CN105056309B - Magnesium metal bone screw that a kind of orientable degraded absorbs and preparation method thereof - Google Patents

Abstract

Magnesium metal bone screw absorbed the invention provides a kind of orientable degraded and preparation method thereof, including bone screw, the bone screw is made up of pure magnesium or magnesium alloy and is provided with screw thread, the bone screw respectively there is different heterogeneous microstructure advantages to be orientated on cross section and longitudinal section so that bone screw cross section degraded during being degraded and absorbed is faster than longitudinal section degraded.The present invention changes the heterogeneous microstructure orientation of pure magnesium and its alloy bone screw, make some crystal faces that advantage orientation be presented in a certain direction, there is different heterogeneous microstructures in a different direction, the different degradation behaviors for making full use of magnesium and its alloy difference crystal face to have, have the function that to regulate and control that bone screw degradation rate more preferably matches with bone growth.Bone screw with the difference of degradation rate in the radial direction, so as to have the characteristic of orientation degraded, can be implanted into the integrality of early stage guarantee helicitic texture, maintain the early stage fastening force of nail in the axial direction.

Description

Magnesium metal bone screw that a kind of orientable degraded absorbs and preparation method thereof

Technical field

The present invention relates to a kind of device of Implantable Medical Device technical field and preparation method thereof, is specifically one kind Magnesium metal bone screw that degraded absorbs and preparation method thereof can be oriented by human body.

Background technology

Bone screw is the implantation instrument that the operations such as Fracture internal fixaiion, osteotomy fixation are largely used on Orthopedic Clinical, is used Way is very extensive.However, the bone screw that Present clinical uses is substantially by the absorbable height of stainless steel, titanium or titanium alloy and part Molecular material is formed, and the problem of some are difficult to overcome be present.The metal material modulus of elasticity such as titanium alloy, stainless steel is far longer than people Compact bone, stress-shielding effect is easily produced around implant site after fracture fixation, osteoporosis may be caused, reduce hand Art therapeutic effect.And nail is taken out in stainless steel and titanium alloy non-degradable, the operation that must be tried again after union, undoubtedly Physical pain and the financial burden of patient can be increased.Resorbable polymeric materials can be degraded by human body to be absorbed, and avoids forever depositing Cause the problem of, but resorbable polymeric materials mechanical property is relatively low, and has more acid small molecule thing in degradation process Matter produces aggregation and causes local acidifying, inflammation is induced, using being seriously restricted.

Because magnesium and its alloy have, good biocompatibility, mechanical strength are higher, can be degraded by human body absorbs, and use In Fracture internal fixaiion can exempt second operation take out, in recent years as degradable absorption orthopaedics inside-fixture at home and abroad by Very extensive concern is arrived, the cumulative year after year such as the related science Research Literature published, patent.

Patent document《Biological and adsorbable bone internal fixation implantation instrument》(publication number CN 101283922A) discloses tool There is bioactivity Absorbale magnesium alloy, include magnalium series, magnesium manganese systems row, magnesium zinc series, magnesium zirconium series, magnesium rare earth metal etc. A variety of serial magnesium alloys, and these alloys make screw, intramedullary nail, fracture dislocation of spine fixation device, the spicule of processing Apparatus is implanted into etc. a variety of, its surface, which has, utilizes ion implanting, thermal spraying, ion plating, sputtering, chemical vapor deposition, electrochemistry Ceramic coating prepared by a variety of methods such as method, to control its degradation rate.Patent document《A kind of biodegradable skull is repaiied Complement》(publication number CN 101385660A) discloses skull repairing body and its screw prepared by a kind of pure magnesium or magnesium alloy processing It is supporting, degradation rate is controlled by surface modification and/or coating degradable biological coating.Patent document《Controlled degradation speed The biological and medicinal implant material of rate and its application》(Authorization Notice No. CN100400114C) is then disclosed one kind and closed with pure magnesium or magnesium Golden material is the material of matrix, and surface coats one layer of degradable high polymer material, carries out biodegradable substep, both ensures to degrade The mechanical property of process in which materials, degradation rate and implant devices active time is matched again, reach the purpose of controlled degradation. In addition, also numerous studies document discloses the orthopaedics inner implantation material or device reported using pure magnesium or magnesium alloy as material.

Remained however, magnesium and its alloy are used for fixation in orthopaedics in some problems, such as degradation rate and bone uptake speed not Match and cause the initial failure of inside-fixture (such as bone screw), lose mechanical support effect, and influence final treatment effect Fruit.The basic ideas for solving the problem at present are by coating technology, adjust degradation rate, degradation rate is declined with mechanical property Subtract, bone uptake speed is mutually matched.But coating technology technique is typically complex, in screw when most coatings are used for bone screw Screw up during the problems such as adhesion is poor, easy to fall off be present.

The content of the invention

The present invention be directed to above-mentioned the deficiencies in the prior art, there is provided one kind can be degraded according to certain orientation inside can Degraded absorbs magnesium metal bone screw and preparation method thereof.

To achieve these goals, the present invention uses following technical scheme：

The present invention provides the magnesium metal bone screw that a kind of orientable degraded absorbs, including bone screw, the synthetism spiral shell Nail is made up of pure magnesium or magnesium alloy and is provided with screw thread, and the bone screw is on cross section and longitudinal section respectively with different micro- See institutional framework advantage orientation so that bone screw cross section degraded during being degraded and absorbed is faster than longitudinal section degraded. Such degradative pathway can ensure to maintain certain screw thread thread depth in degradation process, avoid in implantation early stage due to spiral shell Depth of threat degree rapid decay and cause it is fixed loosely.

Specifically, the magnesium metal bone screw that a kind of orientable degraded absorbs has following feature：

1. the bone screw, on longitudinal section, there is advantage to be orientated and form texture for (0 00 2) crystal face, penetrated when using X When line diffraction (XRD) tests its crystal structure, the X-ray diffraction intensity highest of (0 00 2) crystal face, turn into highest peak；

2. the bone screw, on cross section, there is advantage to be orientated and form texture for (1 0-1 0), (1 0-1 1) crystal face, When testing its crystal structure using X-ray diffraction (XRD), the X-ray diffraction of (1 00 0) crystal face or (1 0-1 1) crystal face Intensity highest, turns into highest peak.

Magnesium has more preferable corrosion resistance in (0 00 2) crystal face, based on features described above so that this bone screw is in difference Degradation rate on direction has otherness, ultimately forms the bone screw that orientation is absorbed with specific degraded.

Further, above-mentioned bone screw includes nail body and turn head, follows closely body and turn head collectively forms screw length.It is long Degree >=3mm.

Further, the nail body is made up of screw thread, wherein thread width >=0.15mm, thread depth 0.1mm~2mm, Thread spacing is 0.5mm~2mm.

Further, the turn head includes bulb lower surface or tapered inferior surface；The wherein sphere of bulb lower surface half Footpath is 1.5mm~8mm, and the cone angle of table is 20 °~90 ° below taper.

Further, there is turn groove on the turn head of the bone screw, turn groove includes a word, cross, Triangle ID, interior Corner, interior hexagonal；Or turn head is outer triangle, outer corner, outer-hexagonal.The diameter or circumscribed circle diameter of turn head are 3mm- 15mm。

The above-mentioned preferable various parameters of the present invention, wherein, thread width >=0.15mm, depth 0.1mm~2mm, between thread It is a kind of screw for possessing wide flat screwed tooth structure away from 0.5~2mm.In such structure, threaded tip has obvious platform, So that threaded tip keeps sufficiently (0 00 2) crystal face arrangement, ensure that threaded tip exposes advantage in degradation process Orientation, will not preferential degradation and cause screw thread to be collapsed, maintain the stability of early structure.And then fully exposed in the side of screw thread (1 0-1 0) or (1 0-1 1) advantage crystal face, the meeting of the magnesium preferential degradation of thread both sides, i.e. thread is preferential " reducing ", rather than First " become short ".Finally sufficient thread depth is being maintained in early days.

Above-mentioned pure magnesium or magnesium alloy includes：Purity not less than 99.9% pure magnesium, Mg-Zn based alloy, magnesium Mn series alloy, Magnesium rare earth-based alloy, magnesium calcium alloy etc..Wherein, pure magnesium or magnesium alloy is all single homogeneous phase, is occurred without the second phase, by This can avoid the occurrence of micro- galvanic corrosion heterogeneous.

The present invention also provides a kind of preparation method for the magnesium metal bone screw that above-mentioned orientable degraded absorbs, including as follows Step：

Step 1：It is more than 99.9% pure magnesium ingot casting using purity, or using magnesium alloy ingot as raw material；By pure magnesium Ingot casting or magnesium alloy ingot hot extrusion are bar, and extrusion temperature is 100 DEG C~500 DEG C, and extrusion ratio is more than 10, extruded barses Discharging speed is less than 20mm/min, extruding and discharging prostomum degree >=150 °, freely rubs unlubricated.Now, extruded barses cross section In (1 0-1 1) crystal face there is most strong X-ray diffraction peak, and the diffraction peak intensity of (1 0-1 0) and (0 00 2) crystal face is not More than (1 0-1 1) crystal face intensity.(1 0-1 1) crystal face has advantage orientation on longitudinal section, and the X ray with maximum intensity spreads out Penetrate peak.

Step 2：The hot extrusion bar of step 1 is subjected to cold working.The temperature of cold working is 10~80 DEG C, bar after processing Reduced cross-sectional area is to original 95%~40%.(1 0-1 0) and (0 00 2) crystal face spread out in bar cross section after cold working Penetrate peak intensity to significantly improve, intensity exceedes the 50% of (1 0-1 1) crystal face, but is less than (1 0-1 1) surface intensity；(0 on longitudinal section The X-ray diffraction peak intensity of 00 2) crystal face exceedes (1 0-1 1) crystal face diffracted intensity, turns into the excellent of maximum diffraction intensity Gesture is orientated crystal face.

The above-mentioned various machined parameters of the present invention have important influence for final result, by the joint of above-mentioned key parameter Procedure of processing can just obtain preferable orientation texture.First, by extrusion process, being formed respectively in extruded rod transverse and longitudinal section has The structure of specific orientation.If the cone angle of extrusion process is insufficient or frictional force is insufficient, possibly can not obtain above-mentioned excellent Gesture is orientated.Secondly, the cold working carried out on the basis of step 1, the advantage orientation in transverse and longitudinal section is further changed, so that The transverse and longitudinal section of bar has entirely different texture composition, and this is to ensure that screw has the basis of specific degraded orientation.Screw thread The macroscopic orientation sensing of tip (such as thread) direction of bar texture orientation is depended on dimensional parameters.Therefore, above-mentioned two The parameter request of the joint of step and each step is key part, and simple only carries out one of step, or technique ginseng Number does not reach requirement, then is difficult to obtain the structural approach of the present invention.

Step 3：Bar after cold working is finished using numerically controlled lathe, processes bone screw.The wherein longitudinal axis of screw Line is exactly the longitudinal axis of the bar in step 2.This processing orientation and screw keep the key being finally orientated.

Further, methods described also includes being polished bone screw, makes its any surface finish zero defect.

Preferably, described cold working includes cold extrusion, cold forging or cold rolling.

Compared with prior art, the invention has the advantages that：

Process technology of the invention by improving and optimizating biologic medical magnesium and its alloy, change pure magnesium and its alloy synthetism spiral shell The heterogeneous microstructure orientation of nail, makes some crystal faces that advantage orientation be presented in a certain direction, has difference in a different direction Heterogeneous microstructure, the different degradation behaviors for making full use of magnesium and its alloy difference crystal face to have, reach regulation and control bone screw The effect that degradation rate more preferably matches with bone growth.After the material is processed into bone screw, in the axial direction and radially Degradation rate is different on direction, so as to which with the characteristic degraded is oriented, the integrality of helicitic texture can be ensured in implantation early stage, Maintain the early stage fastening force of nail.

Brief description of the drawings

The detailed description made by reading with reference to the following drawings to non-limiting example, further feature of the invention, Objects and advantages will become more apparent upon：

Fig. 1 is the magnesium metal bone screw structural representation that the orientable degraded designed by the present invention absorbs；

Fig. 2 is bone screw turn slot structure figure in the present invention；

Fig. 3 be the bone screw in the present invention with microstructure orientation in degradation process, the decay of the profile of screw thread is shown It is intended to；

Fig. 4 be ordinary magnesium alloy bone screw in degradation process, the profile of screw thread decay schematic diagram；

Fig. 5 is degradation process schematic diagram after the bone screw in the present invention is implanted into vivo；Wherein：(a)~(d) is synthetism Screw is progressively degraded absorption process after being implanted into vivo.

Fig. 6 is the bone screw of the present invention and the transverse and longitudinal section XRD diffraction commonly without advantage orientation magnesium alloy bone screw Collection of illustrative plates；Wherein：(a) it is ordinary construction magnesium alloy bone screw cross section XRD diffraction patterns, (b) is ordinary magnesium alloy bone screw Longitudinal section XRD diffraction patterns, (c) are bone screw cross section XRD diffraction patterns of the present invention, and (d) is bone screw longitudinal section of the present invention XRD diffraction patterns；

Fig. 7 is the bone screw of the present invention with commonly soaking degraded 2 weeks in vitro without advantage orientation magnesium alloy bone screw Afterwards, the comparison diagram in kind of screw thread attenuation, wherein:(a) it is that ordinary construction magnesium alloy bone screw soaks degraded 2 weeks in vitro Screw thread pictorial diagram afterwards, (b) are that bone screw of the present invention soaks the screw thread pictorial diagram after degrading 2 weeks in vitro；

In figure, 1 is the thread width of bone screw, and 2 be thread spacing (pitch), and 3 be the total length of bone screw, and 4 are Screw thread form, 5 be the bottom footpath of bone screw, and 6 be the external diameter of bone screw, and 7 be yi word pattern turn groove, and 8 be cross turn groove, 9 be Triangle ID turn groove, and 10 be interior corner turn groove, and 11 be interior hexagonal turn groove, and 12 be before bone screw of the present invention is degraded Thread profile, 13 be the outline in bone screw degradation process of the present invention, and the bone screw degraded of the present invention of 14~16 difference is not With the profile of time rear thread, 17~19 be the deformation outside the different time rear thread of degraded of ordinary construction magnesium alloy bone screw Change process.

Embodiment

With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention Protection domain.

As shown in figure 1, the orientable degraded provided by the invention with specific microstructure orientation absorbs magnesium metal synthetism Screw, be made up of turn head and threaded portion, wherein the width of thread 1 of threaded portion, flight pitch 2 is adjustable, and pass through external diameter 6th, the change of internal diameter 5 determines its depth of thread.Turn head is collectively forming screw length 3 with threaded portion.There is turn on turn head Groove, turn groove can be yi word patterns 7, cross 8, interior triangular 9, interior tetragonal 10 and interior hexagon 11.Turn head also may be used To be outer triangle, outer corner, outer-hexagonal shape.In degradation process, the degradation behavior of thread will comply with certain orientation, from drop Thread shape 12 before solution starts, along y direction degrade it is slightly fast, and along X direction degrade it is slightly slow, then profile by Step is degraded to 14,15,16, by the way that certain directionality is presented as can be seen that it is degraded with the original contrast of thread contour line 13, I.e.：Thread first tends to narrow, then progressively laterally collapses.The shape of screw thread can be so kept in certain degradation cycle, Enough holds and fixed force are provided.Correspondingly, it is the degradation process of common No yield point screw, its thread is from original outer Shape 12 starts, laterally, longitudinal direction degrade simultaneously, be progressively changed into 17,18,19 shape, contrasted with contour line 13 it can be found that its Thread profile is in the state integrally collapsed, therefore it is possible that the situation of initial failure, is unfavorable for bone in degradation process The early stage of folding is fixed.

In terms of overall, the degradation process of screw can be described as follows：It is shaped like (a) in Fig. 5 outside from initially undegraded Starting point, thread are degraded comparatively fast along the longitudinal axis, and X direction degraded is slower, is then gradually degraded as (b) in Fig. 5, (c) profile, But still keep certain helicitic texture, there is provided good fixed force.Smaller fragment (in Fig. 5 shown in (d)) is gradually degraded as, Finally all absorbed by human body.Micro-analysis discovery is carried out for the bone screw, as (1 0-1 1) crystal face on its cross section With preferred orientation (in such as Fig. 6 shown in (c)), and it is then that (0 00 2) crystal face has advantage orientation (in such as Fig. 6 on longitudinal section (d) shown in).Such advantage orientation, ensures have along X direction (i.e. longitudinal section, it is noted that be that longitudinal section is vertical with transverse axis) There is higher corrosion resistance, and it is very fast then being degraded along y direction (i.e. cross section, it is noted that be cross section and axis oriented normal), from And cause screwed tooth structure that there is certain degraded to be orientated, in actual degradation effect such as Fig. 7 shown in (b).Correspondingly, it is general The screw that logical nothing is orientated strongly, advantage orientation on its transverse and longitudinal section (diffraction maximum as shown in marking (b) in Fig. 6, (a) crystal face The high as advantage orientation of intensity), in change such as Fig. 7 of its screw thread in degraded shown in (a).In comparison diagram 7 (a), (b), it can be seen that the bone screw in the present invention can guarantee that screw thread form and the depth of thread initial stage in degraded, and regular screw threads are then There is entirety to collapse, the depth of thread is greatly lowered.

Specific embodiment of the invention given below, concrete application of the present invention etc. is described in detail.

Embodiment 1

Using more than 99.98% pure magnesium ingot casting, bar, extrusion ratio 20, extruded barses discharging are squeezed at 100 DEG C Speed 20mm/min, 180 ° of discharging opening taper are unlubricated.XRD analysis are carried out for the extruded barses, find extruded barses horizontal stroke (1 0-1 1) crystallographic plane diffraction peak is most strong in section, is equally that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section, in Fig. 6 (a), shown in (b) part.

Afterwards, above-mentioned pure magnesium hot extrusion bar is subjected to further cold extrusion, extrusion temperature is 80 DEG C, bar after extruding Reduced cross-sectional area is to original 95%.Found by the further analyses of XRD, after cold working in bar cross section (1 0-1 0) with The diffraction peak intensity of (0 00 2) crystal face significantly improves, and intensity is the 80% of (1 0-1 1) crystal face, is still below (1 0-1 1) face Intensity, show that (1 0-1 1) crystal face is still on cross section has advantage orientation.But it was found that (0 00 2) crystal face on longitudinal section X-ray diffraction peak intensity increase substantially, more than (1 0-1 1) crystal face diffracted intensity, show on longitudinal section (0 00 2) crystalline substance Face has certain advantage orientation.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.15mm, thread depth 0.1mm, thread spacing are 0.5mm.Screw overall length 20mm.Its turn head is divided into bulb lower surface, ball Radius surface 1.5mm, it is flat recess to have turn groove on turn head.

Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, removes surface spikes.

The bone screw is immersed in simulated body fluid, while control is used as using common degradable pure magnesium screw.Degraded two Zhou Hou, the depth of thread of bone screw of the present invention are changed into original 90%, and the screw of control group its depth of thread is drastically Drop to original 60%.

Embodiment 2

Using Mg-5.4Zn alloys, bar, extrusion ratio 60, extruded barses discharging speed 10mm/ are squeezed at 300 DEG C min.XRD analysis are carried out for the extruded barses, it is found that in the extruded barses cross section that (1 0-1 1) crystallographic plane diffraction peak is most strong, Equally it is that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section.

Afterwards, above-mentioned extruded barses are subjected to further cold rolling, rolling temperature is 40 DEG C, bar reduced cross-sectional area after rolling To original 50%.Found by the further analyses of XRD, (1 0-1 0) and (0 00 2) crystal face in bar cross section after rolling Diffraction peak intensity improve, intensity is the 60% of (1 0-1 1) crystal face, but is still below (1 0-1 1) surface intensity, i.e., on cross section (1 0-1 1) crystal face has advantage orientation.But the X-ray diffraction peak intensity of (0 00 2) crystal face increases substantially on longitudinal section, More than (1 0-1 1) crystal face diffracted intensity, i.e., (0 00 2) crystal face has certain advantage orientation on longitudinal section.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.20mm, thread depth 1.0mm, thread spacing are 1mm.Screw overall length 15mm.Its turn head is divided into tapered inferior surface, cone angle 20°.It is cross recess to have turn groove on turn head.

Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, removes surface spikes.

The bone screw is screwed in simulation bone piece, is immersed in simulated body fluid.Screw conduct pair without advantage orientation simultaneously According to.Its withdrawal force is tested after degrading 4 weeks, the withdrawal force of bone screw of the present invention is higher by 20% than control group screw, its root This reason is that screw thread keeps more complete.

Embodiment 3

Using Mg-0.8Mn-1Zn alloys, bar, extrusion ratio 100, extruded barses discharging speed are squeezed at 500 DEG C 5mm/min, 170 ° of discharging opening taper are unlubricated.XRD analysis are carried out for the extruded barses, find the extruded barses cross section In (1 0-1 1) crystallographic plane diffraction peak it is most strong, be equally that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section.

Afterwards, above-mentioned extruded barses are subjected to further cold extrusion, extrusion temperature is 25 DEG C of room temperature, bar section after extruding Product narrows down to original 40%.Found by the further analyses of XRD, after cold extrusion in bar cross section (1 0-1 0) and (0 0 The diffraction peak intensity of 0 2) crystal face improves, and intensity is the 55% of (1 0-1 1) crystal face, but is still below (1 0-1 1) surface intensity, i.e., (1 0-1 1) crystal face has advantage orientation on cross section.But the X-ray diffraction peak intensity of (0 00 2) crystal face is big on longitudinal section Amplitude improves, and more than (1 0-1 1) crystal face diffracted intensity, i.e., (0 00 2) crystal face has certain advantage orientation on longitudinal section.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.30mm, thread depth 2mm, thread spacing are 2mm.Screw overall length 30mm.Its turn head is divided into tapered inferior surface, cone angle 90°.It is interior four chamfered grooves to have turn groove on turn head.

Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, removes surface spikes.

Using goat as animal bone fracture model, the bone screw is headed on the outside of the condyle of femur of right side, fixed bone piece, simultaneously Screw without advantage orientation is as control.After implantation 3 months, dissection materials, the bone screw structure designed by the present invention is found Profile keeps complete, helicitic texture residue 30% or so, and bone piece healing is good；And the helicitic texture of control group disappears substantially, bone Block has slight loosening.Dissection materials are found after being implanted into 1 year, and bone screw largely degraded, residual volume is the pact of initial volume 10%.Surrounding tissue biocompatibility is good, does not find the problems such as inflammatory reaction.

Embodiment 4

Using Mg-Y- rare earth-Zr alloys, bar, extrusion ratio 80, extruded barses discharging speed are squeezed at 500 DEG C 8mm/min, 150 ° of discharging opening taper are unlubricated.XRD analysis are carried out for the extruded barses, find the extruded barses cross section In (1 0-1 1) crystallographic plane diffraction peak it is most strong, be equally that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section.

Afterwards, above-mentioned extruded barses are subjected to further cold extrusion, extrusion temperature is 30 DEG C, and bar sectional area contracts after extruding It is small to arrive original 55%.Found by the further analyses of XRD, after cold extrusion in bar cross section (1 0-1 0) and (0 00 2) The diffraction peak intensity of crystal face improves, and intensity is the 75% of (1 0-1 1) crystal face, but is still below (1 0-1 1) surface intensity, i.e., transversal (1 0-1 1) crystal face has advantage orientation on face.But the X-ray diffraction peak intensity of (0 00 2) crystal face is significantly on longitudinal section Improve, more than (1 0-1 1) crystal face diffracted intensity, i.e., (0 00 2) crystal face has certain advantage orientation on longitudinal section.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.15mm, thread depth 0.50mm, thread spacing are 1.75mm.Screw overall length 25mm.Its turn head is divided into outer-hexagonal shape, Its circumscribed circle diameter is 5mm.Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, removes surface spikes.

Using beasle dog as animal bone fracture model, the bone screw is implanted at left tibias platform, fixed bone piece.Plant After entering 1 month, dissection materials, the helicitic texture residue 60% or so of the bone screw designed by the present invention is found, bone piece is fixed Work well；Dissection materials find that screw thread residue 10% or so, surrounding tissue biocompatibility is good, does not send out after being implanted into half a year The problems such as existing inflammatory reaction.

Embodiment 5

Using Mg-0.8Ca alloys, bar, extrusion ratio 60, extruded barses discharging speed 22mm/ are squeezed at 400 DEG C Min, 165 ° of discharging opening taper are unlubricated.XRD analysis are carried out for the extruded barses, are found (1 in the extruded barses cross section 0-1 1) crystallographic plane diffraction peak is most strong, and equally it is that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section.

Afterwards, above-mentioned extruded barses are carried out into further cold forging to make, temperature is 30 DEG C, and cold forging makes rear bar reduced cross-sectional area To original 55%.Found by the further analyses of XRD, (1 0-1 0) and (0 00 2) is brilliant in bar cross section after cold extrusion The diffraction peak intensity in face improves, and intensity is the 60% of (1 0-1 1) crystal face, but is still below (1 0-1 1) surface intensity, i.e. cross section Upper (1 0-1 1) crystal face has advantage orientation.But the X-ray diffraction peak intensity of (0 00 2) crystal face significantly carries on longitudinal section Height, more than (1 0-1 1) crystal face diffracted intensity, i.e., (0 00 2) crystal face has certain advantage orientation on longitudinal section.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.15mm, thread depth 0.35mm, thread spacing are 1.2mm.Screw overall length 30mm.Its turn head is divided into outer square shape, Its circumscribed circle diameter is 3.6mm.Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, removes surface spikes.

Using new zealand white rabbit as animal model, Intercondylar fracture model is made.It is fixed using the bone screw. After implantation 3 months, X-ray photograph shows that fracture line progressively disappears, and healing is good, and without ectopic osteogenesis, without serious inflammatory reaction, Phenomena such as without bone information.Dissection materials find that screw thread residue 20% or so, surrounding tissue biocompatibility is good after being implanted into half a year Well, not the problems such as not finding inflammatory reaction.

Embodiment 6

Using more than 99.98% high purity magnesium, bar, extrusion ratio 80, extruded barses discharging speed are squeezed at 250 DEG C 15mm/min, 180 ° of discharging opening taper are unlubricated.XRD analysis are carried out for the extruded barses, find the extruded barses cross section In (1 0-1 1) crystallographic plane diffraction peak it is most strong, be equally that (1 0-1 1) crystallographic plane diffraction peak is most strong on longitudinal section.

Afterwards, above-mentioned extruded barses are subjected to further cold rolling, temperature is 25 DEG C, and bar reduced cross-sectional area is to former after rolling 80% come.Found by the further analyses of XRD, (1 0-1 0) and (0 00 2) crystal face spread out in bar cross section after cold rolling Peak intensity raising is penetrated, intensity is the 85% of (1 0-1 1) crystal face, but is still below (1 0-1 1) surface intensity, i.e., (1 on cross section 0-1 1) crystal face has advantage orientation.But the X-ray diffraction peak intensity of (0 00 2) crystal face increases substantially on longitudinal section, surpass (1 0-1 1) crystal face diffracted intensity is crossed, i.e., (0 00 2) crystal face has certain advantage orientation on longitudinal section.

Cold working bar is further processed as bone screw structure.The structure of its threaded portion is：Thread width 0.15mm, thread depth 0.45mm, thread spacing are 1.0mm.Screw overall length 20mm.Its turn head is divided into bulb lower surface, Spherical radius 5mm, turn groove are interior square shape.Finally bone screw is put into electrolytic polishing liquid and carries out electrobrightening, is gone Except surface spikes.

Using new zealand white rabbit as animal model, fracture of radius model is made.It is fixed using the bone screw. After implantation 1 month, the fixed robust of X-ray photograph display, agglutination is smooth, and without ectopic osteogenesis, it is anti-without serious inflammatory Should, without bone information phenomena such as.Dissection materials find that bone screw has been completely absorbed after being implanted into a year and a half, healing completely of fracturing, Surrounding tissue biocompatibility is good, does not find the problems such as inflammatory reaction.

The specific embodiment of the present invention is described above.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow Ring the substantive content of the present invention.

Claims (9)

1. the magnesium metal bone screw that a kind of orientable degraded absorbs, including bone screw, the bone screw is by pure magnesium or magnesium Alloy is made and is provided with screw thread, it is characterised in that the bone screw has different micro- respectively on cross section and longitudinal section See institutional framework advantage orientation so that bone screw cross section degraded during being degraded and absorbed is faster than longitudinal section degraded；

The bone screw is on longitudinal section, and there is advantage to be orientated and form texture for (0 00 2) crystal face, when using X-ray diffraction (XRD) when testing its crystal structure, the X-ray diffraction intensity highest of (0 00 2) crystal face, highest peak is turned into；

The bone screw is on cross section, and there is advantage to be orientated and form texture for (1 0-1 1) crystal face, when using X-ray diffraction (XRD) when testing its crystal structure, the X-ray diffraction intensity highest of (1 0-1 1) crystal face, highest peak is turned into.

2. the magnesium metal bone screw that orientable degraded according to claim 1 absorbs, it is characterised in that above-mentioned synthetism spiral shell Nail includes following closely body and turn head, follows closely body and turn head collectively forms screw length, length >=3mm.

3. it is according to claim 2 it is orientable degraded absorb magnesium metal bone screw, it is characterised in that it is described nail body by Screw thread is formed, and wherein thread width >=0.15mm, thread depth 0.1mm~2mm, thread spacing are 0.5mm~2mm.

4. the magnesium metal bone screw that orientable degraded according to claim 2 absorbs, it is characterised in that the turn head Including bulb lower surface or tapered inferior surface；Wherein the spherical radius of bulb lower surface is 1.5mm~8mm, tapered inferior surface Cone angle is 20 °~90 °.

5. the magnesium metal bone screw that orientable degraded according to claim 4 absorbs, it is characterised in that the turn head On have turn groove, turn groove is a word, cross, Triangle ID, interior corner or interior hexagonal；Or turn head is outer triangle, outer four Angle, outer-hexagonal；The diameter or circumscribed circle diameter of turn head are 3mm-15mm.

6. the magnesium metal bone screw that the orientable degraded according to claim any one of 1-5 absorbs, it is characterised in that institute The pure magnesium or magnesium alloy stated include：Pure magnesium of the purity not less than 99.9%, Mg-Zn based alloy, magnesium Mn series alloy, magnesium Rare Earth close It is any in gold, magnesium calcium alloy, wherein, pure magnesium or magnesium alloy are all single homogeneous phases, are occurred without the second phase.

7. the preparation method for the magnesium metal bone screw that a kind of any one of claim 1-6 orientable degradeds absorb, it is special Sign is, comprises the following steps：

Step 1：It is more than 99.9% pure magnesium ingot casting using purity, or using magnesium alloy ingot as raw material；By pure magnesium ingot casting Or magnesium alloy ingot hot extrusion is bar, extrusion temperature is 100 DEG C~500 DEG C, and extrusion ratio is more than 10, the discharging of extruded barses Speed is less than 20mm/min, discharging opening taper >=150 °, freely rubs unlubricated；Now, (1 0-1 in extruded barses cross section 1) crystal face has most strong X-ray diffraction peak, and (1 0-1 0) and the diffraction peak intensity of (0 00 2) crystal face are no more than (1 0 - 1 1) crystal face intensity；(1 0-1 1) crystal face has advantage orientation on longitudinal section, has the X-ray diffraction peak of maximum intensity；

Step 2：The hot extrusion bar of step 1 is subjected to cold working：The temperature of cold working is 10~80 DEG C, bar section after processing Product narrows down to original 95%~40%, the diffraction of (1 0-1 0) and (0 00 2) crystal face in bar cross section after cold working Peak intensity significantly improves, and intensity exceedes the 50% of (1 0-1 1) crystal face, but is less than (1 0-1 1) surface intensity；(0 on longitudinal section The X-ray diffraction peak intensity of 00 2) crystal faces exceedes (1 0-1 1) crystal face diffracted intensity, turns into maximum diffraction intensity Advantage is orientated crystal face；

Step 3：Bar after cold working is finished using numerically controlled lathe, processes the longitudinal axis of bone screw, wherein bone screw Line is exactly the longitudinal axis of the bar in step 2.

8. the preparation method for the magnesium metal bone screw that degraded absorbs is can be directed to according to claim 7, it is characterised in that：Institute State method to be polished after step 3, in addition to bone screw, make its any surface finish zero defect.

9. the preparation method of the magnesium metal bone screw absorbed according to the orientable degraded of claim 7 or 8, its feature exist In：Described cold working includes cold extrusion, cold forging or cold rolling.