Surgical system for cutting anatomical structures according to at least one target plane

Abstract

A surgical system for cutting a patient's anatomy according to at least one target plane defined in a coordinate system of the anatomy, comprising: (i) a robotic device comprising: - an end effector comprising a cutting tool or a cutting block, - an actuation unit comprising three to five motorized degrees of freedom attached to the end effector configured for adjusting the position and orientation of the cutting tool or the cutting block relative to each target plane; (ii) a passive articulated lockable holding arm supporting the actuation unit; (iii) a tracking unit configured to determine in real time the pose of the cutting plane relative to the coordinate system of the anatomy, the tracking unit comprising a tracker configured to be rigidly attached to the actuation unit and a tracker configured to be rigidly attached to the end effector; (iv) a control unit configured to determine the pose of the cutting plane relative to the target plane and to control the actuation unit so as to align the cutting plane with the target plane.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on May 10, 2019 (application number 201910389767.0, invention title "surgical system for cutting anatomical structures according to at least one target plane", priority date May 14, 2018). Technical Field

[0002] The present invention relates to a robotic system for cutting a patient’s anatomical structure according to at least one target plane. Background Technology

[0003] Total knee arthroplasty typically involves cutting the femoral and tibial epiphyses to remove damaged bone and cartilage and install a knee prosthesis.

[0004] Therefore, surgeons must use a oscillating saw to make five or more cuts to the femur and one or more cuts to the tibia using a cutting block.

[0005] Figure 1 This is a schematic perspective view of a knee intended to receive a knee prosthesis, which includes a femoral component FC and a tibial component TC. Typically, the cuts to be made on the femoral F are: a distal cut along plane F1, an anterior cut along plane F2, a posterior cut along plane F3, and an anterior chamfer F4 and a posterior chamfer F5 connecting the distal plane to the anterior and posterior planes, respectively. Cuts must be made on the tibial T along plane T1.

[0006] Computer-aided systems have been developed to enable surgeons to accurately perform all these planes in a shorter amount of time.

[0007] For example, document WO2014 / 198787 teaches a surgical system including a handheld device comprising: - The base, designed to remain in the user's hands. - An end effector, used to mount a cutting blade, designed to mill a planned volume of a part of the patient's body. - An actuation unit, connected to the base and the end effector, for moving the cutting blade relative to the base to process the planned volume. - A support unit, which is connected to the base or to the end effector, provides a partial mechanical connection between the base or end effector and the part to be treated.

[0008] The system also includes a tracking unit configured to determine the posture of at least one of the cutting blade, end effector, and base in real time relative to the part to be treated.

[0009] The system's control unit is configured as follows: (a) Based on the measured posture, calculate the optimized path of the cutting blade or end effector relative to the base in real time. (b) Determine whether the calculated path of the cutting blade or end effector can be achieved without changing the orientation of the base, and if not, determine possible repositioning of the base relative to the portion to be treated. (c) Configure the actuation unit to move the end effector according to the calculated path, and (d) Repeat steps (a) through (c) until the planned volume has been processed.

[0010] The user interface is used to provide feedback information to the user.

[0011] However, even though the robot described in this document is very effective for milling body parts, the design of the actuation unit in the form of a planar five-bar linkage, as shown in document WO2014 / 198787, is not optimal for sawing body parts. In fact, the degrees of freedom provided by the actuation unit are not suitable for multiple cutting planes to achieve knee arthroplasty using a saw mechanism that coincides with each plane to be cut.

[0012] Document US2011 / 0130761 teaches a robotic system specifically designed to guide a saw for making several cuts in the femur during total knee arthroplasty. The system includes a navigation system located in a position and orientation tracker attached to the bone and instruments.

[0013] The system includes a base rigidly attached to the femur via at least one pin.

[0014] The adjustment system, which includes two screws, is attached to the base via a ball-and-socket joint.

[0015] The cutting block, which includes a slot designed to guide the saw blade within the cutting plane, is attached to an arm that supports two motors.

[0016] The arm is pivotally mounted on the adjustment system, and the orientation of the arm relative to the base can be adjusted by two screws on the adjustment system.

[0017] The arm can rotate relative to the base via a first motor about a first rotation axis, and the cutting block can rotate relative to the arm via a second motor about a second rotation axis, with the two rotation axes being parallel to each other.

[0018] In use, the base is rigidly fixed to the femur by at least one pin, and then the positions of the first and second rotation axes are modified by an adjustment device that is manually operated by the surgeon and has visual feedback from the navigation system.

[0019] Once a suitable location is found, remove the tracker attached to the cut block and stop navigating the cut block.

[0020] The motor is then operated to move the cutting block about two axes of rotation. The surgeon then uses a saw received in the cutting block to cut the bone along each desired cutting plane. Therefore, the system cannot detect or compensate for potential misalignment of the cutting block slot relative to the target plane in real time.

[0021] The main drawback of this system is that the rigid fixation of the base to the femur is highly invasive, as it requires inserting a large pin into the bone to bear the weight of the robot and compensate for the forces applied during sawing by the saw in the cutting block carried by the robot. The large pin, which bears significant weight and responds to critical strength, is susceptible to fracture. Furthermore, weight and strength can cause movement of the pin within the bone, which will significantly affect the system's accuracy.

[0022] Furthermore, the axis of rotation must be adjusted very precisely to achieve all target planes. However, this adjustment is difficult and prone to errors or inaccuracies because it is done manually and only aided by visual feedback provided by the navigation system. If the cutting plane shifts slightly during sawing due to forces applied by the user or the saw, it should be difficult for the user to detect and manually correct these adjustments.

[0023] Furthermore, if the pin is not placed in the correct position due to surgical limitations, anatomical limitations, or misuse, the robot will not be able to position the cutting block to make all incisions accessible, and it will be difficult to reposition the pin in the bone at slightly different locations.

[0024] In addition, the system does not allow tibial cutting when the base is fixed to the femur, so a different specific device is required to cut the tibia, which requires additional time, additional pins, additional systems and effort. Summary of the Invention

[0025] The disclosed embodiments provide a surgical system designed to guide a cutting tool to cut a patient’s anatomical bone structure according to at least one target plane, without requiring any invasive attachments to the patient’s bone, while precisely controlling the position and orientation of the cutting tool to reach the target plane.

[0026] Therefore, the surgical system includes: (i) A robotic device comprising: - End effector, which includes a cutting tool or cutting block, - An actuation unit, comprising three to five degrees of freedom of motion, is attached to the end effector and configured to adjust the position and orientation of the cutting tool or cutting block relative to each target plane. (ii) A passively articulated lockable retaining arm that supports the actuation unit; (iii) A tracking unit configured to determine the orientation of the cutting plane relative to the coordinate system of the anatomical structure in real time, the tracking unit including a tracker configured to be rigidly attached to the actuation unit and a tracker configured to be rigidly attached to the end effector; (iv) A control unit configured to determine the orientation of the cutting plane relative to the target plane and control the actuation unit to align the cutting plane with the target plane. The control unit is configured to implement a control loop that includes the following steps: - (S1) Use the positioning information provided by the tracking unit to determine the posture of the actuator, end effector and anatomical structure; - (S2) Calculate the deviation between the cutting plane and the target plane; - If the deviation is less than the threshold, the cutting tool is allowed to operate and the process returns to step (S1) to determine the new posture of the actuating unit, end effector, and anatomical structure; - If the deviation is greater than or equal to the threshold, then (S3) the cutting plane and the target plane are projected into the coordinate system of the actuation unit. - (S4) Calculate the correction matrix between the plane attached to the output end of the actuation unit and the cutting plane; - (S5) Update the target plane using the correction matrix calculated in step (S4); - (S6) Calculate the new orientation of the actuation unit to align the cutting plane with the updated target plane, and determine the movement to be applied by the motor of the actuation unit; - Activate the actuator to apply the movement.

[0027] A "holding arm" refers to an articulated arm made of at least two sections and capable of being locked in a given position. Holding arms are attached to stabilizing structures in the operating room, such as operating tables, leg retainers, or mobile trolleys with stop wheels.

[0028] "Actuation unit" refers to a series of rigid sections connected together by kinematic degrees of freedom. The actuation unit is rigidly attached to the end of the retaining arm. The actuation unit is controlled by the control unit.

[0029] A "planar mechanism" refers to a mechanism that restricts an object to movement only within a plane, and it has at least two degrees of freedom. For example, a planar mechanism can be made of two translational degrees and one rotational degree.

[0030] "Cut tool" refers to a saw, cutter, laser, or high-pressure water jet that can cut through bone. For knee surgery, cut tools are typically made of a power unit that carries and activates an oscillating saw blade.

[0031] In this article, "anatomical structure" refers to a basically rigid structure such as bone or cartilage or a joint formed by two or more bones.

[0032] In this paper, “pose” refers to the 3D position and 3D orientation of the tool in up to six degrees of freedom. It should be noted that, depending on the application, “pose” may not be determined by all six degrees of freedom, but by only one degree of freedom or a subset including fewer than six degrees of freedom.

[0033] "Alignment" of the cutting plane with the target plane, in this document, means that the cutting plane deviates from the target plane by a distance of less than 1 mm and an angle of less than 1°. Preferably, the cutting plane and the target plane completely coincide. To measure such a distance, a selected point on the target plane is projected onto the cutting plane, and the distance between the projected point and the target plane is measured. The selected point should be located near the anatomical structure to be cut. For example, the selected point could be an anatomical point of the anatomical structure, or the center of the anatomical structure to be projected onto the target plane.

[0034] According to one implementation, the tracking unit is an optical tracking unit, which includes a camera and an optical tracker detectable by the camera.

[0035] The camera is advantageously configured to operate at a frequency that is at least twice the frequency at which the control unit is configured to implement each iteration of the control loop (e.g., each sequence of steps (S1) to (S6)).

[0036] According to one implementation, the camera is configured to operate at a frequency greater than 200 Hz (preferably greater than 300 Hz).

[0037] According to one implementation, the control unit is configured to perform each iteration of the control loop at a frequency greater than 50 Hz (preferably greater than 100 Hz).

[0038] According to one embodiment, the control unit is configured to implement a control loop including an additional step, which includes evaluating between steps (S1) and (S2) whether the current posture of the actuation unit can be calculated based on the positioning information provided by the tracking unit.

[0039] Advantageously, the control unit may be further configured to implement a control loop including an additional step of storing the current posture of the actuation unit in the memory of the control unit, and, if the current posture can be determined, implementing step (S2) using the current posture of the actuation unit.

[0040] The control unit may be further configured to implement a control loop that includes the following additional step: if the current posture of the actuation unit cannot be determined, assessing whether the previous posture of the actuation unit is stored in the memory of the control unit.

[0041] According to one embodiment, the control unit is further configured to implement a control loop including the following: if the previous posture of the actuation unit is stored in the memory of the control unit, then the previous posture is used to implement step (S2).

[0042] The control unit can also be configured to implement a control loop that includes the following: if the previous posture is not stored in the memory of the control unit, then step (S1) is executed again.

[0043] According to one embodiment, the control unit is configured to implement a control loop including: calculating the norm of the correction matrix between steps (S4) and (S5) and comparing the norm with a determined threshold.

[0044] Advantageously, the control unit is configured to implement a control loop including the following: if the norm is less than a threshold, then step (S5) is implemented using the correction matrix.

[0045] If the norm is greater than the threshold, the control unit can be further configured to stop the actuation unit.

[0046] According to one embodiment, the control unit is configured to determine whether the posture of the actuation unit used in steps (S2) to (S4) is a previously stored posture, and: - If the gesture is a previously stored gesture, erase the previously stored gesture from memory and return to step (S1); - If the stated posture is the current posture of the actuation unit, then an error is output.

[0047] According to one embodiment, the robotic device includes a light emitter configured to be activated by a control unit to emit light when the norm of the correction matrix is ​​greater than a threshold.

[0048] According to one implementation, the control unit is configured to output a message to the user to check whether the tracker of the actuation unit is in the camera's field of view.

[0049] According to one implementation scheme, the surgical system includes: (i) A robotic device, the robotic device comprising: - An end effector, the end effector comprising a cutting tool or a cutting block, - An actuation unit, comprising three to five degrees of freedom, attached to the end effector and configured to adjust the position and orientation of the cutting tool or cutting block relative to each target plane. (ii) A passively articulated lockable retaining arm that supports an actuation unit; (iii) A tracking unit configured to determine the orientation of the cutting plane relative to the coordinate system of the anatomical structure in real time, the tracking unit including a tracker configured to be rigidly attached to an actuation unit and a tracker configured to be rigidly attached to an end effector; (iv) A control unit configured to determine the orientation of the cutting plane relative to the target plane and to control the actuation unit to align the cutting plane with the target plane. The control unit is configured to implement a control loop that includes the following steps: - Calculate the deviation between the cutting plane and the target plane based on the relative posture of the actuator, end effector, and anatomical structure provided by the tracking unit; - If the deviation is less than the threshold, the cutting tool operation is allowed; - If the deviation is greater than the threshold, calculate the correction matrix between the plane attached to the output end of the actuation unit and the cutting plane; - Update the target plane using the calculated correction matrix; - Calculate the new pose of the actuation unit to align the cutting plane with the updated target plane.

[0050] Advantageously, in the case of knee arthroplasty, all tibial and femoral cuts can be performed with the patient's leg in the same position and with minimal movement of the system. Attached Figure Description

[0051] Based on the accompanying drawings, other features, embodiments, and advantages of the exemplary embodiments will become apparent from the following detailed description, wherein: - Figure 1 The diagram schematically illustrates the incisions made in the femur and tibia for the purpose of implanting a knee prosthesis. - Figure 2 An overview of the surgical system according to the present invention is shown; - Figure 3A and Figure 3B This is a perspective view of a robotic device according to a first embodiment of the present invention; - Figure 4 This is a perspective view of a robotic device according to a second embodiment of the present invention; - Figure 5 This is a perspective view of a robotic device according to a third embodiment of the present invention; - Figure 6 This is a schematic diagram of the architecture of the actuation unit according to the fourth embodiment of the present invention; - Figure 7 This is a schematic diagram of the architecture of the actuation unit according to the fifth embodiment of the present invention; - Figures 8A-8F They are shown respectively as follows Figures 3A-3B The diagram shows a perspective view of the apparatus during tibial cutting, distal cutting, anterior cutting, posterior cutting, anterior chamfering cutting, and posterior chamfering cutting. - Figure 9 An embodiment of the retaining arm is shown; - Figure 10 Another implementation of the retaining arm is shown; - Figure 11 An embodiment of the support unit attached to the tibia is shown; - Figure 12 An embodiment of the support unit attached to the femur is shown; - Figure 13 An embodiment of the support unit for supporting a soft tissue retractor is shown; - Figure 14 Another embodiment of the support unit for supporting the soft tissue retractor is shown; - Figure 15 An embodiment of cutting ten target planes on the femur using the robotic device according to the invention is illustrated schematically; - Figure 16 This describes an implementation scheme for a compensation control loop that utilizes a tracker attached to an end effector and implemented by a control unit. - Figure 17 An embodiment of a compensation control loop is shown, which is configured to allow operation of the robotic device under intermittent visibility of a tracker attached to the actuator unit; - Figure 18 This illustrates a large robot with six degrees of freedom equipped with a planar mechanism as used in this invention; - Figures 19A-19C An implementation of a user interface is shown, which guides the positioning of the robotic device to make several cuts on the femur and tibia; - Figure 20 The setup of a robotic device according to one embodiment is shown; - Figure 21 The setup of a robotic device according to another embodiment is shown; - Figure 22 The setup of a robotic device according to another embodiment is shown; - Figure 23 yes Figure 21Or an enlarged view of 22, which shows one embodiment of the support unit; - Figures 24A-24C This illustrates an application of a robotic device performing vertical cutting; - Figure 25 One embodiment of the robotic device is shown, wherein the cutting tool is a cutting blade; - Figure 26 An implementation scheme for the motorized planar mechanism is shown; - Figure 27 One embodiment of the device is shown, in which a cutting block is mounted on a slider designed to adjust the distance between the cutting block and the bone to be cut; - Figures 28A-28B A perspective view of a cutting block is shown, which includes two and three slots for inserting cutting tools, respectively.

[0052] - Figures 29A-29F A perspective view of the robotic device is shown, in which the cutting block is positioned to cut the tibia and performs distal femoral cuts, anterior cuts, posterior cuts, anterior chamfer cuts, and posterior chamfer cuts, respectively; - Figure 30 One embodiment of the device is shown, in which a slider on which a cutting block is mounted includes multiple defined positions provided by a rack and pinion mechanism; - Figures 31A-31B Various implementation schemes of the support unit of the device are shown; - Figure 32 The setup of a robotic device with cutting blocks is shown; - Figure 33 It is a flowchart of a surgical procedure for performing at least one osteotomy to implement an embodiment of the present invention. Detailed Implementation

[0053] The following description focuses on knee surgery, particularly total knee arthroplasty (TKA), in which the anatomical structure to be cut is the joint formed by the femur and tibia.

[0054] However, the present invention is not limited to this specific application, but can be applied to a variety of applications. Generally, the embodiments can be used in any surgical intervention requiring at least one osteotomy step. In particular, but not limited to, these concepts can also be implemented in the following surgical applications: unicompartmental knee arthroplasty (UKA), tibial or femoral osteotomy, patellar resurfacing replacement, hallux valgus surgery, hip surgery for cutting the proximal femur, shoulder surgery for cutting the humeral head, spinal surgery for correcting deformities and performing vertebral osteotomy, ankle surgery, and maxillofacial surgery.

[0055] As will be explained in further detail below, the device is used in an environment where at least one target plane along which the anatomical structure must be cut must be planned prior to performing the cut.

[0056] Planning of at least one target plane is performed using the patient’s preoperative images (e.g., CT, MRI, ultrasound images, 2D or 3D X-rays combined with statistical shape models, PET, etc.) or intraoperative 3D data (e.g., intraoperative CT or CBCT, intraoperative MRI, ultrasound images, 2D or 3D intraoperative X-ray images, geometric data provided by a localization system and providing 3D points, 3D point clouds, surfaces reconstructed from 3D point clouds, etc.) or both.

[0057] There are various computer-aided surgical methods that use images or geometric patient data collected during surgery to register a target plane with a coordinate system attached to the anatomical structure to be cut.

[0058] Typically, intraoperative images or data are used to record preoperative images in a unique coordinate system attached to the anatomical structure, and are usually represented by a tracker that can use any computer-aided surgical technique (optical tracker made of reflective markers, optical tracker made of active LEDs, electromagnetic tracker made of coils, inertial sensors, ultrasonic sensors, combinations of RFID sensors, etc.).

[0059] Using any of these conventional computer-aided surgical methods results in a target plane having a known geometric representation in a coordinate system attached to the anatomical structure to be cut, and its movement is tracked in real time by a tracking unit, as will be detailed below. Typically, the surgical planning steps for total knee surgery result in five target planes defined in a coordinate system attached to a tracker fixed to the femur and one target plane defined in a coordinate system attached to a tracker fixed to the tibia.

[0060] Figure 2 An overview of the surgical system according to the present invention is shown.

[0061] Patient P lies on the operating table 500, for example, considering total knee arthroplasty (TKA).

[0062] For this purpose, cutting tools such as saws (which are designed to cut the tibia and femur along at least one target plane (preferably multiple target planes)) are used by users such as surgeons.

[0063] According to one embodiment, the cutting tool is held by an end effector attached to the robot device 100, and by an actuation unit 4 (in Figure 2(Not shown in the figure, but better seen in the following figures) constrained in each target plane. Alternatively, the cutting block, including at least one slot, is held by an end effector and constrained in each target plane by an actuation unit, and the surgeon can freely manipulate the cutting tool through the slot that defines the guide plane.

[0064] The robot device 100 is connected to the control unit 300 of the control actuation unit.

[0065] The control unit typically includes a power supply, an AC / DC converter, a motion controller that powers the motor of the actuation unit, a fuse, and a real-time control system interface circuit.

[0066] The system also includes a tracking unit 200, which enables the relative posture of the robotic device, end effector, and anatomical structure to be cut to be tracked in real time and shared between the real-time control unit and the planning system.

[0067] At least one coordinate system is attached to the anatomical structure, at least one coordinate system is attached to the end effector, and another coordinate system is attached to the robotic device.

[0068] The tracking unit measures the relative motion between the two coordinate systems in real time. Real time means high frequency above 20 Hz (preferably in the range of 100 to 500 Hz) with low latency (ideally less than 15 milliseconds).

[0069] Data obtained by the tracking unit is transmitted to the control unit 300 with low latency via any suitable connection, using wire 301 or wirelessly.

[0070] According to a preferred embodiment, the tracking unit is an optical tracking unit, which includes a camera and an optical tracker detectable by the camera.

[0071] The real-time control unit is able to execute the proposed real-time control algorithm at a reasonably high frequency and with low additional latency in order to compensate for small relative movements between the anatomical structure and the robotic device.

[0072] Preferably, the camera is configured to operate at a frequency at least twice the frequency at which the control unit implements the control algorithm.

[0073] According to a preferred embodiment, the camera is configured to operate at a frequency greater than 200 Hz (preferably greater than 300 Hz, for example, 330 Hz). The control unit is configured to implement the control algorithm at a frequency greater than 50 Hz (preferably greater than or equal to 100 Hz).

[0074] For surgical robotic devices, and more generally for any system that relies on one or more motors, different performance requirements must be defined to select the appropriate motor type (e.g., speed of movement, torque, positioning accuracy, etc.). Additional constraints or limitations (size capacity, available power supply, temperature, humidity, expected service life, etc.) may also be considered.

[0075] Because the robotic device is designed to compensate for small movements in real time, speed is one of the primary criteria. During TKA surgery, the leg is held by the surgeon or assistant, possibly with the aid of wedges or pads (usually located under the foot and / or on the outside of the leg) and / or with the aid of a specialized leg retainer. Therefore, the range of motion of the joint during the incision is very limited. Typically, the center of the femoral knee hardly moves more than 3 cm. Furthermore, the robotic device is held by retaining arms, making significant movement impossible during the incision. However, very small and rapid displacements (typically less than a few millimeters) occur constantly due to factors such as vibration. Therefore, motors are selected to be able to perform high accelerations so that the robotic device can compensate for these small but rapid movements almost in real time.

[0076] The motors of a robotic device are also capable of supporting potentially high loads or forces applied to the end effector. For example, a robotic device configured for TKA (Total Knockout Knockout) can grip a surgical saw (weighing approximately 1.5 kg) and must withstand some normal forces applied by the user while handling the saw during cutting. These constraints define the minimum torque that the motor must support / achieve under normal conditions.

[0077] Furthermore, especially for compact robotic devices, the size of the motors must be kept within limits. Therefore, engineers select suitable motors based on trade-offs between high speed, high torque, and small footprint.

[0078] The real-time control unit calculates the position of the end effector relative to the target plane in real time based on the measured posture.

[0079] In the accompanying drawing, the connection is indicated by line 301, but if the robotic device is battery powered, it can be wireless.

[0080] The control unit and tracking unit can be housed in a trolley 302 that can move within the operating room. They can also be mounted on a separate trolley, an articulated retaining arm, a lighting system, or the tracking unit can be directly mounted on the anatomical structure or attached to some component of the robotic device. For example, the end effector can rigidly support the electromagnetic transmitter, while the electromagnetic sensor can be attached to the anatomical structure.

[0081] The system may also include a visual user interface 400, designed to display feedback information to the user and enable the user to configure the system. Feedback information may include: - Instructions regarding the deviation (distance and / or angle) between the cutting plane and the target plane before cutting the anatomical structure; - An indication of whether the target plane can be achieved using the robot's current position; - Reorient the actuation unit relative to the anatomical structure to be cut so that the actuation unit can align the cutting plane with the target plane; - Instructions regarding the deviation (distance and / or angle) between the cutting plane and the target plane when cutting anatomical structures; The user interface 400 may advantageously include a screen, which may be located on a trolley in the operating room, for example on the same trolley 302 as the control unit and tracking unit, or on a separate trolley, or attached to the wall or ceiling of the operating room.

[0082] In addition to or in lieu of the screen, the user interface may also include indicators arranged on the robotic device itself to provide information to the user. These indicators may be made of LEDs or microdisplays arranged as pointing arrows, numbers, or letters.

[0083] Surgical systems in which the control unit, tracking unit, and / or user interface are embedded within the robotic device itself should still be within the scope of this invention, provided that the embedded units are powered by a sufficiently powerful power supply or battery and their size and weight do not hinder the user from manipulating the robotic device. For example, a miniature camera may be attached to the base of the actuation unit, and markers may be attached to anatomical structures and cutting tools.

[0084] According to one embodiment, the cutting tool is a surgical saw mounted on an end effector attached to an actuation unit. The saw 2 includes a housing 23 and a saw blade 22, the saw blade 22 oscillating in a defined plane (referred to as the "cutting plane") relative to the housing 23 (see details). Figure 3A Therefore, as long as the actuation unit 4 keeps the saw constrained in the target plane in real time, the saw blade can be operated to cut anatomical structures according to the target plane without any cutting blocks. Typically, the cutting plane is parallel to the longitudinal axis of the housing, and the saw blade oscillates on both sides of this axis; this type of saw is known in the medical field as a "sagittal saw".

[0085] According to one embodiment, the end effector is connected to the output of the actuation unit via a planar mechanism. The housing is typically positioned relative to the planar mechanism such that the cutting plane is parallel to the plane of the planar mechanism.

[0086] In the absence of such a planar mechanism, the virtual plane (referred to as the output plane in the following description) is considered to be attached to the output of the actuation unit.

[0087] According to one embodiment, the saw blade moves back and forth along the longitudinal axis of the housing; this type of saw is known in the medical field as a "reciprocating saw". The housing is typically positioned relative to the planar mechanism such that the cutting plane is orthogonal to the plane of the planar mechanism.

[0088] According to an implementation plan (see...) Figure 25 The cutting tool is a cutting blade 2'. In practice, especially if the blade tip is small (e.g., approximately 3 mm in diameter), the operation of the cutting blade constrained within the cutting plane allows for planar cutting. The blade tip can be spherical or cylindrical. Typically, a cylindrical blade tip with a diameter of 3 mm, constrained by a planar mechanism and held in a plane parallel to the cylindrical axis, will be rigid enough to form a large kerf and small enough to perform rapid cutting.

[0089] According to one embodiment (not shown), the cutting tool is a laser with a system for controlling the depth of laser penetration in order to avoid damaging the soft tissue behind the bone.

[0090] According to another embodiment (not shown), the cutting tool can be a high-pressure water jet or any other device that creates an incision in the anatomical structure.

[0091] According to another implementation, in order to cut soft tissue, the cutting tool can be a surgical scalpel or any electrically activated device such as a lancet.

[0092] In the accompanying drawings described below, the cutting tool is typically a saw, without any intended limitation on the invention.

[0093] The actuation unit advantageously includes three to five degrees of freedom. Advantageously, the actuation unit is designed to be as light and compact as possible. In some embodiments, the actuation unit may include six degrees of freedom.

[0094] According to one embodiment, the actuation unit 4 has a serial architecture consisting of multiple moving segments. Throughout the figures, the segments of the actuation unit are numbered 41, 42, and 43. In some embodiments, the actuation unit has three rotational degrees of freedom for adjusting the position and orientation of the cutting plane relative to each target plane. In other embodiments, the actuation unit has two rotational degrees of freedom and one or two translational degrees of freedom. Generally, the actuation unit includes three to five degrees of freedom, of which at least two are rotational degrees of freedom orthogonal to each other. In this document, the term "axis" refers to the geometric rotational or translational axis corresponding to the stated degree of freedom.

[0095] These sections and their components are integrated in an optimal manner, thereby keeping the robotic device as compact and light as possible, while maintaining sufficient strength to support planar joint movement and the cutting tool, as well as to resist some normal pressure applied by the user when operating the cutting tool.

[0096] In this paper, axes and segments are numbered starting from the base (i.e. the part of the robot that remains stationary when the robot is working) and moving toward the cutting tool with increasing numbers; this type of numbering is conventional for serial robot architectures.

[0097] Preferably, the actuation unit has an architecture consisting of three rotational degrees of freedom.

[0098] According to a preferred architecture, these segments are arranged such that the axes of rotation of two adjacent segments (i.e., the first axis and the second axis, or the second axis and the third axis) are substantially parallel to each other, and the first axis is substantially orthogonal to the third axis. Preferably, the axes of rotation of two adjacent segments are parallel to each other, and the first axis is orthogonal to the third axis.

[0099] according to Figures 3A-3B In the preferred embodiment shown, the second axis A2 is parallel to the first axis A1, and the third axis A3 is orthogonal to the first and second axes. Advantageously, the distance between the first and second axes is a fixed distance ranging from 80 mm to 100 mm. In this case, for application to TKA, tibial and femoral cutting can be performed using a single initial position of the robotic device.

[0100] When used in knee arthroplasty (TKA, UKA, etc.), the robotic device can be placed on the medial (internal) or lateral (external) side of the leg of interest. The first axis of rotation A1 is intended to be substantially orthogonal to the sagittal plane of the knee and substantially at the level of the medial or lateral epicondyle. For any application of the robotic device, some easily identifiable anatomical landmarks may be defined and used to align the actuating units within the range of motion.

[0101] according to Figure 4 In the alternative embodiment shown, the second axis A2 is substantially orthogonal to the first axis A1, and the third axis A3 is substantially parallel to the second axis. In a preferred embodiment of this embodiment, the second axis A2 is orthogonal to the first axis A1, and the third axis A3 is parallel to the second axis.

[0102] In use, the first axis of rotation is intended to be substantially parallel to the epicondyle axis of the knee, which is generally substantially parallel to the operating table and orthogonal to the leg axis.

[0103] according to Figure 5 In another configuration shown, the second axis A2 is substantially orthogonal to the first axis A1, and the third axis A3 is substantially orthogonal to the second axis A2. In a preferred embodiment of this configuration, the second axis A2 is orthogonal to the first axis A1, and the third axis A3 is orthogonal to the second axis A2. The first axis A1 and the third axis A3 are separated by a fixed distance.

[0104] and Figure 5 Compared to the architecture, Figures 3A-3B The architecture has the following advantages: taking into account the expected position of the first axis of rotation relative to the knee, the architecture is well-adjusted, meaning that during knee arthroplasty, for all expected target plane positions, small movements of the cutting plane can be achieved by small movements of the actuating unit.

[0105] Advantageously, for application in knee arthroplasty (TKA, UKA, etc.), the size of the actuation unit is sufficient to enable the performance of all femoral and tibial cuts with minimal movement of the robotic device. In this respect, Figure 5 The architecture is superior Figures 3A-3B and Figure 4 The architecture provides greater density for the actuating units. In use, when the first axis is substantially aligned with the epicondyle axis of the femur, Figure 5 The structure is still suitable for knee arthroplasty.

[0106] according to Figure 6 In the embodiment shown, the actuation unit 4 includes two rotational degrees of freedom and one translational degree of freedom, arranged as follows: a first axis A1 as the axis of rotation, a second axis A2 as the axis of translation substantially orthogonal (preferably orthogonal) to A1, and a third axis A3 as the axis of rotation substantially orthogonal (preferably orthogonal) to A1 and A2.

[0107] according to Figure 7 In the embodiment shown, the actuation unit 4 includes two rotational degrees of freedom and two translational degrees of freedom, arranged as follows: a first axis A1 as the translation axis, a second axis A2 as the translation axis substantially orthogonal (preferably orthogonal) to A1, a third axis A3 as the rotation axis substantially orthogonal (preferably orthogonal) to A1 and A2, and a fourth axis A4 as the rotation axis substantially orthogonal (preferably orthogonal) to A3.

[0108] In some implementations, the architecture of the actuation unit enables additional movement within the cutting plane—which can be motorized or non-motorized. By excluding six motorized degrees of freedom, the present invention distinguishes itself from large surgical robots by lower inertia (especially according to the first axis), and therefore by a greater need for greater responsiveness to compensate for bone movement in real time.

[0109] As will be explained in more detail below, the actuation unit 4 is controlled by the control unit 300. The control unit may be integrated into the robot device or located remotely from the robot device.

[0110] The cutting tool is connected to the actuating unit via a planar mechanism specified under reference numeral 24 throughout the drawing, the planar mechanism being configured to constrain the movement of the cutting tool within the cutting plane.

[0111] Advantageously, the cutting tool can be separated from the planar mechanism. Preferably, especially when the cutting tool is not intended to receive a tracker, the attachment device for the cutting tool provides reproducible fixation.

[0112] Several different architectures exist for implementing planar mechanisms. For example, a planar mechanism may consist of only a rotational axis and then a translational axis that carries the cutting tool along its longitudinal direction. Alternatively, a planar mechanism may consist of two orthogonal translational axes and then a rotational axis. According to another embodiment, the planar mechanism may be a slider in the form of an arcuate shape, including a rotational axis and then a translational axis that carries the cutting tool.

[0113] According to one implementation, the planar mechanism 24 is passive, meaning that the mechanism is not motorized and can be freely manipulated by the user. For example, in Figures 8A-8F In the illustrated embodiment, the passive mechanism 24 includes segments 24a-24d connected by three parallel rotation axes 24e-24g orthogonal to the cutting plane. One advantage of this passive mechanism is that it preserves all the user's perception while the saw is manipulated in the bone. For example, surgeons are accustomed to freely manipulating the saw in the cutting block and detecting when the saw blade reaches the posterior part of the bone by sensing changes in bone resistance, and this perception is fully preserved by the passive planar mechanism, which has very low friction at its joints.

[0114] Alternatively, the planar mechanism may also be at least partially effective, i.e., include at least one degree of motion. If the planar mechanism is movable, i.e., it includes at least two degrees of motion (see...). Figure 26 If so, the cutting can be performed automatically. It should be noted that all degrees of freedom are configured to move the cutting tool within the cutting plane.

[0115] Regardless of the implementation, the planar mechanism may include a locking system that locks each of its degrees of freedom once the cutting plane is aligned with the target plane.

[0116] It is possible to sterilize the actuation unit and planar mechanism sterile components before each intervention. However, in a preferred embodiment, the actuation unit, with its cable and equipped with the planar mechanism, is covered by a disposable sterile drape. Additional components of the system can also be protected under the sterile drape. This has the advantage of facilitating and reducing manufacturing and design costs, but also allows for easy use in multiple consecutive surgeries without the need for re-sterilization of the device. As with any conventional surgical instrument, the cutting tool itself is sterile. Typically, it is sterilized before each intervention using an autoclave. Different types of mechanical adapters between the sterile drape and the cutting tool are available. If the saw contains a tracking element (described in more detail below), such an adapter does not require highly precise reproducible fixation, which improves the accuracy of the overall system. The sterile drape covers the planar mechanism to facilitate the design and manufacture of the device. For example, this design allows the use of ball bearing mechanisms that would otherwise be difficult to autoclave.

[0117] The system includes a hinged, lockable retaining arm 5 that supports the actuation unit and is adapted to be connected to a mechanical support such as an operating table, a leg retainer, or mounted on a mobile trolley, the wheels of which can be blocked. The leg retainer is an adjustable mechanism configured to hold the leg in a given flexed position when the patient is lying on the operating table.

[0118] The retaining arm 5 is made of several articulated segments using ball-and-socket joints, rotational and / or translational joints.

[0119] The retaining arm can be manually locked via a knob (mechanical locking system) or actively locked via a dedicated actuator of the locking system. The locking system can be an electrical system, piezoelectric system, hydraulic system, pneumatic system, or a combination of these systems (e.g., a hydraulic cylinder driven by an electric motor). For example, Smith & Nephew sells a device called SPIDER. ™ A passively lockable retaining arm. The actuator can be a button, foot switch, remote button, etc. In order to operate the robot device, the user must keep the actuator active until the desired posture of the robot device has been achieved.

[0120] The arm-supported robotic device maintains its weight and keeps it roughly positioned relative to the anatomy to be treated. It restricts user movement while operating the device—and, in an advantageous implementation, also dampens user and / or patient movement, vibrations of the cutting tool, and reaction forces caused by movement of the actuating unit.

[0121] According to one implementation scheme, the arm is kept passive.

[0122] Advantageously, the holding arm can be gradually braked based on the distance between the robotic device and its target position relative to a tracker fixed to the patient. For example, the braking force can be inversely proportional to the distance of the robotic device from its target position. Alternatively, one or more concentric volumes (e.g., cubes or spheres) can be defined around the target position of the robotic device. The braking force can be adjusted based on the presence of the robotic device in one of these volumes. Thus, as the robotic device approaches the target position, the holding arm is braked and the user can receive force feedback information. Alternatively, the feedback information can be provided in the form of light or sound signals. For example, a variable flash frequency and / or the intensity of the light signal can indicate the distance between the robotic device and its target position. Similarly, a variable frequency, repetition rate, and / or amplitude of an acoustic signal can indicate this distance. In any case, the braking is not complete, so that the user is always able to manipulate the robotic device until its final desired position. The holding arm is then locked upon user action (e.g., by operating an actuator, such as releasing or pressing a button). If the user wants to move the robotic device again, they must operate the actuator again, which releases the holding arm—possibly with the braking force described above. If a new target position for the robotic device is defined, a new braking amount is defined, and the braking is adjusted based on the new volume.

[0123] In one implementation, the arm is equipped with a weight to counteract the weight of the control unit, as it is typically used, for example, in the surgical field, to support and position microscopes.

[0124] In one implementation, the retaining arm has vertical translation capabilities, a spring mechanism to compensate for the weight of the entire system, and a tandem architecture with a large planar structure consisting of three parallel axes and a vertical axis. Each axis is equipped with a locking system.

[0125] Figure 9 An embodiment of the retaining arm 5 is shown, which is secured to the crossbar 501 of the operating table 500 by a clamp 502. The retaining arm is formed by the following motion links, starting from the clamp: a pivot link 51 and a ball joint 52. A central module 53 is provided with an actuator 54, which allows the retaining arm to be unlocked when actuated. Alternatively, such an actuator may be arranged on a higher portion of the retaining arm to facilitate easy manipulation of the arm and the robotic device if the user wishes to change the position of the robotic device relative to the anatomical structure.

[0126] Figure 10 Another embodiment of the retaining arm 5 is shown, which is secured to the crossbar of the operating table 500 by a clamp 501. The retaining arm is formed by six pivot links 51. The retaining arm can be locked by an actuator (not shown).

[0127] Preferably, the connection between the retaining arm and the actuation unit is placed as close as possible to the first section of the actuation unit or to the center of gravity of the robot device to minimize any lever arm effect. The portion of the actuation unit attached to the retaining arm is referred to as the base of the robot device.

[0128] According to one embodiment, the first section of the actuation unit can be fixed relative to the retaining arm. In this case, the second section of the actuation unit must be movable relative to the first section. The advantage of this architecture is that it minimizes the weight of the moving parts of the actuation unit. As a result, the robotic device can be more responsive, which is beneficial for real-time control of the cutting plane.

[0129] According to one embodiment, the first section of the actuation unit is movable relative to the retaining arm. In this case, the first and second sections are preferably embedded in a single housing.

[0130] According to one embodiment, the device may further include a support unit configured to create a partial mechanical connection between the actuating unit and the anatomical structure. The support unit may be attached directly or indirectly to the retaining arm or to the actuating unit. In the latter case, the support unit may be attached to a fixed section of the actuating unit (e.g., a first section if the first section is fixed to the retaining arm) or to a movable section of the actuating unit (which may rotate freely relative to the retaining arm about the rotation axis of the section). (Refer to the following...) Figure 11 and Figure 12 In the described embodiment, the support unit 6 may be attached to an intermediate component 7 that is removably attached to the retaining arm 5 or to the actuation unit 4. This intermediate component 7 may be, for example, a sterile component, which is placed on a sterile cover (not shown) to form a sterile connection between the support unit 6 and the retaining arm or actuation unit. The support unit is typically a sterile component. If the actuation unit is covered with a sterile cover, the connection between the support unit and the actuation unit or retaining arm can be established on the sterile cover via the intermediate component. In the case of a sterile robotic device, the support unit may be directly connected to the robotic device.

[0131] According to one embodiment, the support unit includes at least one element intended to contact the anatomical structure to be cut or a region of the patient's body adjacent to the anatomical structure to be cut, so as to provide a partial mechanical connection between the actuation unit and the anatomical structure.

[0132] If a support unit is used, it is arranged so as not to impede the movement required for the surgical intervention. Specifically, the support unit is arranged so as not to interfere with the movement of the robotic device to achieve each cut.

[0133] Typically, the support unit includes at least one element designed to contact an anatomical structure (the anatomical structure to be cut or adjacent to it, such as soft tissue surrounding the bone to be cut). This element 60 can be attached to the patient via at least one strap 61. For this purpose, the element may include at least one slot through which the strap extends. The strap can be flexible or semi-rigid (e.g., a fastening device for ski boots). The strap can be adjusted in any suitable manner, such as a fastening mechanism, a loop fastener (also known as a Velcro fastener). ™ Alternatively, the strip may be adhesive, or may include at least one portion made of a high coefficient of friction material (e.g., a soft thermoplastic or silicone) placed in contact with the anatomical structure.

[0134] Furthermore, the support unit 6 includes a mechanical connection 62 between the base of the actuation unit (or the retaining arm or the aforementioned intermediate component) and an element of the support unit that contacts the anatomical structure. The connection can be activated when the robot is in use and deactivated when the surgeon needs to move the leg. According to one embodiment, the connection can be rigid. Alternatively, the connection can be hinged and locked in at least one degree of freedom to adjust the distance between the robotic device and the patient, or to accommodate the patient's morphology. Once the robotic device has been positioned and oriented as desired, some degrees of freedom can remain free, as long as the support unit still allows for limiting the movement and vibration of the anatomical structure relative to the actuation unit. The mechanical connection 62 can be made of at least two detachable components 62a, 62b, for example, using quick-locking mechanisms, latches, or magnets. The first component 62a is attached to an element 60 of the support unit that contacts the anatomical structure; the second component 62b is attached to the base of the actuation unit or the retaining arm, or to the aforementioned intermediate component. Therefore, the intermediate components, actuation units, or retaining arms can be easily disconnected from the anatomy by releasing the mechanical connections without removing the support unit from the patient. This is particularly useful when the user wants to change the position or flexion of the leg during the intervention, for example, to check ligament balance or postoperative alignment of the leg.

[0135] Optionally, the support unit may include one or more rods 63 combined with the above-described components, which are intended to contact the anatomical structure (see...). Figures 31A-31B For example, in the case of TKA, this rod can contact the epicondyle. The rod can be rigid or damped (using a spring member). Thus, without rigid attachment to the bone, the rod allows maintaining the distance between the anatomical structure and the robotic device when the aforementioned band is taut in a defined direction.

[0136] In addition to or in place of the rod, the support unit may also include at least one (active or passive) suction cup designed to remain in place on the anatomical structure (bone, skin or other soft tissue) in the event of relative movement between the robotic device and the anatomical structure, and to provide damping.

[0137] In a preferred embodiment, the support unit is attached around the leg.

[0138] The support unit can be attached to the tibia (see...) Figure 11 ) or attached to the femur (see Figure 12 The support unit can also be attached to both the tibia and femur; in this case, the support unit is advantageously hinged so that the leg can be moved (specifically, the flexion of the leg can be adjusted) without removing the support unit.

[0139] According to one embodiment, a retractor is attached to a support unit. The retractor pulls soft tissue to provide the surgeon with a large incision and vision. A first retractor may be attached to the inside of the incision and to the rear of the support unit using a tensionable link. A second retractor may be attached to the outside of the incision and to the rear of the support unit using a tensionable link. During leg manipulation, a quick but powerful mechanical connection is used to detach the support unit from the actuation unit base or retaining arm or intermediate component.

[0140] Figure 13 An embodiment of a puller attached to a support unit is shown.

[0141] Support unit 6 is attached to intermediate component 7, which is itself removably attached to retaining arm 5. Specifically, intermediate component 7 allows for aseptic connection to retaining arm 5 over a sterile cover (not shown). Intermediate component 7 can advantageously carry tracker 202. Support unit 6 includes: a strap 61 supporting base 61, a first fastener 62a extending from base 61; and a connecting member including a second fastener 62b, which mates with the first fastener to form a quick and robust connector 62, the connecting member being attached to intermediate component.

[0142] Each retractor 64 has a curved shape, wherein a first end 64a is configured to contact an anatomical structure, and a second end 64b is configured to attach to a strap 61 of a support unit. More precisely, both rods 65 include slots through which the strap 61 passes, such that the rods 65 are held in a direction projecting away from the leg. Each rod includes a plurality of holes 650. The second end 64b of each retractor is inserted into a selected hole 650 of the corresponding rod 65, thereby causing the first end 64a of the retractor to abut against the anatomical structure and sufficiently retract the soft tissue.

[0143] Figure 14 Another embodiment of the puller attached to the support unit is shown.

[0144] Support unit 6 is attached to intermediate component 7, which is itself removably attached to retaining arm 5. Specifically, intermediate component 7 allows for aseptic connection to retaining arm 5 over a sterile cover (not shown). Intermediate component 7 can advantageously carry a tracker. Support unit 6 includes: a strap 60 supporting a base from which a first fastener extends; and a connecting member including a second fastener that mates with the first fastener to form a quick and robust connector 62, which is attached to the intermediate component.

[0145] Each retractor 64 has a curved shape, wherein a first end 64a is configured to grasp soft tissue, and a second end 64b is configured to attach to a band 61 of the support unit. More precisely, the band 61 is comparable to... Figure 13 The retractor is wider and includes multiple hooks 610 on both sides. The second end 64b of each retractor includes a hole 640. The hole 640 engages with a selected hook 610 of the belt, thereby allowing the first end 64a of the retractor to fully pull the soft tissue.

[0146] Attaching the retractor to the support unit is particularly advantageous because the retractor does not need to be held by the surgeon's assistant, which saves space near the incision.

[0147] The support unit functions as a stabilizer. The support unit may be rigid, damped (e.g., spring-loaded), and / or provide adjustable damping characteristics. Contact between the support unit and the patient's body may be formed by one or more points or at least one surface.

[0148] Before cutting anatomical structures, the user plans the intervention of the planning system based on preoperative and / or intraoperative medical images and data.

[0149] This planning process allows for the identification of each target plane suitable for performing cuts on anatomical structures. It is application-specific.

[0150] For example, as mentioned above, in the case of TKA, planning to implant a prosthesis in the knee typically results in defining five target planes on the femur and one target plane on the tibia. More than five cutting planes may also be defined to secure the prosthesis to the bone, in order to optimize the prosthesis shape, for example, based on individual anatomy. This is in Figure 15 As shown, ten cutting planes f1-f10 are defined to align with the patient's anatomy in a sagittal view of the femur. Using the robotic device according to the invention for this bone preparation is particularly advantageous, as it enables the rapid execution of numerous cuts with high accuracy.

[0151] The planning system may be part of the surgical system according to the invention; otherwise, the planning system may be provided separately and connected to the control unit.

[0152] During surgical interventions, users can use preoperative data / images in conjunction with intraoperative registration methods, or directly use intraoperative data / images. In both cases, the planned outcome includes at least one target plane, the pose of which is determined in the coordinate system of the anatomical structure to be cut.

[0153] The pose of each target plane is then transmitted to the control unit.

[0154] Once the control unit initializes its subsystems, the device is ready for use.

[0155] Before activating the device, the hinged retaining arm is moved by the user to roughly position the actuating unit relative to the anatomical structure, and then locked. The cutting tool is then attached to the planar mechanism.

[0156] When a support unit is also used, it is connected to the anatomical structure to be cut or to an adjacent area of ​​the patient's body to provide partial mechanical connection between the actuating unit and the anatomical structure. This partial mechanical connection provided by the support unit allows the user to make small movements to reposition the device or enables the robotic device to compensate for the patient's involuntary movements. No additional invasive procedures (e.g., implantation of pins) are required on the patient.

[0157] Once the user has started operating the device, the tracking unit continuously feeds back tracking information to the control unit for recalculation and visualization purposes.

[0158] In addition, the user interface provides the user with information about the ability to align the cutting plane with the target plane in the current device position, and, if appropriate, gives instructions on how to properly reposition the device.

[0159] The system also includes a tracking unit 200, which is configured to determine the posture of the saw relative to the anatomical structure to be cut in real time.

[0160] The tracking unit may include the tracking system, which is known in itself.

[0161] Tracking systems commonly used in computer-assisted surgery employ various technologies (passive optics, active optics, electromagnetic, inertial with gyroscope measurement, ultrasound, etc.), which can be used individually or in combination. According to a preferred embodiment, the tracking system is based on passive optics technology.

[0162] The tracking unit includes at least one tracker that can be attached to any component of the actuation unit (e.g., one of the moving segments).

[0163] Because of the encoders or sensors of the motors and the calibration model of the robot (including all axes and distances of the robot segments), the position of each segment of the actuation unit is known in real time. Using this model and well-known geometric modeling techniques in robots, it is possible to calculate the relative positions of all segments. Therefore, if a measurement is known in the coordinate system attached to the robot base using an external tracker, the position of any segment is also known in the same coordinate system. Furthermore, if a tracker is attached to the base of the actuation unit and a second tracker is attached to the anatomical structure, the pose of any segment of the actuation unit is known in the coordinate system of the tracker attached to the anatomical structure.

[0164] In a preferred embodiment, a first tracker is attached to a first or second segment of the actuation unit, and a second tracker is attached to the end effector to provide redundancy and more accurate measurement of the end effector position and orientation for safety purposes, taking into account any mechanical clearance that may exist between the actuation unit and the end effector.

[0165] In addition, at least one tracker is rigidly attached to the anatomical structure of the patient to be cut in order to allow the cutting plane to be positioned relative to the coordinate system of the anatomical structure to be cut.

[0166] Throughout the figures, trackers attached to anatomical structures are indicated by reference numeral 201, trackers attached to actuation units or retaining arms are indicated by reference numeral 202, and trackers attached to end effectors are indicated by reference numeral 203.

[0167] Motion compensation is improved due to the tracker attached to the end effector. This additional tracker allows for reliable determination of the end effector's position and orientation in the robot's coordinate system.

[0168] Instead of attaching the additional tracker to the end effector, it is possible to rigidly attach it to the end of a planar mechanism (if any) opposite the actuation unit. The end of the planar mechanism may include not only an interface capable of receiving any type of cutting tool (sagittal saw, reciprocating saw, scalpel, etc.) as described above, but also other surgical tools (such as drill guides to be used for drilling into a prosthesis) and / or cutting guides. For example, the drill guide may have a toothed end designed to grip the surface of an anatomical structure where drilling is necessary. Advantageously, a shank is positioned at the opposite end of the drill guide for easy manipulation by the surgeon. Thus, once the toothed end has been applied to the anatomical structure, the surgeon can easily change the orientation of the drill guide due to the guiding interface. The drill can carry the tracker, rather than having the end of the planar mechanism carry the tracker.

[0169] The relative motion between the robotic device and the anatomical structure can be compensated by using an additional tracker rigidly attached to the end of the cutting tool or the planar mechanism.

[0170] In the control loop, the actual position of the end effector or the end of the planar mechanism (if any) is used instead of the theoretical position of the output plane of the actuation unit or the planar mechanism.

[0171] This greatly increases confidence in compensation agencies.

[0172] Furthermore, the association between the tracker attached to the cutting tool and the tracker attached to the actuation unit allows for dynamic estimation of the alignment error between them. This alignment error is then used to correct the position and orientation of the planar mechanism relative to the target plane.

[0173] Figure 16 It is a flowchart describing the control loop that allows compensation.

[0174] In step S1, the new posture of the robot device, end effector, and anatomical structure is determined using the positioning information provided by the tracker.

[0175] In step S2, the deviation d between the plane of the end effector (cutting plane) and the target plane is calculated.

[0176] If the deviation d is less than the threshold thr, the cutting tool can be operated and a new posture of the robotic device and anatomical structure can be determined (step S1).

[0177] If the deviation d is greater than or equal to the threshold thr, then in step S3, the plane of the end effector (cutting plane) and the target plane are projected into the coordinate system of the robot device.

[0178] In step S4, the correction matrix T corresponding to the rigidity transformation between the output plane of the actuation unit (or the plane of the planar mechanism, if any) and the cutting plane is calculated. err .

[0179] In step S5, T is used err Update the target plane.

[0180] In step S6, a new posture for the robot device to reach the target plane is calculated. This calculation determines the movement to be applied by the motors of the actuation unit.

[0181] In step S7, the motor of the actuation unit is activated according to step S6.

[0182] Then, the new positions of the robotic device and anatomical structures are determined (step S1).

[0183] Further improvements based on this basic algorithm have been shown to enhance the behavior of robotic devices: - Spatial filtering of the positions of various components (e.g., due to Kalman filters or equivalents); - For example, due to the quaternion averaging technique, for a given time range T err The estimates are averaged. This allows for the reduction of potential oscillations caused by small inconsistencies between the transformation estimates and the more complex realities of the mechanical links.

[0184] Correction matrix T err It can vary depending on the current extension of the planar mechanism, therefore it is not constant. It also depends on the mechanical backlash and deflection of the planar mechanism, the robot's position, and other factors. The correction matrix is ​​calculated in real time, thus allowing for the calculation of T between two iterations, taking into account the user's reasonable movements of the saw. err The deviation is not significant. This correction method is very accurate and effective in compensating for any mechanical defects, gaps, and errors in the model.

[0185] As described above, the control unit can implement this control loop at high frequencies (e.g., frequencies greater than 100 Hz), based on tracking information acquired at at least twice the frequency (e.g., greater than 200 Hz or even greater than 300 Hz). In practice, the implementation of this control loop does not involve complex and lengthy calculations. Parallel computation can be implemented if needed to reduce computation time.

[0186] Furthermore, providing a tracker for the end effector allows for the operation of the robotic device even when the tracker attached to the actuation unit is intermittently visible to the tracking camera. This intermittent visibility can be caused by medical personnel or equipment placed between the tracker and the camera in the operating room.

[0187] Therefore, compared to the control loop described above, this control loop includes some additional steps. This adapted control loop... Figure 17 The steps with the same number in both control loops are identical and will not be described in detail again.

[0188] In step S1, the new posture of the actuator, end effector, and anatomical structure is determined using the positioning information provided by the tracker.

[0189] In step C1, the control unit evaluates whether the current posture of the actuation unit can be calculated based on the positioning information provided by the tracking unit.

[0190] If the current orientation of the actuation unit can be determined, it is stored for later use in the memory of the control unit.

[0191] If the current pose of the actuator cannot be determined (e.g., because the tracker is not visible), the control unit evaluates in step C2 whether the previous pose of the actuator is stored in the control unit's memory. If available, the previously stored pose can be used. If the pose of the actuator is not currently stored, or if the pose of the end effector or anatomical structure cannot be determined, the robot device stops and the system loops back to step S1.

[0192] In step S2, the deviation d between the plane of the end effector (cutting plane) and the target plane is calculated.

[0193] If the deviation d is less than the threshold thr, the end effector can be operated, and a new pose of the robot device, end effector, and anatomical structure can be determined (step S1).

[0194] If the deviation d is greater than or equal to the threshold thr, then in step S3, based on the last known posture of the actuation unit, the plane of the end effector (cutting plane) and the target plane are projected into the coordinate system of the actuation unit.

[0195] In step S4, the correction matrix Terr corresponding to the rigid transformation between the output plane of the actuation unit (or the plane of the planar mechanism, if any) and the plane of the end effector is calculated.

[0196] Then calculate the norm of the correction matrix Terr (standard norm (Terr)).

[0197] If this norm exceeds a defined threshold E (meaning the difference between the expected position of the end effector plane and the actuated output plane is too large), then: • If the current pose of the robot device is a previously stored pose (i.e., the pose of the robot device cannot be determined during the current iteration of the control loop), the robot device stops, the previously stored pose of the robot device is erased, and the control unit loops back to step S1. The basic principle is that the base of the robot device can move in a non-negligible manner, and the system needs to determine the new pose of the robot device; • If the robot's posture is the latest posture (i.e., the posture of the robot can be determined during the current iteration of the control loop), the robot stops and the control unit outputs an error. The basic principle is that, in this case, the difference between the expected position of the end effector's plane and the output plane of the actuation unit (or the plane of the planar mechanism, if any) is too large, and a mechanical problem that cannot be solved by making the tracker visible again may have caused it.

[0198] According to one embodiment, the robotic device may include a light emitter configured to be activated by a control unit to emit light when the norm of the correction matrix is ​​greater than a threshold. For example, the light emitter may include at least one LED that emits continuous light as long as the norm of the correction matrix is ​​less than the threshold, and emits flashing light once the norm of the correction matrix exceeds the threshold. Such a light emitter is advantageously positioned close to the cutting plane. Therefore, visual information invisible to the tracker of the actuation unit can be provided to the user.

[0199] According to one embodiment, the control unit may be configured to output a message to the user to inquire whether the tracker of the actuator unit is in the camera's field of view and / or whether a mechanical problem has occurred. For example, the message may be displayed as text on a screen coupled to the control unit.

[0200] If the norm of the correction matrix Terr is less than the threshold E, then the target plane is updated with Terr in step S5.

[0201] In step S6, a new posture for the robot device to reach the target plane is calculated. This calculation determines the movement to be applied by the motors of the actuation unit.

[0202] In step S7, the motor of the actuation unit is activated according to step S6.

[0203] Then, a new pose for the robotic device, end effector, and anatomical structure is determined (step S1).

[0204] Incidentally, it should be noted that the compensation method described above is also advantageous for large surgical robots with six degrees of freedom, which retain end effectors, with or without planar mechanisms. Specifically, because the planar mechanism is very close to the surgical area, it must remain compact and is therefore prone to bending under the effort exerted by the surgeon during incision. Even if the large surgical robot is precise, it cannot compensate for this bending of the planar mechanism on its own. However, using a tracker on the end effector and implementing the compensation method described above allows this problem to be overcome. Figure 18This large robot is illustrated. The robot 1000 includes an arm 1001 with a tandem architecture comprising six degrees of freedom, connecting the final segment of the arm to a planar mechanism 24 of a cutting tool 2. The robot is used in conjunction with a tracking unit configured to determine the pose of the cutting plane relative to a coordinate system of the patient's anatomy in real time. The tracking unit includes at least one tracker (not shown) configured to attach to the anatomy, a tracker 202 attached to a segment of the robot's arm, and a tracker 203 attached to an end effector. The robot is controlled by a control unit configured to determine the pose of the cutting plane relative to a target plane and to control the arm to align the cutting plane with the target plane. The control unit is configured to implement a compensation method including the following steps: - (S1) Use positioning information provided by the tracker of the tracking unit to determine the posture of the arm, end effector and anatomical structures; - (S2) Calculate the deviation between the cutting plane and the target plane; - If the deviation is less than the threshold, the cutting tool is allowed to operate and the process returns to step (S1) to determine the new posture of the arm, end effector, and anatomical structure; - If the deviation is greater than or equal to the threshold, then (S3) the cutting plane and the target plane are projected into the robot's coordinate system. - (S4) Calculate the transformation between the output plane of the actuation unit or the plane of the planar mechanism and the cutting plane; - (S5) Update the target plane using the transformation calculated in step (S4); - (S6) Calculate the robot’s new pose as it reaches the updated target plane and determine the movement to be applied by the arm’s motors.

[0205] Advantageously, the attachment of the tracker to the end effector and / or actuation unit is reversible and reproducible.

[0206] According to one implementation, instead of attaching the tracker to the actuation unit, the system also includes a tracker attached to an intermediate component. Figure 11-14 As shown in component 7), the intermediate component connects the support unit to the retaining arm or to the actuation unit. If the connection between the robot device and the retaining arm is sufficiently rigid (without any mechanical play), the tracker is attached to the retaining arm, and / or to a tracker that is rigidly connected to any other component of the robot device.

[0207] As mentioned earlier, a user interface is defined to show the user the potential positions and orientations of the actuation units suitable for aligning the cutting plane with the target plane.

[0208] Sometimes, the user interface can provide information to guide the user to reposition the actuator unit in the optimal posture so that the cutting plane can be aligned with the target plane. The user interface can also indicate to the user whether all target cutting planes are reachable from the actuator unit's current position, and if not, in which direction to move to reach the optimal position.

[0209] The user interface can be visual and / or acoustic.

[0210] According to one implementation, the user interface may include a screen connected to the control unit, for example, Figure 2 The screen shown above is 400.

[0211] Figures 19A-19C Three views of the screen are shown, corresponding to different poses of the robotic device. Figure 19A In this situation, the robotic device is in a position and orientation where it cannot perform any planned cuts. This is illustrated by the icon in area A, which represents each of the six target planes required for the TKA intersection. Figure 19B In this scenario, the robotic device is positioned and oriented to perform some (but not all) planned cuts. This is illustrated by icons representing two of the six planned objectives required for TKA to cross in area A. Figure 19C In the scenario shown, the robotic device is positioned and oriented to execute all planned cuts. This is illustrated by the fact that none of the icons in area A represent the six target planes required for the TKA intersection.

[0212] Therefore, using this user interface (other embodiments are described below), the user can position the robotic device so that the system can perform all six cuts of TKA (five femoral cuts and one tibial cut) without repositioning the robotic device. In this way, TKA surgery can be performed faster than with existing technology devices.

[0213] If a realistic 3D model of the anatomical structure is available (i.e., obtained through preoperative or pre-operative imaging of the patient), this model, along with a real-time representation of the cutting tool (e.g., the sheath of the oscillating blade), can be displayed on the screen. For example, if the cutting tool is a saw, the user can see the position of the saw blade tip relative to the bone to ensure that the blade tip does not leave the bone. This control can be automated if the planar mechanism connecting the saw to the actuation unit is motorized.

[0214] During use of the device, the control system checks in real time whether the saw can be aligned with the target plane. If the mobile robotic device causes the saw to be unable to align with the target plane—for example, in the event of vibration and / or involuntary movements of the patient—the information provided to the user can be altered, for example, by changing the color of the arrow or generating acoustic feedback.

[0215] According to another embodiment (not shown), the user interface includes visual indicators such as LEDs. These LEDs may be arranged on a support surface fixed to the robot device. Alternatively, the LEDs may be arranged on a support member separate from the robot device and connected to it via a wire. Alternatively, the LEDs may be arranged on a support member separate from the robot device and wirelessly connected to it. This separate support member may be positioned near the robot device / cutting tool in the user's field of vision.

[0216] In cases where the robotic device cannot compensate for misalignment between the cutting plane and the target plane, the indicator is designed to instruct the user not to activate the cutting tool. For example, a red and flashing light is activated once the tracker and / or cutting tool mounted on the anatomical structure becomes invisible. It turns off or turns green once the tracker's visibility is restored.

[0217] Another way to provide information to the user is through a digital display (e.g., provided by an LCD screen) representing virtual levels. The user can adjust the overall orientation of the robotic device based on a virtual level on the top of the device and another virtual level on the side of the device (opposite to the patient's legs). The distance to the robotic device can be adjusted using support units, and / or using indicators such as LEDs representing arrows pointing in the desired direction, and / or via the user interface screen.

[0218] The system also includes a control unit designed to optimally control the saw's posture to align it with the target plane.

[0219] According to one embodiment, the control unit can be coupled to a surgical saw used to perform the cutting and is configured to allow saw actuation only when the cutting plane is aligned with the target plane. This increases the safety of the system.

[0220] Figure 20 It shows Figures 3A to 3B The implementation scheme of the robot device shown.

[0221] patient( Figure 20 (Only one flexed leg is shown) lying on the operating table 500, with the lower leg supported by a leg retainer 600. Tracker 201 is fixed to the femur, and another tracker 201 is fixed to the tibia.

[0222] One end of the retaining arm 5 is attached to the leg retainer 600, and the other end is attached to the actuation unit 4.

[0223] The retaining arm can be freely manipulated by the user to position the robotic device relative to the patient as needed and to bear the weight of the robot. Once the desired position is achieved, arm 5 can be locked. The retaining arm can serve as a reference. Figure 9 and Figure 10 One of the arms described.

[0224] In this configuration, the robotic device does not include any support units. However, support units (other than the retaining arm) may be provided without departing from the scope of the invention.

[0225] Tracker 202 is fixed to the second section of the actuator unit 4 of the robot device.

[0226] Saw 2 is connected to the third section via a passive planar mechanism 24.

[0227] Tracker 203 is also attached to saw 2, which allows compensation for any mechanical backlash that may exist between the robotic device and the saw.

[0228] Figure 21 It shows Figures 3A-3B Another embodiment of the setup of the robotic device shown.

[0229] patient( Figure 21 (Only one leg is shown) lying on the operating table 500 with the leg in a flexed position. Although not shown, the patient's leg can be held in this flexed position by wedges commonly used in interventional surgery. For example, one wedge can be placed under the foot and another wedge can be placed on the outside of the hip to reduce inward and outward movement of the flexed leg.

[0230] Tracker 201 is fixed to the femur, and another tracker 201 is fixed to the tibia.

[0231] One end of the retaining arm 5 is attached to a crossbar 501 arranged on the operating table 500, and the opposite end is attached to the actuation unit 4. The crossbar to which the retaining arm is attached may be a crossbar located on the same side of the operating table as the leg of interest, or a crossbar located on the side of the operating table opposite the leg of interest.

[0232] The actuation unit is also attached to a band 61 arranged around the upper leg, which provides support unit 6, forming a partial mechanical connection between the anatomical structure and the actuation unit 4. Since the support unit is in direct contact with the anatomical structure to be cut or indirectly in contact with the patient's body area adjacent to the anatomical structure to be cut (here, the soft tissue around the femur), the support unit acts as a partial mechanical connection, restricting the user's movement while operating the device—and, in an advantageous embodiment, also damping the movement of the user and / or patient, vibrations of the cutting tool, and reaction forces caused by the movement of the actuation unit.

[0233] Tracker 202 is fixed to the second section of the actuator unit 4 of the robot device.

[0234] The saw 2 is connected to the third section of the actuation unit 4 via a passive planar mechanism 24.

[0235] Tracker 203 is also attached to saw 2, which allows compensation for any mechanical backlash that may exist between the robotic device and the saw.

[0236] Figure 22 It shows Figures 3A-3B Another embodiment of the setup of the robotic device shown.

[0237] patient( Figure 22 (Only one flexed leg is shown) lying on the operating table 500, with the lower leg supported by a leg retainer 600. Tracker 201 is fixed to the femur, and another tracker 201 is fixed to the tibia.

[0238] One end of the retaining arm 5 is attached to the leg retainer 600, and the other end is attached to the actuation unit.

[0239] As in Figure 21 As in the implementation scheme, the actuation unit 4 is also attached to a belt arranged around the upper leg, which provides support unit 6, forming a partial mechanical connection between the anatomical structure and the actuation unit.

[0240] Figure 23 yes Figure 21 or Figure 22 An enlarged view is provided to better show the support unit.

[0241] The support unit 6 includes a flexible band 61 and a rigid support member 60, which together wrap around the soft tissue surrounding the patient's femur F. The flexible band 61 allows the rigid support member 60 to be tensioned to the leg, and the tension of the flexible band can be adjusted according to the diameter of the patient's leg. Padding of different thicknesses can be inserted between the rigid support member and the patient's skin to accommodate various leg sizes. It is also possible to use a spring mechanism to apply pressure to the sides of the rigid support member, which provides variable adjustment for individual patients. Finally, a mechanical system 62 can be used to remove the rigid support member 60 of the support unit from the actuation unit 4. The distance can be set by discrete positions or a clamping mechanism.

[0242] In any embodiment, the support unit attached to the thigh can be used to perform incisions on the tibia, since the tibia and femur are connected by soft tissue, forming a mechanical connection that stabilizes movement. In another embodiment, the support unit can be attached to the lower part of the leg (tibia), and the actuation unit is used to perform all incisions on the femur and tibia.

[0243] The base 62b of the support unit is attached to the first section 41 of the actuation unit 4 (which is also rigidly attached to the retaining arm) so as to allow free rotation about the first axis.

[0244] The base 62b includes a radially extending member 620 having a central groove 621.

[0245] The base 62b is connected to the support 622 by a screw that slidably engages with the central recess 621. The distance between the actuating unit and the leg can be adjusted by moving the base 62b relative to the screw 622. Once the desired distance is achieved, the screw 622 is tightened to rigidly connect the base to the support 60. Figure 11-12 Other embodiments shown may use radially extending members without such screws and grooves for adjustment, thereby providing a fixed distance between the actuating unit and the leg, and connecting to the actuating unit, retaining arm, or intermediate component only via a pivot link. It is also possible to use a fixing element relative to the base of the actuating unit to eliminate movement and adjustment of the support unit.

[0246] Figure 23 Only one example of the support unit is shown, and technicians can design the support unit to include a greater number of settings (translation and / or rotation) to adjust the position of the robotic device relative to the legs.

[0247] Although the support unit is Figure 21 , Figure 22 and Figure 23 It is indicated by its position around the femur, but it can be attached to the tibia or both the femur and tibia.

[0248] Figures 24A to 24C Another application of the robotic device is illustrated. In this embodiment, the cutting tool is a reciprocating saw orthogonal to the plane of the planar mechanism.

[0249] This saw can be used to perform so-called vertical or sagittal cuts. Specifically, during TKA surgery, these vertical cuts allow for the formation of a box B in the femur, which is configured to receive a post-stabilized (PS) femoral component (see...). Figure 24A During UKA surgery, a reciprocating saw can be used to perform the sagittal cuts required for tibial implant placement.

[0250] Before beginning the cutting, the first step is to align the planar mechanism 24 with the cutting plane (e.g., a sagittal cutting on the tibia, see...). Figure 24B Alignment of the plane. The actuation unit 4 constrains the planar mechanism 24 within a given plane above or below the bone material to be cut.

[0251] If the planar mechanism is active (fully motorized), the saw can be positioned automatically / actively by the system.

[0252] Otherwise, if the planar mechanism is partially active (with a combination of motor and non-motor degrees of freedom) or completely passive, saw 2 must be positioned in 3D due to tracker 203. An interface showing the saw's position and orientation relative to the bone and target plane is displayed to assist the surgeon. The surgeon can then move saw 2 until it reaches the target position and orientation (which is a line when considered in a plane orthogonal to the target plane (hereinafter referred to as the "target line" represented by the dashed line)) (see 24C).

[0253] If the planar mechanism is partially or fully active or equipped with a position locking mechanism, another option is to have the surgeon move the reciprocating saw to the correct position and then lock or restrain the saw blade to keep it within the target line once it has arrived.

[0254] Then, cutting can be performed by moving the reciprocating saw up or down.

[0255] According to the first option, the actuation unit actively displaces the saw by regularly changing the plane of the planar mechanism (lowering or raising it). During this process, the saw's cutting action must be activated so that a cut can be made when the actuation unit actually moves. In a preferred embodiment, the saw's cutting action is turned on or off by the system's control unit. If the planar mechanism is not fully active, the surgeon may have to keep the saw blade in the correct orientation during cutting. At any time, if the planar mechanism's orientation or position deviates from the target line by more than a predetermined threshold (e.g., 2 degrees or 2 mm), the actuation unit will stop lowering or raising the planar mechanism plane. Additionally, for safety reasons, displacement of the planar mechanism plane should only be achieved while the surgeon maintains the cutting action (e.g., using a foot switch and / or pressing a trigger). Once the foot switch or trigger is released, the actuation unit will stop lowering or raising the planar mechanism plane. Optionally, the displacement rate of the planar mechanism plane can be modified based on its forward level during cutting. For example, the speed can be low at the beginning to avoid slippage or other causes of misalignment due to the initial contact between the saw blade and the bone surface; then the actuation unit can move faster in the middle of the cut; and finally it can be gradually slowed down to zero until the cutting limit (e.g., the tibial cutting plane) is reached, with various predetermined speed profiles.

[0256] Alternatively, the surgeon pushes the saw up or down to perform a cut. The robotic device detects the direction and intensity of the force applied by the surgeon, and the actuation unit deflects the plane of the planar mechanism accordingly (maintaining its orientation so that it remains orthogonal to the target plane). If the blade reaches its limit (e.g., a planned or already performed transverse tibial cut in the case of a UKA), the actuation unit stops moving, preventing the saw from being lowered or raised further so that the surgeon feels the limit has been reached. In the same spirit as the previous section, the reaction force applied by the actuation unit can vary depending on the level of progress in the cutting process.

[0257] By default, the description above assumes that the reciprocating saw is rigidly fastened to the planar mechanism. However, it should be possible to use only a partial mechanical connection (e.g., the saw may even rest solely on the planar mechanism, with a simple interface featuring complementary features to prevent unwanted translation between the saw and the planar mechanism). In this case, the planar mechanism will primarily function as a protective device to prevent the saw from cutting too low or too high. It may also partially guide the saw when it is orthogonal to sagittal cutting displacement. Furthermore, to prevent incorrect cutting, the actuation unit can only move when the saw's position and orientation remain within a predetermined range (e.g., 2 mm and 2 degrees) relative to the target line.

[0258] Figure 25 It shows Figures 3A-3B The robot device shown is configured with a cutter 2' serving as the cutting tool.

[0259] Although the tracker shown in the attached figure is an optical tracker, it should be noted that any other tracking technology (e.g., electromagnetic) can be used.

[0260] It should be noted that the above implementation schemes can be combined.

[0261] In addition, the retaining arm—and (if any) the support unit that provides only partial mechanical connection—fully supports the weight of the robotic device without requiring any invasive movements on the patient.

[0262] Therefore, compared with the large screws and pins implanted in the bone in document US2011 / 0130761 (i.e., which penetrate the bone at several centimeters), the robotic device according to the present invention is not directly fixed to the patient, but is held by a retaining arm attached to a component (operating table, leg retainer, etc.) that is non-invasively fixed to the patient, and can be directly connected to the patient by only non-invasive attachment devices (e.g., straps, etc.).

[0263] The micro- or macro-motions (including slow and fast movements) of the robotic device relative to the anatomical structure to be cut are compensated within tolerance ranges and a given time range that defines the accuracy of the device.

[0264] Typically, for orthopedic applications, compensation is required within a few tenths of a millimeter range to achieve sufficient accuracy; this compensation necessitates ultra-fast motion detection and measurement, as well as calculating the compensating motion to be applied and executing the required compensating motion.

[0265] Large surgical robots with six degrees of freedom are very rigid but also very bulky and expensive; moreover, they have considerable inertia (especially in the first segment of movement), which is incompatible with real-time control of the cutting plane. On the other hand, existing small, lightweight robots cannot be used if they are not rigidly attached to the anatomical structure. In contrast, the present invention provides a compact, lightweight robotic device that allows for real-time control of the cutting plane without requiring any invasive fixation of the patient.

[0266] Although a cutting tool has been previously described with reference to an end effector attached to an actuating unit, embodiments include a cutting block mounted on the end effector, which is itself attached to the actuating unit, for example, via the aforementioned planar mechanism or via a slider (see...). Figure 27 The cutting block includes at least one slot that defines a guide plane corresponding to the cutting plane of the cutting tool. Each slot allows the cutting tool held in the user's hand to be constrained within the corresponding guide plane. The cutting tool can be a sagittal saw, a reciprocating saw, or even a cutting blade as described above.

[0267] According to a specific implementation plan, the cutting block 2000 may include two slots 20, 20' (see...). Figure 28A ) or three slots 20, 20', 20'' (see Figure 28B Therefore, once the cutting block is positioned to align one slot with the target plane, only slight adjustments to the cutting block's orientation are needed to align another slot with another target plane. The slots can even be positioned in a given relative position, such that once one slot is aligned with a target plane, at least one other slot is also aligned with another target plane. In this way, it is possible to perform several cuts without moving the cutting block and the robotic device.

[0268] To provide optimal guidance for the saw blade and prevent any deviation, the width w of the slot should be as large as possible. For example, but not limited to, the width of the slot can be in the range of 10mm to 25mm.

[0269] The planar mechanism or slider provides additional translational freedom along axis A4, which is parallel to the plane defined by slot 20 (see...). Figures 29A-29F and Figure 27This slider allows the distance between the rotation axes of the actuating units to remain small, and the additional translation along the slider provides the cutting block with access to further regions of the anatomical structure. According to one embodiment, the slider is manually operated. Figure 30 As shown, the slider may be equipped with a rack and pinion mechanism 210 to provide multiple defined positions. According to one embodiment, the slider may be biased by an elastic member such as a spring (not shown). According to one embodiment, the slider may be motorized, thereby providing a fourth degree of freedom of motion controlled by a control unit within the target plane. Once the position of the cutting block has been adjusted, the slider can be stopped to prevent any further movement of the cutting block.

[0270] The planar mechanism also allows the cutting block to pivot about a fifth axis A5, which is substantially orthogonal to the plane defined by slot 20. This allows the cutting block to be positioned closer to the bone without changing the orientation of the guide plane. This rotational degree of freedom of the cutting block can also be combined with the translational degree of freedom provided by the aforementioned slider.

[0271] In some implementations, the support unit may be positioned between the cutting block and the patient.

[0272] For example, such as Figure 31A As shown, the cutting block 2000 includes at least one flexible interface (e.g., one or more silicone pads 56) configured to contact the anatomical structure. In this way, the cutting block can be pressed against the anatomical structure (e.g., using a slider as described above), thereby ensuring partial mechanical connection. Pressure can be applied to the retaining arm 5 in combination with a leg retainer that keeps the knee substantially still. However, it is still possible to slide the flexible interface a few degrees or millimeters along the anatomical structure to adjust its position. In this embodiment, the actuation unit is connected to the anatomical structure via the cutting block 2000, and the support unit is made of silicone pads 56. According to a preferred embodiment, the flexible interface includes two silicone pads disposed on both sides of the slot 20 of the cutting block, with sufficient distance between the two pads to avoid damage to them during sawing. Instead of silicone, any soft, biocompatible material can be used.

[0273] According to another embodiment (not shown), the cutting block may include an interface made of multiple sharp teeth. In this way, the cutting block can be pressed and held against the anatomical structure by the teeth, thereby ensuring partial mechanical connection.

[0274] According to another embodiment, the cutting block can be secured to the anatomical structure via pin 57 (see...). Figure 31B The pin can be automatically drilled out and removed using a dedicated motor controlled by a control unit.

[0275] The tracking unit may include a tracker that is attached to the cutting block or to the cutting tool.

[0276] This cutting block, in particular, allows for the cutting of the sidewalls of the box within the anatomical structure to create notches. This is necessary for positioning a posteriorly stable femoral implant that incorporates a box in its design, requiring notches to be formed in the bone for a perfect fit.

[0277] Figure 32 The setup of the robot device in this situation is shown.

[0278] patient( Figure 32 Only one flexed leg is shown lying on the operating table 500. Tracker 201 is fixed to the femur, and another tracker 201 is fixed to the tibia.

[0279] One end of the retaining arm 5 is attached to the worktable, and the other end is attached to the actuation unit.

[0280] In this setup, the robotic device does not include any support units. However, support units may be provided in addition to holding arm 5.

[0281] Tracker 202 is fixed to the second section of the actuator unit of the robot device.

[0282] The cutting block 2000 is connected to the third section of the actuation unit 4 via a passive planar mechanism 24.

[0283] Tracker 203 is also attached to the cutting block, which allows for compensation of any mechanical backlash that may exist between the robotic device and the cutting block.

[0284] The cutting tool is a reciprocating saw 2, whose blade passes through the slot of the cutting block 2000.

[0285] The operation of the control unit will be described in more detail below.

[0286] Figure 33 This is a flowchart of a complete surgical intervention aimed at performing at least one osteotomy, such as total knee arthroplasty. It should be noted that the initial and final steps are not necessarily part of this invention.

[0287] In step 101, the patient's anatomical structures in the area to be treated by surgical intervention are acquired. This acquisition can be performed in a manner known per se, such as using an imaging device for acquiring images of bone and / or a local pointer (digital probe) for acquiring multiple points on the bone surface, as this is commonly used in image-free surgical navigation techniques.

[0288] In step 102, surgical planning is performed based on the acquired patient anatomy. This planning step results in the definition of the pose of the target plane intended for cutting.

[0289] In step 103, the user positions the robotic device with the holding arm in a coarse location designed to allow cutting to be performed according to the target plane. In this step, the patient's anatomy is also equipped with at least one tracker. The robotic device and end effector are also equipped with at least one tracker to enable positioning of the relative positions of the robotic device, end effector, and the anatomy to be cut. In this step, particularly if several cuts are to be performed without repositioning the robotic device, the user can use the user interface to determine the appropriate position and orientation of the robotic device.

[0290] In step 104, the order of cuts to be performed is selected. For this, the control unit retrieves the pose of the corresponding target plane. If several cuts are to be performed, they can be stored in the system in a specific order and loaded sequentially. Otherwise, the user interface allows the user to select specific cuts. It should be noted that this step can be performed at any time before step 105.

[0291] In step 105, the control unit receives tracking data from the tracker. Therefore, the control unit is able to calculate the current position of the robot device and the end effector relative to the anatomical structure to be cut.

[0292] Based on the current position of the robot device, the end effector, the pose of the target plane, and the kinematic design of the robot device, the controller calculates in step 106 the movement of the actuation unit that allows access to the target plane. In step 107, the control unit checks whether the robot device can reach the target plane from its current position (i.e., without moving the support unit). If so, the control unit commands the actuation unit to move the cutting tool or cutting guide to the desired position to align the cutting plane with the target plane (step 108).

[0293] If the current position of the robot device does not allow alignment on the target plane, the control unit warns the user that it cannot and prohibits cutting (step 109) and calculates the new position of the robot device to reach the target plane in step 110 (the new position means moving the retainer unit), and then performs steps 105 to 107 again.

[0294] In step 108, once the cutting plane is aligned with the target plane, the control unit allows cutting (e.g., by providing the user with an indication that the cutting plane is aligned with the target plane, and / or by allowing the user to begin operating the cutting tool). The user performs the cutting by operating the cutting tool within the cutting plane. During this cutting step, the control unit uses tracking data to check whether the cutting plane remains aligned with the target plane (see the loop between steps 105 and 108).

[0295] Once the cutting is complete (after step 108), the user indicates to the control unit that the cutting is complete. This indication can be made, for example, by pressing a foot switch or a button.

[0296] In step 111, the user or control unit checks whether there are any cuts yet to be made.

[0297] If not, a postoperative examination can be performed in step 112.

[0298] If further cutting is still required, repeat steps 105-108 (and, if appropriate, 109 and 110) until all planned cutting has been performed.

Claims

1. A surgical system for cutting a patient's anatomical structure (F, T) according to at least one target plane, said at least one target plane being defined in a coordinate system of the anatomical structure, said surgical system comprising: (i) A robotic device (100), the robotic device (100) comprising: - An end effector, the end effector comprising a cutting tool or a cutting block, - Actuation unit (4), the actuation unit (4) having three to five degrees of freedom of motion, the actuation unit (4) being attached to the end effector and configured to adjust the position and orientation of the cutting tool or the cutting block relative to each target plane; (ii) A passively hinged lockable retaining arm (5) that supports the actuation unit (4); (iii) A tracking unit (200) configured to determine in real time the orientation of the cutting plane relative to the coordinate system of the anatomical structure, the tracking unit including a tracker configured to be rigidly attached to the actuation unit and a tracker configured to be rigidly attached to the end effector; (iv) A control unit (300) configured to determine the orientation of the cutting plane relative to the target plane and control the actuation unit to align the cutting plane with the target plane. The control unit is configured to implement a control loop including the following steps: - (S1) The poses of the actuation unit (4), the end effector (2), and the anatomical structure are determined using the positioning information provided by the tracking unit (200); - (S2) Calculate the deviation between the cutting plane and the target plane; - If the deviation is less than the threshold, the operation of the cutting tool is allowed and the process returns to step (S1) to determine a new posture of the actuation unit, the end effector, and the anatomical structure; - If the deviation is greater than or equal to the threshold, then (S3) the cutting plane and the target plane are projected into the coordinate system of the actuation unit; - (S4) Calculate the correction matrix between the plane attached to the output end of the actuation unit and the cutting plane; - (S5) Update the target plane using the correction matrix calculated in step (S4); - (S6) Calculate the new posture of the actuation unit (4) to align the cutting plane with the updated target plane, and determine the movement to be applied by the motor of the actuation unit; - Activate the actuation unit (4) to apply the movement.

2. The surgical system of claim 1, wherein the tracking unit is an optical tracking unit, the optical tracking unit comprising a camera and an optical tracker capable of being detected by the camera.

3. The surgical system of claim 2, wherein the camera is configured to operate at a frequency that is at least twice the frequency at which the control unit is configured to perform each iteration of the control loop.

4. The surgical system of claim 2 or 3, wherein the camera is configured to operate at a frequency greater than 200 Hz, preferably greater than 300 Hz.

5. The surgical system according to any one of claims 2 to 4, wherein the control unit is configured to perform each iteration of the control loop at a frequency greater than 50 Hz, preferably greater than 100 Hz.

6. The surgical system according to any one of claims 2 to 5, wherein the control unit is configured to implement the control loop including an additional step, the additional step including evaluating between steps (S1) and (S2) whether the current posture of the actuation unit can be calculated based on the positioning information provided by the tracking unit.

7. The surgical system of claim 6, wherein the control unit is further configured to implement the control loop including an additional step comprising storing the current posture of the actuation unit in the memory of the control unit, and implementing step (S2) with the current posture of the actuation unit if the current posture can be determined.

8. The surgical system of claim 6, wherein the control unit is further configured to implement the control loop including the additional step of: if the current posture of the actuation unit cannot be determined, evaluating whether a previous posture of the actuation unit is stored in the memory of the control unit.

9. The surgical system of claim 8, wherein the control unit is further configured to implement the control loop comprising: if the previous posture of the actuation unit is stored in the memory of the control unit, then the previous posture is used to implement step (S2).

10. The surgical system of claim 8, wherein the control unit is further configured to implement the control loop comprising: if the previous posture is not stored in the memory of the control unit, then step (S1) is performed again.

11. The surgical system according to any one of claims 2 to 10, wherein the control unit is configured to implement the control loop comprising: calculating the norm of the correction matrix between steps (S4) and (S5) and comparing the norm with a determined threshold.

12. The surgical system of claim 11, wherein the control unit is configured to implement the control loop comprising: if the norm is less than the threshold, then using the correction matrix to implement step (S5).

13. The surgical system of claim 11, wherein if the norm is greater than the threshold, the control unit is configured to stop the actuation unit.

14. The surgical system according to claim 13 in conjunction with claim 7 or 8, wherein the control unit is configured to determine whether the posture of the actuation unit used in steps (S2) to (S4) is a previously stored posture, and: - If the gesture is a previously stored gesture, then erase the previously stored gesture from the memory and return to step (S1); - If the posture is the current posture of the actuation unit, then an error is output.

15. The surgical system of claim 13 or 14, wherein the robotic device includes a light emitter configured to be activated by the control unit to emit light when the norm of the correction matrix is ​​greater than a threshold.

16. The surgical system according to any one of claims 13 to 15, wherein the control unit is configured to output a message to a user to check whether the tracker of the actuation unit is in the field of view of the camera.

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