System for cruciate ligament replacement using surgical navigation

Abstract

System for cruciate ligament replacement using a surgical navigator, without diagnostic tests, comprising a first and a second sensor (1, 2) fixed in place during surgery, on the femur (4) and tibia (5) respectively; instrumentation navigated with sensors (6), comprising a femoral guide (9) and a tibial guide (10); the sensors (1, 2, 6) being natural and / or artificial landmarks; where the surgical navigator comprises virtual and augmented reality software and artificial intelligence that allows determining a coordinate axis and simulating and navigating the femoral and tibial tunnels (7, 8), obtaining the exit point (12) of the tibial tunnel (8), the simulation of the graft (3), the isometric entry point (11) of the femoral tunnel (7) and the trajectory of the femoral tunnel (7) for an isometry of the graft (3).

Description

System for cruciate ligament replacement using surgical navigation Technical field of the invention The present invention pertains to the technical field of medicine, specifically to arthroscopic surgery for the reconstruction of anterior and posterior cruciate ligaments, collateral ligaments and reinforcement ligaments. Background of the Invention In the field of traumatology, for degenerative pathologies or acute injuries of the joints there is a method of repairing said joint, arthroscopy, which consists of a non-invasive procedure by which the surgeon accesses the patient's joint through small incisions in the skin called portals, and introduces all kinds of instruments (arthroscopy tools) to repair the injury that has occurred. For joint repair by arthroscopic procedures, there is a variety of instruments based on mechanical methods to resolve the pathologies of the patients. Specifically, for the repair of the anterior and posterior cruciate ligament, the state of the art includes appropriate instruments that allow the replacement, by arthroscopic procedures, of an injured or ruptured ligament with a new ligament or graft. Currently, these procedures can be supported by the surgeon's direct view, through the insertion of a miniature camera through one of the portals created in the joint. The camera is connected to a video monitor in the operating room. When this procedure is performed, the surgeons' only view is through a very small tube, without any reference to the three dimensions, making it very difficult to orient themselves in space and resulting in a complicated procedure that takes a long time to master. Furthermore, this imaging technique requires very close magnification because the area being operated on is very small. This magnification makes it impossible to see all the soft tissues and bones as a whole, meaning that all types of bone implants lack millimeter precision and a quantitative evaluation of the results. Another possibility, distinct from direct visualization, is the use of surgical planning and navigation software along with appropriate guided surgical instruments. This allows for an approximate reconstruction of the patient's limb to be displayed on a screen by taking measurements of key points from different parts of the bone. This reconstruction is merely an approximation, as this technology actually allows for the measurement of bone axes. These software programs obtain images from diagnostic tests such as CT (Computed Tomography) or MRI (Magnetic Resonance Imaging) in DICOM (Digital Imaging and Communications in Medicine) format. From these images, a reconstruction of the relevant bone and soft tissue structures, such as muscles, ligaments, tendons, organs, etc., is performed. Once the reconstruction is complete, specific cutting guides, guides for drilling and inserting specific instruments, or custom-made surgical instruments for each patient are designed using other CAD software. Therefore, the surgical instruments consisting of the sensors implanted in the femur and tibia require a prior tracking process; that is, a process of obtaining the exact shape and position of the bone to provide this information to the software. For this tracking process, the patient must undergo a CT scan or MRI to create a 3D reconstruction of the bones. Subsequently, in the operating room, the surgeon must track the bone by touching different points so that the navigation system recognizes its position, placing the sensor in a specific location. This entire preliminary tracking process exposes the patient to excessive radiation, greatly lengthens the time required to perform cruciate ligament reconstruction under suitable conditions, and entails a high healthcare cost. Another critical problem encountered in these types of cruciate ligament reconstruction procedures is that these systems do not provide surgeons with information about the elongation of the graft or the orientation and position of the femoral and tibial tunnels, which leads to many errors in the placement of these tunnels and, consequently, to graft ruptures due to improper elongation. The knee is not a hinge; it is a joint in which the medial condyle rotates about its center, while the lateral condyle rotates and translates between 6 and 8 mm during knee flexion and extension. Therefore, the tibia moves over the femur, and from a lateral or sagittal view, the tibial point relative to the femoral point does not mathematically describe an arc. Studies show a wide variability in the shapes and sizes of both the insertion areas and the lengths of the ligament bodies. Isometricity implies a state of constant length for the graft fibers. In an isometric position of the graft, the tension on it is uniform throughout its range of motion. All surgeons strive to obtain a graft that is isometric and constant in each cycle of knee flexion and extension, but with these systems, it is a very complicated task because the line connecting the femoral entry point to the tibial insertion point is considered an arc with a concentric point. However, this line is not real, as already indicated, since the knee does not behave like a hinge. Therefore, technical errors are the main cause of problems in cruciate ligament reconstruction, the primary one being the creation of bone tunnels in a non-anatomical position. Small errors, quantifiable as few millimeters in the choice of the femoral entry point, can cause significant changes in the length and tension of the graft, modifying the knee's kinematics and, consequently, the graft's elongation with each repetition cycle. Thus, a graft placed too anteriorly on the femur and fixed in extension will result in a ligament that is under tension and excessively elongated in flexion, causing a flexion deficit. If the graft is under tension in flexion, there will be unacceptable laxity in extension. Furthermore, if this is combined with a very anterior tibial tunnel, the graft will also be over-tensioned in the final degrees of extension due to impingement by the roof of the notch or due to a deficit in those final degrees. On the other hand, when the femoral tunnel is very posterior, the graft is stretched in extension and weakened. If it holds without rupturing, it causes a flexion contracture with a deficit in extension in the final degrees. Therefore, inadequate tension, whether excessive or insufficient, can lead to failure of cruciate ligament reconstruction in both bone-tendon-bone and hamstring grafts. Uncontrolled tension increases vascularization of the graft and delays graft integration, in addition to increasing joint stress, causing stiffness, pain, and subsequently, osteoarthritis. Insufficient tension results in residual instability. Given all the problems that arise due to the error in defining the femoral and tibial tunnels that occurs with current ligament replacement systems, it is necessary to find a way to improve these cruciate ligament reconstruction systems or to find another type of system that allows for greater efficiency in locating these tunnels and that also solves the problems due to prior bone tracking. Description of the invention The system for replacing a cruciate ligament using a surgical navigator, without prior diagnostic tests, presented here, for its replacement by a new ligament or plasty, comprises a first and a second sensor of natural or artificial markers, capable of being anchored in a location of the femur and tibia of the patient respectively, both locations being fixed in surgical time, such that they allow the determination of a coordinate axis. It also includes a navigated instrument with sensors of natural and / or artificial landmarks, consisting of a femoral guide for obtaining an entry point of a femoral tunnel and a tibial guide for its placement in a specific anatomical position corresponding to the entrance of the tibial tunnel, the order of placement of the femoral guide and the tibial guide being alternative. For its part, the surgical navigator comprises virtual and augmented reality software and artificial intelligence that, from the data obtained through the first and second sensor, allows the determination of a coordinate axis and, from the data obtained through the sensors of the navigated instrument, is capable of simulating and navigating the femoral and tibial tunnels, obtaining the simulation of the plasty in virtual and augmented reality and a measurement of the length of the plasty based on the kinematics of the tibia on the femur of the patient, so that, through artificial intelligence, it determines the isometric entry point of the femoral tunnel, the ellipse that describes the exit point of the tibial tunnel on the entry point of the femoral tunnel, and the trajectory of this femoral tunnel for an isometry of the plasty. The surgical navigation-guided cruciate ligament replacement system proposed here represents a significant improvement over the state of the art. This is because a system is achieved that is capable of monitoring the behavior of the plasty by evaluating the specific kinematics of the patient, and this without the need to perform no prior diagnostic testing. This is a very significant advantage of this system, as monitoring the graft's behavior allows for determining the ideal position of the femoral tunnel to minimize elongation of the graft. In other words, it determines the most isometric entry point for the femoral tunnel. All of this is achieved without tracking any bone, meaning without having to touch multiple points on the bone with sensors for the navigation system to recognize its position, making it less invasive for the patient. No prior diagnostic tests are required, as the system simply navigates two tunnels determined by the instruments and positioned in space by sensors temporarily anchored to the bones. This offers advantages such as reduced patient radiation exposure and lower healthcare costs per patient. Furthermore, after placing a sensor with a quick-release pin on the tibia and femur, the navigation system is ready to operate in just a few seconds, significantly reducing treatment time. Another important advantage of this system is that it allows navigating the paths of other tunnels that may need to be made in the same bone to avoid confluence between them. Thus, in cases where there is residual rotational instability after anterior cruciate ligament (ACL) reconstruction surgery, worse functional outcomes are expected, and the rate of re-ruptures and the need for revision surgery increases. In these cases, knee stabilization using an extra-articular Lemaire graft is necessary. The problem that arises in these cases is that a second tunnel must be created in the femur. This system allows for navigation of the trajectory of this additional tunnel, enabling a simulation that calculates the distance to the femoral tunnel for ligament reconstruction by measuring the amount of bone stock between the five walls of both tunnels. The surgeon can modify the trajectory as many times as needed until the safe distance is adequate. This is a significant advantage of this system. Thus, it is a very effective system that makes it possible to improve the processes of cruciate ligament reconstruction, obtaining greater surgical precision, and facilitating both the work of the surgeon and obtaining a satisfactory final result for the patient. Brief description of the drawings In order to aid a better understanding of the characteristics of the invention, according to a preferred embodiment thereof, a series of drawings are provided as an integral part of this description, where, for illustrative and non-limiting purposes, the following has been represented: Figure 1 shows a perspective view of the first and second sensors in their position on the femur and tibia of a system for replacing a cruciate ligament using a surgical navigator, for a first preferred embodiment of the invention. Figure 2 shows a perspective view of the placement of the tibial guide and the simulation of the tibial tunnel, of a system for replacement of a cruciate ligament using a surgical navigator, for a first preferred embodiment of the invention. Figure 3 shows a perspective view of the placement of the antegrade femoral guide and the simulation of the femoral tunnel, of a system for replacing a cruciate ligament using a surgical navigator, for a first preferred embodiment of the invention. Figure 4 shows a perspective view of the placement of the retrograde femoral guide and simulation of the femoral tunnel, of a system for replacement of a cruciate ligament using a surgical navigator, for a second preferred embodiment of the invention. Figure 5 shows an on-screen simulation from the software of the present invention, with the simulation of the femoral and tibial tunnels and the graft, including a representation of the femur and tibia bones, of a system for cruciate ligament replacement using a surgical navigation system, for a first preferred embodiment of the invention. Figure 6 shows an on-screen simulation from the software of the present invention, with the simulation of the femoral and tibial tunnels and the graft as they actually appear, without the representation of the femur and tibia bones, of a system for cruciate ligament replacement using a surgical navigation system, for a first preferred embodiment of the invention. Figure 7.- Shows a perspective view of the measurements of the plasty in different positions of the tibia, of a system for replacing a cruciate ligament using a surgical navigator, for a first preferred embodiment of the invention. Figure 8 shows a perspective view of the measurements of the graft in different positions of the tibia for an isometric graft, of a system for replacement of a cruciate ligament using a surgical navigator, for a first preferred embodiment of the invention. Detailed description of a preferred embodiment of the invention As shown in the figures provided, it can be observed that in a first preferred embodiment of the invention, the system for cruciate ligament replacement using a surgical navigation system, without prior diagnostic testing, proposed herein, for replacing the cruciate ligament with a new ligament or graft (3), comprises a first and a second sensor (1, 2) of natural and / or artificial landmarks, capable of being anchored to a location on the patient's femur (4) and tibia (5), respectively, both locations being fixed during the surgical procedure. As shown in Figure 1, in this first preferred embodiment of the invention, the first sensor (1) is anchored to the anterior surface of the femur (4) and the second sensor (2) is anchored to the anterolateral metaphyseal region of the tibia (5). However, these first and second sensors (1, 2) can be anchored to any anatomical location on the femur (4) and tibia (5) where the surgeon finds it convenient.What's really important is that they remain in a fixed location during surgery. The system also includes a navigated instrumentation with sensors (6), these sensors being of natural and / or artificial marks. In this implementation mode, all sensors of natural and / or artificial marks, i.e., the first and second sensors (1, 2) and the sensors of the navigated instrumentation, have Aruco markers. The navigated instrumentation consists of a femoral guide (9) for obtaining an entry point of a femoral tunnel (7) and a tibial guide (10) for its placement in a specific anatomical position corresponding to the entrance of the tibial tunnel (8), the order of placement of the femoral guide (9) and the tibial guide (10) being alternative. In this first preferred embodiment of the invention, as shown in Figure 3, the femoral guide (9) is an antegrade guide (9.1), however, in other embodiments, the femoral guide (9) can be a retrograde guide (9.2), as shown in Figure 4, for a second embodiment. In this system, the surgical navigator comprises virtual and augmented reality software and artificial intelligence that, based on the data obtained through the first and second sensors (1, 2), allows the determination of a coordinate axis. Likewise, once the coordinate axis has been established, and based on the data obtained from the sensors (6) of the navigated instrument, the navigator is able to simulate and navigate the femoral and tibial tunnels (7, 8), obtaining a simulation of the graft (3) in virtual and augmented reality, and a measurement of the graft length (3) based on the kinematics of the tibia (5) on the femur (4) of the patient. With all this, the surgical navigator, using artificial intelligence, determines the isometric entry point (11) of the femoral tunnel (7), the ellipse described by the exit point (12) of the tibial tunnel (8) on the entry point (11) of the femoral tunnel, and the trajectory of this femoral tunnel (7) for an isometric view of the graft (3). In this first preferred embodiment of the invention, after the placement of the first and second sensors (1, 2), the tibial guide (10) is placed, as shown in Figure 2. In this case, the anatomical position of said tibial guide (10) for the exit point (12) of the tibial tunnel (8) is taken to be the center of the tibial spines, 7 mm from the posterior part of the junction of both inverted crests of the tibia (5), with a medial angle of 30º at the level of the center of the anterior tibial tuberosity (TTA). The browser reads the trajectory of the tibial tunnel (8) in a few seconds and performs a simulation of it, which is represented in Figure 2, based on the selected diameter and length. The tibial tunnel (8) is then drilled. In other implementations, it is possible to simulate the trajectory of the tibial tunnel (8) and not drill it until later, once the entry point (11) of the femoral tunnel (7) has been determined and the femoral tunnel (7) is drilled. Next, the femoral tunnel (7) is simulated, and for this purpose the antegrade femoral guide (9.1) is placed, as shown in Figure 3. In other embodiments, it can be done in reverse order, that is, first simulate the femoral tunnel (7) and then the tibial tunnel (8), but in any case the femoral and tibial guides (9, 10) should not be placed simultaneously, but alternately. In this first mode of implementation, an antegrade femoral guide (9.1) is used and placed by the surgeon in the medial femoral condyle (4), 8 mm from the cartilage line, both posteriorly and cranially. At this point, the navigation system marks the trajectory of the femoral tunnel (7) and simulates it in the system, as shown in Figure 3. The surgeon can change the entry point (11) of the femoral tunnel (7) as many times as desired. In the case of the second embodiment in which a retrograde femoral guide is used (9.2), represented in Figure 4, the navigator detects that it is a retrograde guide and performs the same functions as in the previous case. In both cases, the entry point (11) of the femoral tunnel (7) is determined. Knowing the exit point (12) of the tibial tunnel (8) and the entry point (11) of the femoral tunnel (7), the browser performs a simulation of the graft (3), as shown in Figures 5 and 6. In Figure 5, a representation of the femur and tibia bones (4, 5) has been added for a better understanding of the image, but what is actually shown on the screen to the surgeon is what appears in Figure 6. Next, considering the entry point (11) of the femoral tunnel (7) to be fixed in space, the surgeon performs the flexion and extension movement of the knee, keeping the femur (4) fixed and moving the tibia (5) by means of flexion and extension maneuvers. The tibia (5) is left hanging from the operating table to allow these movements to be performed freely. During this process of movement of the tibia (5) with respect to the femur (4), the navigation software tracks the exit point (12) of the tibial tunnel (8) on the entry point (11) of the femoral tunnel (7), simulating the future behavior of the intra-articular graft (3) in the range of motion of the knee according to the patient's kinematics, as shown in Figure 7. In this way, the maximum value in flexion, in extension and, above all, the value of the elongation of the graft (3) in each flexion and extension cycle is determined. Since the knee is not a hinge, but the tibia bone (5) has a displacement movement on the femur (4), from a lateral, or sagittal, view, the exit point (12) of the tibial tunnel (8) on the femur mathematically does not describe an arc, but an ellipse, therefore, an elongation of the plasty (3) occurs in each flexion and extension cycle, which is recorded by the navigation software of the present invention. Figure 7 shows the result of the elongation of the graft in a flexion and extension movement of the knee (the rotation of the tibia is indicated by an arrow, but the tibia is not represented in the rotation movement for greater clarity) and in this case the graft shows a variable elongation, which is greater for the extension position of the knee. Once the surgeon has performed the flexion and extension movements of the patient's knee, the navigation software using artificial intelligence determines in the sagittal view the entry point (11) of the most isometric femoral tunnel (7) that will allow a constant elongation value of the plasty (3), and which can be represented with a target-shaped graphic. In other words, the moment when no elongation of the graft (3) is detected during the 5 flexion and extension movements, as shown in Figure 8, where the graft maintains the same length in any knee position, means that the entry point (11) of the femoral tunnel (7) has been found, allowing for isometric alignment of the graft (3), and the femoral tunnel (7) is then drilled. This isometric entry point (11) is marked in the navigation software with a target-shaped graphic. The tibial tunnel (8) has already been drilled, but the femoral tunnel (7) has been left undrilled until now in order to be able to change its entry point (11) if necessary, looking for the isometry of this entry point (11). Furthermore, in this first preferred embodiment of the invention, based on the data provided by an anterograde femoral guide (9.1) located on the side of the femur (4) and the trajectory of the femoral tunnel (7), the surgical navigator is capable of navigating possible trajectories of an additional tunnel for performing an extra-articular reinforcement plasty, for example of the Lemaire type, determining the trajectory that presents a certain safety distance to the femoral tunnel (7). Therefore, in cases where the surgeon wishes to create new bone tunnels for the implantation of reinforcement grafts, the trajectories of the femoral and tibial navigation instruments are recorded. Using these same instruments, a new trajectory for the reinforcement graft is projected, and the software is able to measure the distance between the potential new tunnel and the existing tunnels for the femur and tibia, ensuring that the tunnels do not overlap. This prevents the new reinforcement tunnel from crossing the cruciate ligament tunnel and rupturing the graft.

Claims

1. A system for cruciate ligament replacement using a surgical navigation system, without prior diagnostic testing, for its replacement with a new ligament or graft (3), characterized in that it comprises: • a first and a second sensor (1, 2) of natural and / or artificial landmarks, capable of being anchored to a location on the femur (4) and tibia (5) of the patient respectively, both locations being fixed during the surgical procedure; • a navigated instrument with sensors (6) of natural and / or artificial landmarks, comprising a femoral guide (9) for obtaining an entry point (11) of a femoral tunnel (7) and a tibial guide (10) for its placement in a specific anatomical position corresponding to the entrance (13) of the tibial tunnel (8), the order of placement of the femoral guide (9) and the tibial guide (10) being alternative; wherein the surgical navigation system comprises virtual and augmented reality software and artificial intelligence that,Based on the data obtained through the first and second sensors (1, 2), a coordinate axis is determined, and based on the data obtained through the sensors (6) of the navigated instrument, it is possible to simulate and navigate the femoral and tibial tunnels (7, 8), obtaining the simulation of the graft (3) in virtual reality and augmented reality, and a measurement of the length of the graft (3) as a function of the kinematics of the tibia (5) on the femur (4) of the patient, so that through artificial intelligence it determines the isometric entry point (11) of the femoral tunnel (7), the ellipse that describes the exit point (12) of the tibial tunnel (8) on the entry point (11) of the femoral tunnel and the trajectory of the femoral tunnel (7) for an isometry of the graft (3).

2. System according to claim 1, wherein the sensors (1, 2, 6) of natural and / or artificial marks are sensors with Aruco markers.

3. System according to any of claims 1 or 2,where the femoral guide (9) is an anterograde guide (9.1).

4. System according to any of claims 1 or 2, wherein the femoral guide (9) is a retrograde guide (9.2).

5. System according to any of the preceding claims, wherein the determined anatomical position of the tibial guide (10) for the exit (12) of the tibial tunnel (8) is at the center of the tibial spines, 7 mm from the posterior aspect of the junction of both inverted crests of the tibia (5), with a medial angle of 30° at the level of the center of the anterior tibial tuberosity (ATT).

6. System according to any of the preceding claims, wherein the first sensor (1) is anchored on the anterior surface of the femur (4) and the second sensor (2) is anchored in the anterolateral metaphyseal area of ​​the tibia.

7. System according to any of the preceding claims,Where, based on the data provided by an antegrade guide (9.1) located on the side of the femur (4) and the trajectory of the femoral tunnel (7), the surgical navigator is able to navigate possible trajectories of an additional tunnel for performing an extra-articular reinforcement plasty, determining the trajectory that presents a certain safety distance to the femoral tunnel (7).

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