0087] In this way, an axial pre-tightening force can be applied between the lead screw and the nut by the pre-tightening spring, avoiding axial shaking caused by thread clearance and affecting the fracture fixation effect; meanwhile, the detection value of the pressure sensor can be better ensured to be stable and reliable.

[0088] Wherein, the boss on the lead screw is formed by a pre-tightening nut 15 located in the pre-tightening chamber and screwed on the lead screw.

[0089] In this way, not only is it convenient to set and install the boss, but also the magnitude of the pre-tightening force can be further changed by adjusting the position of the pre-tightening nut on the lead screw, so that it has a good pre-tightening effect without affecting the transmission of the lead screw and nut itself.

[0090] Wherein, the outer shell 13 of the pre-tightening chamber is obtained from a cylindrical member fixedly installed on the force-bearing end half body, and the outer end of the cylindrical member fixes the adjusting nut.

[0091] In this way, the installation of the structure is more convenient.

[0092] Wherein, a pressure sensor 16 for detecting its axial force is further installed on the support arm 2.

[0093] In this way, it is convenient to detect the axial force-bearing condition of the support arm, serving as an information basis for adjusting and feedback control.

[0094] Wherein, the pressure sensor 16 is installed between the end of the force-bearing end half body and the corresponding Hooke hinge, making it convenient to install.

[0095] Wherein, it further includes a computer (not shown in the computer structure diagram). One end of the computer is connected to the pressure sensor, and the other end is connected to the axial adjustment motor. In this way, with the aid of a computer system for auxiliary calculation and control, the calculation difficulty of manual operation is greatly reduced, and the convenience of using the equipment is improved.

[0096] Among them, a fracture graphic simulation module, a control center, and an adjustment output control module are sequentially connected in the computer. The control center includes an adjustment parameter calculation module. The computer also has a man-machine operation graphic interface respectively connected to the fracture graphic simulation module, the adjustment parameter calculation module, and the adjustment output control module. The fracture graphic simulation module can calculate and simulate the bone structure graphic of the fracture part (the calculation and simulation method is the prior art and will not be elaborated here) by importing multi-angle X-ray films of the fracture part, and obtain the bone deformity parameters. The adjustment parameter calculation module can calculate the installation attitude graphic situation of the device according to the obtained fracture part structure graphic and bone deformity parameters (including the deformation amount of the fractured part of the bone), combined with data and / or manual judgment. The adjustment parameter calculation module can also obtain the parameter situation to be adjusted according to the fracture part structure graphic, the bone deformity parameters, and the detection feedback signal of the pressure sensor after the device is installed. The adjustment output control module is used to convert the parameter situation to be adjusted into an output control signal and send it to the axial adjustment motor. The man-machine operation graphic interface is used to input operation instructions and display the obtained graphics and output instructions. In this way, it is convenient to realize automatic detection calculation and adjustment calculation through computer assistance, and better assist in realizing the fixation and orthopedic operation of the device. During the use of the device, the computer can detect the pressure sensor data feedback in real time to judge whether it is necessary to adjust the axial length of the support arm to ensure the healing effect of the fracture site.

[0097] Among them, the control center of the computer further includes a support arm stiffness timing adjustment module. The support arm stiffness timing adjustment module is respectively connected to the pressure sensor, the man-machine operation graphic interface, and the adjustment output control module. The adjustment output control module is connected to the variable stiffness joint. The support arm stiffness timing adjustment module can generate a variable stiffness joint adjustment signal through the (time and stiffness) adjustment parameter instructions input by the man-machine operation graphic interface and the signals detected by the pressure sensor, and output the signal to the variable stiffness joint through the adjustment output control module to achieve control and adjustment. In this way, it is possible to better utilize the computer system to realize the auxiliary calculation and control of the support arm stiffness adjustment operation in the device.

[0098] Among them, the process of the support arm stiffness timing adjustment module to realize detection, control, and adjustment can be as follows: After the fracture site initially forms callus (3 - 4 weeks), after the two fixing rings of the external bone fixation assistance maintenance system are respectively fixed at both ends of the human fracture position, first output an instruction to control the movement of the axial adjustment motor, so that the two ends of the fractured bone are axially displaced by a certain distance. This distance is the axial deformation amount of the callus part of the bone, denoted as dx. At this time, the control center reads the sensor values f1 - f6, and fits the force condition at the callus part through a mathematical method, denoted as Obtain the load-deformation relationship Compare this value with the allowable load-deformation relationship Iδ The ratio of the values is recorded as Based on this indicator, fracture rehabilitation is divided into two stages: the first stage, when K <K δ (K δ : The critical point ratio of the treatment stage), the variable stiffness joint is set to rigidity (the fractured part of the bone is not subjected to any load, and the fracture ends cannot produce relative displacement, preventing the patient from causing malformation or secondary fracture); the second stage K>K δ , set the variable stiffness joint to be flexible (at this time, the patient enters the rehabilitation training stage, and the bone can already bear a certain load. First, adjust the variable stiffness joint in the rod according to the stiffness of the bone end, so that the bracket will not absorb all the energy during rehabilitation training, avoid stress shielding, and promote bone healing). The specific rigidity and flexibility value range of the variable stiffness joint can be obtained through calculation, experiment and doctor's experience.

[0099] In this way, the stiffness of the support arm can be better adjusted to better avoid secondary injury to the fracture during the rehabilitation process, which is more conducive to the recovery of the fracture.

[0100] In this embodiment, see Figures 5-11 The variable stiffness joint 5 includes a first connecting plate 21 and a second connecting plate 22 which are coaxially arranged opposite to each other. A connecting shaft 23 is axially arranged at one end of the first connecting plate 21 facing the second connecting plate. A plurality of spiral abutment springs 24 are evenly distributed along the circumference at the outer end of the connecting shaft 23. The abutment spring 24 is arranged along the diameter direction and the inner end abuts on the connecting shaft 23. The outer end is connected to the second connecting plate 22 through a force adjustment mechanism.

[0101] In this way, the first connection plate and the second connection plate in the variable stiffness joint are respectively installed on a part of the support arm, so that the two parts of the support arm are connected as a whole by the first connection plate and the second connection plate. When in use, the force adjustment mechanism applies force to the abutment spring to adjust the abutment force of the abutment spring on the connection shaft, thereby adjusting the axial stiffness. In this way, there is no need to maintain power supply for a long time, the structure is simple and the cost is low.

[0102] The outer peripheral surface of the connecting shaft 23 facing the abutment spring 24 has an outward mounting protrusion 25, the outer end of the mounting protrusion 25 is correspondingly provided with a spring mounting groove, and the inner end of the abutment spring abuts against the inner end of the spring mounting groove.

[0103] In this way, the stability and reliability of the spring installation can be better guaranteed, the direction of the spring force application can be guaranteed to be directly opposite to the axis center line, and the stability and reliability of the stiffness adjustment can be guaranteed.

[0104] The axial center position of the first connecting plate 21 is fixedly connected and installed with the connecting shaft 23 through a connecting shaft fixing bolt.

[0105] In this way, it is convenient to set up the structure and install and disassemble the components.

[0106] Among them, the force application adjusting mechanism includes a nut sleeve 26. At both ends of the inner ring of the nut sleeve 26, there are symmetric internal threads respectively, which are respectively engaged with an adjusting ring 27 arranged at a circumferential interval. The outer surface of the adjusting ring 27 has an external thread that mates with the internal thread of the nut. The second connecting disk 22 is also provided with an adjusting ring anti-rotation structure for preventing the adjusting ring from rotating. The force application adjusting mechanism further includes a spring seat 28 arranged at the outer end of the abutting spring. On the upper and lower sides of the outer end of the spring seat 28, there is a diagonally arranged adjusting baffle 29 that can slide respectively. The outer ends of the two adjusting baffles 29 approach each other and the inner ends open to form a horizontal figure-eight shape. The inner ends and the upper and lower ends of the two adjusting baffles 29 are rotatably connected to the corresponding adjusting rings 27 respectively. The outer ends of the adjusting baffles 29 are rotatably connected to a cage 30 relatively fixed on the second connecting disk.

[0107] In this way, during use, only by rotating the nut sleeve can the two adjusting rings be driven to move linearly in the same or opposite directions, and then the inner ends of the adjusting baffles are driven to move axially along the joint, changing the inclination angle of the adjusting baffles, and further squeezing or relaxing the abutting spring, so that the radial pressure of the abutting spring on the connecting shaft increases or decreases, realizing the adjustment of the axially movable performance of the connecting shaft, that is, realizing the adjustment of the axial stiffness of the joint. By adopting this method, the adjustment of the spring pressing force is realized through the screw-nut transmission and then combined with the inclined plate extrusion and cooperation transmission, and then the adjustment of the axial stiffness is realized, which has the following advantages. First, the overall structure is compact, and the force transmission is stable and reliable. The force application is converted from the circumferential rotational motion through multiple force transmissions and conversions into the radial motion force application, so that the device has good self-locking performance and will not easily become unstable. Second, through multiple force transmissions and conversions (especially the inclined surface of the inclined plate cooperates to convert and transmit the force application direction), the transmission ratio of the adjustment is very large, and a large stiffness adjustment effect can be obtained with a small input, so that the adjustable range of the axial stiffness will be very large. In addition, the initial inclination angle of the adjusting baffle can be pre-adjusted and set, and it is very convenient to realize the control adjustment of the conversion of the adjustment accuracy requirements. When the inclination angle of the adjusting baffle is smaller, a larger stiffness change adjustment can be realized with a smaller adjustment distance. Finally, an important point is that in this structure, the axial stiffness adjustment is realized by relying on the radial pressing of the spring on the connecting shaft. Therefore, when the axial bearing force of the connecting disk changes during the adjustment process, it will basically not affect the change of the radial pressing force of the spring. Therefore, it can have good stability and reliability. Therefore, the force application adjusting mechanism can adjust and realize a large range of continuously controllable stiffness changes, realize a large range of stiffness adjustment with small energy loss, and is extremely stable and reliable.

[0108] Wherein, a roller 31 is arranged along the joint axis at the outer end of the spring seat 28. The axial direction of the roller 31 is perpendicular to the axial direction of the abutting spring. The outer circumferential side of the roller is in abutting and cooperating setting with the adjusting baffle 29.

[0109] In this way, the rolling cooperation of the roller can better realize the force transmission between the obliquely arranged adjusting baffle and the abutting spring, ensuring better reliability.

[0110] Wherein, a threaded adjusting hole is arranged at the middle position of the outer end of the spring seat 28 opposite to the spring. An adjusting bolt 32 is installed in the threaded adjusting hole. The front end of the adjusting bolt 32 abuts against the end of the abutting spring.

[0111] In this way, when needed, the pre-tightening force of the adjusting spring can be conveniently changed by adjusting the bolt.

[0112] Wherein, a bearing sleeve 33 is formed by the forward extension of the inner end of the spring seat 28. The outer end of the abutting spring 24 is located inside the bearing sleeve 33. The bearing sleeve 33 has a mating section that can be slidably inserted into the spring installation groove on the connecting shaft.

[0113] In this way, in this structure, the front mating section of the bearing sleeve is inserted into the spring installation groove, and a small gap is formed between the outer wall of the mating section and the inner wall of the spring installation groove, which can produce a very important effect. That is, if a large axial force suddenly occurs between the first connecting disk and the second connecting disk due to an accident (such as falling or collision), at this time, the first connecting disk and the second connecting disk generate a large axial movement, which will cause the spring installation groove to directly drive the whole spring seat to move in the same direction through the cooperation with the mating section of the bearing sleeve. Furthermore, the outer end of the spring seat and the corresponding side adjusting baffle are pressed tightly. The adjusting baffle on this side can compress the spring seat inward, and then the spring presses and clamps the connecting shaft, correspondingly improving the axial stiffness so that it can withstand or offset part of the axial force generated by the accident. The self-adaptive emergency protection effect of the device is realized, reducing or avoiding the safety risks caused by accidents. Wherein, the thread between the nut sleeve and the adjusting ring is a self-locking thread. The realization of the above self-adaptive emergency protection effect is better guaranteed.

[0114] Among them, the cage 30 is integrally cylindrical and is coaxially and spacedly arranged inside the nut sleeve 26. An adjustment baffle installation window 35 is opened in the middle of the cage 30, and the outer end of the adjustment baffle 29 is rotatably installed on the adjustment baffle installation window 35; both ends of the outer peripheral surface of the cage 30 have a circle of inwardly concave limit grooves. A threaded ring 36 is fixedly installed inwardly at each end of the inner cavity of the nut sleeve 26. The internal threads at both ends of the nut sleeve are arranged on the inner circumferential surface of the threaded ring 36. The threaded ring 36 is rotatably clamped and limited in the limit groove. A plurality of relief windows 37 are also opened in the limit groove of the cage. A plurality of outwardly extending mounting protrusions 38 are evenly distributed on the outer surface of the adjusting ring 27. The external threads on the adjusting ring 27 are arranged on the outer end surface of the mounting protrusion 38. The mounting protrusion 38 passes through the relief window 37 and is in threaded cooperation with the outer end of the threaded ring 36. Both sides of the mounting protrusion 38 are in contact with both sides of the relief window 37 to form the anti-rotation structure of the adjusting ring.

[0115] In this way, the whole structure is ingenious, compact, stable and reliable, avoiding mutual interference of movements and ensuring the stability of movement and force transmission.

[0116] As an option, vertical grooves and rotation scales along the axial direction are evenly distributed on the outer surface of the nut sleeve 26. This facilitates manually applying force to rotate the nut sleeve for stiffness adjustment.

[0117] As another option, a nut adjustment motor is also installed on the second connection disk, and the nut adjustment motor is in transmission connection with the nut sleeve (not shown in the figure).

[0118] In this way, it is convenient to realize the electric control adjustment of the stiffness by controlling the nut adjustment motor. During implementation, the nut adjustment motor is connected to a computer, and automatic control can be realized according to preset programs and instructions.

[0119] During implementation, the variable stiffness joint can also be another structure realized by using magnetorheological fluid technology. See Figures 12-14, the variable stiffness joint includes a first cylinder 41 and a second cylinder 42. The open end of the first cylinder 41 is slidably inserted into the open end of the second cylinder 42 and cooperates to form a closed chamber 45 (the other ends of the first sleeve and the second sleeve are respectively installed on a part of the support arm, so that the two parts of the support arm are connected into a whole by the first cylinder and the second sleeve). The outer side wall of the first cylinder 41 is attached to the inner side wall of the second cylinder 42, and a dynamic sealing structure 43 is arranged between them. The first half of the open end of the first cylinder is axially provided with a relief groove 44, and the relief groove 44 is located in the closed chamber 45. A plurality of partitions 46 arranged at intervals along the axial direction are also arranged radially in the closed chamber 45. Some partitions are fixedly arranged on the inner side wall of the first cylinder, and the other part of the partitions pass through the relief groove and are fixed on the inner side wall of the second cylinder. The partitions fixed to the first cylinder and the partitions fixed to the second cylinder are staggered and arranged at intervals. The closed chamber is also filled with magnetorheological fluid, and a magnetic field generating and controlling device 47 is also arranged inside the first cylinder and the second cylinder near the closed chamber.

[0120] In this way, when the variable stiffness joint of this structure is used, the magnetic field generating and controlling device is connected to the computer. The computer can control and adjust the size of the magnetic field by controlling the magnetic field generating and controlling device according to the preset program and instructions, and change the viscosity and hardness of the magnetorheological fluid. Furthermore, the axial stiffness between the first cylinder and the second sleeve can be adjusted and controlled. The variable stiffness joint of this solution has the advantages of simple structure and convenient control and adjustment, but the defect is that it is necessary to keep the magnetic field generated by the magnetic field generating and controlling device in a stable state for a long time, consuming a large amount of electric energy, and it is easy to cause control instability due to reasons such as power fluctuations.

Claims

1. An external bone fixation assistance and retention system, comprising two oppositely arranged fixing rings, wherein a plurality of mounting holes are arranged on the fixing rings to form a bone pin mounting structure, and a plurality of support arms are also hingedly arranged between the two fixing rings, characterized in that, Each support arm is also equipped with a variable stiffness joint capable of adjusting the axial stiffness of the support arm; The variable stiffness joint comprises a first connecting plate and a second connecting plate arranged coaxially opposite to each other, a connecting shaft is axially arranged at one end of the first connecting plate facing the second connecting plate, a plurality of spiral abutting springs are evenly distributed along the circumference at the outer end of the connecting shaft, the abutting springs are arranged along the diameter direction and the inner end abuts on the connecting shaft, and the outer end is connected to the second connecting plate through a force adjustment mechanism; The outer peripheral surface of the connecting shaft facing the abutment spring position has an outward mounting protrusion, the outer end of the mounting protrusion is correspondingly provided with a spring mounting groove, and the inner end of the abutment spring abuts against the inner end of the spring mounting groove; The force adjustment mechanism includes a nut sleeve, two ends of the inner ring of the nut sleeve are respectively provided with a section of symmetrical internal thread and respectively matched with an adjusting ring arranged at a circumferential interval, the outer surface of the adjusting ring has an external thread and the internal thread of the nut is matched, and the second connecting disk is also provided with an adjusting ring anti-rotation structure for preventing the adjusting ring from rotating. The force adjustment mechanism also includes a spring seat arranged at the outer end of the abutting spring, and the upper and lower sides of the outer end of the spring seat are respectively slidably abutted with an obliquely arranged adjusting baffle, the outer ends of the two adjusting baffles are close to each other and the inner ends are opened in a horizontal figure eight shape, the inner ends of the two adjusting baffles are rotatably connected to the adjusting rings corresponding to the upper and lower ends, and the outer ends of the adjusting baffles are rotatably connected to a retaining frame relatively fixed on the second connecting disk; The outer end of the spring seat is provided with a roller along the axial direction of the joint, the axis direction of the roller is perpendicular to the axis direction of the abutting spring, and the circumferential outer side of the roller is abutted and matched with the adjusting baffle; A threaded adjustment hole is arranged at the middle of the outer end of the spring seat, facing the spring. An adjustment bolt is installed in the threaded adjustment hole. The front end of the adjustment bolt abuts against the end of the abutting spring. The inner end of the spring seat extends forward to form a bearing sleeve, the outer end of the abutting spring is located in the bearing sleeve, and the bearing sleeve has a matching section that can be slidably inserted into the spring installation groove on the connecting shaft; The retaining frame is cylindrical as a whole and is coaxially arranged on the inner side of the nut sleeve at intervals. An adjusting baffle installation window is provided in the middle of the retaining frame, and the outer end of the adjusting baffle can be rotatably installed on the adjusting baffle installation window; both ends of the outer circumferential surface of the retaining frame have a circle of inwardly concave limiting grooves, and both ends of the inner cavity of the nut sleeve are respectively fixed inward with a threaded ring, and the internal threads at both ends of the nut sleeve are arranged on the inner ring surface of the threaded ring, and the threaded ring can be rotatably clamped and limited in the limiting groove, and a plurality of clearance windows are also provided in the limiting groove of the retaining frame, and a plurality of outward mounting protrusions are evenly distributed on the outer surface of the adjusting ring, and the external threads on the adjusting ring are arranged on the outer end surface of the mounting protrusion, and the mounting protrusion passes through the clearance window and cooperates with the outer end thread of the threaded ring, and the two sides of the mounting protrusion and the two sides of the clearance window are attached to form the adjusting ring anti-rotation structure.

2. The bone external fixation auxiliary retention system according to claim 1, characterized in that, The support arm is also provided with an axial length adjustment structure.

3. The bone external fixation auxiliary holding system according to claim 2, wherein, There are six support arms, which are staggered obliquely so that one end of each two adjacent support arms are close to each other and the other end is separated to form a V-shape or an inverted V-shape. The connection positions of each two support arms on the fixing ring are evenly distributed along the circumference.

4. The bone external fixation auxiliary holding system according to claim 3, characterized in that, The fixed ring is integrally circular and has three outwardly convex connecting parts evenly distributed around the perimeter. The ends of each adjacent pair of support arms are connected to the connecting parts, and the connecting parts of the two fixed rings are arranged with a 60-degree offset. Both ends of the support arm are respectively hinged to the fixed ring through a Hooke joint.

5. The bone external fixation auxiliary retention system according to claim 2, wherein The axial length adjustment structure includes two halves that are axially butted to form the main body of the support arm. One half is the force-applying end half, and the other half is the force-receiving end half. At the axial center of the end of the force-applying end half, a lead screw extends axially outward. The rear end of the lead screw is rotatably installed on the force-applying end half and is connected to an axial adjustment motor on the force-applying end half. The front end of the lead screw is threadedly engaged and passes through an adjustment nut fixed at the end of the force-receiving end half and then is located in a lead screw holding cavity within the force-receiving end half.

6. The bone external fixation auxiliary holding system according to claim 5, characterized in that, The lead screw holding cavity has a section of inner cavity that is in contact with the outer circumference of the lead screw. The outer end of the lead screw holding cavity also has a pre-tightening chamber located on the outer circumference of the lead screw. The outer shell of the pre-tightening chamber is rigidly connected to the adjustment nut. Inside the pre-tightening chamber, there is a spiral pre-tightening spring that is movably sleeved on the lead screw. One end of the pre-tightening spring abuts against a convex platform protruding outward from the circumference of the lead screw, and the other end abuts against one end of the inner cavity of the pre-tightening chamber. The outer shell of the pre-tightening chamber is a cylindrical member installed and fixed on the force-receiving end half, and the adjustment nut is fixed at the outer end of this cylindrical member.

7. The bone external fixation auxiliary retention system according to claim 5, characterized in that, A pressure sensor for detecting its axial force is also installed on the support arm. The pressure sensor is installed between the end of the force-receiving end half and the corresponding Hooke joint.

8. The bone external fixation auxiliary retention system according to claim 7, wherein, It also includes a computer. One end of the computer is connected to the pressure sensor, and the other end is connected to the axial adjustment motor. Inside the computer, there is a fracture pattern simulation module, a control center, and an adjustment output control module that are connected in sequence. The control center includes an adjustment parameter calculation module. The computer also has a human-machine operation graphic interface that is respectively connected to the fracture pattern simulation module, the adjustment parameter calculation module, and the adjustment output control module. The fracture pattern simulation module can calculate and simulate the bone mass structure pattern of the fractured part by importing multi-angle X-ray films of the fractured part and obtain bone deformity parameters. The adjustment parameter calculation module can calculate the equipment installation attitude graphic situation based on the obtained bone structure pattern of the fractured part and the bone deformity parameters, combined with data and / or manual judgment. The adjustment parameter calculation module can also obtain the required adjustment parameter situation based on the bone structure pattern of the fractured part, the bone deformity parameters, and the detection feedback signal of the pressure sensor after the equipment is installed. The adjustment output control module is used to convert the required adjustment parameter situation into an output control signal and send it to the axial adjustment motor. The human-machine operation graphic interface is used to input operation instructions and display the obtained graphics and output instructions. The control center of the computer further includes a support arm stiffness timing adjustment module. The support arm stiffness timing adjustment module is respectively connected to the pressure sensor, the human-machine operation graphic interface, and the adjustment output control module. The adjustment output control module is connected to the variable stiffness joint. The support arm stiffness timing adjustment module can generate a variable stiffness joint adjustment signal based on the adjustment parameter instructions input through the human-machine operation graphic interface and the signals detected by the pressure sensor, and output the signal to the variable stiffness joint through the adjustment output control module to achieve control and adjustment.

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