ES2836879A1 - Patient-specific surgical medical instruments for posterior spinal instrumentation and positioning and stabilization system (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

A patient-specific surgical medical instrument for performing spinal surgeries, by means of posterior instrumentation, characterized by at least two contact elements, at least one guide element, a clamping-connection device and an infographic element. This instrument is characterized because it will be generated by combining at least two contact elements that represent a negative cast of the bone relief that is exposed from a posterior approach to the spinal tract to be intervened, allowing the patient instruments to be positioned. specific in a unique and invariable location (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

Patient surgical medical instruments - specific for posterior spinal instrumentation and positioning and stabilization system

Technical sector

The present invention belongs to the field of personalized surgical equipment for each patient. Specifically, patient-specific surgical instruments whose function will be to facilitate and increase precision in the introduction of implants that are commonly used in spinal surgeries that involve a posterior approach.

For its design, images obtained from stratified image studies of the patient will be used, such as computed axial tomography (from now on T.A.C) capable of generating three-dimensional images of the patient's axial skeleton.

For its manufacture, additive manufacturing methods will generally be used, such as 3d printing in sterilizable and biocompatible material.

Background of the invention

In the field of spine surgery, the most commonly used approach is the posterior one. Through this, the surgeon performs the necessary gestures for the implantation of instruments; The instruments that the surgeon most frequently implants in spinal surgery through the posterior approach are screws, whose name will be determined by their location within the anatomical structure of the vertebra or the anatomical structure involved. : as examples the pedicle screws commonly used in thoracic and lumbar surgery, the lateral mass screws commonly used in cervical tract surgery, the sacroiliac screws used in surgery involving the sacral segment, as well as the more specific screws used in surgery involving the C1 and C2 vertebrae whose trajectories are variable and will depend on the surgeon's preferences.

The vertebrae observed from a posterior view have two parts that are generally more or less symmetrical, whose axis of symmetry is constituted by a single posterior element that is the spinous process, therefore, the screws implanted in each vertebra will generally be two, one a each side of the spinous process.

For the correct introduction of these screws, the surgeon takes as a reference the different anatomical structures present in the part of the vertebra exposed through the posterior route. These are usually: spinous processes, lamina, joint processes or masses and transverse processes.

The procedure for the introduction of the screws inside the vertebrae begins after the approach and exposure of the bone surface of these, that is, the separation of the muscles and soft tissues adhered to the posterior bone surface of the vertebrae involved. The surgeon usually chooses the insertion point through which he initially introduces a blunt awl to carve the hole through which he will later insert the screw, one on each side of the spinous process.

For this, the surgeon, throughout the process, usually confirms the correct positioning of the instruments, relying on the complementary tests carried out during the surgery: fundamentally intraoperative radiological studies that demonstrate the desired trajectory in both planes or electro-neurophysiological studies that demonstrate the integrity of the neurological structures. These tests performed during surgery lengthen the surgical procedure and in many cases fail to prevent neurological damage or guarantee optimal positioning.

An alternative to the usual procedure explained above is represented by cannulated screws. This begins with the introduction of a guide wire or K-wire, verifying its position using X-rays; This needle will subsequently be inserted through the screw into the hole that these present at their tip. In this way, when the screws are inserted into the bone, they will follow the path through which the guide wire was previously inserted.

The purpose of these screws is to achieve maximum grip, avoiding invading or injuring the important nearby anatomical structures such as the structures of the nervous or vascular system: spinal cord, nerves, arteries or veins.

Given the complexity of the technique of correct screw placement inside the vertebrae, navigated surgery systems have emerged, as well as different types of patient-specific guides.

Navigated or computer-assisted surgery often requires the use of complex computer systems that require calibration that often lengthens the surgical process.

As for the patient-specific guides, they are usually adapted to the posterior elements of the vertebra to achieve the proper positioning that allows creating a hole through which the screws will later be inserted in the desired position.

The object of this invention is a patient-specific surgical medical instrument whose elements and devices that comprise it favor and optimize safety and precision in surgery in the implantation of screws inside the vertebrae. For this, the patient-specific surgical medical instrument invariably has the combination of the following elements and devices: contact element, guide element, clamp-connection element and infographic. The use of this instrument will allow an evolution of the surgical technique by favoring the correct positioning of the necessary instruments on the anatomical surface of the vertebra, at the same time increasing the contact surface of the guide, contributing to greater ergonomics, safety, and precision in the execution of the surgery.

This patient-specific surgical medical instrument can be used in the execution of the necessary holes, with optimal positioning, through which the screws will then be inserted into the affected vertebrae.

This patient-specific medical instrument is made up of a clamping device, connection of the contact and guide parts that will offer an advantage / improvement / advance in the positioning of the instruments necessary for the execution of the surgery. These technical advantages are as follows:

- By bringing the two contact elements into contact, the overall contact surface of the guide is increased, increasing the precision of the guide.

- The shape and arrangement of this contact element will favor the grip of the guide while introducing conventional instruments: drill, guide wire or similar, keeping the position of the guide stable throughout the procedure.

- It will allow the patient-specific surgical medical instruments to be pressed against the bone, improving cohesion and adaptation between vertebra and guide.

Therefore, thanks to the existence of the connecting-holding element that emerges from both contact surfaces and that joins in the form of an arch or bridge passing over the midline avoiding the upper part of the spinous process, allowing this mode of restraint by the surgeon:

- It will increase the precision of the system since it doubles the contact surface and therefore reduces the possibility of incorrect positioning of the instruments in their unique and determined position.

- The existence of the handle that protrudes from the surgical field, avoiding the structures present in the midline and with a transversal connecting element with a specific thickness, allows the stable grip and pressure of this instrument on the bone surface. This will facilitate the application of the specific patient instruments on the bone surface and will make it possible to cancel the vibrations derived from drills or pneumatic and electric motors, preventing the position of the specific patient instruments from varying while drilling the holes in the vertebra.

Furthermore, this fastening-connection element may be removable, allowing the disconnection of both contact elements, and thus allowing its use with vertebral instrumentation systems with cannulated screws. In these cases this element will be called the fastening-connection / disconnection element.

Explanation of the invention

For the design and manufacture of this specific patient surgical medical instruments will require obtaining images from stratified and computerized medical studies, preferably from T.A.C. Capable of generating a three-dimensional image of the spinal tract to be intervened.

These images will be sent to the design center where, through a process of segmentation of the different strata that make up the study, they will be transformed into a three-dimensional solid in the form of a closed mesh.

From this solid, the specific patient surgical instruments will be created, which will invariably be formed from the combination of the following elements and devices:

- Contact element: representing a negative cast of the bone relief that is exposed from a posterior approach to the spinal tract to be intervened. Therefore, it will allow the positioning of the instruments in a single and invariable location. Each patient-specific instrument will present at least two contact elements initially separated from each other, at least one on each side of the spinous process or midline.

- Guide element: Generally cylindrical in shape and equipped with a hole through which conventional instruments (for example, a drill) are inserted in charge of producing the hole following the desired path, through which the screw will subsequently be inserted. Each patient-specific surgical instrument will present, at least, one guide element, although, as a general rule, there will be two elements, one on each side of the midline, initially, separated from each other, corresponding to the screws that will be inserted in each of the sides of the vertebra. Alternatively, a guide wire can be inserted inside the guide element if a cannulated screw system is used.

- Clamping device - connection of contact and guide elements. That emerges from both contact surfaces and that joins in the form of an arch or bridge passing over the midline avoiding the upper part of the spinous process. Whose function will be to unite the aforementioned elements that have been generated on both sides of the spinous process and which will also serve to improve the holding of the patient instruments -specifies while carving the hole with the drill or similar. Depending on the type of instrumentation system with which it is used, this element may be detachable from the rest of the guide to allow its use with the cannulated screw system. In these cases it will be called the connection / disconnection clamping element.

- Infographic or informative elements: Consisting of letters, numbers and symbols that will inform the surgeon about which vertebra they should position the instruments and in which direction.

The final design of the patient-specific instruments will be formed from the combination of these four elements and the device, and its manufacture may be carried out using any additive manufacturing system in biocompatible and sterilizable material.

After exposing the posterior bone surface of the vertebrae, the surgeon will proceed to position the patient-specific instruments on the exposed bone surface, which will be attached to a single and precise location, introducing, inside the guide element, a drill or similar. with which the hole is made inside the vertebra. Next, and after the removal of the instruments, the surgeon will proceed to insert the corresponding screw into the drilled hole.

Alternatively, when the surgical technique used is through the use of cannulated screws, the combination of these patient-specific instruments will allow the two guide wires or K-wires to be inserted in the desired location in a mostly convergent position. In this way, the patient-specific surgical instruments will be removed thanks to the disconnection or uncoupling of the clamping device, which will allow the removal of the rest of the elements of said instruments. To then proceed with the introduction of the cannulated screws through the guide wire.

Brief description of the drawings

To complete the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of the description in which, with an illustrative and non-limiting nature, it has been represented the next:

Figure 1 shows a left posterior perspective where a patient-specific surgical instrument adapted to the corresponding bone surface can be seen:

1. Contact element adapted to the corresponding bone surface, allows the placement of specific patient instruments in a unique position.

2. Connecting / clamping element that increases the overall contact surface by joining both contact elements, at the same time allowing a stable clamping. Passing over the spinous process and avoiding contact with it.

3. Guide element: inside which the elements are inserted with which the holes are to be made with the desired trajectory.

Figure 2 shows a right anterior perspective of the same instrument adapted to the posterior surface of the corresponding vertebra.

Figure 3 shows a lower view of the instruments where the duplication / parity of contact and guide elements joined by a bridge is observed, where the information related to the vertebral level is observed in relief.

1. Both contact elements.

2. Both guiding elements.

3. Connection / fastening element with detail of the infographic relative to the vertebral level. Figure 4 shows a front perspective of the contact element and holes of the guide element (3). The negative ene relief of the lamina (1) and the transverse (2) of the corresponding vertebra is shown.

Figure 5 shows a left posterior perspective of specific patient instruments for the introduction of screws in the lateral masses of C1:

1. Contact element adapted to the bone surface offered by the posterior arch of C1.

2. Connection / clamping element: which increases the overall contact surface by joining both contact elements, at the same time allowing a stable clamping. Passing over the spinous process and avoiding contact with it.

3. Guide element: inside which the elements are inserted with which the holes are to be made with the desired trajectory.

Figure 6 shows a right anterior perspective of a specific patient instrument for the introduction of screws in the lateral masses of C1.

Figure 7 shows a bottom view of the instruments where the duplication / parity of contact and guide elements joined by a bridge is observed, where the information relative to the vertebral level is observed in relief.

1. Both contact elements.

2. Both guiding elements.

3. Connection / fastening element with detail of the infographic relative to the vertebral level. Figure 8 shows a front perspective of the contact element and holes of the guide element (2). The surfaces of the contact elements with the negative relief shape of the rear arc of C1 (1) are shown.

Figure 9 shows a left lateral perspective of the patient-specific instrument for cannulated screws with the handle disengaged to demonstrate modularity of the patient-specific instrument:

1. Detachable handle.

2. Example of a coupling system, segment with a rectangular shape that is inserted.

3. In the specific hole of the contact elements on each side.

Figure 10 shows a right side perspective of the specific patient instruments for cannulated screws:

1. Detachable handle.

2. Example of a coupling system, segment with a rectangular shape that is inserted

Figure 11 shows a representation of both contact elements adapted to the bone surface with guide wire inserted through guide elements. It can be seen how when the handle is removed, the modularity allows the extraction of the complete patient-specific instruments, keeping both convergent guide wires positioned.

Preferred embodiment of the invention

The patient-specific surgical instruments, object of this invention, are created from the TAC images of the patient. These images will be transformed into a three-dimensional solid in the form of a closed mesh through a process of segmentation of the images obtained from the study.

Patient-specific instruments will invariably be created from the combination of these elements and devices:

Contact element:

This consists of a negative cast of the exposed bone surface of the vertebra in question. In all vertebrae there are two symmetrical or similar parts on both sides of a single element that constitutes the axis of symmetry of the vertebra, this is the spinous process. Therefore, at least two contact surfaces will be generated for each vertebra at least one on each side of the midline, which will initially be separated. The exposed bone area, on which the contact element will be generated, will receive various names depending on the spinal tract involved:

- Thoracic and lumbar spine: They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, lower part of the spinous process, articular processes or processes and transverse processes.

- Sacral spine: They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, Processes or articular processes, ilium and sacral aileron.

- Cervical spine (except C1 or atlas): They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, articular processes and lower part of the spinous process.

- C1 or atlas: In the case of the first cervical vertebra, it does not present a spinous process or lamina, instead the axis of symmetry will be constituted by the posterior tubercle. Contact elements may be generated from the exposed bone surface of the posterior arch and joint processes.

Guide element:

This will consist of a hollow cylinder through which the drill or guide wire will be inserted. The longitudinal axis of the cylinder will coincide with the desired trajectory of the screw and generally said cylinder will be attached to the contact element on each side. Therefore, at least one guide element will be generated, although in almost all cases it will be two guide elements per vertebra initially separated from each other. The direction of the element within the guide vertebra should avoid nearby vascular and neurological elements and achieve maximum grip.

The trajectory of the instruments introduced inside the guide element and, therefore, that of the screws inside the vertebra will be determined by the preferences of the surgeon, as well as by the segment of the spinal column to be intervened.

The inner channel of the guide element will have an adequate diameter to house the drill or guide wire that is planned to be used during surgery, allowing its passage without excessive play so that the planned direction is respected.

Clamping device-connection or clamping device connection / disconnection:

The generation of this element is the main differential feature with respect to the existing techniques in the field of instrumentation! patient - specific already present in the state of the art.

Its design will be similar to a bridge or connecting arch between the two contact elements, already mentioned, passing over the spinous process and interspinous ligaments at a certain distance from them, avoiding interfering with them whenever possible. For this, this device consists of:

- Two arms that arise from each of the contact elements preferably following the direction of the normal of the contact surface and in the opposite direction to the bone surface, passing over and avoiding- the elements of the midline such as the upper part of the spinous processes. Thus, allowing the grip to press the contact elements of the patient-specific instruments against the bone surface.

- The two arms will be joined at a certain distance by means of a joint that may be a transverse arm or in the form of an arc. This transverse arm or arch will constitute the grip zone.

The diameter of this element must be adequate to maintain a stability of the guide avoiding its deformation while it is applied and pressed against the bone, as well as to allow an adequate grip by the surgeon.

Occasionally, when this instrument is used in significant or large deformities of the spine, such as scoliosis, its direction should be as close as possible to normal, trying to respect the nearby bone structures; Sometimes, to get as close as possible to the normal of the contact surface, the direction of these must invade the space of the spinous process and interspinous ligaments; so the surgeon must sacrifice these during surgery by resecting them before applying the specific patient instruments, thus achieving a better adaptation to the surface of the vertebra. Generally, this will not be a problem since this assumption will only occur in important deformities (at the apex of a scoliosis) that usually present a significant rigidity of this tract of the spine that is also going to be instrumented, so the sacrifice of These structures will not affect the future stability of the segment.

When instruments are used in combination with cannulated screws to remove instruments while keeping the K-wires in the same position, the on / off clamping device will disengage from the contact elements. The coupling zone will preferably be located somewhere along the arms projecting from the contact zone.

As an example, figure 9 shows a simple coupling mechanism consisting of a quadrangular stem that arises from the arms close to the gripping area that are inserted into the corresponding cavity in the arms close to the contact area. The degree of constriction of these elements must be sufficient to allow manipulation of the guide without spontaneous disengagement while applying the specific patient instruments, but at the same time the handle can be extracted without altering the position of the needles. K inside the vertebra. Considering that the pressure exerted by the surgeon while inserting the guide wires into the bone will favor the stability of the coupling of these instruments.

Informational elements or infographics:

Typically, the surgical process requires the use of two or more patient-specific instruments. Therefore, the implementation of the information on the correspondence between the specific patient instruments and the vertebral level will facilitate the surgeon's work during the procedure. This infographic can be made in relief or in any other way at any point on the specific patient instruments. In figure 3 this information is shown in relief in the grip area of the clamping / connecting device.

It will be displayed in the form of letters corresponding to the spinal tract: S: sacrum. L: lumbar. T: thoracic. C: cervical. In addition to the number corresponding to the level within the aforementioned tract.

In addition, symbols can be implemented that facilitate the surgeon in the correct positioning in the cranial-caudal direction.

Claims (7)

1. A patient-specific surgical medical instrument (9) for performing spinal surgeries, by means of posterior instrumentation, characterized by at least two contact elements (1), at least one guide elements (3), a device for fastening-connection (2) and an infographic element, which includes obtaining images from stratified and computerized medical studies, from CT studies (computerized axial tomography), magnetic resonance or similar, which will generate a three-dimensional image of the spinal tract to be intervened and which, after a process of segmentation of the different strata that make up the study, will be transformed into a three-dimensional solid in the form of a mesh closed, said instruments comprising the combination of at least two contact elements (1) that represent a negative cast of the bone relief that is exposed from a posterior approach to the spinal tract to be intervened, allowing the patient instruments to be positioned specific in a single and invariable location and characterized by at least two guide elements (3), cylindrical in shape and equipped with a hole through which conventional instruments (for example, a drill) are inserted in charge of producing the hole following the path desired, through which the screw will subsequently be inserted, and also comprising a device clamping and connection of contact and guide elements. 2. Method according to claim 1, characterized in that the design and manufacture of the specific patient instruments comprises obtaining images from stratified and computerized medical studies, from T.A.C. (computerized axial tomography), magnetic resonance or similar, which will generate a three-dimensional image of the spinal tract to be intervened and which, after a segmentation process, of the different strata that make up the study, will be transformed into a three-dimensional solid in the form of a mesh closed. This instrument is characterized because it will be generated by combining at least two contact elements that represent a negative cast of the bone relief that is exposed from a posterior approach to the spinal tract to be intervened, allowing the positioning of the specific patient instruments in a single and invariable location, also comprising at least two guide elements with a cylindrical shape and equipped with a hole through which conventional instruments (for example, a drill) are inserted in charge of producing the hole following the desired path, through which the hole will be inserted subsequently the screw, and also comprising a device for holding and connecting the contact and guide elements. 3. Fastening-connection device, according to claims 1 and 2, which will join the two contact elements together with the two guide elements that have been positioned on both sides of the spinous process characterized by two arms arising from each of the contact elements following the direction of the normal of the contact surface and in the opposite direction to the bone surface and avoiding, whenever possible, the elements of the midline such as the upper part of the spinous processes. Thus allowing that with the grip the contact element of the patient-specific instruments can be pressed against the bone surface that comprises two arms, they will be joined at a certain distance by means of a union that may be a transverse arm or in the form of an arc. . This transverse arm or arch will constitute the grip area; and, furthermore, the device comprising a suitable diameter to maintain a stability of the instruments avoiding its deformation while it is applied and pressed against the bone, as well as to allow a suitable grip by the surgeon. 4. Infographic or informative elements, according to claims 1 to 3, characterized by: Consisting of letters, numbers and symbols that will inform the surgeon about which vertebra they should position the instruments and in which direction. 5. A patient-specific surgical medical instrument for performing spinal surgeries, by means of posterior instrumentation, characterized by at least two contact elements, at least one guide elements, a fastening device -connection / disconnection and an infographic element, which includes obtaining images from stratified and computerized medical studies, from CT studies (computerized axial tomography), magnetic resonance or similar, which will generate a three-dimensional image of the spinal tract to be intervened and which, after a segmentation process, of the different strata that make up the study, will be transformed into a three-dimensional solid in the form of a mesh closed. This instrument is characterized because it will be generated by combining at least two contact elements that represent a negative cast of the bone relief that is exposed from a posterior approach to the spinal tract to be intervened, allowing the positioning of the specific patient instruments in a single and invariable location, also comprising at least two guide elements with a cylindrical shape and equipped with a hole through which conventional instruments (for example, a drill) are inserted in charge of producing the hole following the desired path, through which the hole will be inserted subsequently the screw, and also comprising a device for holding and connecting the contact and guide elements. 6. Clamping-connection / disconnection device according to claim 5 that will join the two contact elements together with the two guide elements that have been positioned on both sides of the spinous process characterized by two arms that arise from each of the contact elements following the direction of the normal of the contact surface and in the opposite direction to the bone surface and avoiding, whenever possible, elements of the midline such as the upper part of the spinous processes. It can be disconnected from the rest of the elements to facilitate their removal, keeping the guide wire positioned in the cannulated screw instrumentation systems. In these cases it will be called a fastening element - connection / disconnection. 7. System for the positioning and implementation of specific patient instruments, for the instrumentation of the vertebral column, by posterior route, on the anatomical surface of the vertebra, increasing the contact surface, ergonomics, precision and safety in the creation of the holes through which the screws will be inserted into the vertebrae comprising: Contact element: This consists of a negative cast of the exposed bone surface of the vertebra in question. In all vertebrae there are two symmetrical or similar parts on both sides of a single element that constitutes the axis of symmetry of the vertebra, this is the spinous process. Therefore, at least two contact surfaces will be generated for each vertebra at least one on each side of the midline, which will initially be separated. The exposed bone area, on which the contact element will be generated, will receive various names depending on the spinal tract involved: - Thoracic and lumbar spine: They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, lower part of the spinous process, articular processes or processes and transverse processes. - Sacral spine: They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, Processes or articular processes, ilium and sacral aileron. - Cervical spine (except C1 or atlas): They can be distinguished as exposed bone elements from which the negative mold that constitutes the contact element can be generated are: Lamina, articular processes and lower part of the spinous process. - C1 or atlas: In the case of the first cervical vertebra, it does not present a spinous process or lamina, instead the axis of symmetry will be constituted by the posterior tubercle. Contact elements may be generated from the exposed bone surface of the posterior arch and joint processes. Guiding element: This will consist of a hollow cylinder through which the drill or guide wire will be inserted. The longitudinal axis of the cylinder will coincide with the desired trajectory of the screw and generally said cylinder will be attached to the contact element on each side. Therefore, at least one guide element will be generated, although in almost all cases it will be two guide elements per vertebra initially separated from each other. The direction of the element within the guide vertebra should avoid nearby vascular and neurological elements and achieve maximum grip. The trajectory of the instruments introduced inside the guide element and, therefore, that of the screws inside the vertebra will be determined by the preferences of the surgeon, as well as by the segment of the spinal column to be intervened. The inner channel of the guide element will have an adequate diameter to house the drill or guide wire that is planned to be used during surgery, allowing its passage without excessive play so that the planned direction is respected. Clamping device-connection or clamping device connection / disconnection: Its design will be similar to a bridge or connecting arch between the two contact elements, already mentioned, passing over the spinous process and interspinous ligaments at a certain distance from them, avoiding interfering with them whenever possible. For this, this device consists of: - Two arms that arise from each of the contact elements preferably following the direction of the normal of the contact surface and in the opposite direction to the bone surface, passing over and avoiding- the elements of the midline such as the upper part of the spinous processes. Thus, allowing the grip to press the contact elements of the patient-specific instruments against the bone surface. - The two arms will be joined at a certain distance by means of a joint that may be a transverse arm or in the form of an arc. This transverse arm or arch will constitute the grip zone. The diameter of this element must be adequate to maintain a stability of the guide avoiding its deformation while it is applied and pressed against the bone, as well as to allow an adequate grip by the surgeon. This element is disconnected from the rest of the elements to facilitate their removal, keeping the guide wire positioned in the cannulated screw instrumentation systems.