CN100384386C - Anti-loosening pedicle screws - Google Patents

Abstract

The invention relates to a special spinal internal fixation instrument for orthopedics, namely an anti-loosening pedicle screw. The screw includes screw-in type screw core, expansion type screw core, and hollow pedicle screw whose front part can be expanded. Wherein, by screwing different shapes of cores into the hollow pedicle screw, the front section of the pedicle screw driven into the vertebral body of the spine is stretched, resulting in a change in shape; at the same time, local bone density and bone strength are improved, thereby Avoid pedicle screw loosening and prolapse.

Description

Anti-loosening pedicle screws

field of invention

The invention relates to a special spinal internal fixation instrument for orthopedics, namely an anti-loosening pedicle screw. The screw includes screw-in type core, expansion type core, and hollow pedicle screw whose front part can be expanded. Wherein, by screwing different shapes of cores into the hollow pedicle screw, the front section of the pedicle screw driven into the vertebral body of the spine is stretched, resulting in a change in shape; at the same time, local bone density and bone strength are improved, thereby Avoid pedicle screw loosening and prolapse.

technical background

In recent years, the research and development of spinal internal fixation system has been greatly developed. A large number of new spinal internal fixation systems such as the universal spinal system (hereinafter referred to as USS) (AO/ASIF organization improved on the basis of its original spinal internal fixation system) The emergence of the new combined spinal general system) has made great progress in spinal surgery. However, the pedicle screws currently used clinically do not have the function of preventing loosening. For example, after the USS Schanz nail is implanted into the vertebral body through the pedicle, its shape does not change, and there are risks such as loosening and screw withdrawal. Especially in the case of patients with osteoporosis, the existing pedicle screws are prone to loosening and prolapse, resulting in surgical failure. At present, the only preventive measure is intravertebral injection of bone cement. Therefore, an effective and operable anti-loosening pedicle screw is needed to effectively solve this problem.

Contents of the invention

In order to overcome the anti-loosening function that the existing clinical pedicle screws do not possess, the present invention provides an anti-loosening pedicle screw, which includes a screw-in type screw core, a distraction type screw core and an anterior part that can be The open hollow pedicle screw, wherein the front end of the pedicle screw is opened by being screwed into an appropriate screw core, such as in an umbrella shape, so as to avoid the loosening and prolapse of the pedicle screw.

The invention relates to an anti-loosening pedicle screw, which includes screw-in and expansion screw cores, and a pedicle screw whose front part can be expanded. Specifically, the pedicle screw whose front part can be expanded is a hollow pedicle screw. In order to ensure that the hollow pedicle screw has a good elastic modulus and compliance, the thickness of the tube wall of the screw should have an appropriate range (for example, preferably 0.1-0.5mm), so that it can be supported after being screwed into an appropriate screw core. Open, especially in the shape of an umbrella, and at the same time, the mechanical strength of the hollow screw should be guaranteed.

In order to facilitate the screwing of the hollow pedicle screw into the vertebral body of the vertebra, the posterior section of the hollow pedicle screw, preferably from the end to about 1/16-about 1/4 of the screw's full length, can be Such as external hexagonal type.

In the present invention, the hollow pedicle screw is also provided with an external thread, and its front part also has, for example, a part whose length is about 1/16-about 1/2 of the full length from the front end, preferably from the front end. About 1/16-about 1/3 part of the full length, preferably about 1/16-about 1/4 part of the full length from the front end, preferably about 1/16-about 1/6 part of the full length from the front end, Preferably about 1/16 to about 1/8 of the full length from the front end, preferably about 1/16 to about 1/10 of the full length from the front end, preferably about 1/16 to about 1/10 of the full length from the front end /12 parts, at least two, preferably three, four, five, six, seven, eight, ten, twelve or more slits that run through the entire wall of the screw tube.

The inner diameter of the hollow pedicle screw gradually becomes thinner from the end to the front where the anterior gap appears, for example, it gradually becomes thinner along a straight line along the polishing surface; or the inner diameter of the hollow pedicle screw gradually becomes thinner where the anterior gap occurs, The throwing surface is an arc with a small curvature. Correspondingly, the tube wall of the hollow pedicle screw is gradually thickened, and the inner wall is gradually thickened in an arc or straight line with a small curvature. Except for the part with gaps, the rest of the hollow pedicle screw has internal threads to facilitate screwing in and taking out of different screw cores. In order to facilitate screwing in and taking out of the hollow pedicle screw, the tail of the hollow pedicle screw may have, for example, an external hexagonal or cross-shaped screw buckle.

In the present invention, the screw core includes a screw-in type screw core and an expansion type screw core. Wherein the shape of the screw-in type screw core is completely consistent with the inner diameter of the hollow pedicle screw, and the length of the front part is, for example, 1/16-1/2 part of the full length from the front end, preferably 1/16 of the full length from the front end -1/3 part, preferably 1/16-1/4 part of the full length from the front end, preferably 1/16-1/6 part of the full length from the front end, preferably 1/16-1/16 of the full length from the front end /8 part, preferably 1/16-1/10 part of the full length from the front end, preferably 1/16-1/12 part of the full length from the front end, the diameter is gradually tapered, without external thread, just in line with the hollow cone The inner diameter of the anterior segment of the pedicle screw was narrowed and matched.

The rest of the screw-in screws have external threads, and the external threads cooperate with the internal threads of the hollow pedicle screw to realize the screw core screwing in and out. After the screw-in screw core is screwed into the hollow pedicle screw, the mechanical strength of the hollow pedicle screw can be increased, and bone tissue can be prevented from entering the hollow pedicle screw through the gap at the front, so that the pedicle screw can be easily A root screw is inserted into the vertebral body through the pedicle.

In the present invention, at the front section of the expandable screw core, for example, the length is 1/16-1/2 of the full length from the front end, preferably 1/16-1/3 of the full length from the front end , preferably 1/16-1/4 part of the full length from the front end, preferably 1/16-1/6 part of the full length from the front end, preferably 1/16-1/8 part of the full length from the front end, preferably 1/16-1/10 part of the full length from the front end, preferably 1/16-1/12 part of the full length from the front end without external threads, the length of the part without external threads is the same as that of the hollow pedicle screw Corresponds to the tapering part of the front part.

Different from the screw-in screw core, the diameter of the front part of the expansion screw core does not gradually become thinner uniformly, but keeps the same diameter until the front end becomes an arc with a large curvature of the throwing surface. This feature makes the diameter of the front section of the spreader screw core, for example, a length of 1/16-1/2 of the full length from the front end, preferably 1/16-1/3 of the full length from the front end, preferably from the front end 1/16-1/4 of the full length, preferably 1/16-1/6 of the full length from the front end, preferably 1/16-1/8 of the full length from the front end, preferably the full length from the front end 1/16-1/10 of the part, preferably 1/16-1/12 of the full length from the front end, is always larger than the corresponding inner diameter of the front section of the cannulated pedicle screw. Except for the above-mentioned parts, the diameter of the rest of the expansion screw core is completely consistent with the inner diameter of the hollow pedicle screw, and also has an external thread matched with the internal thread of the hollow pedicle screw, which is used to increase the screw diameter. The strength of expanding the hollow pedicle screw when inserting the expanding screw core. At the same time, in order to facilitate screwing in and taking out of the expansion screw core, the tail of the screw core may have, for example, a hexagonal or cross-shaped screw buckle.

When the positioning is clear and the pedicle screw of the present invention is screwed into the vertebral body, it is necessary to screw in the hollow pedicle screw and the screw-in screw core to prevent bone tissue from entering the hollow pedicle screw and increase the Mechanical strength of cannulated pedicle screws. When the front end of the pedicle screw with the screw-in screw core is screwed into the vertebral body and placed properly, the screw-in screw core is taken out and the distraction-type screw core is screwed in. Since the diameter of the front part of the spread-type screw core is thicker than the inner diameter corresponding to the front part of the hollow pedicle screw, and because there are many through longitudinal gaps in the front part of the hollow pedicle screw, the tube wall gradually thickens, so when screwing in When the screw core is expanded, the front part of the pedicle screw is gradually expanded, for example, it is expanded in an umbrella shape, and the shape changes, and at the same time, the local surrounding bone density and strength increase. Therefore, the pedicle screw of the present invention is not easy to loosen and come out.

In order to achieve the design requirements of the present invention, the material of the pedicle screw and the screw core of the present invention can be titanium alloy, because titanium alloy has ideal elastic modulus, good tissue compatibility and fatigue resistance, and can Persist in the human body for a long time. Those of ordinary skill in the art also know that as long as they have ideal elastic modulus, materials with good tissue compatibility and fatigue resistance can be used to prepare the pedicle screw and screw core of the present invention.

The beneficial effects of the present invention are: the front part of the pedicle screw is stretched in the vertebral body, resulting in increased bone density and strength around it, and at the same time, due to the change of the external shape, the biomechanical strength is increased, so it is not easy to loosen and come out. Simultaneously, the structure is simple and the operation is convenient.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig.1 The perspective view and cross-sectional schematic diagram of the hollow pedicle screw, in which 1 is the gap where the front part of the hollow pedicle screw penetrates the tube wall; 2 is the external thread part of the hollow pedicle screw; 3 is the hollow pedicle screw The outer hexagonal buckle part at the end; 4 is the tube wall part of the hollow pedicle screw; 5 is the thickened tube wall part of the front part of the hollow pedicle screw; 6 is the front part of the hollow pedicle screw, and its inner diameter gradually changes Thin, the polishing surface can be a straight line or an arc with a small curvature; 7 is the internal thread of the rest of the hollow pedicle screw.

Fig. 2 is a perspective view of the screw-in screw core, wherein 8 is the inner hexagonal screw part at the tail of the screw-in screw core; 9 is the external thread part of the screw-in screw core; 10 is the front part of the screw-in screw core, Its diameter tapers gradually.

Fig. 3 is the perspective view of the spread-type screw core, wherein 11 is the internal hexagonal screw part at the end of the spread-type screw core; 12 is the external thread part of the spread-type screw core; 13 is the front section of the spread-type screw core, Its diameter does not change significantly, and the front end of the polished surface gradually becomes an arc with a large curvature.

The schematic diagram of the anti-loosening pedicle screw internal fixation system described in Fig. 4, Fig. 4 (a) is the perspective view of the combination of hollow pedicle screw and screw-in type screw core; Fig. 4 (b) is the combination of hollow pedicle screw and screw core The cross-sectional view of the screw-in screw core combination, wherein the screw-in screw core 16 is closely matched with the hollow pedicle screw 15; Fig. After the pedicle screw 15 with the screw-in screw core 16 is screwed into the vertebral body, the screw-in screw core 16 is taken out, and the spread-type screw core 17 is screwed into the hollow pedicle screw 15. The diameter of the front end of the screw core 17 is thicker than that of the screw-in screw core, so that the front section of the hollow pedicle screw 15 is stretched to obtain the screw-in screw core and hollow pedicle screw combination 18 after stretching.

Fig. 5 (a) schematic diagram of pedicle screw screwed into vertebral body disclosed in the prior art; (b) schematic diagram of anti-loosening pedicle screw of the present invention screwed into vertebral body, wherein the anti-loosening pedicle screw of the present invention Its front segment is stretched in the vertebral body 19, so it is not easy to loosen and come out.

Detailed ways

As shown in Figure 4: when the pedicle screw is screwed into the pedicle screw, the hollow pedicle screw 15 and the screw-in screw core 16 are screwed in to prevent bone tissue from entering the hollow pedicle screw, and at the same time increase the hollow space. The mechanical strength of the pedicle screw can avoid the fracture of the front part of the hollow screw or other accidents. When the screw is screwed into the vertebral body and placed properly, take out the screw-in screw core 16 and screw it into the spread-type screw core 17. Since the diameter of the front section of the spread-type screw core is thicker than the inner diameter of the front section of the hollow pedicle screw, its tube wall gradually increases. At the same time, because there are many longitudinal gaps penetrating the tube wall in the front part of the hollow pedicle screw, when screwing in the spreader core, the front part of the screw is gradually spread out in an umbrella shape, and the shape changes.

As shown in Figure 5: compared with the existing pedicle screw, the pedicle screw of the present invention changes the shape of the front end of the vertebral body 19, and at the same time increases the local bone strength and density of the front section of the hollow pedicle screw. Therefore, the pedicle screw of the present invention is not easy to loosen and come out.

Claims (1)

1. the special-purpose anti-loosen conal arch root screw of an orthopaedics, it is made of hollow pedicle screw, screw-in spiral shell core and bracing type spiral shell core,

Wherein said hollow pedicle screw tube wall has external screw thread; Its back segment part, about 1/4 place of the about 1/16-from end to the screw total length has that the outer-hexagonal spiral shell is buckled or the cross spiral shell is buckled; Its leading portion part also has length for from two of the part of about 1/16-about 1/2 of front end total length or more connect the slit of whole screw tube wall, the hollow screw internal diameter is tapered by the tip forward extreme direction in leading portion slit appearance place, and throwing face linearly or the very little camber line of curvature; Accordingly, the tube wall progressive additive, and all the other tube walls of the described hollow pedicle screw outside place, described slit are partly with female thread;

Wherein said screw-in spiral shell core shape and hollow pedicle screw internal diameter fit like a glove, its leading portion partial-length is for to be tapered from the 1/16-1/2 of front end total length section diameter, do not have external screw thread, the footpath matched within lucky and hollow pedicle screw leading portion attenuated; The remainder of described screw-in spiral shell core all has external screw thread, and the female thread of its external screw thread and hollow pedicle screw cooperatively interacts, and is screwed into and takes out to realize the spiral shell core; Described spiral shell core afterbody also can have interior hexagon or criss-cross spiral shell to buckle;

Wherein said bracing type spiral shell core is in its leading portion part, and length is not with the length of externally threaded part corresponding with the tapered part of hollow pedicle screw leading portion for not having external screw thread from the 1/16-1/2 of front end total length part; The diameter of bracing type spiral shell core leading portion part is not evenly to attenuate gradually, but keeps same diameter, until the curved very big camber line of the throwing face that gradually becomes foremost; Threaded portion is not exceptionally to remove leading portion, the remainder diameter of described bracing type spiral shell core and hollow pedicle screw internal diameter fit like a glove, also have the external screw thread that matches with described hollow pedicle female thread, be used to increase the strength that struts the hollow pedicle screw when being screwed into described bracing type spiral shell core, described spiral shell core afterbody has interior hexagon or criss-cross spiral shell to buckle.

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