RU2212865C1 - Device for implanting lumbar intervertebral disk prosthesis - Google Patents

Abstract

FIELD: medical engineering. SUBSTANCE: device has two articulated branches connected via multi-link hinge-and-lever mechanism with cantilevers and having working lips at the ends with fixing members and controllable squeezing mechanism on branch handles and controllable mechanism for moving the device. The controllable mechanism has handle mounted on strip and connected to the cantilever via worm. The cantilever has longitudinal hole for hinges to pass to mount the strip thereon. Symmetric recesses are made in the cantilevers to give cavity for receiving prosthesis having guide member axially mounted inside of the cavity. One end of the guide is between the working lips and the other one is attached to central articulation link of the hinge-and-lever mechanism. EFFECT: high accuracy in embedding prosthesis; accelerated and simplified operation; reduced risk of traumatic complications. 4 cl, 4 dwg

Description

 The invention relates to devices for implantation of structures in the spine and can be used in neurosurgery, neurotraumatology, orthopedics, including neuroorthopedics and traumatology.

 The device is intended, in particular, for operations performed from ventral access.

 Known devices for implantation of a vertebral prosthesis [1, 2], containing two sliding support brackets, at the ends of which are made working jaws with locking elements. The brackets are fixed at the ends of the movement mechanism, made in the form of an axial sleeve with an internal thread for a screw guide axis, with the first bracket connected to the axis and the second to the sleeve. To drive the mechanism for moving the brackets on an axial cylindrical sleeve located between the brackets, key-hole holes are made.

 After accessing the vertebral bodies, localizing the site of damage and exposing two adjacent segments above and below the level of injury, when installing the device, a discectomy is performed above and below the level of injury and working jaws are inserted into the intervertebral spaces so that the working fixing elements abut against certain parts of adjacent bodies vertebrae, and the axial cylindrical sleeve was located on the side of the vertebral bodies. The key rod is inserted into the hole and the sleeve is rotated around the guide axis, thereby distracting the vertebrae by a predetermined amount at the initial stage of the operation.

 The devices allow distraction of the vertebrae strictly in parallel. However, using these devices it is impossible to reposition vertebrae. The devices are not convenient in operation, since it is difficult to rotate the sleeve with a key-rod and at the same time it is difficult to hold the device, there is not enough operational space for implant insertion (the sleeve is in close proximity to the vertebrae).

 The devices used for implantation of a lumbar prosthesis [3-5] are widely known, containing two articulated jaws, at the ends of which working jaws are made.

 The working jaws of these devices are injected into the intervertebral space of two adjacent vertebrae, by compressing the jaws the vertebrae are distilled. Implantation of the prosthesis is carried out manually. The device [4] allows reposition of the vertebrae.

 A common drawback of such devices is that in the process of distraction, the vertebrae do not move apart in parallel (scissor effect), as a result of which the main efforts fall on the front edges of the vertebral limbs, which can cause their destruction. After implantation of the prosthesis during decompression, the vertebrae will also not compress in parallel, which can cause a displacement of the correctly installed prosthesis. The installation accuracy of the prosthesis is low. Ro-graphic control is required, which lengthens the operation time and increases radiation exposure.

 In addition, the efforts exerted by the hand of the surgeon on the branches of the branches are significant and amount to ≈500 N, which is extremely dangerous during neurosurgical operations. This is due to the fact that, by design, these devices are a single-link lever, and to facilitate the applied effort it is impossible, on the one hand, to increase the length of the jaw handles (the hand has limited dimensions), on the other hand, to reduce the size of the working jaws, determined by the size of the vertebrae, and reduce the length of the working ends of the jaws (small leverage shoulders), providing sufficient operating space for implantation of the prosthesis.

 A device [3] for implanting a prosthesis contains two spring-mounted articulated jaws, at the ends of which working jaws are made.

 The device allows you to expand the intervertebral space. However, the inability to fix the jaws in a compressed state and the need to hold them manually causes great difficulties for the surgeon. In addition, when implanting the prosthesis manually without fixing the jaw, repeated vertebral displacements are possible, the accuracy of the prosthesis installation is low. The device does not allow reposition of the vertebrae.

 The device [4] for open reposition of the displaced vertebrae contains two articulated jaws, one of which is equipped with a working notched jaw, and on the other jaw there is a flat supporting platform along which the pusher of the adjusting mechanism moves. Moving is carried out by means of a screw and a handle.

 With the help of this device, it is possible to expand the intervertebral space and to repair the displaced vertebrae. However, the small-area pusher during reposition severely injures the ventral surface of the vertebra, causing fractures of the upper anterior limb of the vertebrae.

 In addition, the small size of the levers of the instrument does not provide freedom for manipulations during reposition and distraction of the vertebrae.

 Spikes - clamps of removable platforms do not provide stable and non-traumatic engagement of the vertebra and often slide off its surface, roughly injuring the end plate of the vertebral body. The device lacks measuring devices for the magnitude of distraction and reposition of the vertebrae, which can lead to damage to the nerve structures of the spinal canal.

 The inability to fix the jaws in a compressed state and the need to hold them manually with the simultaneous rotation of the handle cause great difficulties for the surgeon. In addition, when implanting the prosthesis without fixing the jaw, repeated vertebral displacements are possible, the accuracy of the prosthesis installation is low.

 The implantation device [5] contains two articulated jaws, guides are made on the inner surfaces of the working jaws, along which a prosthesis is installed using a pusher, and a screw compression device is made on the jaw handles.

 The device expands the intervertebral space. The screw compression device allows you to reduce the efforts of the doctor during distraction and provides fixation of the jaws. The execution on the inner surfaces of the working jaws of the guides provides a more accurate installation of the prosthesis. However, this device does not allow reposition of the vertebrae.

 A device [6] for implanting a lumbar prosthesis is also known, comprising two articulated jaws connected through a multi-link articulated lever mechanism with working jaws, on the outer surface of which ribs are made. On the arms of the jaw made screw compression device. Depending on the application, the working jaws are fixed at the ends rigidly or pivotally. Rigidly fixed jaws are used for distraction of the vertebrae, articulated jaws are used to reposition the vertebrae.

 The multi-link articulated mechanism allows you to reduce the effort required to compress the jaw, to provide sufficient operating space for the introduction of the prosthesis. A screw compression device allows the jaws to be locked in a compressed state.

 However, the design of the device does not allow the working jaws to be pushed apart in parallel, and therefore, during the distraction process, the vertebrae also do not move apart in parallel (scissor effect), as a result of which the main efforts fall on the front edges of the vertebral limbs, which can cause their destruction. After implantation of the prosthesis, in the process of decompression, the vertebrae will also not compress in parallel, which can cause a displacement of the correctly installed prosthesis. The installation accuracy of the prosthesis is low. Ro-graphical control is required, which lengthens the operation time and increases radiation exposure.

 The device does not allow for distraction of the vertebrae, reposition of the vertebrae and implantation of the prosthesis in one operation of introducing working jaws into the intervertebral space. At the first stage of the operation, a device with articulated working jaws is used and the vertebrae are repositioned. Then this device is removed and a device with rigidly fixed working jaws is introduced, vertebra distraction and prosthesis implantation are carried out.

 The double insertion of working jaws into the intervertebral space increases the possibility of injury to the anterior edges of the vertebral limbs. In addition, since reposition is performed on closed vertebrae, the efforts necessary to displace them are significant, therefore, the probability of injury to the vertebrae due to their mutually adjoining movement, as well as the ribs of the working jaws, increases.

 The absence of sighting and measuring devices in the device does not ensure the safety of its use in contact with neurovascular structures of the vertebral canal.

 The closest to the claimed technical essence and the achieved result is an implantation device containing two articulated jaws, which are connected through brackets with a multi-link articulated lever mechanism to the brackets at the ends of which working jaws are made. The jaw handles are equipped with a screw compressing mechanism and a rod with a scale [7].

 The device allows through the use of brackets to carry out plane-parallel sliding of the working jaws (distraction). The presence of a rod with a scale allows you to accurately set the required amount of distraction.

 The device does not contain controls and structural elements used for implantation of the prosthesis. The surgeon carries out the implantation of the prosthesis manually, which reduces the accuracy of immersion of the prosthesis, leads to an increase in the invasiveness of the operation and the time it takes, since Ro-scopic and Ro-graphical monitoring of the position of the implanted prosthesis is required. In addition, the device does not allow reposition of the vertebrae.

 The basis of the invention is the creation of a device for implanting a prosthesis of the intervertebral disc, mainly of the lumbar region, which allows to increase the accuracy of immersion of the prosthesis, while reducing the time of the operation and reducing its invasiveness, as well as to simplify the manipulation of the surgeon, by means of which a single sequential operation cycle including vertebral distraction, vertebral reposition, and implant implantation.

 The problem is solved in that the device for implanting a prosthesis of the intervertebral disc of the lumbar, containing two articulated jaws connected through a multi-link articulated lever mechanism with brackets, at the ends of which there are working jaws with clamps and an adjustable compressive mechanism on the jaws handles, is additionally equipped with an adjustable a movement mechanism including a handle located on the bar and wormly connected to a bracket having a longitudinal hole, inside of which there are hinges on which this strap is installed, symmetrical recesses are made in the brackets, forming a cavity under the prosthesis, inside of which there is a guide along its axis, one end of which is located between the working jaws, and the other is attached to the central link of the articulated lever mechanism.

 The latches are made in the form of atraumatic ribs. The guide is equipped with a measuring scale and on the surface of the bar of the adjustable movement mechanism a measuring scale with a risk is applied, one end of which is fixed to the bracket.

 Providing the device with an adjustable movement mechanism, including a handle located on the bar, the rotation of which is transmitted through the worm gear to the upper bracket having a longitudinal hole, as well as a measuring scale mounted on the surface of the bar, allow for accurate reposition of the vertebrae, restoring their anatomically correct position.

 The presence in the device of a “cavity” under the prosthesis and a guide with a measuring scale applied on it, along which the prosthesis is inserted into the intervertebral space, simplifies its installation and increases the accuracy of implantation, thereby reducing the invasiveness of the operation.

 Thus, the claimed device provides the ability to conduct a single sequential operation cycle, including vertebra distraction, reposition of the vertebrae and implantation of the lumbar intervertebral disc prosthesis while simplifying the operation, reducing the time of its carrying out, increasing the accuracy of the prosthesis immersion and reducing the morbidity.

 The invention is illustrated by drawings.

 Figure 1 shows a General view of the device, side view (extreme position with closed working jaws).

 Figure 2 shows a General view of the device, side view (extreme position with offset and maximally diluted working jaws).

 Figure 3 shows a General view of the device, a top view.

 Figure 4 shows a General view of the prosthesis.

 The device consists of two pivotally connected (upper 1 and lower 2) branches, which respectively, through a multi-link lever-hinge mechanism, are connected to brackets 3, 4, at the ends of which working jaws 5 are made, two on each. On the outer surfaces of the working jaws 5, clamps are made in the form of atraumatic ribs 6. The bracket 3 is connected to the multi-link articulated lever mechanism by means of two upper hinges 7, and the bracket 4 is connected to two lower hinges 8, and the lower bracket 4 is mounted rigidly on the lower hinges 8, and a longitudinal hole 9 is made in the upper bracket 3, allowing it to move relative to the upper hinges 7. A U-shaped bar 10 is attached to the upper hinges 7, on which the handle 11 is mounted, which can be rotated through the worm the primary gear (not shown) is connected to the upper bracket 3. A measuring scale 12 is applied to the surface of the strap 10, and a risk 13 is attached to the upper bracket 3 at one end. The handle 11 with a worm gear, the strap 10, the measuring scale 12 and risk 13 form adjustable movement mechanism. Instead of a worm gear, any mechanical gear that converts rotational motion into translational, in particular gear or friction, can be used. The measuring scale can be located on the upper surface of the bracket 3 or made circular on the handle 11.

 The middle hinges 14 are connected to the upper 7 and lower 8 hinges by means of levers 15, and between themselves by a rod 16, and a guide 17 is mounted to the working (front) part of the rod 16, passing between the working jaws 5 and inside the cavity 18 formed by the recesses in the upper 3 and bottom 4 bracket. The end of the guide 17 reaches the ends of the working jaws 5. On the surface of the guide 17 there is a measuring scale 19. The cavity 18 formed in the upper 3 and lower 4 brackets is a “chamber” into which the prosthesis 20 is installed before the operation.

 The adjustable screw compression mechanism of the device contains a handle 21, on the axis of which a threaded rod 22 is fixed, passing through threaded holes made in compression joints 23, 24 at the ends of branches 1, 2. The threads on the upper and lower parts of the rod 22 and, respectively, in the upper 23 and lower 24 compression joints made multidirectional. On the side surfaces of the compression joints 23, 24 is a measuring scale (not shown), which allows you to adjust the amount of distraction of the working jaws 5.

 The prosthesis 20 of the lumbar intervertebral disc contains a hollow body 25 with coaxial openings 26 on the front and rear surfaces, fixation elements 27 and longitudinal symmetrical recesses 28 on the upper and lower surfaces. (The prosthesis is the subject of an independent invention and is not considered in detail in the claimed invention).

 The device operates as follows.

 The mechanical operation of the device is as follows. In the initial position, the working jaws 5 are closed without bias, the screw compression mechanism is maximally diluted (Fig. 1). The lines connecting the centers of the upper, central and lower hinges 7, 8, 14 form two symmetrical parallelograms. Accordingly, the levers 15 of the articulated link mechanism, the rod 16 and the brackets 3, 4 (their rear) are located in a similar configuration. Rotating the handle 21, compress the jaws 1, 2, which causes them to rotate around the central rear hinge 16, while the small shoulders of the jaws 1, 2, while rotating, move the rear upper 7 and lower 8 hinges relative to the central rear hinge 14. Similar movements are made all front hinges 7, 8, since they are rigidly attached to the rear. In the final state, when the arms of branch 1, 2 are closed, the lines connecting the axis of the hinges form two symmetrical rectangles. The distance between the upper 7 and lower 8 hinges is maximum and is the size of the two small shoulders of the levers 15. Accordingly, the working jaws 5 of the brackets 3, 4 are maximally spaced (Figure 2). The design allows you to repeatedly increase the effort exerted on the adjustable screw mechanism, providing the separation of the working jaws 5 strictly in parallel. The magnitude of the extension of the working jaws 5 is controlled on a measuring scale.

 Rotating the handle 11 of the adjustable movement mechanism, the worm gear is actuated, which ensures the displacement of the upper bracket 3 relative to the upper bracket 10 and, accordingly, relative to the lower bracket 4. The magnitude of the displacement is controlled by the position of the risks 13 on the measuring scale 12. After the manipulations are completed, the device comes to the state shown in Fig.2, when the upper and lower jaws 5 are maximally divorced and offset from one another.

 Medical use of the device is as follows. The device is used for ventral interventions on the vertebrae after performing a dysectomy. Preliminarily, along the guide 17, the prosthesis 20 is inserted into the "chamber" 18, by rotation of the handle 21, full alignment of the working jaws 5 is achieved (zero clearance). The working jaws 5 of the device are injected into the intervertebral space at a controlled depth. After establishing the sight of the device (not shown in the drawing) along the sagittal axis of the patient’s body by rotation of the handle, the intervertebral space is expanded by the required amount. The value is controlled on a measuring scale. If the patient has displacement of the vertebrae in the sagittal plane by rotation of the handle 11, the upper working jaws 5 are moved and the displaced vertebra is repaired, restoring the interrupted anatomical relations in the vertebral segment. The amount of bias is controlled by the position of the risks 13 on the measuring scale 12.

 After distraction and reposition of the vertebral bodies, the prosthesis 20 is immersed along the guide 17 into the intervertebral space to the required depth, the value of which is controlled by the operator on a measuring scale 19.

 After implantation of the prosthesis 20 by reverse rotation of the handle 21, the clearance is reduced by closing the working jaws 5. The bodies of adjacent vertebrae tightly clamp the prosthesis 20. Longitudinal symmetrical recesses 28, made on the upper and lower surfaces of the prosthesis 20, provide free exit of the working jaws 5 of the device from the operation area.

 Thus, the proposed device provides the ability to install the device strictly along the sagittal axis of the patient’s body, control the magnitude of the distraction and reposition of the vertebral bodies, as well as the simultaneous implantation of a disc prosthesis into the intervertebral space at a controlled depth.

 Manipulations on the device are easy, free, safe for neurovascular formations of the vertebral canal of the vertebrae that are moved to the interrupted anatomical position.

 Strictly parallel movement of the working jaws does not lead to a displacement of the prosthesis at the time of compression by the adjacent vertebral bodies at the final stage of the operation.

 The design makes it easy to hold the device motionless throughout the operation, eliminates trauma and injury to tissues and vessels that are held in the designated position and eliminates the associated postoperative complications.

 The reasons that worsen the view of the surgical field due to involuntary movements of the device are excluded, and the load on the surgeon's hands is sharply reduced.

List of references
1. Patent RU, 2085140, "Spinal distractor", op. July 27, 1997

 2. Patent RU, 2012278, "Spinal retractor", op. 05/15/1994

 3. US patent, 5314477, "Prosthesis for intervertebral discs and instruments for implanting it", op. May 24, 1994

 4. Copyright certificate SU, 567445, "Device for the open introduction of displaced vertebrae", op. 12/25/1972

 5 PCT International Application, WO 00/44288, "Surgical instrument for inserting intervertebral implants", op. 08/03/2000

 6. PCT International Application, WO 00/19911, "Spinal disc space distractor", op. 04/13/2000

 7. Copyright certificate SU, 680732, "Device for applying a retainer", op. 08/25/1979 (prototype).

Claims (4)

 1. A device for implanting a prosthesis of the intervertebral disc of the lumbar, containing two articulated jaws connected through a multi-link articulated lever mechanism with brackets, at the ends of which are made working jaws with clamps and an adjustable compression mechanism on the jaw handles, characterized in that it is equipped adjustable displacement mechanism, including a handle located on the bar, and worm-connected to a bracket having a longitudinal hole, inside of which hinges pass, on which this bar is installed, symmetrical recesses are made in the brackets, forming a cavity under the prosthesis, inside of which there is a guide along its axis, one end of which is located between the working jaws, and the other is attached to the central link of the multi-link articulated lever mechanism.  2. The device according to claim 1, characterized in that the latches are made in the form of atraumatic ribs.  3. The device according to paragraphs. 1 and 2, characterized in that the guide is equipped with a measuring scale.  4. The device according to paragraphs. 1-3, characterized in that on the surface of the strap there is a measuring scale with a notch, one end of which is fixed to the bracket.

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