WO2011004222A1

WO2011004222A1 - Pedicular screw system

Info

Publication number: WO2011004222A1
Application number: PCT/IB2009/054006
Authority: WO
Inventors: Kamil Bal
Original assignee: Kamil Bal
Priority date: 2009-07-10
Filing date: 2009-09-14
Publication date: 2011-01-13

Abstract

The invention is a multi-axial pedicle screw system which is developed for using in the spinal treatment of diseases of the thoraco- lumbar spine and especially for connecting at least two stabilization assemblies, and for connection and spinal fusion between the vertebrae. It comprises a load transferring rod(5), a screw head(3) which holds the rod(5), a screw body(2) which fits multi-axially on the screw head(3), a clip(6) which keeps the rod(5) in the screw head(3), a clip screw(7) which locks the clip (6) and the rod (5) from the top and a multi-axial transverse connector (8) that connects two parallel rods (5) to each other. The invention is especially concerned with easier locking of rods (5) to the screw heads (3) by using the clip (6), fixation of two parallel rods with the multi-axial transverse connector and with increasing the efficiency.

Description

DESCRIPTION

PEDICULAR SCREW SYSTEM

Technical Field

The invention relates to a medical operation kit, which is used in the treatment of diseases on thoraco-lumbar spine and developed especially for connecting at least two stabilization assemblies in a vertebra and for spinal fusion, more specifically the invention relates to a pedicle screw kit.

Background Art

Several surgical methods and techniques have been developed in the treatment of diseases (spine fractures, spine dislocations, scoliosis, kyphosis, lordosis, tumours, and spondylolisthesis) on thoraco-lumbar spine.

In almost all of these surgical methods and techniques, an instrument (screw, plate, rod, bone products) is used. The general benefits of instruments can be listed as: to prevent progress of spinal deformities, to prevent repetition of corrected deformities, to enable re- establishment of spinal stability and relieving the pain by limiting the movement.

These instruments are used in treatments of diseases like spine fractures, spine dislocation, scoliosis, kyphosis, lordosis, tumor-related spinal instabilities and spondylolisthesis.

One of the instruments used in the treatment of diseases on thoraco-lumbar spine is pedicular screw systems. In 1940s, King and Tourney used bone screws for spinal fixation. Boucher in 1959 was the first to use pedicle screws. In the late 1970s, Roy-Camille was the first to use screws and hooks, connecting them with rods or plates. Over the years, the pedicle screw systems are continuously developed to achieve a better fixation. Today there are more than 100 pedicle screw systems available in international market.

Pedicle screw systems in general comprise of mono-axial or multi-axial pedicle screws, set screws, rods, hooks, transverse connectors and single or double domino connectors.

The general advantages of using pedicle screws for spinal stabilization are: the pedicle screws are very effective in rigid spine stabilization, instrument level can be short, even short structures are strong, standard spinal curvature can be maintained, load distribution is homogenous, adjacent level protection is available and best method for sacrum instrumentation is to use screws.

At the present day, U-head (tulip head) screws are most widely used type in pedicle screw systems. One of the first examples of these screws can be seen in patent application no: US5261912. Application no's; US5466237, TR200301904, EP0672388 and WO9812976 are also examples for this screw systems. Generally in U-head screws; after implanting the screw on the spine, by the help of U-shaped head of screw, the rod is placed on top of the screw. The set screw is then placed on the appropriate place of the screw head and the set screw is tightened to lock the screw and the rod. However, conventional U-head screw systems have disadvantages like the obligation of locking and closing the system at one time and in case of an improper rod-screw placement, the inappropriate locking of the set screw. As can be seen from Application No: TR200301904, one part of the set screw of some systems are broken off after final assembly. In case of a revision surgery or during operation when the screw is needed to be moved along the rod, as a result of non- possibility of taking out the screw and the rod, movement over the rod after completing the assembly cannot be performed.

In many thoraco-lumbar surgeries where pedicle screws are used, in order to horizontally connect and to fix vertically placed rods, the transverse connectors are used. It is possible to group the connectors into two groups as multi-axial and mono-axial. The connectors described in Application No: US5899903 and TR200807071 are examples for mono-axial connectors. However, both examples are single size and after adjusting the length of the connector and locking the system, it is necessary to cut the excess part of the connector with the help of an instrument. The connector mentioned in Application No. US5980823 is an example for multi-axial connector. But, an additional piece is necessary for axiality in this example. The transverse connector example in Application No: US20020169448 is a multi-axial type but in this system, several connector pieces are required for different sizes.

Disclosure of the Invention

The aim of the invention starting from the current status of the technique is: to achieve fusion in spine surgery operations and to eliminate the existing defects with the help of improvements made in multi-axial pedicle screw system used for connection between segments.

Another aim of the invention is to enable the rods- one of the elements of pedicle screw system- to lock on multi-axial screw heads by using clip system and even after the locking process to enable screws to move on the rods. This way, rod is locked to multi-axial screw heads easily and more effectively compared to conventional U-head screw systems, a stronger and safer structure is achieved. The proposed system even gives the surgeon possibility to easily revise the incorrect stabilization provided by the mobility achieved after locking, it. As an advantage, during a revision surgery, the clip can be broken and taken out thus the rod can be moved without applying any force on the multi-axial screw head and on the bone where the screw is fixed.

Another aim of the invention is connecting the rods to each other which are- placed on at least two facing screw couple by using a multi-axial transverse connection element, in a safer manner and thus having a more rigid structure. As an advantage, this multi-axial transverse connector can be angled in both vertically and horizontally. As an advantage, this multi-axial transverse connection element can be adjusted to different sizes as per their lengths. In this way, transverse fixation can be achieved regardless of the distance and the height between the multi-axial pedicle screws implanted on thoraco-lumbar spine.

In order to reach the mentioned aims; improvements have been made on screw body, screw head, clip locking system of multi-axial pedicle screw and multi-axial transverse connector. Brief Description of Drawings

In order for the skilled person to understand the invention better, technical drawings and detailed explanations regarding the numbers mentioned in the drawings are submitted below. :

1. The general view of the screw locked with the rod

2. The cross-sectional view of the screw locked with the rod

3. The view of separated structure elements

4. The cross-sectional view of multi-axial transverse connector

5. The angular view of multi-axial transverse connector

6. The general overview of the system

The parts in the figures are numbered, and these numbers correspond to;

1. Multi-axial pedicle screw

2. Screw body

2.1. Screw tip

2.2. Screw tooth

2.3. Screw body head

2.4. Body head threads

2.5. Implanting instrument hole

3. Screw head

3.1. Instrument slot

3.2. Clip shoulder groove

3.3. Screw hole

4. Washer 5. Rod

6. Clip

6.1. Clip branch

6.2. Clip locking shoulder

7. Clip Screw

8. Multi-axial transverse connector

8.1. Transverse connector branches

8.2. Transverse connector screws

8.3. Transverse connector fixed part

8.4. Transverse connector adjustment part

8.5. Tightening balls

8.6. Stopping ledge Detailed Description of the Invention

The mentioned invention of multi-axial pedicle screw system comprises of; a multi-axial pedicle screw (1) with a screw body (2) screwed into the bone which connects the structure to the spine, a screw head (3) which holds the rods (5), a washer (4), a clip (6) which enables fixing the rods to screw head (3) and a clip screw (7), a load transferring rod (5) and a multi-axial transverse connector (8). The screw body (2) of which details and cross-sections seen in Fig. 2 and 3 comprises of; screw tip (2.1), screw tooth (2.2), screw body head (2.3), screw head threads (2.4) and implanting instrument hole (2.5).

As an advantage, the screw tip (2.1) is blind and screw teeth (2.2) starts from this blind tip. In this way, there will be no need to open a space in the bone before implanting screw body (2) into the bone. With this screw tip (2.1), screw body (2) can be fixed to the bone with less effort.

From screw tip (2.1) to screw head (2.3), there are one-way force transferring screw teeth (2.2). As an advantage, these screw teeth (2.2) are parallel to each other and in conical shape starting from the blind tip along the screw body (2). In this way, the screw body (2) can be fixed to the bone with minimum effort and minimum damage to the bone structure and a better gripping can be achieved. Screw body head (2.3) which is in sphere type and having a convex shape in vertical axis, is passed through screw hole (3.3) on the screw head (3) and put into its place. After inserting the screw body (2) into the bone by the help of holes between screw body head (2.3) and screw hole (3.3), angulation of screw head (3) is possible. As an advantage, this angulation can be up to 70 degrees in every direction.

Screw body head (2.3) is covered by parallel extending body head threads (2.4). These body head threads (2.4) are squeezed between screw body (2) and washer (4) after system is locked. In this way, screw body movements and any loosening of the system due to spine movements in future are prevented.

On top of screw body (2), there is the implanting instrument hole (2.5). With the help of an instrument with a suitable tip to the hexagonal implanting instrument hole (2.5), multi- axial pedicle screw is implanted on the spine. As an advantage, screw body (2) ranges from 4.0mm to 8.0mm, the screw body ranges from 20mm to 60mm respectively in diameter and length. In this way, it is possible to supply multi-axial pedicle screw (1) in suitable size and length for every level on thoracolumbar spine. Screw head (3), preferably with U-like shaped, comprises of; instrument slot (3.1), clip shoulder Groove (3.2) and screw hole (3.3). Screw hole (3.3) is circular shaped and its diameter is fixed for all lengths. Screw hole (3.3) lets screw body (2) to pass through it but keeps screw body head (2.3). Screw head (3) has totally four instrument slots (3.1)- two on each side - perpendicular to rod's (5) placement plane. With a tube shaped instrument having suitable teeth to this instrument slots (3.1) and having a diameter to let clip move inside, screw head (3) is fixed tightly and a suitable position to insert rod (5) and clip (6) is obtained. As an advantage, loading on screw body (2) in the bone is prevented.

As an advantage, with a tube shaped instrument having suitable teeth for instrument slots (3.1), screw head can be moved 360 degrees around its own axis and totally up to 70 degrees around screw body (2) axis in every direction. In this way, rod (5) can be placed on its slot on screw head (3) precisely.

There are totally two clip shoulder grooves (3.2) on other sides of screw head (3). Clip shoulder groove (3.2), after clip (6) is locked to screw head (3), prevents clip (6) being departed from screw head (3) by holding clip locking shoulders (6.2) on both sides. As an advantage, the surfaces of screw head (3) on which there is clip shoulder groove (3.2), is inclined outwards. Hence, while fixing the clip (6) to screw head (3), clip locking shoulder (6.2) is slipped over this inclination and sits in clip shoulder Groove (3.2).

Washer (4) enables the equal distribution and evenly application of force imposed by clip screw (7) after rod (5) is inserted into the slot on screw head (3). The washer (4) which is inserted to the slot in the screw head (3) by imposing a pressure enables easy movement of screw body head (2.3) and also prevents screw body (2) to depart from screw head (3) due to its suitable structure. There is a hole in the centre of washer (4) which enables the implanting instrument to pass through.

6mm- diameter rod (5) is placed into its slot on the screw head (3) such that it touches to washer (4). As seen in Fig. 6, rod (5) placed on at least two parallel screw heads (3), enables load transferring between multi-axial pedicle screws (1). As an advantage, rod (5) has thirteen length options between 50mm and 500mm.

Clip (6), has a reverse U shape, enabling it to fit on screw head (3) from the top. Clip branch (6.1) is wide and long enough to hold screw head (3) from both sides tightly. Clip (6), hold by a suitable instrument, is passed through the tube-shaped instrument which holds instrument slots (3.1) on screw head (3). Clip (6) touching the screw head (3), is pushed until clip locking shoulders (6.2) fit in to clip shoulder grooves (3.2). After fitting is achieved, the rod (5) cannot move out from the slot in the screw head (3).

In traditional U-head systems, especially during scoliosis surgeries, after the rod is placed in screw head and set screw is fixed, a necessity arises to distract or compress the distance between screw heads. When applying this in traditional nut closing systems, because of the difficulty in doing the tightening adjustment, distraction and compression cannot be made effectively, thus surgeon has to do the tightening and loosening many times to move the screw head. In this invention, as an advantage, even after the rod (5) is locked to screw head (3) with clip (6), it can be moved multi-axially with screw head (3) or within screw head (3) forwards/backwards. Despite locking, because of free movement of screw heads over the rod, distraction or compression of the distance between screws heads can be achieved, the distance between screw heads can be adjusted and after locking with clip, there is no need for any tightening or loosening. After setting the position of screw heads (3) on rod (5), the system can be locked by using the clip screw (7). As an advantage, after the clip (6) is locked on the screw head (3), it cannot move out of its place. In case of a revision surgery, in order to take the clip (6) out of its place, the upper part of clip branches (6.1) should be cut with a suitable instrument and clip should be splitted into two. During the revision surgery of conventional U-head screw systems using set screw, while taking out the set screw, a load is imposed on screw body and screw body can move in the bone, thus may loose its firmness. As an advantage, in our system, by breaking out the clip (6), it is possible to take the rod (5) away from screw head (3) without imposing a load on screw body (2).

As an advantage, while the clip is being locked, the system can be reducted. While the clip (6) is gripped and pushed downwards with a suitable instrument, passed through inside of tube shaped instrument which holds the instrument slots (3.1) on screw head(3); with the help of instruments, the system can be reducted, that is pulling the screw head (3) - which is in a lower position compared to rod- up, in a way pulling the screw body (2) and the part of vertebra it is fixed on upwards or by pushing down the rod which is in the upper position compared to screw head(3), the rod(5) is placed on screw head(3) as desired. As an advantage, there is no need for another type of screw specifically designed for this procedure as it is the case in conventional U-head systems. So, the system can also be utilized for up to second and third degree spondylolisthesis without any need for an addition.

After clip (6) is fixed on screw head (3), the structure is locked by using clip screw (7). Preferably with the help of a torque instrument, clip screw (7) is tightened by applying force from the top. Clip screw (7) -which touches the rod (5)- transfers the pressure to the washer (4) and screw body (2) by squeezing the rod. When clip screw (7) is tightened finally, all structure elements are locked and fixed as the way they are assembled.

Multi-axial transverse connector (8) is designed to maintain the connection between at least four multi-axial pedicle screw (1) - implanted in at least two facing vertebra- and at least two rods positioned in parallel on these multi-axial pedicle screws (1).

Multi-axial transverse connector (8) where cross-sectional view is given in Fig. 4 comprises of; transverse connector branches (8.1), transverse connector fixed part (8.4) and transverse connector screws (8.2).

Transverse connector branches (8.1) are identical to each other and as an advantage; they are designed to fit into the rod (5) from the top. As an advantage, multi-axial transverse connector (8), has four different adjustable lengths ranging from 30mm to 70mm. This way, it can be used in all types of spine structure and rod (5) distance.

The length adjustment in multi-axial transverse connector (8) is done by the help of transverse connector adjustment part (8.4) which moves freely on horizontal plane inside the transverse connector fixed part (8.3). Transverse connector adjustment part (8.4) is pushed into transverse connector fixed part by applying pressure or using treads and teeth and with the help of stopping ledge (8.6), two parts don't break apart from each other. After fitting the multi-axial transverse connector (8) on rods (5), with the help of tightening balls (8.5) on the tip of transverse connector adjustment part (8.4) and transverse connector fixed part (8.3), departure of multi-axial transverse connector (8) from rod (5) is prevented.

As an advantage, multi-axial transverse connector is designed to give angulation on both vertical and horizontal plane. So, regardless of the height difference between rods facing each other, fixation is possible.

The angulation in multi-axial transverse connector (8) is done with the help of tightening balls (8.5). These sphere like tightening balls (8.5) moves in their slots and enables angulation. After placing multi-axial transverse connector (8) on rods (5) and making the necessary length/size and angle arrangements, it is locked with transverse connector screws (8.2). Preferably with a torque instrument, a force from the top is applied to the transverse connector screws (8.2). The force applied to transverse connector screws (8.2) on transverse connector branches (8.1) is transferred to tightening balls (8.5), from there to rods (5) and locks the rods (5) in the transverse connector branches (8.1) with the desired angulation. The force applied to transverse connector screw (8.2) on the transverse connector fixed part (8.3), is transferred from here to transverse connector adjustment part (8.4), hence by squeezing the transverse connector adjustment part (8.4) in the transverse connector fixed part (8.3), thus locks the structure in desired length/size.

In conventional transverse connector systems, angulation can be made only one-way. In case of angulations obtained from branches that transverse connector is fixed to the rod, either these branches are immovable or if these branches are movable, the part between two rods cannot be lengthened/shortened. In the systems where the part between the branches-that are connected to rod-are lengthened/shortened, angulation can be achieved from the centre. This causes a ledge in the middle of the structure. As an advantage, in multi-axial transverse connector (8), the angulation can be done both by transverse connector branches (8.1) and tightening balls (8.5) and also, with the help of transverse connector adjustment part (8.4) and transverse connector fixed part (8.3) between two transverse connector branches (8.1), lengthening/shortening can be adjusted. As seen in Fig. 5, regardless of distance and height difference between the rods (5), transverse connection can be achieved.

As an advantage, in order to be bio-compatible, all parts of the system are manufactured from titanium-aluminium-vanadium alloy. As an advantage, in order to increase the holding on to the bone surfaces, screw head (3), screw body (2), clip (6) and clip screw (7) are ceramic blasted.

Best Mode for Carrying Out the Invention

Multi-axial pedicle screw (1), by applying force and turning with an instrument suitable to screw head (3) and implanting instrument hole (2.5) in screw body (2), is implanted in to the bone by the help of one-way load transferring screw teeth (2.2). After inserting at least two multi-axial pedicle screws (1), a rod (5) with suitable length, is put on its place on screw head (3). Then, a tube shaped instrument which has suitable teeth for instrument slots (3.1) on the screw head (3) is attached to screw head (3) and the fixation of screw head is achieved and rod (5) is kept in its place. Clip (6), with the help of an instrument which holds the clip (6) from the upper parts of clip branches (6.1) is passed through the inside of this tube like instrument and the instrument holding the clip (6), is turned inside the tube like instrument and a pressure is applied to clip (6). Pressure is continued until clip locking shoulders (6.2) are fit into clip shoulder grooves (3.2) on screw head (3) and an audible locking sound is heard. Then, necessary angulation is done on screw head (3) and clip screw (7) is fit into its place on clip (6) and preferably with a torque instrument, final tightening is done. In this way, rod (5) is fit into its place and multi-axial pedicle screw (1) is fixed at suitable angle. The same procedure is applied to the other side of the vertebra. Finally, multi-axial transverse connector (8) is placed on two rods (5) parallel to each other. Using transverse connector fixed part (8.3) and transverse connector adjustment part (8.4), the length of multi-axial transverse connector is adjusted. After giving the desired angulation to the multi-axial transverse connector on vertical and horizontal plane, transverse connector screws (8.2) are final tightened, preferably with a torque instrument. Hence, both multi- axial transverse connector (8) and whole structure are fixed/stabilized. The described application is shown in Fig. 6. The invention is described by way of example above. Of course, the invention cannot be limited with the above described applications and the person skilled in the art can implement various variants of the invention without going beyond the ambit of the patent.

Claims

1. A multi-axial pedicle screw system used in spine surgery operations especially for connecting at least two stabilization assemblies in a vertebra and providing spinal fusion between the vertebra characterized in that it comprises; a load transferring rod (5), a screw head (3) which holds the rod (5), a screw body (2) which is placed multi-axially in screw head (3), a clip (6) which keeps rod (5) in screw head (3), a clip screw (7) which locks clip (6) and rod (5) from the top and an adjustable multi-axial transverse connector (8) which connects two parallel rod to each other having a fixed part (8.3) and adjustment part (8.4).

2. A multi-axial pedicle screw system according to Claim 1, characterized in that multi-axial screw(l) comprises a screw body (2) which has parallel screw teeth (2.2) starting from the blind screw tip (2.1) and stretching along the conical shape of screw body (2).

3. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a screw body (2) with body head threads (2.4) which are a parallel to each other in order to increase the clinging of washer (4) to screw body head (2.3).

4 A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises multi-axial pedicle screw(l) passing through, the screw hole (3.3) and screw body head (2.3)being bigger than screw hole (3.3) enabling the screw (1) to be angulated up to 70 degrees in all directions,

5. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a multi-axial pedicle screw (1) ranging from 4.0mm to 8.0mm in diameter and ranging from 20mm to 60mm in length in order to be compatible to all kinds of levels on thoraco-lumbar spine.

6. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a circular shaped washer (4) placed on to screw head (3) having a hole in the middle enabling instrument to pass through it and enabling evenly distribution and regularly application of the force applied by clip screw (7) from the top after the rod (5) is placed.

7. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises preferably a U-like shaped screw head(3), having clip shoulder grooves (3.2) keeping clip locking shoulders (6.2), and having instrument holes (3.1), enabling suitable instrument to have a good grip on both opposing faces and having inclination enabling clip (6) to slide along the other two faces of the screw head (3) during locking.

8. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a rod (5) with diameter of 6.0mm, having sizes ranging from 50mm to 500mm in order to comply with all kinds of positions on thoraco-lumbar spine.

9. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a reverse U-shaped Clip (6) which keeps rod (5) in screw head (3), having clip locking shoulders (6.2), preventing the rod (5) to move away from screw head (3) after locking and enabling the movement and angulation on the rod (5) in this locked position.

10. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises a multi-axial transverse connector (8) placed between two parallel rods (5) in order to stabilize the structure that fitted on the rods (5) from the top, enabling angulation in vertical and horizontal plane having transverse connector branches (8.1), transverse connector screws (8.2), transverse connector fixed part (8.3), transverse connector adjustment part (8.4), tightening ballls (8.5) and stopping ledge (8.6)

11. A multi-axial pedicle screw system according to one of the previous claims characterized in that all the parts are made of titanium-aluminium-vanadium alloy in order to be bio-compatible and sand blasted to increase clinging to the bone surfaces.

12. A multi-axial pedicle screw system according to one of the previous claims characterized in that it comprises;

• a load transferring rod (5) with diameter of 6.0mm, having sizes ranging from 50mm to 500mm in order to comply to all kinds of positions on thoraco-lumbar spine.

• a U-like shaped screw head (3), having clip shoulder grooves (3.2) keeping clip locking shoulders (6.2), and having instrument holes (3.1), enabling suitable instrument to have a good grip on both opposing faces and having inclination enabling clip (6) to slide along the other two faces of the screw head (3) during locking.

• a pedicle screw(l) which sits multi-axially on screw head(3),

o with a blind screw tip (2.1), having parallel screw teeth (2.2) starting from the blind tip and stretches along the conical shape of the screw body (2), o with parallel body head threads (2.4) in order to increase the clinging between screw body head (2.3) and washer (4),

o that passes through the screw hole (3.3) and since the screw body head (2.3) is bigger than screw hole (3.3), screw head (3) can be angulated up to 70 degrees in all directions,

o with length ranges from 20mm to 60mm, diameter ranging from 4.0mm to 8.0mm in order to comply with all kinds of levels on thoraco-lumbar spine, • a reverse U-shaped clip which keeps rod (5) in screw head (3), having clip locking shoulders (6.2), preventing the rod (5) to move away from screw head(3) after locking and enabling the movement and angulation on the rod (5) in this locked position,

• a clip screw (7) which locks the clip (6) and rod (5) from the top,

• a washer with a hole in the middle enabling instrument to pass through it and enabling evenly distribution and regularly application of the force applied by clip screw (7) from the top after the rod is placed in its place on screw head(3)

• a multi-axial transverse connector-having transverse connector branches(8.1), transverse connector screws(8.2), transverse connector fixed part(8.3), transverse connector adjustment part(8.4), tightening bolts(8.5), stopping ledge(8.6)- which is placed between two parallel rods(5) in order to stabilize the structure that fitted on the rods(5) from the top, enabling angulation in vertical and horizontal plane, that are made of titanium-aluminium-vanadium alloy in order to be bio-compatible and are sand blasted to increase the clinging to bone surfaces.

13., A multi-axial transverse connector used in pedicle screw systems to be placed between two rods(5) parallel to each other, in order to stabilize the system characterized in that it can be fit on rods (5) from the top enabling angulation in vertical and horizontal plane comprising a transverse connector branches (8.1), transverse connector screws (8.2), transverse connector fixed part (8.3), transverse connector adjustment part (8.4), tightening balls (8.5), and stopping ledge (8.6)