Device, system, and method for determining the alignment of the tibial coronal region.

Abstract

A system and method for measuring tibial varus or valgus angles using a surgically implanted measurement device is disclosed. An exemplary embodiment may include receiving, using at least one processor, first data from the measurement device, where a housing of the measurement device is coupled to a patient's musculoskeletal system, the first data including a plurality of measurements from each of an accelerometer and a gyroscope included in an inertial measurement unit disposed within the housing; receiving, using at least one processor, first measurements of anatomical features of the patient's leg; determining a tibial varus or valgus angle based on the first measurements; and outputting the determined tibial varus or valgus angle on a display. In some embodiments, instructions for implementing the method may be stored on a non-transitory computer-readable medium.

Description

Technical Field

[0001] The present disclosure generally relates to the measurement of physical parameters, and more particularly, but not exclusively, to medical electronic devices for high-precision orthopedic alignment.

Background Art

[0002] The mammalian skeletal system varies among species. Further changes can occur due to environmental factors, wear from use, and aging. Orthopedic joints of the skeletal system typically include two or more bones that move in relation to each other. Movement is enabled by muscle tissue and tendons attached to the skeletal system of the joint. Ligaments positionally hold and stabilize one or more joint bones. Cartilage is a wear surface that prevents bone-to-bone contact, distributes loads, and reduces friction.

[0003] There has been significant growth in the repair of the human skeletal system. In general, orthopedic joints have evolved using information from simulations, mechanical prototypes, and patient data that are collected and used to initiate improved designs. Similarly, the tools used in orthopedic surgery have been improved over the years but have not changed substantially. Thus, the basic procedures for orthopedic joint replacement are standardized to meet the general needs of a broad population distribution.

[0004] Tools, procedures, and artificial joints meet general needs, but each replacement procedure varies significantly from patient to patient. Correction of these individual diversities depends on the skill of the surgeon to adapt and fit the replacement joint using the tools available for a particular situation. The solution of the present disclosure solves these and other problems in the art.

Summary of the Invention

[0005] In certain embodiments of this disclosure, a system for measuring one or more parameters of the musculoskeletal system is disclosed. The system may include a measurement device. The measurement device may include a housing configured to be coupled to the patient's musculoskeletal system, an inertial measurement unit located within the housing, and a transmitter configured to output a plurality of measurements. The inertial measurement unit may include an accelerometer and a gyroscope. The inertial measurement unit may be configured to record a plurality of measurements using the accelerometer and gyroscope. The system may further include an artificial knee joint including a tibial prosthetic component coupled to the proximal end of the patient's tibia. The housing of the measurement device may be configured to be detachably coupled to the tibial prosthetic component. The system may further include a display and a computing device for determining the varus or valgus angle of the patient's tibia. The computing device may include at least one processor, a communication component operably connected to the processor, and a memory operably connected to the processor for storing a plurality of instructions executable by the processor to perform a plurality of operations. Multiple actions may include receiving first data from a measuring device, which includes multiple measurements from an accelerometer and a gyroscope, respectively; receiving a first measurement of the patient's tibia length; determining the varus or valgus angle of the tibia based on the first data and the first measurement; and outputting the determined varus or valgus angle of the tibia to a display.

[0006] In exemplary embodiments, a method for measuring tibial varus or valgus angle using a surgically implanted measuring device may include receiving first data from the measuring device using at least one processor, wherein the housing of the measuring device is coupled to the patient's musculoskeletal system, and the first data includes a plurality of measurements from an accelerometer and a gyroscope, each included in an inertial measuring unit located within the housing; receiving first measurements of anatomical features of the patient's leg using at least one processor; determining the tibial varus or valgus angle based on the first measurements; and outputting the determined tibial varus or valgus angle to a display. In some embodiments, a plurality of instructions for implementing the method may be stored on a non-temporary computer-readable medium.

[0007] To achieve the above and related objectives, several exemplary embodiments are described herein in relation to the following description and accompanying drawings. However, these embodiments represent only some of the various ways in which the principle of the subject matter of the claims may be employed, and the subject matter of the claims shall encompass all such embodiments and their equivalents. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings. [Brief explanation of the drawing]

[0008] The accompanying drawings incorporated herein and forming part thereof illustrate various exemplary aspects of this disclosure and, together with the description, are useful in illustrating the principles of this disclosure. [Figure 1] Figure 1 shows an example of a skeletal structure of a part of a leg according to an exemplary embodiment. [Figure 2] Figure 2 shows an exploded view of a knee joint including a prosthesis system according to an exemplary embodiment. [Figure 3] Figure 3 shows an example of a prosthesis component incorporating an inertial measurement unit according to an exemplary embodiment. [Figure 4-1]Figure 4 shows a flowchart of an exemplary embodiment of a method for determining the varus / valgus angle of the tibia according to a particular aspect of the present disclosure. [Figure 4-2] This is a continuation of Figure 4. [Figure 5A] Figure 5A shows an exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5B] Figure 5B shows an exemplary embodiment of the output generated by the computer system when performing the method shown in Figure 4. [Figure 5C] Figure 5C shows an image of the patient's legs in the position shown in Figure 5B. [Figure 5D] Figure 5D shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5E] Figure 5E shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5F] Figure 5F shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5G] Figure 5G shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5H] Figure 5H shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5I] Figure 5I shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5J] Figure 5J shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5K] Figure 5K shows a further exemplary embodiment of the output generated by the computer system when performing the method of Figure 4. [Figure 5L]FIG. 5L shows a further exemplary embodiment of the output generated by a computer system when executing the method of FIG. 4. [Figure 5M] FIG. 5M shows a further exemplary embodiment of the output generated by a computer system when executing the method of FIG. 4. [Figure 5N] FIG. 5N shows a further exemplary embodiment of the output generated by a computer system when executing the method of FIG. 4. [Figure 5O] FIG. 5O shows a further exemplary embodiment of the output generated by a computer system when executing the method of FIG. 4. [Figure 5P] FIG. 5P shows a further exemplary embodiment of the output generated by a computer system when executing the method of FIG. 4. [Figure 6A] FIG. 6A shows a flowchart of an exemplary embodiment of a method for performing varus / valgus angle identification of the tibia in the method of FIG. 4. [Figure 6B] FIG. 6B shows an example of an offset distance between the heel and ankle of a patient's leg. [Figure 7A] FIG. 7A shows an exemplary embodiment of a shim according to a particular aspect of the present disclosure. [Figure 7B] FIG. 7B shows the shim of FIG. 7A disposed in place between a measurement device and a tibial prosthesis component. [Figure 7C] FIG. 7C shows a graph illustrating various experimental results for determining the varus / valgus angle of the tibia for various preset varus / valgus angles of the tibia according to a particular aspect of the present disclosure. [Figure 8] FIG. 8 shows a block diagram of a measurement system or computer according to an exemplary embodiment. [Figure 9] FIG. 9 shows an example of a communication network for measurement and reporting according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments of the present disclosure are, in a broad sense, directed to the measurement of physical parameters, and more specifically, to devices, systems, and methods for orthopedic alignment. Various aspects of such a disclosure may improve measurement accuracy, improve surgical outcomes, and / or reduce costs or time in surgery. The following description of the exemplary embodiment(s) is illustrative only and is in no way intended to limit the invention, its uses, or its applications. Specific aspects of the present disclosure are described in more detail below. In the event of conflict with terms and / or definitions incorporated by reference, the terms and definitions provided herein shall prevail.

[0010] As used herein, the term "comprising," "including," or any other variation thereof, is intended to cover a non-exclusive inclusion such that a process, method, composition, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, composition, article, or apparatus. The term "exemplary" is used in the sense of "example" rather than "ideal." As used herein, the singular forms "a," "an," and "the" include plural references unless the context dictates otherwise. The terms "approximately" and "about" refer to being substantially the same as the referenced number or its value. The term "or" is used disjunctively, and thus, a list set by the term "or" may include any arbitrary number of items within the list. As used herein, the terms "approximately" and "about" are to be understood to encompass ±10% of the specified amount or value (e.g., "about 90%" can refer to a range of values from 81% to 99%).

[0011] For the sake of simplification and clarity of one or more drawings, elements in the drawings are not necessarily to scale, are only schematic, and are not limiting. The same reference number in different drawings refers to the same element unless otherwise specified. Furthermore, for the sake of simplification of explanation, descriptions and details of well-known steps and elements have been omitted. Note that if an article is defined in one drawing, it may not be described or further defined in subsequent drawings.

[0012] In the claims and / or detailed description, terms such as “first,” “second,” and “third” are used to distinguish between similar elements and are not necessarily used to describe any order, whether temporal, spatial, ranking, or any other way. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances and can operate in any order other than those described or shown herein.

[0013] Processes, techniques, apparatus, and materials known to those skilled in the art may not be described in detail, but are intended to be part of the description to a practical degree where necessary. The orientation of the x, y, and z axes in orthogonal Cartesian coordinates is assumed to be such that the x and y axes define a plane at a given position, and the z axis is orthogonal to the xy-plane. These rotation axes around the Cartesian axes of a device are defined as yaw, pitch, and roll. In the Cartesian coordinate orientation defined in this paragraph, the yaw rotation axis is the z axis passing through the body of the device. Pitch changes the orientation of the longitudinal axis of the device. Roll is the rotation around the longitudinal axis of the device.

[0014] The orientation of the X, Y, and Z axes of the Cartesian coordinate system is chosen to enable graphical display on a computer screen with an orientation that is most easily relatable to the user. Therefore, whenever the device itself moves upward, for example, away from the ground, the image of the device will move upward on the computer display. The same applies to movement to the left or right.

[0015] The terms “motion detection,” “tilt sensing,” and “orientation” are also intended to have specific meanings. “Motion detection” generally encompasses the detection of movement of an object that exceeds a specified threshold on one or more coordinate axes, for example, a specific threshold on one or more Cartesian axes relating to both static and dynamic acceleration. “Heading” generally encompasses the orientation of the longitudinal axis of a module or device that detects motion and orientation, and movement in a certain direction. “Tilt” generally encompasses the orientation of the body relative to the vertical axis. The term “slope” is used interchangeably with the term “tilt.” “Tilt detection” generally encompasses the measurement of acceleration due to gravity on one or more axes. “Orientation” generally encompasses yaw and “tilt.” While accelerometers and gyroscopes are provided as valid examples in the description of the embodiments, it should be noted that any tracking device (e.g., GPS chips, acoustic rangefinders, magnetometers, inclinometers, hybrid sensors, MEMs) may be used within the scope of the embodiments described.

[0016] It should be noted that the term “flexion value” is used herein. For the purposes of this disclosure, a flexion value of approximately 180 degrees represents full extension of the joint, while any value other than 180 degrees represents a flexed state of the joint where the bones on both sides of the joint cross to form an angle other than 180 degrees. It should also be noted that tolerances are known to those skilled in the art, and for example, subjective tolerances for angle measurements may be between 1 and 3 degrees.

[0017] At least one embodiment relates to a musculoskeletal orthopedic (e.g., knee) balancer system, which helps surgeons determine the alignment and load of orthopedic implants in real time. While this system is applicable to all orthopedic surgeries (e.g., spine, shoulder, knee, hip), the following example deals with knee surgery as a non-limiting example of one embodiment of the present invention.

[0018] Non-limiting embodiments described herein relate to quantitative measurements based on orthopedic surgery and are referred to herein as motor systems. A motor system includes a sensor system that provides quantitative data and feedback to the surgeon visually and / or aurally and / or tactilely. The motor system provides the surgeon with real-time dynamic data regarding loading in each compartment of the knee, contact and fit of tibial-femoral implants throughout the full range of motion, and information regarding angled osteotomies and leg alignment.

[0019] Generally, kinematics is the study of the action of forces in response to the movement of the body or a system of body. Disclosed herein is a system for the kinematic evaluation of the musculoskeletal system. The kinematic system may be for the placement of multiple prosthetic components, or for the monitoring and evaluation of components permanently placed in the musculoskeletal system. For example, the placement of a prosthetic component may require the formation of one or more bone surfaces to receive the device or component. The bone surface is osteotomized to position the prosthetic component in a position relevant to the mechanical axis of the joint. The kinematic system is designed to make quantitative measurements of at least the load, load location, and alignment with respect to the forces applied to the joint, as well as those applied to the final joint placement. Sensory measurement components are designed to allow ligaments, tissues, and bones to be in place while quantitative measurement data is being acquired. This is important because the osteotomy takes into account kinematic forces that can change significantly from the alignment, load, and load location when the joint is reconstructed by kinematic evaluation and subsequent osteotomy.

[0020] Measurement data complements the surgeon's subjective feedback to ensure optimal placement. Quantitative measurements can also be used to determine adjustments to bone, prosthesis components, or tissue before final placement, or to fine-tune the placement. Permanent sensors on the final prosthesis component can provide periodic data related to the implant's condition during use. Data collected during surgery and over the long term (post-surgery) can be used to determine parameter ranges for surgical placement and to improve future prosthesis components. Often, several measured parameters or multiple different measurements are used to perform quantitative assessments. Parameters can be evaluated in terms of orientation, alignment, direction, displacement, or position, as well as motion, rotation, or acceleration along one axis or a combination of axes, by wireless sensing modules or devices positioned on or within the body, equipment, appliance, medium, equipment, or other physical systems. A graphical user interface can support the integration of measurement data. Parameters can be evaluated with respect to orientation, alignment, direction, displacement, or position, as well as motion, rotation, or acceleration along one axis or combination of axes, by wireless sensing modules or devices positioned on or within a body, equipment, appliance, medium, equipment, or other physical system.

[0021] The motion system is designed to quantitatively measure at least the load, load location, or alignment related to the forces applied to the joint, as well as those applied to the final joint placement. The motion system can support the actual osteotomy for optimal contact point(s), balance, load magnitude, and alignment across the range of motion. One or more measurement components with multiple sensors are designed to allow ligaments, tissues, and bones to remain in place while quantitative measurement data is acquired and reported in real time. This is important because osteotomy takes into account kinematic forces that can substantially change alignment, load, and load location once the joint is reconstructed by kinematic assessment and subsequent osteotomy. Furthermore, the measurement data can be transmitted to an in-operating computer that can analyze the data and propose a workflow for the surgical team to achieve the desired results. In addition, the motion system supports real-time adjustments such as osteotomy, prosthesis component rotation, or ligament tension using real-time measurements to validate the surgical procedure or proposed workflow.

[0022] This specification concludes with claims defining features of the invention that are considered novel, but the invention is expected to be better understood from consideration of the following description in conjunction with the drawings depicted, which carry similar reference numerals.

[0023] In this specification, the exemplary embodiments of the measuring devices shown below are illustrative and do not limit their use to other parts of the body. A measuring device may be a tool, instrument, implant, insert, or prosthesis that measures at least one parameter or supports the placement of a prosthesis component in the musculoskeletal system. Measuring devices may be used in the bones, knees, hips, ankles, spine, shoulders, hands, wrists, feet, fingers, toes, and other areas of the musculoskeletal system. Generally, the multiple principles disclosed herein are intended to be adaptable for use in all locations of the musculoskeletal system.

[0024] Referring to the drawings, Figure 1 is a diagram of a leg 10 according to an exemplary embodiment. The leg 10 may be a right leg or a left leg. The leg 10 includes a femur 12 and a tibia 14. A dashed line 16 indicates the functional axis of the leg 10. The functional axis of the leg 10 includes a dashed line 16 drawn through the center 160 of the femoral head 28 to the center 180 of the ankle joint 18. The dashed line 16 is aligned to pass through the center 165 of the knee joint 185, approximately at the medial tibial spine. The knee joint 185 includes lateral and medial articular surfaces 187 and 189 that support the movement of the leg. The alignment of the leg 10 with respect to the functional axis 16 minimizes wear on the articular surfaces of the prosthesis and reduces the mechanical stress applied to the wear surfaces. Similarly, the alignment of the leg 10 with respect to the functional axis 16 reduces stress on the multiple prosthesis components coupled to the femur 12 and tibia 14. The alignment of knee joint 185 further includes balancing the lateral compartment 187 and the medial compartment 189 of knee joint 185.

[0025] The dashed line 22 is the vertical axis shown relative to the functional axis 16 and the anatomical axis 20. The dashed line 24 is the horizontal axis 24, perpendicular to the vertical axis 22. The horizontal axis 24 is shown between the distal end of the femur 12 and the proximal end of the tibia 14. The vertical axis 22 aligns with the pubic symphysis, which is a midline cartilaginous joint adjacent to the pelvic region. The anatomical axis 20 is shown by the dashed line 20. The anatomical axis 20 is not a straight line because it passes through the intramedullary canal of the femur 12 and the intramedullary canal of the tibia 14. The functional axis 16 and the anatomical axis 20 are the same from the knee joint to the center of the ankle of the leg. Both the functional axis 16 and the anatomical axis 20 are different from the vertical axis.

[0026] The femur 12 and tibia 14 may be misaligned with respect to the functional axis 16 of the leg 10. In an aligned leg, the functional axis 16 makes an angle of approximately 3 degrees with the vertical axis. Ideally, the surgeon places a knee joint prosthesis component aligned with the functional axis 16 of the leg 10 to optimize the reliability and performance of the knee joint 185. Alignment processing may include measuring leg misalignment and compensating to keep the leg alignment with respect to the functional axis within a predetermined range. Typically, the predetermined range is determined by the prosthesis component manufacturer based on clinical evidence supporting the reliability and performance of the joint when the misalignment is kept within the predetermined range. Several mechanical fixtures have been used to measure leg alignment in the operating room. Mechanical fixtures can be cumbersome, time-consuming to install, and inaccurate. One problem with mechanical fixtures is that the center of the femoral head is not available for direct measurement by the fixture. In cases of leg deformity, surgeons may require alignment offset from the functional axis. Generally, leg alignment can be adjusted during trial placement by osteotomy, rotation of prosthesis components, adjustment of ligament tension, shimming of prosthesis components, and other techniques. In one embodiment, a real-time alignment measurement device uses a triaxial gyroscope (or three separate gyroscopes) in combination with a triaxial accelerometer (or three separate accelerometers) to provide alignment measurement data during prosthesis component testing. The alignment measurement data can be used to verify the alignment or to support corrections to position the leg in alignment.

[0027] Figure 2 is an exploded view of an artificial knee joint system 40 according to an exemplary embodiment configured to measure leg alignment. The artificial knee joint includes a femoral prosthesis component 48 coupled to the distal end of the femur 42, an insert 68 (e.g., an alignment measurement device), and a tibial prosthesis component 50 coupled to the proximal end of the tibia 44. To support real-time alignment measurement, an inertial measurement unit 62 is coupled to the knee joint, for example, via the insert 68. In one embodiment, the inertial measurement unit 62 is coupled to the tibia 44. The inertial measurement unit 62 includes three gyroscopes and three accelerometers, the first, second, and third gyroscopes and the first, second, and third accelerometers being aligned with the Xa, Ya, and Za axes, respectively. Each gyroscope measures the angular velocity corresponding to rotation around the axis as shown in the drawing. Each accelerometer similarly measures the change in motion (acceleration) corresponding to one of the Xa, Ya, and Za axes.

[0028] The proximal end of the tibia 44 has a created bone surface 46. The created bone surface 46 of the tibia 44 is osteotomized relative to a reference. For example, the proximal end of the tibia 44 can be osteotomized relative to the transepicondylar axis. Alternatively, other references may be used. Osteotomies of the femur and tibia can also be performed relative to the vertical axis 22, the functional axis 16, or the anatomical axis 20. The created bone surface 46 may have a medial-lateral inclination, anterior-posterior inclination, or a compound slope that supports precise leg movement and proper rotation of the femoral component 48 throughout the range of motion.

[0029] The tibial prosthesis component 50 includes an upper surface 54 and a lower surface 56. In one embodiment, the upper surface 54 is the main surface of the tibial tray. The tibial tray supports and holds the insert 68 relative to the tibial prosthesis component 50. The tibial prosthesis component 50 may have one or more retaining features for bonding to the created bone surface 46. In one embodiment, the tibial prosthesis component 50 has a keel 52 or stem that is inserted into an opening 66 drilled in the tibia 44. The opening 66 defines the position of the tibial prosthesis component 50 on the created bone surface 46. The keel 52 positions, holds, and reinforces the bonding of the tibial prosthesis component 50 to the tibia 44. The keel 52 may be configured to be positioned within the medullary canal of the tibia 44. The tibial prosthesis component 50 can be rotated from a reference position. In one embodiment, the position of the tibial prosthesis component 50 on the tibia 44 is referenced to the medial third of the tibial tubercle. The rotation of the tibial prosthesis component from this reference position can be measured and fed to an alignment measuring device 68. For example, the rotation may be used to influence the movement of the patella toward the femoral prosthesis component 48. The rotation of the tibial prosthesis component 50 may also be used to influence the alignment, balance, and contact points of the femoral prosthesis component 48 toward the insert 50. Once the position of the tibial prosthesis component 50 is determined, the bottom surface 56 of the tibial prosthesis component 50 can be bonded to the created bone surface 46 in order to further retain the tibial prosthesis component 50 on the tibia 44. Bonding of the tibial prosthesis component 50 to the tibia 44 typically includes mechanical attachment, adhesive, or cement, or other bonding mechanisms known in the art.

[0030] The base surface 56 of the tibial prosthesis component 50 is bonded to the created bone surface 46. In one embodiment, the base surface 56 is substantially parallel to the created bone surface 46. Similarly, the upper surface 54 of the tibial prosthesis component 50 is substantially parallel to the base surface 56 or the created bone surface 46. The proximal opposing surface of the insert 68 is bonded to the upper surface 54 of the tibial prosthesis component 50. The insert 68 may have one or more retaining features that bond to the tibial prosthesis component 50. The proximal opposing surface of the insert 68 is substantially parallel to the upper surface 54 of the tibial prosthesis component 50.

[0031] In one embodiment, the inertial measurement unit 62 is or includes a MEMs (micro-electromechanical) integrated circuit. For example, one or more of the gyroscope or accelerometer may be or include a MEMs integrated circuit. The form factor of the MEMs gyroscope integrated circuit or MEMs accelerometer integrated circuit supports placement within or coupling to a prosthesis component for measuring the alignment of the musculoskeletal system. MEMs integrated circuits are generally solid-state devices formed using photolithography. Such MEMs integrated circuits may have a form factor that supports placement within a prosthesis component or module that can be coupled to a bone surface.

[0032] In one embodiment, the MEMS gyroscope has a resonating mass that changes with angular velocity and outputs a signal corresponding to the angular velocity. For example, in some embodiments, the MEMS gyroscope may be configured to output a signal proportional to the angular velocity of the IMU62. In one embodiment, the MEMS accelerometer has a mass-spring system that changes in response to an applied acceleration, for example, against the biasing of the springs in the mass-spring system. In one embodiment, the MEMS integrated circuit includes at least one gyroscope and at least one accelerometer and / or an accelerometer / gyroscope hybrid. The MEMS integrated circuit can generally provide analog or digital outputs.

[0033] In one embodiment, measurement data from the inertial measurement unit 62 is transmitted to a computer 43 configured to process and display leg alignment information. Typically, the inertial measurement unit 62 includes a mounting surface 63. The mounting surface 63 can correspond to the planes of two of the Xa, Ya, and Za axes of the inertial measurement unit 62. In one embodiment, the Xa-Ya plane of the inertial measurement unit 62 is positioned substantially parallel to the created bone surface 46 of the tibia 44 and the corresponding parallel surfaces of the tibial prosthesis component 50 and the insert 68. In one embodiment, the inertial measurement unit 62 is positioned within a trial insert, e.g., insert 68. The trial insert is used to support the placement of an artificial knee joint. The trial insert with the inertial measurement unit 62 can measure the alignment of changes or modifications to the leg and support before final placement to ensure that the alignment is within a predetermined range for optimal performance and reliability. The trial insert may also include other sensors to provide measurement data on other parameters located near the leg, or to support the placement of prosthesis components.

[0034] The inertial measurement unit 62 may also be positioned within other prosthesis components or modules. For example, the inertial measurement unit 62 may be positioned within the final insert or final tibial prosthesis component to perform alignment measurements over a long period (postoperatively) and monitor changes in alignment. As disclosed herein above, the position of the tibial prosthesis component 50 may be aligned to or relative to the medial third of the tibial tuberosity or any other preferred reference point. The orientation of the inertial measurement unit 62 is such that the Z-axis Za is substantially perpendicular to the surface 54. The orientation of the insert 68 corresponds to the position of the tibial prosthesis component 50. The insert 68 incorporating the inertial measurement unit 62 is positioned such that the X-axis Xb is aligned in the anterior-posterior direction of the insert 68 and the Y-axis Yb is aligned in the medial-lateral direction of the insert 68. Further aspects of how the axes of the inertial measurement unit 62, the insert 68, the vertical axis 22, the functional axis 16, and the anatomical axis 20 relate to each other and can be determined using the inertial measurement unit 62, for example, through a calibration procedure, are described below.

[0035] Figure 3 shows an example of a prosthesis component incorporating an inertial measurement unit 82 according to an exemplary embodiment. Generally, the inertial measurement unit 82 can be housed within the prosthesis component 70 or coupled to the musculoskeletal system to measure alignment. The inertial measurement unit 82 can measure the alignment of the musculoskeletal system or the position of bones. The inertial measurement unit 82 can have a predetermined orientation relative to the prosthesis component 70 through a calibration process, for example, as described in more detail below. The prosthesis component 70 can be a trialing device, which is a temporary device used during placement to measure multiple parameters and determine the proper fit of the artificial joint. The prosthesis component 70 can also be a permanent prosthesis component for long-term monitoring or measurement of alignment. For example, changes in alignment over time may indicate inappropriate loading on the joint surface, which, if not corrected, can accelerate wear over time. The inertial measurement unit 82 is positioned within the knee joint, but the inertial measurement unit 82 is not limited to the knee prosthesis component, and similarly, it can be applied to other parts of the biological structure such as the musculoskeletal system, hip joint, shoulder, spine, ankle, elbow, wrist, fingers, toes, and wrist. Similarly, the inertial measurement unit 82 can be positioned within other knee components such as the patellar button, tibial prosthesis component, or femoral prosthesis component to support alignment measurement or other measurements.

[0036] In one embodiment, the prosthesis component 70 includes a support structure 72 having a plurality of articular surfaces 74 and a support structure 76. The support structures 72 and 76 are joined together to form a housing. The housing includes at least one cavity for electronic circuits and sensors. In one embodiment, the circumferential surface of the support structure 72 is joined to the circumferential surface of the support structure 76. These circumferential surfaces can be joined together using an adhesive that seals the cavity from the external environment. The interior and exterior of the prosthesis component 70 can be sterilized before use and stored in a package. The support structures 72 and 76 include a bio-compatible polymer such as polycarbonate, PEEK, or ultra-high molecular weight polyethylene. The selected polymer can support the loads applied by the musculoskeletal system and provide a low-friction surface and reduced wear for joint movement.

[0037] According to one or more embodiments, the measuring device includes, for example, an inertial measuring unit 82 housed within a prosthesis component 70, a sensor 80, an electronic circuit 78, and a power supply 88. A remote system, such as a computer 43, may be located close to the prosthesis component 70. For example, the remote system may be located in an operating room where the surgical team can view the measurement data supplied by the sensor and the inertial measuring unit 82. The remote system receives the measurement data from the sensor 80 and the inertial measuring unit 82 via a wired connection or wireless transmission. Typically, wireless transmissions are short-range, typically less than 10 meters, and can be encrypted for security. The remote system may include a computer with a display that receives and processes the measurement data from the prosthesis component 70. The computer may include software programs that support the calculation and visualization of the measurement data. In one embodiment, the measurement data can be displayed to the surgeon in real time, allowing modifications to be made based on quantitative measurements. Alternatively, the remote system may be a microprocessor-based device capable of launching software, such as a smartphone or handheld device, which allows the patient or other user to evaluate the measurement data transmitted from the prosthesis component 70.

[0038] The prosthesis component 70 is coupled to the tibial prosthesis component 90. The tibial prosthesis component 90 is coupled to the tibia and includes a tibial tray 92 that holds the prosthesis component 70. The tibial tray 92 includes a surface 94 configured to be coupled to the bottom surface 86 of the structure 76. The articular surface 74 is coupled to multiple condyles of the femoral prosthesis component and / or multiple parts of the femur to support the movement of the knee joint and leg. Multiple load sensors 80 can be placed beneath the multiple articular surfaces 74. A measuring device 68 can measure the load applied to the multiple articular surfaces 74 and the location of the load. The load applied to the multiple articular surfaces 74 is distributed to the bottom surface 86 of the support structure 76 that is coupled to the tibial prosthesis component 90. The surface area of ​​the bottom surface 86 is greater than the condylar contact area of ​​the femoral prosthesis component with respect to the multiple articular surfaces 74.

[0039] As described above, the measurement device 68 includes an inertial measurement unit 82 for measuring the alignment of the leg with respect to the functional axis of the leg. The inertial measurement unit 82 includes three gyroscopes and three accelerometers. The first gyroscope and first accelerometer have rotation axes aligned in the anterior-posterior direction of the prosthesis component 70 corresponding to axis Xa. The second gyroscope and second accelerometer have rotation axes aligned in the inward-outward direction of the prosthesis component 70 corresponding to axis Ya. The third gyroscope and third accelerometer have rotation axes perpendicular to the Xa-Ya plane corresponding to axis Za.

[0040] The electronic circuit 78 can be housed within the prosthesis component 70 together with the inertial measurement unit 82 and can be aligned with respect to the inertial measurement unit 82 as described above, or with other predetermined alignments. As described above, the inertial measurement unit 82 is a small form factor device that can be placed within the prosthesis component 70 or a device coupled to the musculoskeletal system. The sensor 80 can measure parameters of the musculoskeletal system or parameters near the prosthesis component 70.

[0041] The electronic circuit 78 is mounted on a printed circuit board 84 that is mounted centrally within the cavity of the prosthesis component 70. The electronic circuit 78 is mounted in an area of ​​the prosthesis component 70 that has little to no joint load, which can increase the reliability of the electronic circuit 78 and prevent damage to the electronic circuit 78. Multiple load sensors 80 are coupled to the electronic circuit 78 and are located below the joint surface 74. In one embodiment, the multiple load sensors 80 and the electronic circuit 78 are coupled to a flexible, standalone printed circuit board (not shown). In one embodiment, the multiple load sensors 80 can be integrated into a printed circuit board (not shown) to simplify assembly, improve reliability, and enhance the performance of the measuring device 68. Three or more load sensors 80 are used to measure the locations on the multiple joint surfaces 74 where loads are applied. An inertial measurement unit 82 is mounted on the printed circuit board 84 and coupled to the electronic circuit 78. The inertial measurement unit 82 is mounted so that three gyroscopes and three accelerometers are oriented relative to the prosthesis component 70. In one embodiment, the Xa-Ya plane of the inertial measurement unit 82 is substantially parallel to the base surface 86 of the prosthesis component 70 and the surface 94 of the tibial prosthesis component 90. In one embodiment, the reference coordinate system of the inertial measurement unit 62 with respect to the base surface 86 and / or the surface 46 of the tibia 44 is determined, for example, through calibration and / or alignment processes as described below.

[0042] The electronic circuit 78 and the inertial measurement unit 82 are isolated from the external environment when the support structure 72 is coupled to the support structure 76 in Figure 3. The electronic circuit 78 may include a power supply 88, passive components, power regulation, power management circuit, conversion circuit, digital logic, analog circuit, microprocessor, microcontroller, digital signal processor, memory, ASIC, interface circuit, or communication circuit. In one embodiment, the 3-axis gyroscope supplies measurement data to a computer in real time using radio frequency wireless transmission.

[0043] According to one or more embodiments, the technique for determining the varus / valgus angle of the tibia using an accelerometer combined with a gyroscope is performed using a 3D vector-based mathematical method. The anatomical reference coordinate system of the patient's tibia is determined, for example, for the inertial measurement unit 62 / 82 of a measurement device 60 incorporating one or more features from the embodiments described above. Under such an approach, the measurement device 60 may have a predetermined reference coordinate system of the inertial measurement unit 62 related to the anatomical reference coordinate system of the tibia, based on calibration processes related to the tibial prosthesis component 50, particularly the upper surface 54, for example, as will be described in more detail below.

[0044] The placement of the tibial prosthesis component 50 can establish the center point and / or axis of the tibia relative to the inertial measurement unit 62. According to one or more embodiments, the measurement device 60 may be firmly mounted in a reproducible position within the tibial prosthesis component 50 to collect / generate calibration data for the measurement device 60, which may be considered when determining the varus / valgus angle of the tibia. Calibration of the measurement device 60 can significantly improve the accuracy of determining the varus / valgus angle of the tibia.

[0045] Generally, errors arising in measurements from accelerometers and gyroscopes may include, for example, bias errors, scale factor errors or scaling errors, and / or positional or skew errors. Bias errors typically relate to errors that exist regardless of the force or velocity induced on the sensor, for example, regardless of the external input detected by the accelerometer or gyroscope. Generally, bias errors represent the largest source of error for the inertial measurement unit 62 and may be the greatest contributor to accuracy improvement when properly calibrated. Scaling errors relate to how well the sensor output corresponds to the applied external action, for example, force or velocity input. Positional or skew errors may arise from improper configuration or alignment of the three sensing axes in the accelerometer or gyroscope.

[0046] In the various methods and processes described below, various operations are described as being performed or carried out by components described elsewhere in this disclosure, for example, components or devices from Figure 2 or Figure 3. However, it should be understood that in various embodiments, operations including those described below can be performed using the various components described above. Furthermore, it should be understood that in various embodiments, various steps can be added, omitted, and / or rearranged in any preferred manner.

[0047] In exemplary embodiments, the first calibration process for the measuring device 60 may include recording multiple measurements from the accelerometer and gyroscope while moving the inertial measurement unit 62 between different poses / orientations. As used herein, the term “pose” generally encompasses position and / or orientation, and may include the relative positions and / or orientations of various elements to each other, such as the position / orientation of the tibia 44 relative to the femur 42, the position / orientation of the inertial measurement unit 62 relative to the measuring device 60, and so on. In exemplary embodiments, the first calibration process may include moving the inertial measurement unit 62, for example when mounted in the measuring device 60, between 14 different static poses, i.e., six poses oriented in the positive and negative directions with respect to each of the Xb, Yb, and Zb axes that define the reference coordinate system of the measuring device 60, and eight poses corresponding to diagonal vectors in four different Cartesian quadrants. However, it should be understood that in various embodiments, any number of preferred poses in any preferred orientation may be used. In various embodiments, the inertial measurement unit 62 may be positioned either inside or outside the measurement device 60. Multiple measurements obtained in the position of the inertial measurement unit 62 can be used to generate the skew matrix, scaling matrix, and bias matrix for the accelerometer and gyroscope of the inertial measurement unit 62, respectively.

[0048] Obtaining the above matrix may involve filtering the data collected from the gyroscope. For example, a Butterworth second-order filter may be applied. In some embodiments, some of the measurements, for example, a predetermined number of measurements at the start or end of the movement toward attitude, may be discarded.

[0049] The bias matrix for a gyroscope can be obtained, for example, by averaging raw data from multiple static measurements included in multiple measurements related to multiple measurements collected at each attitude. For example, the bias matrix may include an offset for each axis Xb, Yb, Zb based on the average of multiple static measurements for that axis from multiple measurements. The skew and scaling matrices of a gyroscope can be obtained using optimization with a cost function. For example, the cost function may relate to a comparison between the estimated gravity direction and the measured gravity direction identified using an accelerometer.

[0050] For example, a second calibration process can be performed to determine the reference coordinate system of the inertial measurement unit 62 with respect to the bottom surface 56 of the housing 50 of the measuring device 60. As mentioned above, the margin of the varus / valgus angle of the tibia is generally 1 to 3 degrees. Therefore, even a slight offset due to material or machining tolerances that affects the orientation of the inertial measurement unit 62 when housed in the measuring device can be significant. Such errors can be taken into account and / or reduced by considering any relative orientation between the reference coordinate system of the inertial measurement unit 62 and the measuring device 60 through the second calibration process.

[0051] In some embodiments, a second calibration process, such as a registration operation, may be performed. For example, the reference coordinate system of the inertial measurement unit 62 may be registered in two dimensions through the second calibration process. The second calibration process may include, for example, collecting multiple measurements from the accelerometer and gyroscope of the inertial measurement unit 62 in a plurality of different static orientations. In an exemplary embodiment, eight static orientations of the measurement device 60 on which the inertial measurement unit 62 is mounted are used, and these orientations are separated by 45 degrees in rotation around the z axis. Data from the gyroscope may be used to detect when the inertial measurement unit 62 is moving and to identify, for example, a portion of the time when the inertial measurement unit 62 is stationary corresponding to each orientation. In each orientation identified based on each portion of the time when the inertial measurement unit 62 is stationary, a gravity vector can be determined based on data from the accelerometer during the corresponding portion of time. Next, multiple points defined by multiple gravity vectors can be fitted to a circle in three-dimensional space, and the center, normal vector, and radius of the circle can be determined. These can then be used to determine the average gravity direction in various orientations, and these can be used to define, for example, the reference coordinate system (Xa, Ya, and Za) of the inertial measurement unit 62 relative to the reference coordinate system of the measurement device 60. In some embodiments, a second calibration process, such as the type described above, can at least partially correct the misalignment between the rotation axis of the inertial measurement unit 62 and the direction of gravity. It should be understood that the above-described calibration / alignment examples are illustrative only, and any appropriate technique may be used to reduce misalignment through calibration, etc.

[0052] In some embodiments, calibration data, such as the matrix and reference coordinate system data described above, may be stored in memory mounted on the measuring device 60. In some embodiments, such data may be stored in a database within entries related to the measuring device 60 and / or the inertial measurement unit 62.

[0053] Figure 4 shows an exemplary method for determining the varus / valgus angle of the tibia using, for example, one or more techniques or apparatus from the various embodiments described elsewhere in this disclosure. In addition, Figures 5A–5P show an exemplary clinical flow for measuring leg alignment using various steps of the method in Figure 4. In various embodiments, the workflow according to this disclosure may be performed using more or fewer steps and is not limited to the order of the steps shown. While the various examples described herein relate to the knee, other embodiments may relate to, for example, the hip, knee, shoulder, ankle, elbow, spine, hand, wrist, foot, bones, and / or the musculoskeletal system, and are not limited to the knee.

[0054] In step 400, the physician or healthcare provider may perform one or more osteotomies, for example, an osteotomy of the distal femur and / or an osteotomy of the proximal tibia. Typically, the osteotomy of the proximal tibia is performed to remove a minimum amount of the proximal tibia while ensuring sufficient removal of diseased or otherwise undesirable bone, for example, to form surface 46 (Figure 2).

[0055] Optionally, in step 405, the display of the computer 43 may be configured to output a number of workflow instructions, such as those shown in Figures 5A to 5P, which will be described in more detail below. Figure 5A shows an exemplary embodiment of the output of the computer 43 in a workflow for determining and / or estimating the bias of the measuring device 60.

[0056] In step 410, a first measurement of the patient's anatomical features can be obtained. In some embodiments, the first measurement may include, for example, the length of the patient's tibia, for example, the distance between the center of the patient's heel and the center of the inertial measurement unit 62. However, in various embodiments, any suitable anatomical feature of the patient, for example, the patient's leg, may be used. In various embodiments, the first measurement may be obtained manually using a measuring device such as a ruler, laser device, or scale, and / or programmatically using imaging analysis processing performed on medical imaging of the patient's tibia, etc. As shown in Figure 5A, the workflow may include an interactive field 505 for the entry of the first measurement.

[0057] In step 415, one or more trial prosthesis components may be inserted into a portion of the knee joint 185. For example, a femoral prosthesis component 48 may be connected to the distal end of the femur 42, or an insert 58 and a tibial prosthesis component 50 may be connected to the proximal end of the tibia 44.

[0058] In step 420, the measuring device 60, including the inertial measuring unit 62, may be inserted into the knee joint 185 in a manner such as that described with respect to one or more of the above-described embodiments, and may be coupled to and / or inserted into, for example, a tibial prosthesis component 50.

[0059] In step 425, the patient's leg is moved to an extended rest position. As shown in Figure 5A, the workflow may include an example of a patient's leg in a desired posture. For example, Figure 5A shows an extended rest position, where the knee joint 185 is in a straight position such that the femur and tibia are approximately in a straight line and the foot is facing upward. In step 430, the interactive element 505 can be activated. In step 435, the inertial measurement unit 62 may collect one or more measurements from the accelerometer and gyroscope. In some embodiments, the computer 43 may collect one or more measurements as those measurements are acquired and transmitted by the inertial measurement unit 62. In some embodiments, one or more measurements may be temporarily stored, for example, in the volatile memory of the measurement device 60, before being transmitted and received by the computer 43.

[0060] In step 440, the computer 43 receives one or more measurements and can determine the bias of the inertial measurement unit 62 based on those measurements. Since the patient's legs are in an extended, resting position, any measurement of acceleration or motion using the inertial measurement unit 62 can therefore be considered a bias. Such a bias can be used, for example, to calibrate the inertial measurement unit 62 when taking further measurements.

[0061] In some embodiments, another device, such as an external control unit, may receive one or more measurements, for example, as a temporary storage device or intermediary for the computer 43. In some embodiments, another device, such as an external control unit, may perform one or more of the operations described elsewhere as being performed by the computer 43. Any suitable configuration or architecture can be used. As shown in Figure 5A, the workflow may include a progress indicator 510 that shows progress in acquiring one or more measurements and / or determining the initial reference coordinate system.

[0062] In some embodiments, the inertial measurement unit 62 and / or the computer 43 may be configured to detect the motion of the inertial measurement unit 62 based on one or more measurements, for example, using a technique similar to one or more of the techniques described above. In response to the detection of motion during bias identification of the measurement device 60, the computer 43 may be configured to output one or more of an error message and an interactive element that can be operated to repeat the bias identification of the measurement device 60.

[0063] In step 445, the computer 43 may output a further set of commands to move the patient's musculoskeletal system, which, when executed, cause the accelerometer and gyroscope to generate data usable to determine the varus / valgus angle of the tibia. Figures 5B–5F show exemplary embodiments of such multiple command outputs. In some embodiments, the output in Figure 5B is displayed in response to the computer 43 receiving data, for example, containing one or more measurements from a preceding workflow step(s). In other words, in some embodiments, the measuring device 60 transmits several different parts of data, containing several measurements from the accelerometer and gyroscope, which the computer 43 can receive, so that the several different parts may correspond to several different postures or movements of the patient's leg. In some embodiments, the output of multiple commands, for example, using the computer 43 to move and / or position the patient's musculoskeletal system is repeated. For example, the computer 43 outputs a command for each of the movements or postures, thereby allowing repetition between the current corresponding movement or posture and the next corresponding movement or posture to be based on receiving a portion of the data from the measuring device 60 corresponding to the current corresponding movement or posture.

[0064] In one example, Figure 5B shows the output of commands to achieve the initial position of the patient's legs. In step 450, the patient's legs can be moved and / or positioned according to the commands shown in the output, for example, as shown in Figure 5C. As shown in Figure 5B, the computer 43 may include a further interactive element 515. In step 455, the interactive element 515 may be activated.

[0065] In step 455, in response to the activation of the interactive element 515, the computer 43 may output further commands regarding the patient's leg movements. As shown in Figure 5D, the movements may begin from a resting position, and from that resting position, they may change in a static-to-dynamic sequence, for example, the leg being swung back and forth, as shown in Figure 5E. In step 460, the computer 43 may receive further data, including multiple measurements corresponding to the movements from the accelerometer and gyroscope.

[0066] Any number of postures and / or movements can be used, but in exemplary embodiments, the multiple postures and movements used to determine the varus / valgus angle of the tibia consist of the resting position described above for determining the bias of the measuring device 60, and the anterior-posterior movement described above. This simple procedure requires a stable heel and a stable position of the sensor relative to the tibia, followed by a rolling motion around the heel. Thus, techniques according to one or more embodiments of the present disclosure can enable the determination of the varus / valgus angle of the tibia with reduced time and difficulty compared to procedures requiring additional movements and / or postures.

[0067] Optionally, in step 465, the computer 43 may perform further data validation. In some embodiments, performing validation may include determining one or more of the maximum linear rate, maximum angular velocity, or time integral error of multiple measurements in the further data.

[0068] Any suitable technique may be used to determine one or more of the maximum linear velocity, maximum angular velocity, or time integral error of multiple measurements in further data. In exemplary embodiments, determining the time integral error may include determining the measured final gravity direction (based on one or more static measurements received from the accelerometer in the final portion of the multiple measurements, such as one or more measurements corresponding to the final static posture of the leg detected by the inertial measurement unit 62 during the procedure), determining the estimated gravity direction (e.g., from the time-integrated angular velocities of the multiple measurements), and determining the angular error between the measured final gravity direction and the estimated gravity direction.

[0069] In some embodiments, the verification may further include determining whether one or more of the maximum linear velocity, maximum angular velocity, and time integral error exceed a predetermined threshold. Any suitable predetermined threshold can be used.

[0070] Optionally, in step 470, for example in response to a validation failure, the computer 43 may output a prompt to retrieve further data and / or a possible explanation for the validation failure, receive replacement data corresponding to the repetition of the operation, and replace the further data with the replacement data. Figures 5G to 5N show various exemplary outputs from the computer 43 in response to failures in the validation of further data for various reasons.

[0071] In Figure 5G, the computer 43 may output a prompt indicating that the patient's leg movement is inconsistent, prompting further data acquisition. Such a validation failure may be detected based, for example, on one or more of the maximum angular velocity, mean angular velocity, or any appropriate criteria. In some embodiments, such a validation failure may be detected based, for example, on a determination that the maximum linear jerk, based on linear acceleration, linear motion, etc., exceeds a predetermined threshold.

[0072] In Figure 5H, the computer 43 may output a prompt indicating that heel or ankle movement has been detected, prompting for further data acquisition. Such a verification failure may be detected, for example, based on a determination that the error related to the rotation axis of the inertial measurement unit 62 is greater than a predetermined threshold.

[0073] In Figure 5I, the computer 43 may output a prompt indicating that a change in the position of the inertial measurement unit 62 has been detected, and may prompt for further data acquisition. Such verification failures may be detected based on, for example, the residual acceleration error, such as the root mean square residual acceleration error, which is determined after, for example, the rotation center of the inertial measurement unit 62 has been determined.

[0074] In Figure 5J, the computer 43 may output a prompt indicating that the leg movement was too slow, prompting the reacquisition of further data. Such verification failures may be detected, for example, based on the maximum angular velocity and / or maximum linear velocity.

[0075] In Figure 5K, the computer 43 may output a prompt indicating that the leg movement was too fast, prompting for further data acquisition. Such a verification failure may be detected, for example, based on the maximum angular velocity and / or maximum linear velocity.

[0076] In Figure 5L, the computer 43 may output prompts indicating that the legs were moving while the bias of the measuring device 60 was being acquired, and that the acquisition was timed in that manner, prompting a reacquisition of the bias of the measuring device 60. Such a verification failure may be detected based on the detection of movement during the acquisition of the bias of the measuring device 60, for example, by using one or more of the techniques described above.

[0077] In Figure 5M, the computer 43 may output a prompt indicating that the acquisition of the bias of the measuring device 60 is invalid, and may prompt the computer to reacquire the bias of the measuring device 60. Such a verification failure may be detected, for example, based on a time integration error.

[0078] In Figure 5N, the computer 43 may output a prompt indicating that communication between the computer 43 and the measuring device 60 is poor, prompting further data acquisition. Such verification failures may be detected, for example, based on the reception of corrupted and / or incomplete data.

[0079] In step 475, the computer 43 may obtain calibration data for the inertial measurement unit 62, for example, from the onboard memory of the measuring device 60 and / or from the bias identification in step 440 described above. In step 480, the computer 43 may apply the calibration data to multiple measurements in further data collected by the measuring device 60, for example, after the measurement data has been validated and / or before determining the varus or valgus angle of the tibia of the patient's leg. However, it should be understood that the calibration data may be applied to multiple measurements of the inertial measurement unit 62 at any preferred step or time in various embodiments.

[0080] Optionally, in step 480, the computer 43 may perform preprocessing operations on multiple measurements. For example, in some embodiments, the computer 43 may remove one or more measurements that exceed a predetermined maximum angular acceleration. Any appropriate preprocessing operations may be performed. In step 485, the computer 43 may determine the varus or valgus angle of the tibia based on further data and the first measurements, as will be described in more detail below.

[0081] In step 490, the computer 43 can be made to output the determined varus or valgus angle of the tibia. Figures 5O and 5P show exemplary embodiments of the output from the computer 43, including the determined valgus and varus angles, respectively. In some embodiments, the determined angles are output as the nearest 1 / 2 degree, the nearest 1 / 10 degree, etc. In some embodiments, the determined varus or valgus angle of the tibia may be further output so as to be stored in the patient's medical record, for example, in a medical record database. In some embodiments, outputting the determined angles includes, for example, generating a graphical indicator showing the determined angle, such as a graphical depiction of the knee which may include the tibia, femur, and any other parts of the knee joint, and outputting a graphical display in addition to, or instead of, a numerical display of the determined angle.

[0082] In various embodiments, various actions may be performed in response to the output of the determined tibia varus or valgus angle. For example, if the determined tibia varus or valgus angle is greater than 3 degrees, further osteotomy of the tibia 44, insertion of shims to adjust the orientation of the measurement device 60 and / or the inertial measurement unit 62 may be performed. In another embodiment, ligament release of one or more ligaments of the leg may be performed. Any preferred action may be performed in response to the determination of the tibia varus or valgus angle. If a tibia varus or valgus angle of less than 3 degrees is determined, the trial prosthesis may be removed and / or a permanent prosthesis may be placed.

[0083] Figure 6A shows an exemplary embodiment of a method for determining the varus or valgus angle of the tibia of a patient's leg, for example, with respect to step 485 of the method in Figure 4. As described above, multiple measurements obtained by the accelerometer and gyroscope of an inertial measurement unit 62 located in a measurement device 60 coupled to the patient's musculoskeletal system may be received by, for example, a computer 43. In addition, as previously described, a first measurement related to the length of the patient's tibia may be measured and / or received by, for example, a computer 43. Thus, in various embodiments, the computer 43 can determine the varus or valgus angle of the tibia based on the additional data and the first measurement. In some embodiments, a specific portion of the varus or valgus angle of the tibia may be determined before and / or in conjunction with the verification process described above.

[0084] In step 605, the computer 43 can calculate the orientation of the inertial measurement unit 62 for each of the multiple measurements by performing a time integral of the angular velocity for each of the multiple measurements. The orientation may be a three-degree-of-freedom orientation (e.g., pitch, yaw, and roll). In some embodiments, performing a time integral of the angular velocity for each of the multiple measurements includes defining an initial quaternion for the initial orientation and then applying a quaternion integration using the angular velocities from the multiple measurements.

[0085] In step 610, the computer 43 can further modify the data by removing the gravitational acceleration for each measured acceleration in the multiple measurements. The acceleration measured from the accelerometer generally includes the gravitational acceleration, and therefore the gravitational component can be subtracted before using the multiple measurements in the rigid-body dynamics formulation. In some embodiments, the estimated gravitational acceleration can be determined based on the gravity normal and the estimated direction of gravity (e.g., the -z axis of the global reference coordinate system). As a result, the linear acceleration at the center point of the inertial measurement unit 62 can be estimated in the global reference coordinate system. As described above, in some embodiments, verification processes, such as the verification process performed in step 465 of the method in Figure 4, can be performed on the multiple measurements after the gravity vector has been removed.

[0086] In step 615, the computer 43 can determine a first vector (r) connecting a point on the rotation axis of the patient's musculoskeletal system to the center point of the inertial measurement unit, based on multiple measurements. In some embodiments, the motion may be defined such that the determined vector is constant with respect to the reference coordinate system of the inertial measurement unit 62 across multiple measurements.

[0087] In step 620, the computer 43 can determine the average axis of rotation (u) of the multiple measurements. Any suitable technique can be used to determine the average axis of rotation for the multiple measurements. For example, in some embodiments, the average axis of rotation may be determined by unitizing the average of the angular velocity measurements of multiple measurements that exceed a predetermined minimum angular velocity.

[0088] In step 625, the computer 43 can modify several measurements based on the reference coordinate system of the inertial measurement unit 62 relative to a reference frame of the tibia. For example, the average axis of rotation and the first vector (r) may be used to define a normal (n) that is perpendicular to the axis of rotation (u) and points toward the center of the inertial measurement unit 62. The normal (n) and the first measurement of tibia length may both be used to find a third vector (t) that is parallel to the average axis of rotation and connects the center point of the patient's heel to the normal (n). The third vector (t) and the normal (n) may be used, for example, with an offset of the reference coordinate system of the inertial measurement unit 62 relative to the tibia / knee (e.g., from a second calibration process) to define a position vector extending from the heel to the center of the knee. Thus, the heel reference frame may be defined as having a z-axis aligned with the position vector. Furthermore, by temporarily setting the y-axis of the heel coordinate system to be parallel to the x-axis of the inertial measurement unit, the heel reference coordinate system can be completely defined. Figure 6B shows an example of a position vector from the heel to the center of the knee.

[0089] Returning to Figure 6A, in step 630, the computer 43 can modify several measurements to correct an offset vector between the patient's heel and ankle (for example, having a predetermined size in three dimensions). Figure 6B shows an example of an offset vector, e.g., a position vector from the ankle to the heel. In various embodiments, the magnitude and direction of the offset vector may be measured and / or predetermined, and / or estimated based on population or other data, for example, as a population mean. A second position vector connecting the ankle to the center of the knee can then be defined based on the offset vector and the heel reference coordinate system. Thus, the tibia reference coordinate system can be defined by aligning the z-axis of the tibial reference coordinate system with the second position vector. The tibial reference coordinate system can be fully defined by temporarily setting the y-axis of the tibial reference coordinate system to be parallel to the x-axis of the inertial measurement unit 62.

[0090] Referring again to Figure 6A, in step 635, the computer 43 can determine the orientation or position of the measuring device 60 based on a plurality of measurements. For example, the orientation may be determined based on the orientation of the tibial reference coordinate system relative to the reference coordinate system of the inertial measurement unit 62, along with a known relationship between the reference coordinate system of the inertial measurement unit 62 and the reference coordinate system of the measuring device 60 (e.g., through a calibration process). For example, the alignment angle between the reference coordinate system of the tibial implant 50 and the reference coordinate system of the tibia corresponds to the varus or valgus angle of the tibia, as described below.

[0091] In step 640, the computer 43 can decompose the orientation of the measuring device 60, determined in step 635, into three-axis rotations in the reference coordinate system of the tibia. In step 645, the computer 43 can then determine the varus or valgus angle of the tibia based on the three-axis rotations.

[0092] With respect to Figure 6, the method described above is merely illustrative, and it should be understood that in various embodiments, multiple steps may be added, modified, omitted, and / or rearranged in any appropriate manner.

[0093] As mentioned above, the range of vertebral or eversion angles of the tibia that can be aligned is relatively small, for example, about 1 to 3 degrees. Therefore, accurate identification of the vertebral or eversion angle of the tibia by the measuring device 60 may be important for achieving positive outcomes for the patient. Several experiments were conducted to verify the accuracy of the measuring device 60. Specifically, proximal tibia osteotomy was performed on the legs of cadavers, and the resulting 0.43-degree vertebral or eversion angle of the tibia was directly measured using a CT scan. In each of the five experiments described below, shims that produced different angle corrections (-4 degrees, -2 degrees, 0 degrees, +2 degrees, and +4 degrees, respectively) were placed between the tibial prosthesis component 50 and the measuring device 60. Figure 7A shows an exemplary embodiment of the shim 700, and Figure 7B shows the shim 700 of Figure 7A placed between the tibial prosthesis component 50 and the measuring device 60. Each experiment was repeated five times, for a total of 25 experiments.

[0094] Figure 7C shows a graph of the offset between (i) the measured shim angle and (ii) the angle determined using the measuring device 60, for example, according to one or more of the methods or techniques described above. In other words, the offset can be defined for each experiment as the angle measured by the measuring device (angle measured by CT scan (0.43 degrees) + corresponding shim angle correction).

[0095] In the graph in Figure 7C, the central error bar 710 corresponds to the potential inaccuracy inherent in CT scan measurements, and the lateral error bar 720 shows the typical tolerance for tibial varus or valgus angles of 3 degrees or less from the true value. From the 25 experiments described above, the maximum relative difference between the expected angle and the measured angle was 1.29 degrees. Furthermore, the standard deviation of the 25 experiments ranged from 0.27 degrees to 0.60 degrees across multiple shims with different angle variations.

[0096] As these experimental results demonstrate, determining the varus or valgus angle of the tibia using the techniques of one or more embodiments of the present disclosure may not only be more accurate than the generally accepted range for the varus or valgus angle of the tibia, but as described above, it may also dramatically reduce processing time, complexity, difficulty, and cost.

[0097] Figure 8 is a block diagram of a measuring device or computer according to an exemplary embodiment. In the form of System 250, the exemplary schematic representation of a machine, system, or computer allows a set of instructions within the system to be executed, which in turn causes the machine to perform one or more of the methodologies considered above. In some embodiments, the machine operates as a standalone device. In some embodiments, the machine can be connected to other machines (e.g., using a network). In a networked deployment, the machine can operate within the capabilities of a server or client user machine in a server-client user network environment, or as a peer machine in a peer-to-peer (or distributed) network environment.

[0098] A machine may include a server computer, a client user computer, a personal computer (PC), a tablet PC, a laptop computer, a desktop computer, a control system, a logic circuit, a sensor system, an ASIC, an integrated circuit, a network router, a switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) specifying the actions to be performed by that machine. It will be understood that the devices of this disclosure include a wide range of electronic devices that provide voice, video, or data communications. Furthermore, although a single machine is shown, the term “machine” shall be construed to also include any collection of machines that individually or collectively execute a set (or more) of instructions to perform one or more of the methodologies considered herein.

[0099] System 250 may include a processor 252 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), or both), main memory 254, and static memory 256, which communicate with each other via bus 258. System 250 may further include a video display unit 260 (e.g., a liquid crystal display (LCD), a flat panel, a solid-state display, or a cathode ray tube (CRT)). System 250 may also include an input device 262 (e.g., a keyboard), a cursor control device 264 (e.g., a mouse), a disk drive unit 266, a signal generating device 268 (e.g., a speaker or remote control), and a network interface device 270.

[0100] The disk drive unit 266 may be other types of memory, such as flash memory, and may include a machine-readable medium 272 on which one or more sets of instructions 274 (e.g., software) embodying one or more of the methodologies or functions described herein, including those methods shown above. The instructions 274 may also reside fully or at least partially in the main memory 254, static memory 256, and / or processor 252 while they are being executed by the system 250. The main memory 254 and processor 252 may also be considered machine-readable media.

[0101] Dedicated hardware implementations, including but not limited to application-specific integrated circuits, programmable logic arrays, and other hardware devices, can similarly be constructed to implement the methods described herein. Applications that can include devices and systems of various embodiments broadly include a wide range of electronic and computer systems. Some embodiments implement functionality within two or more specific interconnected hardware modules or devices, either with relevant control and data signals communicated between and through modules, or as part of an application-specific integrated circuit. Thus, examples of systems are applicable to software, firmware, and hardware implementations.

[0102] According to various embodiments of this disclosure, the methods described herein are for operation as software programs running on a computer processor. Furthermore, software implementations may include, but are not limited to, distributed processing or component / object distributed processing, parallel processing, or virtual machine processing, and may be constructed to implement the methods described herein.

[0103] This disclosure envisions a machine-readable medium containing an instruction 274, or a machine-readable medium that receives and executes an instruction 274 from a propagated signal, so that a device connected to a network environment 276 can transmit or receive voice, video, or data, and communicate over the network 276 using the instruction 274. Furthermore, the instruction 274 can be transmitted or received over the network 276 via a network interface device 270.

[0104] In exemplary embodiments, the machine-readable medium 272 is shown to be a single medium, but the term “machine-readable medium” should be interpreted to include a single medium or multiple mediums (e.g., a centralized or distributed database, and / or associated caches and servers) that store one or more sets of instructions. The term “machine-readable medium” should also be interpreted to include any medium that can store, encode, or carry a set of instructions for machine execution, causing the machine to execute one or more of the methodologies of this disclosure.

[0105] Accordingly, the term “machine-readable media” shall be interpreted as including, but not limited to, solid-state memory such as memory cards or other packages containing one or more read-only (non-volatile) memories, random-access memories, or other rewritable (volatile) memories; magneto-optical or optical media such as disks or tapes; and carrier signals such as signals that embody computer instructions in a transmission medium; and / or attachments of digital files to email or other self-contained information archives or sets of archives shall be considered equivalent distribution media to tangible storage media. Accordingly, this disclosure shall be deemed to include one or more machine-readable media or distribution media, including equivalents and successor media listed herein and recognized in the art in which the software implementations herein are stored.

[0106] While this specification describes components and functions implemented in embodiments with reference to specific standards and protocols, this disclosure is not limited to such standards and protocols. Each standard for the Internet and other packet-switched network transmissions (TCP / IP, UDP / IP, HTML, HTTP, etc.) represents an example of the current state of the art. Such standards are periodically superseded by faster or more efficient equivalents that have essentially the same functionality. Therefore, alternative standards and protocols with the same functionality are considered equivalents.

[0107] Figure 9 shows a diagram of a communication network 280 for measurement and reporting according to an exemplary embodiment. Simply put, the communication network 280 extends extensive data connectivity to other devices or services. As illustrated, the measurement and reporting system 304 can be communicatively coupled to the communication network 280 and any associated systems or services.

[0108] For example, the measuring device 304 can share its parameters of interest (e.g., angle, load, balance, distance, alignment, displacement, motion, rotation, and acceleration) with a remote service or provider for analysis or reporting of the status or outcome of surgery. This data can be shared, for example, with a service provider to monitor progress, or with a planner for surgical monitoring purposes or effectiveness studies. Furthermore, the communication network 280 can be associated with an electronic medical record (EMR) system to implement medical information technology practices. In other embodiments, the communication network 280 can be communicably coupled to a hospital information system (HIS), hospital information technology (HIT) and hospital information management (HIM), electronic health records (EHR), computerized physician order entry (CPOE), and computerized decision support systems (CDSS). This provides the functionality of various information technology systems and software applications to communicate and exchange data accurately, efficiently, and consistently, and to use the exchanged data.

[0109] The communication network 280 can provide wired or wireless connectivity via a local area network (LAN) 292, a wireless local area network (WLAN) 288, a cellular network 294, and / or other radio frequencies (RF). The LANs 292 and WLANs 288 can be communicably coupled to the internet 908 via a central office, etc. The central office can house a common network switch for distributing telecommunications services. Telecommunications services may include traditional POTS (Basic Telephone Services) and broadband services such as cable, HDTV, DSL, VoIP (Voice over Internet Protocol), IPTV (Internet Protocol Television), and Internet services.

[0110] Communication network 280 can support circuit-switched and / or packet-switched communications using common computing and communication technologies. The standards for the Internet 296 and other packet-switched network transmissions (TCP / IP, UDP / IP, HTML, HTTP, RTP, MMS, SMS) represent examples of the current state of technology. Such standards are periodically superseded by faster or more efficient equivalents that have essentially the same functionality. Therefore, alternative standards and protocols with the same functionality are considered equivalents.

[0111] The cellular network 294 can support voice and data services via many access technologies, including GSM-GPRS, EDGE, CDMA, UMTS, WiMAX, 2G, 3G, WAP, software-defined radio (SDR), and other known technologies. The cellular network 294 can be coupled to a base station receiver 290 under a frequency reuse plan for communication with mobile devices 282.

[0112] Next, the base station receiver 290 can connect the mobile device 282 to the internet 296 via a packet-switched link. The internet 296 can support application services and service layers to deliver data from the measurement device 304 to the mobile device 282. The mobile device 282 can also connect to other communication devices via the internet 296 using a wireless communication channel.

[0113] Furthermore, the mobile device 282 can connect to the internet 296 via the WLAN 288. A Wireless Local Access Network (WLAN) provides radio access within a local geographical area. A WLAN typically consists of a cluster of access points (APs) 284, also known as base stations. The measurement system 304 can communicate with other WLAN stations, such as the laptop 286, within the base station area. In a typical WLAN implementation, the physical layer uses various technologies, such as 802.11b or 802.11g WLAN technologies. The physical layer may also use other access technologies, such as infrared, frequency-hopping spread spectrum in the 2.4GHz band, direct-sequence spread spectrum in the 2.4GHz band, or the 5.8GHz ISM band or higher ISM bands (e.g., 24GHz).

[0114] Through the communication network 280, the measurement system 304 can establish connections with a remote server 298 on the network and with other mobile devices for data exchange. The remote server 298 can have access to a database 300, which may be stored locally or remotely and may contain application-specific data. The remote server 298 can also host application services directly or via the internet 296.

[0115] It should be noted that there is very little data available regarding implanted orthopedic devices. Most data is obtained empirically by analyzing orthopedic devices used in human subjects or for simulated purposes. Wear patterns, material issues, and failure mechanisms have been studied. While information can be gathered through this type of research, substantial data on initial placement, postoperative use, and long-term use can be obtained from a measurement perspective. Just as each individual is different, the placement of each device also differs, with variations in initial loading, balance, and alignment. Measuring data and using that data to place orthopedic devices significantly improves the consistency of implant procedures, reduces rework, and maximizes device lifespan. In at least one exemplary embodiment, the measured data can be collected, stored, and analyzed in a database. For example, once relevant samples of measured data are collected, they can be used to define the optimal initial measurement settings, geometric shapes, and alignments to maximize the lifespan and usefulness of implanted orthopedic devices.

[0116] Although the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that many modifications can be made therewith without departing from the spirit and scope of the invention. Each of these embodiments and its obvious variations is intended to be within the spirit and scope of the invention. The technical concepts that can be understood from the above embodiments are described below as an addendum. (Note 1) A method for measuring the varus or valgus angle of the tibia using a surgically implanted measuring device, Receiving first data from the measurement device using at least one processor, The housing of the measurement device is connected to the patient's musculoskeletal system. The first data described above includes multiple measurements from an accelerometer and a gyroscope, each of which are included in an inertial measurement unit located within the housing, and is received. Using at least one of the aforementioned processors, a first measurement of the anatomical features of the patient's leg is received, Based on the first measurement value, the varus or valgus angle of the tibia is determined, A method comprising outputting the determined varus or valgus angle of the tibia to a display. (Note 2) The method according to Appendix 1, further comprising connecting the housing to the patient's musculoskeletal system before receiving the first data. (Note 3) The method according to Appendix 1, further comprising, when executed, outputting to the display a command to cause the accelerometer and the gyroscope to generate the first data, or to cause the patient to assume the movement or posture of the musculoskeletal system. (Note 4) The different portions of the first data correspond to the respective movements or postures of the patient's musculoskeletal system. Outputting the command to the display to cause the patient to assume the musculoskeletal movement or posture is, This includes repeatedly outputting the respective commands for each movement or posture to the display, The method described in Appendix 3, wherein the repetition between the current corresponding movement or posture and the next corresponding movement or posture is based on receiving a portion of the first data corresponding to the current corresponding movement or posture. (Note 5) The verification of the first data is further performed using the at least one processor. In response to the first data failing the verification, the at least one processor: The display will output a prompt for reacquiring the aforementioned multiple measurement values, Receiving second data from the measuring device, which includes a further number of measurements from each of the accelerometer and the gyroscope, The method according to Appendix 1, configured to replace the first data with the second data so that the varus or valgus angle of the tibia can be determined based on the second data and the first measurement. (Note 6) Performing the aforementioned verification means Using at least one of the processors, the maximum linear velocity, maximum angular velocity, and time integral error of each of the multiple measured values ​​in the first data are determined. The method according to Appendix 5, comprising determining whether each of the maximum linear velocity, the maximum angular velocity, and the time integral error exceeds a predetermined threshold. (Note 7) To determine the aforementioned time integral error, Based on one or more static measurements received from the accelerometer in the final portion of the plurality of measurements, the final measured direction of gravity is determined. The estimated direction of gravity is determined from the time-integrated angular velocity of the aforementioned multiple measured values, The method according to Appendix 6, comprising determining the angular error between the measured final gravity direction and the estimated gravity direction. (Note 8) Acquiring calibration data of the inertial measurement unit stored in the memory of the measurement device, The method according to Appendix 1, further comprising correcting the plurality of measurements based on the calibration data before determining the varus or valgus angle of the tibia. (Note 9) The method according to Appendix 1, further comprising preprocessing the first data by removing at least one or more of the plurality of measured values ​​that exceed a predetermined maximum angular acceleration. (Note 10) Determining the varus or valgus angle of the tibia is: The orientation of the inertial measurement unit is calculated for each of the multiple measured values ​​by performing time integration of the angular velocity for each of the multiple measured values. The first data is modified by removing the gravitational acceleration from each of the multiple measured values, Based on the aforementioned multiple measurement values, a vector is determined that connects a point on the rotation axis of the patient's musculoskeletal system to the center point of the inertial measurement unit, The average rotation axis for the multiple measured values ​​is determined by unitizing the result of averaging the angular velocity measured values ​​of the multiple measured values ​​that exceed a predetermined minimum threshold, The plurality of measurement values ​​are corrected based on the reference coordinate system of the inertial measurement unit with respect to the reference coordinate system of the patient's tibia. The plurality of measurements are corrected based on the offset vector between the patient's heel and the patient's ankle. Based on the aforementioned multiple measurement values, the orientation of the measuring device is determined, The orientation of the measuring device is decomposed into a three-axis rotation of the patient's tibia in a reference coordinate system, The method according to Appendix 1, which includes determining the varus or valgus angle of the tibia based on the three-axis rotation. (Note 11) A system for measuring the varus or valgus angle of a patient's tibia, A measuring device, said measuring device is A housing configured to connect to the musculoskeletal system of the patient, The housing includes an inertial measurement unit, The aforementioned inertial measurement unit is Accelerometer and, Includes a gyroscope, The inertial measurement unit is configured to record a plurality of measured values ​​using the accelerometer and the gyroscope, and the measurement device is configured A system comprising a transmitter configured to output the aforementioned multiple measured values. (Note 12) The system according to Appendix 11, further comprising an artificial knee joint including a tibial prosthesis component coupled to the proximal end of the tibia of the patient, wherein the housing of the measuring device is configured to be detachably coupled to the tibial prosthesis component. (Note 13) The display and A computing device for determining the varus or valgus angle of the tibia of the patient, At least one processor, A communication component operably connected to at least one of the processors, The system further comprises a memory operably connected to the at least one processor and storing a plurality of instructions that can be executed by the at least one processor to perform a plurality of operations, wherein the plurality of operations are The measurement device receives first data, which includes multiple measured values ​​from the accelerometer and the gyroscope, To receive a first measurement of the tibia length of the patient, Based on the first data and the first measurement, the varus or valgus angle of the tibia is determined, The system according to Appendix 11, which includes outputting the determined varus or valgus angle of the tibia to the display. (Note 14) The aforementioned multiple operations are, The system according to Appendix 13, further comprising, when executed, outputting to the display a command to cause the patient to assume a movement or posture of the musculoskeletal system, which causes the accelerometer and the gyroscope to generate the first data. (Note 15) The different portions of the first data correspond to the respective movements or postures of the patient's musculoskeletal system. Outputting the command to the display to cause the patient to assume the musculoskeletal movement or posture is, This includes repeatedly outputting the respective commands for each movement or posture to the display, The system described in Appendix 14, wherein the repetition between the current corresponding movement or posture and the next corresponding movement or posture is based on receiving a portion of the first data corresponding to the current corresponding movement. (Note 16) The measurement device further includes a memory for storing calibration data for the inertial measurement unit, The aforementioned multiple operations are, To acquire the calibration data for the inertial measurement unit, The system according to Appendix 13, further comprising correcting the plurality of measurements based on the calibration data before determining the varus or valgus angle of the tibia. (Note 17) The aforementioned multiple operations are, The system according to Appendix 13, further comprising preprocessing the first data by removing at least one or more of the multiple measured values ​​that exceed a predetermined maximum angular acceleration. (Note 18) Determining the varus or valgus angle of the tibia is: The orientation of the inertial measurement unit is calculated for each of the multiple measured values ​​by performing time integration of the angular velocity for each of the multiple measured values. The first data is modified by removing the gravitational acceleration from each of the multiple measured values, Based on the aforementioned multiple measurement values, a vector is determined that connects a point on the rotation axis of the patient's musculoskeletal system to the center point of the inertial measurement unit, The average rotation axis for the multiple measured values ​​is determined by unitizing the result of averaging the angular velocity measured values ​​of the multiple measured values ​​that exceed a predetermined minimum threshold, The plurality of measurement values ​​are corrected based on the reference coordinate system of the inertial measurement unit with respect to the reference coordinate system of the patient's tibia. The plurality of measurements are corrected based on the offset vector between the patient's heel and the patient's ankle. Based on the aforementioned multiple measurement values, the orientation of the measurement system is determined, The posture of the measurement system is decomposed into a three-axis rotation of the patient's tibia in a reference coordinate system, The system according to Appendix 13, comprising determining the varus or valgus angle of the tibia based on the three-axis rotation. (Note 19) A non-temporary computer-readable medium for storing multiple instructions that can be executed by a processor to perform multiple operations, wherein the multiple operations are: This involves receiving the first data from the measurement system, The housing of the measurement system is connected to the patient's musculoskeletal system. The first data described above includes multiple measurements from an accelerometer and a gyroscope, each of which are included in an inertial measurement unit located within the housing, and is received. To receive a first measurement of the tibia length of the patient, Based on the first data and the first measurement, the varus or valgus angle of the tibia is determined, A non-temporary computer-readable medium that includes outputting the required varus or valgus angle of the tibia to a display. (Note 20) The aforementioned multiple operations are, The non-temporary computer-readable medium according to Appendix 19, further comprising, when executed, outputting to the display a command to cause the patient to assume a movement or posture of the musculoskeletal system, which causes the accelerometer and the gyroscope to generate the first data.

Claims

1. A system for measuring the varus or valgus angle of a patient's tibia, An artificial knee component configured to bond to the bone of the patient, wherein the artificial knee component includes a measuring device, the measuring device includes an inertial measuring unit, the inertial measuring unit includes an accelerometer and a gyroscope, and the inertial measuring unit is configured to record a plurality of measurements using the accelerometer and the gyroscope, The system includes a transmitter configured to output the aforementioned multiple measurement values ​​to a computing device, The computing device is configured to determine the varus or valgus angle of the tibia based on the plurality of measured values.

2. The display and A computing device for determining the varus or valgus angle of the tibia of the patient, At least one processor, A communication component operably connected to at least one of the processors, The system further comprises a memory operably connected to the at least one processor and storing a plurality of instructions that can be executed by the at least one processor to perform a plurality of operations, wherein the plurality of operations are The measurement device receives first data, which includes multiple measured values ​​from the accelerometer and the gyroscope, To receive a first measurement of the tibia length of the patient, Based on the first data and the first measurement, the varus or valgus angle of the tibia is determined, The system according to claim 1, further comprising outputting the determined varus or valgus angle of the tibia to the display.

3. The aforementioned multiple operations are, The system according to claim 2, further comprising, when executed, outputting to the display a command to cause the accelerometer and the gyroscope to generate the first data, or to cause the patient to assume a musculoskeletal movement or posture.

4. The different parts of the first data correspond to the respective movements or postures of the patient's musculoskeletal system. Outputting the command to the display to cause the patient to assume the musculoskeletal movement or posture is, This includes repeatedly outputting the respective commands for each movement or posture to the display, The system according to claim 3, wherein the repetition between the current corresponding movement or posture and the next corresponding movement or posture is based on receiving a portion of the first data corresponding to the current corresponding movement.

5. The measurement device further includes a memory for storing calibration data for the inertial measurement unit, The aforementioned multiple operations are, To acquire the calibration data for the inertial measurement unit, The system according to claim 2, further comprising correcting the plurality of measurements based on the calibration data before determining the varus or valgus angle of the tibia.

6. The aforementioned multiple operations are, The system according to claim 2, further comprising preprocessing the first data by removing at least one or more of the plurality of measured values ​​that exceed a predetermined maximum angular acceleration.

7. Determining the varus or valgus angle of the tibia is: The orientation of the inertial measurement unit is calculated for each of the multiple measured values ​​by performing time integration of the angular velocity for each of the multiple measured values. The first data is modified by removing the gravitational acceleration from each of the multiple measured values, Based on the aforementioned multiple measurement values, a vector is determined that connects a point on the rotation axis of the patient's musculoskeletal system to the center point of the inertial measurement unit, The average rotation axis for the multiple measured values ​​is determined by unitizing the result of averaging the angular velocity measured values ​​of the multiple measured values ​​that exceed a predetermined minimum threshold, The plurality of measurement values ​​are corrected based on the reference coordinate system of the inertial measurement unit with respect to the reference coordinate system of the patient's tibia. The plurality of measurements are corrected based on the offset vector between the patient's heel and the patient's ankle. Based on the aforementioned multiple measurement values, the attitude of the system is determined, The posture of the system is decomposed into three-axis rotations of the patient's tibia in a reference coordinate system, The system according to claim 2, comprising determining the varus or valgus angle of the tibia based on the three-axis rotation.

8. A non-temporary computer-readable medium for storing multiple instructions that can be executed by a processor to perform multiple operations, wherein the multiple operations are: This involves receiving the first data from the measurement system, The artificial knee component equipped with the aforementioned measurement system is bonded to the patient's bone. The first data described above includes multiple measured values ​​from an accelerometer and a gyroscope, respectively, included in the inertial measurement unit of the measurement system, and is received. To receive a first measurement of the tibia length of the patient, Based on the first data and the first measurement, the varus or valgus angle of the tibia is determined, A non-temporary computer-readable medium that includes outputting the required varus or valgus angle of the tibia to a display.

9. The aforementioned multiple operations are, The non-temporary computer-readable medium according to claim 8, further comprising, when executed, outputting to the display a command to cause the accelerometer and the gyroscope to generate the first data, or to cause the patient to assume a musculoskeletal movement or posture.

10. The system according to claim 1, wherein the measuring device is configured to be detachably coupled to the artificial knee component.

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