CN104287819B - The pedicle screw assemblies that a kind of Medical flexible double thread, resistance to plucking go out - Google Patents

Abstract

The invention relates to a medical retractable double-threaded, pull-out-resistant pedicle screw assembly. A threaded control shaft is arranged in the hollow cavity of the screw body, and the threaded control shaft cooperates with a connecting rod, and the connecting rod is connected with a telescopic screw. The retractable screw is set in a number of holes on the outer wall of the front end of the nail body, and the cross section of the screw control shaft is a butterfly structure, including the central axis and the first support body and the second support body arranged symmetrically along the central axis. Support body; the outer sides of the first support body and the second support body are fixed with two sliding pieces that match the connecting rod; the cross section of the sliding piece is crescent-shaped, and the two sliding pieces are arranged opposite; Control the shaft to adjust the rise and fall of the retractable screw, and realize the unscrewing of the thread by rotating the thread control shaft, which improves the stability of spinal internal fixation during secondary screw placement for osteoporosis or revision, and reduces the incidence of loosening or even prolapse.

Description

A medical retractable double-threaded, pull-out-resistant pedicle screw assembly

technical field

The invention belongs to the field of medical auxiliary equipment, and in particular relates to a medical retractable double-threaded and pull-out-resistant pedicle screw assembly.

Background technique

Spinal fusion is one of the main treatments for many diseases of the spine. The number of spinal fusion operations in the United States is increasing year by year. From 1998 to 2008, the number of cervical, thoracic, and lumbar fusions increased by 90% per 100,000 population. , 61% and 141% (RajaeeSS, BaeHW, KanimLE, DelamarterRB. Spinalfusion in the United States: analysis of trends from 1998 to 2008. Spine (PhilaPa 1976) 2012; 37(1): 67-76). Spinal fusion is mostly realized by posterior pedicle screw + fixation rod-screw rod system, but with the aging of the population and the resulting increase in the incidence of osteoporosis, as well as the loosening of the pedicle screws, the spinal cord Fusion failures require more revision surgery (RajaeeSS, KanimLEA, BaeHW. National trends in revision spinal fusion in the USA: Patient characteristics and complications. Bone Joint J 2014; 96B(6): 807-16), and traditional pedicle screw fixation techniques are greatly challenged. For osteoporosis and vertebral bodies with secondary screw placement during revision, the traditional pedicle screw fixation is easy to loose, and it is difficult to achieve firm fixation; in recent years, domestic and foreign scholars have carried out various explorations and improvements, including screw sheath, expansion Although screw components, injectable screw components, etc. can also achieve osteoporosis and revision vertebral pedicle screw fixation, the change of screw components after expansion or injection is irreversible. Once there is a problem with the pedicle screw, the internal fixation needs to be removed, and these improvements cannot achieve smooth removal.

Biomechanical studies have shown that the holding force of the pedicle screw-bone interface is proportional to the contact area and depth. The deep thread can increase the contact area with the bone, and improve the holding force and pull-out resistance of the screw. The thread depth of commonly used pedicle screws is 1 mm.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings in the prior art, and to provide a medical retractable double-threaded, pull-out-resistant pedicle screw assembly, which is firmly fixed and can improve the holding force and pull-out resistance of the screw. advantage.

In order to achieve the above object, the present invention adopts the following technical solutions: comprising a hollow nail body, the tail of the nail body is fixed with a nail tail; the hollow cavity of the nail body is provided with a rotatable threaded control shaft, and the threaded control shaft is provided with a rotation groove One end of the nail goes through the nail tail;

The outer wall of the nail body is fixed with a number of fixed threads, the outer wall of the front end of the nail body is provided with a number of holes, and a number of retractable screws are arranged in the holes, and a connecting rod is fixed at the bottom of the retractable screw, and one end of the connecting rod is arranged on the Inside the threaded control shaft;

The cross-section of the threaded control shaft is a butterfly structure, including a central axis and a first support body and a second support body arranged symmetrically along the center line of the central axis; the inner sides of the first support body and the second support body are fixed On the central axis, two sliding pieces matched with the connecting rod are fixed on the outer sides of the first support body and the second support body;

The cross-section of the slides is crescent-shaped, and the two slides are arranged opposite to each other.

The nail tail is bowl-shaped, and an internal thread is provided on its inner wall.

The lengths of the two hypotenuses of the first support body and the second support body are equal, and the angles of the base angles are both 45°.

The materials of the threaded control shaft, the connecting rod and the nail tail are medical titanium alloy.

The diameter of the threaded control shaft is smaller than the diameter of the hollow cavity.

The height of the fixing thread is 0.8-1.2 mm.

The length of the telescopic screw is 1.5-2.5 mm.

The outer diameter of the hollow nail body is 6-7 mm.

The inner diameter of the hollow cavity is 2.5-3.5 mm.

The bottom of the connecting rod is fixed with a second sliding piece matched with the first sliding piece.

The present invention has the following beneficial effects: compared with the prior art, the present invention sets a threaded control shaft in the hollow cavity of the nail body, and the threaded control shaft cooperates with a connecting rod, and the connecting rod is connected with a telescopic screw, and the telescopic screw is set A number of holes are opened on the outer wall of the front end of the nail body, and because the cross-section of the threaded control shaft is a butterfly structure, it includes the central axis and the first support body and the second support body symmetrically arranged along the central axis midline; the first The outer sides of the support body and the second support body are fixed with two sliding pieces matched with the connecting rod; the cross-section of the sliding piece is crescent-shaped, and the two sliding pieces are arranged oppositely; thus the shaft can be controlled by rotating the screw thread, and the adjustable The rise and fall of the telescopic screw greatly facilitates the use. The thread can be unscrewed by rotating the thread control shaft, which can improve the stability of spinal internal fixation and reduce the incidence of loosening or even prolapse during osteoporosis or revision. When the internal fixation needs to be removed under special circumstances, the retractable screw can be retracted by rotating the threaded control shaft, realizing the perfect combination of pull-out resistance and removable. Reduce the risk of pedicle screw loosening and pulling out. At the same time, the retractable screw design also ensures that the pedicle screw can be removed under special circumstances, effectively improving clinical efficacy.

Furthermore, since the nail tail is in the shape of a bowl, the inner wall is provided with internal threads, thereby reducing the difficulty for users to operate the nail body and making it more convenient for doctors to use.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention.

Fig. 2 is a schematic diagram of the structure of the screw control shaft in the retracted original state of the present invention.

Fig. 3 is a schematic diagram of the structure of the threaded control shaft when the present invention is in an extended state.

detailed description

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

1-3, the present invention includes a hollow nail body 1, the tail of the nail body 1 is fixed with a nail tail 5; the hollow cavity 6 of the nail body 1 is provided with a rotatable threaded control shaft 3, and the threaded control shaft 3 One end provided with a rotating groove runs through the nail tail 5; the outer wall of the nail body 1 is fixed with a number of fixed threads 7, and the outer wall of the front end of the nail body 1 is provided with a number of holes, and a number of retractable screws 8 are arranged in the holes. The bottom of 8 is fixed with connecting rod 4, and one end of connecting rod 4 is arranged in threaded control shaft 3; A supporting body 9 and a second supporting body 10; the inner sides of the first supporting body 9 and the second supporting body 10 are all fixed on the central axis 2, and the outer sides of the first supporting body 9 and the second supporting body 10 are fixed with two The sliding sheet 12 matched with the connecting rod 4; the cross section of the sliding sheet 12 is crescent-shaped, and the two sliding sheets 12 are arranged oppositely. The cross section of the nail tail 5 is U-shaped, and an internal thread 11 is provided on its inner wall. The lengths of the two hypotenuses of the first support body 9 and the second support body 10 are equal, and the angles of the base angles are both 45°. The materials of the threaded control shaft 3, the connecting rod 4 and the nail tail 5 are all medical titanium alloys. The diameter of the threaded control shaft 3 is smaller than the diameter of the hollow cavity 6 . The height of the fixing thread 7 is 0.8-1.2 mm. The length of the retractable screw 8 is 1.5-2.5 mm. The outer diameter of the hollow nail body 1 is 6-7 mm. The inner diameter of the hollow cavity 6 is 2.5-3.5 mm. The bottom of the connecting rod 4 is fixed with a second sliding piece 13 matched with the first sliding piece 12 .

How to use: During spinal surgery, after the pedicle screw channel is accurately established at the pedicle, the pedicle screw assembly can be used to ensure that the height of the double threads is consistent, and when the retractable screw 8 is in the original position, After the conventional pedicle screw is implanted, the central shaft 2 in the shaft 3 can be controlled by rotating the thread of the screw tail opening by using the rotating core propeller, so that the extension of the telescopic screw 8 in the pedicle screw can be realized, and the height of the screw can be improved. bone retention. If it is necessary to take out the pedicle screw, the central shaft 2 in the screw thread control shaft 3 is controlled to retract the retractable screw 8 in the screw, so that it can be taken out smoothly.

When using:

Stretched state: the central shaft 2 in the shaft 3 is controlled by rotating the screw thread, and since the inner sides of the first support body 9 and the second support body 10 are fixed on the central shaft 2, the first support body 9 and the first support body 9 are driven by the central shaft 2 when rotating. The second support body 10 rotates together, and the two side walls of the first support body 9 and the second support body 10 squeeze the connecting rod 4 connected with the telescopic screw 8, so that the telescopic screw 8 rises and stretches out the threaded control shaft 3 Outside; after turning 90°, one end of the connecting rod 4 fixed with the second sliding piece 13 is engaged in two first sliding pieces 12 forming a butterfly structure, and the butterfly structure positions the telescopic screw 8 to prevent it from sliding , so that it can be fixed firmly; the deep thread can increase the contact area with the bone, and improve the holding force and pull-out resistance of the screw.

Indented state: rotate the central axis 2, the rotation angle is 90°, because the bone has pressure on the retractable screw 8, after the retractable screw 8 loses the support of the first support body 9 and the second support body 10, the bone can be stretched The pressure of the screw 8 causes it to retract into the threaded control shaft 3, thereby greatly reducing the holding force, at which point the device can be easily removed from the bone.

Claims (10)

1. A medical retractable double thread, anti-pulling out pedicle screw assembly, comprising a hollow nail body (1), the tail of the nail body (1) is fixed with a nail tail (5); the nail body (1) The hollow cavity (6) is provided with a rotatable threaded control shaft (3), and one end of the threaded control shaft (3) provided with a rotation groove runs through the nail tail (5); the outer wall of the nail body (1) A number of fixing threads (7) are fixed on the top, and a number of holes are opened on the outer wall of the front end of the nail body (1), which is characterized in that: A plurality of retractable screws (8) are arranged in the holes, and a connecting rod (4) is fixed on the bottom of the retractable screw (8), and one end of the connecting rod (4) is arranged in the threaded control shaft (3); The cross-section of the threaded control shaft (3) is a butterfly structure, including the central shaft (2) and the first support body (9) and the second support body (10) arranged symmetrically along the center line of the central shaft (2). ); the inner sides of the first support body (9) and the second support body (10) are all fixed on the central axis (2), and the outer sides of the first support body (9) and the second support body (10) are fixed with two A first sliding piece (12) matched with the connecting rod (4); The cross-section of the slide (12) is crescent-shaped, and two first slides (12) are arranged opposite to each other. 2. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the nail tail (5) is bowl-shaped, and the inner wall is provided with an inner thread (11). 3. A medical retractable double-threaded, anti-pulling out pedicle screw assembly according to claim 1, characterized in that: the first support body (9) and the second support body (10) The lengths of the two hypotenuses are equal, and the angles of the base angles are both 45°. 4. A kind of medical retractable double-threaded, anti-pulling out pedicle screw assembly according to claim 1, characterized in that: the threaded control shaft (3), connecting rod (4) and nail tail ( 5) The materials are all medical titanium alloys. 5. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the diameter of the threaded control shaft (3) is smaller than that of the hollow cavity (6) diameter. 6. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the height of the fixing thread (7) is 0.8-1.2 mm. 7. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the length of the retractable screw (8) is 1.5-2.5 mm. 8. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the outer diameter of the hollow screw body (1) is 6-7 mm. 9. A medical retractable double-threaded, pull-out-resistant pedicle screw assembly according to claim 1, characterized in that: the inner diameter of the hollow cavity (6) is 2.5-3.5 mm. 10. A medical retractable double-threaded, anti-extraction pedicle screw assembly according to claim 1, characterized in that: the bottom of the connecting rod (4) is fixed with the first sliding piece ( 12) Cooperating second slide (13).