EP-4734856-A1 - MOTORIZED ORTHOPEDIC TENSOR AND METHODS OF USING THE SAME

Abstract

Systems and methods related to an orthopedic tensor for a knee joint. The tensor is motorized and operates in a force control mode and a displacement control mode. A control system controls the tensor in the force control mode to apply forces to the knee joint until a predetermined force is reached. The control system captures a plurality of force-displacement data pairs from the tensor as a result of the forces applied by the tensor in the force control mode. Control of the tensor is switched from the force control mode to the displacement control mode to perform an extension test whereby a displacement of the tensor is progressively decreased according to displacements from the plurality of force-displacement data pairs until the knee joint can reach an acceptable full extension pose during, or after completion of, the extension test.

Inventors

• KANG, HYOSIG
• BECHTOLD, KEVIN
• KASODEKAR, Snehal
• EBBITT, PETER L.
• BOWLING, DAVID GENE

Assignees

• MAKO Surgical Corp.

Dates

Publication Date

20260506

Application Date

20240626

Claims (20)

1. 1. A surgical system configured to evaluate a knee joint, the surgical system comprising: a tensor that is motorized and configured to operate in a force control mode and a displacement control mode; and a control system coupled to the tensor and being configured to: control the tensor in the force control mode to apply forces to the knee joint until a predetermined force is reached; capture a plurality of force-displacement data pairs from the tensor as a result of the forces applied by the tensor in the force control mode; and control the tensor to switch from the force control mode to the displacement control mode and control the tensor in the displacement control mode to perform an extension test whereby a displacement of the tensor is progressively decreased according to displacements from the plurality of force-displacement data pairs until the knee joint can reach an acceptable full extension pose during, or after completion of, the extension test.
2. 2. The surgical system of claim 1, wherein the control system is configured to control the tensor in the force control mode to apply forces to the knee joint until the predetermined force is reached when a current pose of the knee joint is at a first acceptable flexion pose.
3. 3. The surgical system of claim 2, wherein the knee joint includes a femur and a tibia, and the surgical system further includes a localizer and a display device, and wherein the control system is configured to: track a pose of the femur and a pose of the tibia with the localizer; control the display device to provide visual guidance to aid in placing the current pose of the knee joint in the first acceptable flexion pose; capture, with the localizer, the current pose of the knee joint relative to the first acceptable flexion pose; and control the display device to provide a visual confirmation in response to the current pose of the knee joint being at the first acceptable flexion pose.
4. 4. The surgical system of claim 2, wherein the first acceptable flexion pose is a value between 2-15 degrees of knee joint flexion.
5. 5. The surgical system of claim 1, wherein the knee joint includes a femur and a tibia, and the surgical system further includes a localizer and a display device, and wherein the control system is configured to: track a pose of the femur and a pose of the tibia with the localizer; and control the display device to provide a visual representation of a current pose of the knee joint based on the poses of the femur and the tibia tracked by the localizer.
6. 6. The surgical system of claim 5, wherein the control system is configured to measure a gap of the knee joint based on the pose of the femur and the tibia tracked by the localizer.
7. 7. The surgical system of claim 5, wherein the control system is configured to: capture, with the localizer, the current pose of the knee joint relative to the acceptable full extension pose; and control the display device to provide a visual confirmation in response to the current pose of the knee joint being at the acceptable full extension pose.
8. 8. The surgical system of claim 1, wherein the acceptable full extension pose is a value from 0-2 degrees of knee joint flexion.
9. 9. The surgical system of claim 1, wherein the control system is configured to: generate a look-up table based on the plurality of force-displacement data pairs captured from the tensor; and perform the extension test according to displacements from the look-up table.
10. 10. The surgical system of claim 1, wherein the control system is configured to: capture a target displacement of the tensor at a time when the predetermined force was reached, the target displacement being indicative of a target gap of the knee joint; and prior to performing the extension test, control the tensor in the displacement control mode to place the tensor at the target displacement; and perform the extension test by progressively decreasing the displacement of the tensor starting from the target displacement.
11. 11. The surgical system of claim 1, wherein the control system performs the extension test by being configured to automatically and progressively decrease the displacement of the tensor according to displacements from the plurality of force-displacement data pairs.
12. 12. The surgical system of claim 1, wherein the tensor comprises a user control input, and wherein the control system performs the extension test by being configured to progressively decrease the displacement of the tensor in response to the user control input and according to displacements from the plurality of force-displacement data pairs.
13. 13. The surgical system of claim 1, wherein during, or after completion of, the extension test, the control system is configured to identify a first force-displacement data pair that enabled the knee joint to reach the acceptable full extension pose.
14. 14. The surgical system of claim 13, wherein, after completion of the extension test, the control system is configured to: control the tensor to switch from the displacement control mode to the force control mode and control the tensor in the force control mode to apply a second predetermined force to the knee joint when the knee joint is in a second acceptable flexion pose.
15. 15. The surgical system of claim 13, wherein, before the control system controlling the tensor in the force control mode to apply forces to the knee joint until the predetermined force is reached, the control system is configured to: control the tensor in the force control mode for applying a second predetermined force to the knee joint when the knee joint is in a second acceptable flexion pose.
16. 16. The surgical system of claim 14, wherein the knee joint includes a femur and a tibia, and the surgical system further includes a localizer and a display device, and wherein the control system is configured to: track a pose of the femur and a pose of the tibia with the localizer; and control the display device to provide visual guidance to aid in placing a current pose of the knee joint at the second acceptable flexion pose; capture the current pose of the knee joint relative to the second acceptable flexion pose; and control the display device to provide a visual confirmation in response to the current pose of the knee joint being at the second acceptable flexion pose.
17. 17. The surgical system of claim 14, wherein the second acceptable flexion pose is a value from 80-105 degrees of knee joint flexion.
18. 18. The surgical system of claim 14, wherein the control system is configured to obtain the second predetermined force from a force from the first force-displacement data pair that enabled the knee joint to reach the acceptable full extension pose.
19. 19. The surgical system of claim 14, wherein the control system is configured to obtain the second predetermined force from one of: a predetermined joint balancing force, a force based on a surgeon preference, a force obtained from statistical data, or a force from any of the forcedisplacement data pairs.
20. 20. The surgical system of claim 14, wherein while the knee joint is at the second acceptable flexion pose and during, or after, application of the second predetermined force to the knee joint, the control system is configured to: capture a second force-displacement data pair from the tensor.

Description

MOTORIZED ORTHOPEDIC TENSOR AND METHODS OF USING THE SAME CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The subject application claims priority to and all the benefits of United States Provisional Patent App No. 63/524,241, filed June 30, 2023, the entire contents of which are hereby incorporated by reference. BACKGROUND [0002] Knee arthroplasty involves replacement of articular surfaces of the knee joint to restore function. An important part of a successful knee arthroplasty procedure involves evaluating the soft tissue or ligaments of the knee joint to ensure proper stability, laxity, stiffness, and/or range of motion of the joint. To date, many surgeons still prefer to assess the knee joint ligaments using traditional, manual methods and devices. [0003] One known device for evaluating the knee joint is a knee distractor which has one or more upper paddles for engaging the femur and a lower paddle for engaging the tibia. The paddles move apart to provide a measurement related to the force or spacing between the joint. However, conventional distractors have many shortcomings. [0004] Conventional distractors have limited adjustability. For example, conventional distractors can be “one-size-fits-all” and not configured to accommodate various sized bones of the knee joint. In attempt to accommodate larger sized bones, these types of distractors require a bulky size, which increases the difficulty of inserting the distractor into the knee. Some conventional distractors configurations are limited to only evaluate either the left knee or the right knee, but not both. For example, some conventional distractors include curved paddles to avoid impingement with the patellar tendon. However, the curved paddles may not he removable, and hence, are designed to circumvent the patellar tendon for only the left or right knee. To circumvent the patellar tendon on both knees, some conventional designs require the curved paddles to be removed and replaced with a different (oppositely curved) set of paddles. Replacing these components prolongs the evaluation process (during which the patient is under anesthesia) and increases complexity and cost. [0005] Conventional distractors are at risk of slipping out of the knee joint during the evaluation process. Slippage can cause potential damage to the knee joint, inaccurate measurements, and inconvenience to the surgeon. This issue is particularly prominent with mid-resection workflows, wherein the tibia is resected prior to the evaluation. The rigid, minimally adjustable, configurations of conventional distractors have limited contact coverage of the paddle with the corresponding bone and, in turn, increases susceptibility to slippage. Alternatively, conventional distractors require the lower paddle to be invasively fastened to the resected tibial plane to reduce slippage. Fastening the lower paddle to the resected tibia adds additional surgical steps and trauma to the bone. [0006] Conventional distractors also are not optimized for cleaning or sterilization. Some distractors include exposed parts, such as springs, actuators, or measurement devices that require thorough sterilization and are susceptible to damage from the sterilization process. Time consuming disassembly of components of the distractor may be needed for cleaning or other purposes. The sterilized components are at risk of failure or wear and tear. [0007] Most conventional distractors are not motorized and do not utilize the advantages of computer aid, such as surgical navigation and/or clinical applications. Therefore, the surgeon often must rely on their subjective knowledge and skill to predict the state of the joint ligaments. In turn, the joint evaluation and surgical outcome can be sub-optimal with conventional distractors. One particularly challenging part of the knee evaluation process involves determining the optimal laxity of the knee joint required to enable the knee to reach full extension. Distracting the knee at 0 degrees (full extension) will likely produce inaccurate measurements due to posterior capsule tightness. To assess the tension of the knee at full extension, surgeons typically use a trial-and-error process in which the surgeon inserts the manual distractor in a mid-flexion pose and uses an educated guess to set the tension of the distractor. The knee is then moved towards full extension. If the knee is unable to reach full extension, the surgeon must reset the tension of the distractor and repeat the assessment. Such a process prolongs the evaluation process, produces sub-optimal results, and is inconvenient to the surgeon. SUMMARY [0008] This Summary introduces a selection of concepts in a simplified form that are further described below in the Detailed Description below. This Summary is not intended to limit the scope of the claimed subject matter nor identify key features or essential features of the claimed subject matter. [0009] According to a first aspect, a tensor is provided that