A bone plate that automatically converts from rigid fixation to elastic fixation

Abstract

The present invention provides a limb fixation plate that can automatically transition from rigid AO fixation to elastic BO fixation. The plate comprises a bone plate with screw holes for fixation via bone screws, a through-slot / recess, and a slider. When a spacer is added between the slider and the through-slot / recess and the bone screw is fixed, a rigid connection is formed between the slider, the plate, the nail, and the fractured bone. Initially, the entire system forms a stable, rigid structure, and the fracture / fixation complex is statically fixed. As the spacer gradually degrades and absorbs within the body, the connection between the slider and the plate gradually loosens. However, the positional relationship between the nail, the slider, and the bone remains rigid. The slider, constrained by the nail, can only slide axially along the plate under external forces acting on the bone. This creates an axially non-rigid connection between the slider and the plate, and the entire system gradually transitions to axially non-rigid dynamic fixation. This facilitates fracture healing and eliminates the need for plate removal surgery.

Description

Technical Field

[0001] The invention belongs to the field of medical devices, and in particular relates to a bone plate which can automatically transform from firm fixation to elastic fixation. Background Art

[0002] After more than 50 years of evolution, the mainstream international fracture fixation method has shifted from rigid fixation (AO) theory and instruments to flexible fixation (BO) theory and instruments. However, from the perspective of the fracture healing process, early rigid fixation can prevent fracture end displacement and fixation failure, providing conditions for early functional training. Meanwhile, switching to relatively weaker elastic fixation in the middle and late stages of fracture healing helps reduce stress shielding at the fracture ends, allowing them to receive axial physiological stress stimulation conducive to bone healing, thereby improving bone healing quality and reducing disuse osteoporosis within the protection of the fixation device. In other words, rigid fixation is superior to elastic fixation in the early stages of fracture healing, while elastic fixation is superior to rigid fixation in the middle and late stages of fracture healing. However, implants that can provide sufficient fixation strength to weight-bearing bones in the early stage of fixation cannot be converted into elastic fixation in the middle and late stages, and surgery is required to reduce the fixation strength. For example, after fixing a fracture with an intramedullary nail, sometimes another minor operation is required 3 months after the operation to remove the locking screw at one end of the intramedullary nail to convert the initial static fixation into dynamic fixation. However, this method is often not accepted by patients. Patients who have undergone plate fixation do not have to undergo another surgery unless nonunion or delayed union of the fracture has occurred. Therefore, the incidence of delayed union, nonunion and refracture of fractures is still difficult to reduce. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology, meet the needs of patients, and provide a bone plate that can automatically convert from strong AO fixation to elastic BO fixation over time in the body without the need for surgery in the later stage.

[0004] The present invention includes a bone plate with a slider attached and fixed by bone screws. The bone plate spans the bone ends and is placed on the bone surfaces on both sides of the fracture ends. The bone end on one side is fixed to the bone plate directly or through the slider, and the bone end on the other side is fixed to the bone plate through the slider.

[0005] The invention is characterized in that a degradable gasket made of rigid degradable biomaterial is installed between the slider fixed on the other side of the bone fracture and the joint of the bone plate. The bone nail, slider, degradable gasket, bone plate and the two ends of the broken bone fixedly connected to the bone plate form a stable fracture / fixation complex at the initial stage of fixation, forming a stable static fixation.

[0006] As the degradable gasket is gradually degraded and absorbed in the body, the connection between the slider and the bone plate where the degradable gasket is placed gradually loosens, but the positional relationship between the bone nails, the slider and the bones they fix remains a stable rigid structure. Only the connection between the slider and the bone plate where the degradable gasket is placed becomes a clearance fit. The fracture ends constrained by the bone plate, the slider and the bone nails can and can only slide axially closer along the bone plate under the action of external force, that is, the fracture / fixation complex becomes an axial non-rigid connection, and the fixation of the entire fixation system gradually turns into an axial non-rigid dynamic fixation.

[0007] The bone plate includes a bone screw through hole and a slide groove; the slider is a slider embedded in the bone plate slide groove, and the slider is provided with at least one bone screw through hole.

[0008] The side wall of the slider is a smooth plane, and the side wall of the slider and the inner wall of the slide groove are matched in a surface contact manner in the radial direction. The slider and the slide groove have a sliding gap in the axial direction of the bone plate, and the degradable gasket is an embedded degradable gasket filling this sliding gap; the bone screw is connected to the bone plate with a smooth ordinary nail head or a threaded locking nail head through the bone screw through hole on the bone plate and the bone screw through hole on the slider attached to the bone plate to complete the assembly and fixation of the fracture / fixation system.

[0009] The slide groove is a through groove that passes through the surface of the bone plate. A key groove is provided on one or both side walls of the slider. A key pin hole is provided on the side wall of the slide groove corresponding to the key groove. The axial length of the key groove along the slider is greater than the key pin diameter and allows the key pin and the key groove to move relative to each other. The key pin is fixedly connected in the key pin hole and extends into the key groove to limit the slider to only perform axial translation movement in the through groove.

[0010] The slide groove is a through groove that passes through the surface of the bone plate. The inner walls on the left and right sides of the slider are respectively provided with dovetail-shaped or rectangular protrusions, and the inner walls of the through groove are respectively provided with groove bands matching the protrusions, forming a matching dovetail or rectangular groove mortise and tenon structure for connection. The protrusion is embedded in the groove band and can slide in the groove band to limit the slider to only perform axial translation movement in the through groove.

[0011] The slide groove is a through groove that passes through the surface of the bone plate. The two side walls of the slider and the two inner walls of the through groove are both arc-shaped and symmetrical concentric circles. The slider is rotatably embedded in the through groove through their common axis, and the insertion direction of the bone screw can be changed by deflecting the slider through the common axis during the fracture fixation operation; after the fixation operation is completed, the two arc-shaped inner walls of the through groove surround the two side walls of the slider to limit the slider to only axial translation in the through groove.

[0012] The slider is provided with a deformation seam arranged along the axial direction of the slider. The deformation seam enables the closed bone screw through hole on the slider to become a completely open or partially open bone screw through hole, so that the slider has the condition of transverse elastic deformation. When the bone screw is screwed into the bone screw through hole, an extrusion force can be applied to the side walls of the bone screw through hole on both sides of the deformation seam and the side walls of the slider are urged to squeeze the inner wall of the groove.

[0013] The fully open deformation seams all penetrate the side wall of the slider of the bone screw through hole, and the partially open deformation seams are opened from shallow to deep, or from the inner edge to the outer edge, but do not penetrate the side wall of the slider.

[0014] The sliding groove is a groove that does not pass through the surface of the bone plate, and the sliding block is embedded in the groove.

[0015] A through hole is provided at the bottom of the groove, which is larger than the diameter of the bone screw. When the degradable gasket is gradually decomposed, the integrated slider and the bone end can move axially along the through hole along with the bone screw.

[0016] A degradable gasket with the same shape as the bottom of the slider and which is degradable is also provided between the bottom of the slider and the groove. After the bone screw passes through the bone screw hole on the slider and is fastened to the bone through the degradable gasket, the connection between the slider and the bone plate is a rigid connection.

[0017] The sliding clearance between the slider and the slide groove in the axial direction of the bone plate is 0.2-1 mm, the thickness of the embedded degradable gasket is 0.2-1 mm, and the thickness of the laid degradable gasket is 0.1-0.5 mm.

[0018] The degradable gasket is made of metal magnesium or zinc or a composite of magnesium and zinc that can be degraded in a living body, or a composite of magnesium and polylactic acid coated thereon, or a composite of zinc and polylactic acid coated thereon, or a composite of magnesium and zinc and polylactic acid coated thereon.

[0019] The degradable gasket is a complete gasket, or several layers of gaskets made of the same composite material or different composite materials are stacked and used to control the degradation rate.

[0020] The beneficial effects of the present invention are as follows: fracture internal fixation performed using the present invention can achieve rigid fixation in the early stages. As the fracture heals, the biomaterial gradually degrades, the axial fixation strength gradually weakens, the contact between the fracture ends gradually tightens, and the mutual axial compressive stress between the two ends gradually increases. When the biomaterial is completely degraded, the two fracture ends will obtain physiological axial compressive stress that is not affected by fixation while continuing to maintain lateral and rotational stability. Therefore, not only does it not require a second surgery to convert static fixation to dynamic fixation before the fracture heals, but it also does not require a second surgery to remove the internal fixation device after the fracture heals because there is no stress shielding. This not only improves the quality of fracture fixation and reduces the risks of delayed fracture healing, nonunion, and internal fixation device breakage or loosening, but also accelerates healing, shortens the course of treatment, reduces disability, and reduces costs, generating significant social and economic benefits.

[0021] The present invention not only allows the surgical operation to be performed in the same manner as the bridge-jointed combined fracture internal fixation device disclosed in Publication No. CN200510010654.3, by first placing a connecting rod, then placing a connecting block on the side of the connecting rod, and fixing it with a bone screw, i.e., a method equivalent to first determining the direction of the bridge deck (connecting rod), suspending the bridge deck at the intended fixation position, and then driving piles to build bridge piers (screwing nails); but also allows the present invention to use a fixation method different from all existing limb internal fixation devices, by first screwing in a headless bone screw according to the fracture fixation requirements, then placing the connecting rod beside the bone screw, sleeved with the connecting block, and finally fixing it with a compression nut. Moreover, the bone screw and the connecting block do not need to be perpendicular, i.e., a method equivalent to first selecting a pile site to build a bridge pier (screwing nails), and then erecting the bridge deck (connecting rod). Compared with the previous method, the present invention is more flexible and free. Even if the axis of the through hole of the connecting block is at the edge of the bone, the screw insertion direction can be appropriately adjusted to screw the bone screw into the more solid bone as possible, thereby better meeting the fixation requirements of complex comminuted fractures and reducing the need for bending and shaping the connecting rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural rendering of the keyway-inserted mosaic bone plate of Example 1;

[0023] Figure 2 This is a structural rendering of the second embodiment of the mortise and tenon-riveted mosaic bone plate;

[0024] Figure 3 It is a two-dimensional structural diagram of two plug-in embedded sliders / through slots in Examples 1 and 2;

[0025] Figure 4 This is a structural rendering of the rotary inlaid bone plate of Example 3;

[0026] Figure 5 A two-dimensional schematic diagram of the assembly process of the rotary inlaid slider / through slot of Example 3;

[0027] Figure 6 A two-dimensional schematic diagram of the locking fit of the rotary inlaid slider / through slot of Example 3;

[0028] Figure 7 This is a diagram showing the various rotary inlaid sliders of Example 3 and their structural effects in fixing two fractures;

[0029] Figure 8 This is a structural rendering of the third embodiment for fixing bone end fractures;

[0030] Figure 9 This is an assembly rendering of the flat groove type bone plate of Example 4.

[0031] Wherein: 1 - slider; 1(a) - multi-hole slider; 1(b) - single-hole slider; 11 - axial keyway; 12 - bone screw through hole; 13 - side wall; 14 - protrusion; 15 - deformation joint;

[0032] 2-Embedded degradable gasket; 21-Pavered degradable gasket; 22-Non-degradable gasket;

[0033] 3-bone plate; 31-through slot; 32-key pin hole; 33-screw hole; 34-key pin; 35-inner wall; 36-groove band; 37-groove; 38-groove bottom surface; 39-through hole;

[0034] 4-bone screws;

[0035] a-the center of the bone screw's swing circle; b-the angle of the bone screw's swing; c-the horizontal adjustment distance of the bone screw;

[0036] A1-distal fracture end; A2-proximal fracture end; A3-fracture line. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0038] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below; it should be understood that in the description of the present application, the terms "left and right", "up and down", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, "end" refers to the axial edge, "side" refers to the radial edge, "top surface" refers to the side of the bone plate facing the surgeon, "bottom" is the opposite of the "top surface", "proximal fracture end" and "distal fracture end" are bounded by the fracture line, the former refers to the relatively fixed end closer to the shoulder joint or hip joint, and the latter refers to the relatively free end farther away from the above-mentioned joints. These terms are only for the convenience of describing the present application, and do not require that the present application must be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0039] There are many ways to implement the present invention. In summary, they can be divided into two categories, namely through grooves and grooves, according to whether they penetrate the entire layer of the bone plate. Correspondingly, the shapes and combination methods of the through grooves and the sliders in the through grooves are correspondingly divided into two categories, namely, inlay type and flat type, that is, the through grooves correspond to inlay type, and the grooves correspond to flat type; further, when the shapes and combination methods of the sliders and the through grooves are inlay type, the inlay methods of the sliders and the through grooves can be divided into two categories, namely, plug-in inlay type and rotation inlay type; further, the plug-in inlay type combination method can be divided into two categories, namely, mortise and tenon type and keyway type.

[0040] The specific embodiments are further described below with reference to the accompanying drawings.

[0041] Example 1:

[0042] Figure 1 This is a structural effect diagram of the present invention using a through-slot type bone plate with a keyway insert-inlaid structure for fixing a single fracture of the backbone. In the figure, the right side of the fracture line A3 is the distal end A1 of the fracture, and the left side of the fracture line A3 is the proximal end A2 of the fracture; the bone screw through hole 12 on the side of the distal end A1 of the fracture fixed by the bone plate 3 is a locking screw hole without a slider, and the number is not limited to Figure 1 The two shown; the bone plate 3 fixing the proximal end A2 of the fracture has a through groove 31, all the bone screw through holes 12 are provided on the slider 1 within the through groove 31, Figure 1The slider 1 shown is a simplified porous slider 1 (a) structure with only two bone screw through holes 12, and the bone screw through holes 12 are also locking screw holes; the shape of the slider 1 is basically the same as the through slot 31 of the bone plate 3, only the length is slightly shorter than the through slot 31, and the width is the same but with a clearance fit; preferably, the slider 1 is 0.2-1mm shorter than the through slot 31, that is, the axial gap between the slider 1 and the through slot 31 is 0.2-1mm, which is used to embed an embedded degradable gasket 21 with the same shape and size as the gap; the porous slider 1 (a) has an axially arranged keyway 11 on at least one side, and the center of the keyway 11 is 1. The corresponding side walls of the bone plate 3 are provided with key pin holes 32. Preferably, two pairs, i.e., four key slots / key pin hole pairs, are provided on both sides of the bone plate 3. After the slider 1 is inserted into the through slot 31 and the key pin 34 is inserted into the key slot 11 through the key pin hole 32 and the key pin 34 is fixed, the slider 1 is connected to the bone plate 3 as a whole and the slider 1 can only be axially translated in the through slot 31; to meet the needs of different fracture fixation, preferably, the length of the key slot 11 allows the slider 1 to translate 1 mm to both ends at least; the connection method between the key pin 34 and the key pin hole 32 can be in various forms such as screwing, riveting, and welding.

[0043] The number of the bone screw through holes 12 of the bone plate 3 and the number of the fixed bone screw through holes 12 and the sliding bone screw through holes 12 distributed at both ends of the fracture line can be selected according to preoperative planning and actual conditions during surgery.

[0044] It must be emphasized that during surgery, the gap between the slider 1 and the through groove 31 must be left close to the fracture line A3. Only in this way can the gap restored after absorption by the embedded degradable gasket 21 be utilized, so that the axial stress generated by muscle tension and limb movement can obtain space to drive the distal end A2 of the fracture to drive the bone screw 4 and the bone plate 3 fixed thereon to translate toward the proximal end A1 of the fracture, so that the contact between the distal end A1 of the fracture and the proximal end A2 of the fracture is closer, thereby generating axial compressive stress stimulation between the fracture ends that is conducive to fracture healing.

[0045] Example 2:

[0046] Figure 2 This is a structural rendering of the present invention's through-groove type bone plate using a mortise and tenon-and-tenon inlay structure for fixing a single bone fracture. In the figure, except that the inlay method of the slider 1 and the through-groove 31 is changed to a rectangular inserted mortise and tenon structure, the rest are the same as those in Example 1; that is, rectangular protrusions 14 are respectively provided on the left and right inner walls of the slider 1, and groove bands 35 matching the protrusions 14 are respectively provided on the two side inner walls of the through-groove 31, forming a matching rectangular groove-shaped mortise and tenon structure for connection, and the protrusion 14 is embedded in the groove band 35 and can slide in the groove band 35, so as to limit the slider 1 to only axial translation movement in the through-groove 31.

[0047] The mortise and tenon rivet structure may also be in other forms such as a dovetail groove; Figure 3 The left side of the center line is the mortise and tenon structure, and the right side is the two-dimensional schematic diagram of the keyway / key pin hole structure after assembly.

[0048] Example 3:

[0049] Figure 4 This is a structural effect diagram of the present invention using a through-slot bone plate with a rotating inlaid structure for fixing a single fracture of the backbone. In the figure, except for the inlaid structure of the slider 1 and the through-slot 31, the rest of the structure is the same as that of the first embodiment.

[0050] In the third embodiment, the two side walls of the slider 1 and the two inner walls of the through groove 31 are set to be symmetrical concentric circles, and the slider 1 is inserted into the through groove 31 in a rotating manner. Figure 5 、 Figure 6 As shown; in order to facilitate the sliding block 1 to be screwed into the through groove 31, the edges on both sides of the through groove 31 of the bone plate 3 can be chamfered into an arc shape. In this way, the sliding block 1 can be easily screwed into the through groove 31; secondly, the sliding block 1 can be horizontally rotated with the longitudinal axis of the bone plate 3 as the rotation axis during the fixation process, thereby steplessly adjusting the angle between the axis of the bone screw through hole 12 on the sliding block 1 and the vertical axis of the bone plate surface, making it convenient for the bone screw 4 to pass through the bone plate 3 at an inclined angle, find a thicker and stronger bone to be screwed into the bone, thereby increasing The invention has the advantages of strong fixing strength and forming a cross-pinning structure that is more resistant to loosening and pulling out of nails; thirdly, it does not destroy the inclusiveness of the slide groove 31 to the slider 1, so that the slider 1 cannot fall out of the through groove 31 under any external force except the same rotation mechanism as when it is embedded in the through groove 31, and after tightening the bone screw 4 that passes through the bone screw through hole 12 on the slider 1 and is fixed in the bone, the slider 1 squeezed by the bone screw 4 can still squeeze the through groove 31, so that the slider 1 and the through groove 31 are connected as a whole to form a complete bone plate 3.

[0051] In order to facilitate the sliding block 1 to be screwed into the through groove 31, a deformation seam 15 can be provided on one end side wall of the single-hole sliding block 1 (b) along the axial direction of the bone plate 3, which runs through the entire layer of the sliding block 1, so that the closed bone screw through hole 12 on the sliding block 1 becomes an open bone screw through hole 12, and the other end side wall of the sliding block 1 symmetrical to the side wall with the deformation seam 15 is a complete side wall structure, or an incomplete side wall structure with a crack that does not penetrate the side wall and is opened from shallow to deep or from the inner edge to the outer edge, so that the sliding block 1 has the conditions for lateral elastic deformation; the multi-hole sliding block 1 (a) has the same or similar structure as the single-hole sliding block 1 (b) at both ends, but the side walls between all the bone screw through holes 12 on the entire multi-hole sliding block 1 (a) are all provided with deformation seams 15 along the axial direction, so that the two sides of the entire sliding block 1 are maintained in continuity only by the complete side wall or the remaining partial side wall at one end; Figure 7 Various slider 1 structures of the third embodiment are shown.

[0052] Figure 7 It also explains the key points for placing the embedded gasket 21 when fixing two fractures of the bone shaft. First, all the bone screw holes 12 at the proximal end A2 and the distal end A1 of the fracture must be set on the slider 1, and all the embedded degradable gaskets 21 must be placed in the through groove 31 at one end close to the fracture line A3; second, the bone screw holes 12 on the free bone segment in the middle of the fracture cannot slip. If the bone screw holes 12 on the bone plate corresponding to the free bone segment are set on the slider instead of directly on the bone plate, a non-degradable gasket 20 of the same shape and size should be embedded in the gap to eliminate the gap and enhance the rigidity between the slider 1 and the bone plate 3.

[0053] Figure 8 This is a structural rendering of embodiment three of the present invention for fixing bone end fractures. In the figure, A2 represents the shaft of the tubular bone, which is located proximal to the fracture line; A1 represents the epiphysis of the tubular bone near the joint, such as the distal end of the radius, which is located distal to the fracture line; the bone screw through hole 12 for fixing the A1 side is also a locking screw hole without a slider, but the bone screw through hole 12 can only be arranged mainly in a transverse direction, and accordingly the bone plate 3 of the broken end can only be widened transversely, so that the entire bone plate 3 becomes a "T" shape or an "L" shape.

[0054] Example 4:

[0055] Figure 9 This is a structural effect diagram of the flat groove type bone plate used for fixing diaphyseal fractures in the present invention. In the figure, except for the structure of the slider 1 and the slide groove, the rest of the structure is the same as that of the embodiment 1.

[0056] Figure 9In the embodiment, the sliding groove on the left side of the bone plate 3 is set as a groove 36 with a smooth surface located on the top surface of the bone plate 3 but not penetrating the entire layer of the bone plate 3. The width of the groove 36 is greater than the diameter of the bone screw 4, and a through hole 38 for the bone screw 4 to pass through is opened in the center of the bottom surface 37 of the groove. The size and shape of the through hole 38 allow the bone screw 4 passing through the slider 1 to move axially along the bone plate 3; the shape of the slider 1 is basically the same as that of the groove 36, except that the length is slightly shorter than the groove 36, and the width is the same as the groove 36 but with a clearance fit; the size and position of the bone screw through hole 12 on the slider 1 also correspond to the through hole 38 on the groove 36, and can be laid in the groove 36; preferably, the slider 1 is 0.2-1mm shorter than the groove 36, that is, the axial gap between the slider 1 and the groove 36 is 0.2-1mm, and an embedded degradable gasket 21 with the same shape and size as the gap can be embedded at the end of the slider 1 near the fracture line A3.

[0057] In the fourth embodiment, a degradable gasket 22 having a shape and size adapted to the shape of the bottom surface 37 of the groove and having a thickness of less than 1 mm, preferably a thickness of 0.1-0.5 mm, can be laid between the slider 1 and the groove 36 so as to eliminate the micro-movement between the slider 1 and the groove 36 at the initial stage of fixation, and a gap is formed between the slider 1 and the groove 36 after the degradable gasket 22 is degraded and absorbed, which does not hinder the sliding of the two and does not cause the slider 1 to undergo lateral rotation micro-movement.

[0058] like Figure 9 As shown, the bone plate 3 using a flat-laying slider can use an embedded degradable gasket 21 and a laid-type degradable gasket 22 at the same time.

[0059] The degradable gasket 2 described in the above-mentioned embodiments 1 to 4 of the present invention is made of metallic magnesium or zinc or a composite of magnesium and zinc that can be degraded in a living body, or a composite of magnesium and polylactic acid coated thereon, or a composite of zinc and polylactic acid coated thereon, or a composite of magnesium and zinc and polylactic acid coated thereon; the degradable gasket can be a complete gasket, or several layers of gaskets made of the same composite material or different composite materials can be stacked and used to control the degradation rate.

[0060] The above embodiments are preferred implementation methods of the present invention and are not exhaustive of other embodiments. Therefore, any modifications, equivalent replacements, and improvements made using the description and drawings disclosed in the present invention should be included in the scope of protection of the present invention.

[0061] The embodiments disclosed in the present invention are preferred embodiments, but are not limited to them. Ordinary technicians in this field can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. As long as they do not deviate from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A bone plate capable of automatically converting from rigid fixation to elastic fixation, comprising a plate with a slider attached and fixed by bone screws, the plate spanning a bone fracture end and positioned on the bone surfaces on both sides of the fracture end, wherein the bone on one side of the fracture end is fixed to the plate by the bone screw directly or through the slider, and the bone on the other side of the fracture end is fixed to the plate by the bone screw through the slider; Its characteristics are: A degradable gasket made of a rigid degradable biomaterial is installed between the slider fixed to the other side of the bone fracture and the bone plate. The bone nail, slider, degradable gasket, bone plate and the two ends of the broken bone fixed to the bone plate form a stable fracture / fixation complex at the beginning of fixation, forming a stable static fixation. As the degradable gasket is gradually degraded and absorbed in the body, the connection between the slider and the bone plate at the location where the degradable gasket is placed gradually loosens. However, the positional relationship between the bone screws, the slider and the bones they fix remains a stable rigid structure. Only the connection between the slider and the bone plate at the location where the degradable gasket is placed becomes a clearance fit. The fracture ends constrained by the bone plate, the slider and the bone screws can and can only slide axially closer along the bone plate under the action of external force. That is, the fracture / fixation complex becomes an axial non-rigid connection, and the fixation of the entire fixation system gradually turns into an axial non-rigid dynamic fixation. The bone plate includes a bone screw through hole and a slide groove; the slider is a slider embedded in the bone plate slide groove, and the slider is provided with at least one bone screw through hole; The side wall of the slider is a smooth plane, and the side wall of the slider and the inner wall of the slide groove are in contact with each other in the radial direction. The slider and the slide groove have a sliding gap in the axial direction of the bone plate, and the degradable gasket is an embedded degradable gasket that fills this sliding gap. The bone screw is connected to the bone plate with a smooth ordinary nail head or a threaded locking nail head through the bone screw through hole on the bone plate and the bone screw through hole on the slider attached to the bone plate, thereby completing the assembly and fixation of the fracture / fixation system. The degradable gasket is made of metal magnesium or zinc or a composite of magnesium and zinc that can be degraded in a living body, or a composite of magnesium and polylactic acid coated thereon, or a composite of zinc and polylactic acid coated thereon, or a composite of magnesium and zinc and polylactic acid coated thereon.

2. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The slide groove is a through groove that passes through the surface of the bone plate. A key groove is provided on one or both side walls of the slider. A key pin hole is provided on the side wall of the slide groove corresponding to the key groove. The axial length of the key groove along the slider is greater than the key pin diameter and allows the key pin and the key groove to move relative to each other. The key pin is fixedly connected in the key pin hole and extends into the key groove to limit the slider to only perform axial translation movement in the through groove.

3. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The slide groove is a through groove that passes through the surface of the bone plate. The inner walls on the left and right sides of the slider are respectively provided with dovetail-shaped or rectangular protrusions, and the inner walls of the through groove are respectively provided with groove bands matching the protrusions, forming a matching dovetail or rectangular groove mortise and tenon structure for connection. The protrusion is embedded in the groove band and can slide in the groove band to limit the slider to only perform axial translation movement in the through groove.

4. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The slide groove is a through groove that passes through the surface of the bone plate. The two side walls of the slider and the two inner walls of the through groove are both arc-shaped and symmetrical concentric circles. The slider is rotatably embedded in the through groove through their common axis, and the insertion direction of the bone screw can be changed by deflecting the slider through the common axis during the fracture fixation operation; after the fixation operation is completed, the two arc-shaped inner walls of the through groove surround the two side walls of the slider to limit the slider to only axial translation in the through groove.

5. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The slider is provided with a deformation joint arranged along the axial direction of the slider, and the deformation joint makes the closed bone screw through hole on the slider become a completely open or partially open bone screw through hole, so that the slider has a transverse elastic deformation condition. When the bone screw is tightened into the bone screw through hole, an extrusion force can be applied to the side walls of the bone screw through hole on both sides of the deformation joint, thereby causing the two side walls of the slider to squeeze the inner wall of the through groove; The fully open deformation seams all penetrate the side wall of the slider of the bone screw through hole, and the partially open deformation seams are opened from shallow to deep, or from the inner edge to the outer edge, but do not penetrate the side wall of the slider.

6. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The sliding groove is a groove that does not pass through the surface of the bone plate, and the sliding block is embedded in the groove; A through hole is provided at the bottom of the groove, which is larger than the diameter of the bone screw. When the degradable gasket is gradually decomposed, the integrated slider and the bone end can move axially along the through hole along with the bone screw.

7. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 6, characterized in that: A degradable gasket with the same shape as the bottom of the slider and which is degradable is also provided between the bottom of the slider and the groove. After the bone screw passes through the bone screw hole on the slider and is fastened to the bone through the degradable gasket, the connection between the slider and the bone plate is a rigid connection.

8. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1 or 7, characterized in that: The sliding clearance between the slider and the slide groove in the axial direction of the bone plate is 0.2-1 mm, the thickness of the embedded degradable gasket is 0.2-1 mm, and the thickness of the laid degradable gasket is 0.1-0.5 mm.

9. The bone plate capable of automatically converting from rigid fixation to elastic fixation according to claim 1, characterized in that: The degradable gasket is a complete gasket, or several layers of gaskets made of the same composite material or different composite materials are stacked and used to control the degradation rate.

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