CUTTING DEVICE FOR REVISION ARTHROPLASTY
A cutting device is provided that includes a pair of cutting blades joined at a pivot point. The cutting blades are driven by an actuator to cause the cutting blades to pivot about the pivot point. The cutting device is configured to remove material underneath a surface of an implant installed on a bone during a revision arthroplasty procedure. The cutting device may travel along a length of the bone just underneath the surface of the implant to remove material and free the implant from the bone. A method for removing material underneath a surface of an implant installed on the bone is also provided. A system for removing material underneath the surface of an implant installed on the bone with the cutting device is also provided.
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This application is a continuation of U.S. patent application Ser. No. 16/620,536, filed Dec. 9, 2019; which in turn is a U.S. National Phase of PCT/US2018/037021, filed Jun. 12, 2018; which in turn claims priority benefit of U.S. Provisional Patent Application No. 62/518,409, filed Jun. 12, 2017, the contents of all the aforementioned are hereby incorporated by references.
FIELD OF THE INVENTIONThe present invention in general, relates to revision orthopedic surgery, and more particularly to a new and useful system and method for planning and executing the removal of an implant in revision hip and knee surgery.
BACKGROUND OF THE INVENTIONJoint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced with a prosthetic joint. Joint arthroplasty is commonly performed for hips, knees, elbows, and other joints. Hip arthroplasty includes the insertion of a prosthetic femoral stem component into the intramedullary canal of the femur. A ball or head associated with the end of the stem articulates within a patient's natural acetabulum, or a prosthetic acetabular component fitted within the acetabulum of the patient in the case of total hip arthroplasty.
It is important that the femoral stem be securely positioned within the femur so as to achieve adequate initial fixation, as well to promote long term stability of the implant. Femoral components can have various design characteristics to provide optimal fixation properties, such as surface features for encouraging bony ingrowth, tailored flexibilities for reducing stress shielding, and particular surface properties for controlling adhesion to cement. While such femoral components may extend the useful life of the implant, a surgical revision of the prosthesis may become necessary after an extended period of time.
One problem associated with the revision of a femoral component is the difficulty of removing the primary implant along the longitudinal axis of the femur. For example,
Surgeons currently use techniques such as chipping away at material 108 (e.g., cement, bony ingrowth) surrounding the stem 104, performing trochanteric osteotomies, or using slap hammers to forcibly remove the stem 104 from the femur (F). However, these techniques are labor intensive, imprecise and can damage the surrounding anatomy.
Thus, there is a need in the art for a system and method to more efficiently remove an implant from a bone during orthopedic revision procedures.
Examples illustrative of embodiments are described below with reference to figures attached hereto. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.
The present invention will now be described with reference to the following embodiments. As is apparent by these descriptions, this invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, features illustrated with respect to one embodiment can be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. In addition, numerous variations and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention. Hence, the following specification is intended to illustrate some particular embodiments of the invention, and not to exhaustively specify all permutations, combinations and variations thereof.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
DefinitionsUnless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below.
As used in the description of the invention and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Also, as used herein, “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).
As used herein, the term “registration” refers to the determination of the spatial relationship between two or more objects or coordinate systems such as a computer-assist device and at least one of a bone, or an image data set of a bone.
As used herein, the term “target bone” refers to a bony structure in need of a surgical procedure, treatment, repair or any combination thereof.
While the present invention is illustrated visually hereafter with respect to a femur as an example of the target bone for which the present invention is applied, it is appreciated that the present invention is equally applicable to other bones of a human, non-human primate, or other mammals.
Furthermore, it should be appreciated that while the systems and methods described herein teach the removal of a femoral implant in revision hip arthroplasty, any of a wide variety of different bone implants may likewise be removed according to the teaching of this invention (e.g., a knee implant and shoulder implant). It is further contemplated that the system and method may be useful for the precise cutting of material around other external objects in the industrial, carpentry, or other medical fields.
Manual Intramedullary Canal Cutting ProcedureEmbodiments of the present invention describe a method and system for removing an implant from a bone. With reference to
With respect to
Referring to
In various embodiments, the cutting device 300 is manufactured from a single piece of material and shaped using a plasma or laser cut. For example, as shown in
In a particular embodiment, the spring shaped sections (306a, 306b, 306c) and/or individual expandable rows (316a, 316b) are removable units where the removable units may be removed and inserted between the cutting segments (304a, 304b, 304c). Having removable units may be particularly advantageous for a couple reasons. First, different sizes and shapes of the removable units may be inserted between the cutting segments (304a, 304b, 304c) based on the application of the cutting device 300. Second, worn-out spring shaped sections (306a, 306b, 306c) and/or individual expandable rows (316a, 316b) may be replaced easier without a need to completely replace the entire cutting device 300.
In a particular embodiment, with respect to the plurality of cutting teeth (310a, 310b, 310c), the cutting teeth (310a, 310b, 310c) are configured to cut, rub, or otherwise remove material 108 surrounding an implant while the cutting device 300 is rotated around the implant. The cutting ends (308a, 308b, 308c) may include any number of cutting teeth (310a, 310b, 310c) which may vary in shape, size, and angular orientation based on the particular application of the cutting device 300. In a specific inventive embodiment, the cutting ends (308a, 308b, 308c) and/or cutting teeth (310a, 310b, 310c) may be removably coupled to the cutting segments (304a, 304b, 304c) where the cutting ends (308a, 308b, 308c) and/or cutting teeth (310a, 310b, 310c) are made of a stiffer material than the other components of the cutting device 300. For example, the cutting ends (308a, 308b, 308c) may be made of stainless steel, grade 17-4 PH, for its high strength and resistance to corrosion in which it is suitable for more rigid cuts, while the other components of the cutting device 300 are made of nitinol.
With reference to
The cutting device 300 may be rotated by a drill 204, motor, or other actuating mechanism. In various embodiments, the base 312 of the cutting device 300 may be configured to couple directly to the drill 204, where the drill 560 drives the cutting device 300. In another embodiment, a distal end of a drive shaft (not shown) is attached to the cutting device 300 and a proximal end of the drive shaft is attached to a drill 204, motor, or other actuator. The drive shaft may be attached on the inside of the tube 302 at the base 312. In a particular embodiment, the distal end of the drive shaft includes two or more prongs, the number of prongs based on the number of cutting segments (304a, 304b, 304c), where each individual prong attaches inside the tube 302 on each individual cutting segment (304a, 304b, 304c). The prongs may be further configured to attach at an angle so as to permit the prongs to expand and collapse with the cutting segments (304a, 304b, 304c) and still rotate the cutting device 300 during the cutting procedure. A flexible sleeve may be present around the drive shaft to protect the surrounding anatomy while driving the cutting device 300. To translate the cutting device 300 along the length of the implant 100, a user may apply pressure on the drill. In other embodiments, the cutting device 300 is rotated and translated by a computer-assisted surgical system as described below. In yet another embodiment, the cutting device 300 is manually rotated and translated.
In various embodiments, the base 312 of the cutting device 300 is coupled to a vacuum device mechanism where the vacuum device is configured to intake the material 108 during the cutting procedure.
With reference to
With reference to
With reference to
In another embodiment and referring to
In a particular embodiment and referring to
In various embodiments, the driving shaft 614 is attached to a drill, motor, or other actuator to rotate the drive shaft 614 and therefore the cam 618. As the cam 618 rotates, the blades (606a, 606b) are rapidly pivoted relative to one another, creating a scissoring action (e.g., the blades (606a, 606b) oscillate or reciprocate about the pivot point). In one embodiment, the cam 618 is oval-shaped. When the longer axis of the oval-shaped cam 618 contacts the blades (606a, 606b), the blades (606a, 606b) are forced apart. Then, as the cam 618 rotates towards the shorter axis of the cam 618, the connecting projections 620 act as a spring forcing the blades (606a, 606b) back towards one another. This creates the scissoring action of the blades (606a, 606b), where the plurality of cutting teeth (608a, 608b) cut, rub, and/or otherwise remove material 108 surrounding an implant.
In various embodiments, the cutting device 600 is made out of a flexible and durable material such as nitinol. The cutting teeth (608a, 608b) and other components may be made of a stiffer material, such as stainless steel, to create enough force to remove the material 108 surrounding an implant and/or to drive the components of the cutting device 600. In a particular embodiment, the cutting device 600 is particularly thin, on the order of 1-5 mm in thickness, and 3-7 mm wide so as to sufficiently cut between the material 108 surrounding the implant without having to remove too much bone stock. In addition, the flexibility and strength of the cutting device 600 is of particular importance. The cutting device 600 needs to be flexible, yet strong enough to travel along the length of an implant and into hard-to-reach anatomical areas. For example,
In various embodiments, the plurality of cutting teeth (608a, 608b) of the blades (606a, 606b) are designed and angled to grab the material 108 during cutting such the cutting device 600 is pulled deeper into the bone. In other words, as the cutting device 600 operates, the scissoring action of the cutting teeth (608a, 608b) force the cutting teeth (608a, 608b) deeper into the material 108.
With reference to
The power controller 638 controls current flowing through the wires 634 and therefore the selective induction of a magnetic field near the FSMA 630. The power controller 638 may pulse direct current to induce and remove the magnetic field at a desired pulse frequency to actuate the blades at desired frequency. In another embodiment, the power controller 638 controls the frequency of alternating current to control the presence/absence of a magnetic field. The power controller 638 may control the frequency of alternating current up to 1000 Hz to cause the blades to actuate at approximately 1000 Hz. In a specific embodiment, the frequency is chosen to match the resonance frequency of the surrounding material 108 to optimize cutting of specific materials.
It should be appreciated, that although the FSMA 630 is shown having an active ‘closed’ state, the FSMA 630 may be treated to have an active ‘open’ state, where the FSMA 630 forces the bottom portion of the blades (606a, 606b) (i.e. below the pivot point 610) away from one another in the presence of a magnetic field. In such a case, the teeth (608a, 608b) may be angled inward towards a center axis of the cutting device 600′ to cut material upon activation, and the spring 632 biased to pull the bottom portion of the blades (606a, 606b) toward one another in the absence of a magnetic field.
In a particular embodiment, if the power controller 638 and wire 634 coiled around the core 636 is unable to produce a magnetic field of sufficient strength to activate the FSMA 630, a magnetic field may be induced externally. For example, the knee of a patient may be situated inside an external magnetic coil to selectively induce a magnetic field to actuate the blades (606a, 606b) to remove total knee arthroplasty implant components.
There are a couple advantages of the cutting device 600′ as compared to cutting device 600. For one, the cutting device 600′ no longer requires a rigid drive shaft 614 for driving the blades (606a, 606b), which greatly increases the flexibility and capabilities of the device 600′. Second, the blades (606a, 606b) may be actuated at a much higher frequency, with greater control and safety.
Robotic ProcedureEmbodiments of the present invention may also utilize a computer assisted surgical system and a patient specific surgical plan to create a precise plan and procedure for removing an implant from the femur. With reference to
The bone models are obtained (Block S210-S220) by generating a three-dimensional (3-D) bone model from an image data set of the subject's anatomy. The image data set may be collected with an imaging modality such as computed tomography (CT), dual-energy x-ray absorptiometry (DEXA), magnetic resonance imaging (MRI), X-ray scans, ultrasound, or a combination thereof. The 3-D bone model(s) are readily generated from the image data set using medical imaging software such as Mimics® (Materialise, Plymouth, Mich.) or other techniques known in the art such as the one described in U.S. Pat. Nos. 5,951,475. Scan data of the subject's bone may include any of the structural/anatomical features such as size, shape, thickness, and curvatures. Besides structural features, the scan data may include additional bone property data including bone density and bone microarchitecture data. The scan data may be collected by a system and process described herein by a system and process specific to the bone imaging technique.
The user is able to view and manipulate the bone model and bone property data in a pre-operative planning software program having a graphical user interface (GUI). The GUI includes widgets and other tools which allow a user or computer assisted surgical system to customizably design a plan for revising the implant, including removing the primary implant with the devices and methods described herein, and prepare the cavity for a new implant. A robotic system for executing the cut plan is further described below.
A computer-assisted surgical system capable of removing an implant with such precision is desirable. Examples of a computer-assisted surgical system include a 1-6 degree of freedom hand-held surgical system, an autonomous serial-chain manipulator system, a haptic serial-chain manipulator system, a parallel robotic system, or a master-slave robotic system, as described in U.S. Pat. Nos. 5,086,401, 7,206,626, 8,876,830 and 8,961,536, U.S. Pat. App. No. 2013/0060278, and PCT Intl. App. No. US2015/051713.
With reference to FIG.12, a particular embodiment of a robotic surgical system 700 to remove an implant and revise an orthopedic implant procedure is shown in the context of an operating room (OR). The surgical system 700 generally includes a surgical robot 702, a computing system 704, and a tracking system 706.
The surgical robot 702 includes a movable base 708, a manipulator arm 710 mounted to the base 708, an end-effector flange 712 located at a distal end of the manipulator arm 710, an end-effector assembly 714 removably attached to the flange 712, and a tool 716 removably assembled to the end-effector assembly 714. The base 708 may include a set of wheels 718 to maneuver the base 708, which may be fixed into position using a braking mechanism such as a hydraulic brake. The manipulator arm 710 includes various joints and links to manipulate the tool 716 in various degrees of freedom. The joints may be prismatic, revolute, or a combination thereof. The tool 716 may be any device to contact, perform work or install an implant on the subject's anatomy including for example a burr, a saw, an end-mill, a cutter, a laser engraver, forceps, a claw, electrocautery device, a drill, a pin driver, a reamer, an ultrasonic horn, or a probe. The tool 716 and manipulator are controlled by commands from the computing system 704 and/or tracking system 706. In various embodiments, the tool 716 is the cutting device (300, 600).
The computing system 704 generally includes a planning computer 720 including a processor; a device computer 722 including a processor; a tracking computer 724 including a processor; and peripheral devices. Processors operate in system 700 to perform computations associated with the inventive method. It is appreciated that processor functions are shared between computers, a remote server, a cloud computing facility, or combinations thereof. The planning computer 720, device computer 722, and tracking computer 724 may be separate entities as shown, or it is contemplated that their operations may be executed on just one or two computers depending on the configuration of the surgical system 700. For example, the tracking computer 724 may have the operational data to control the manipulator 710 and tool 716 of the surgical system 700 without the need for a device computer 722. Or, the device computer 722 may include operational data to plan the surgical procedure and design the implant without the need for the planning computer 720. In any case, the peripheral devices allow a user to interface with the surgical system components and may include: one or more user-interfaces, such as a display or monitor 726; and user-input mechanisms, such as a keyboard 728, mouse 730, pendent 732, joystick 734, foot pedal 736, or the monitor 726 may have touchscreen capabilities.
The planning computer 720 contains hardware (e.g., processors, controllers, and memory), software, data and utilities that are dedicated to the implant design and planning of a surgical procedure, either pre-operatively or intra-operatively. This may include reading medical imaging data, segmenting imaging data, constructing three-dimensional (3D) virtual models, storing computer-aided design (CAD) files, and generating surgical plan data. The final surgical plan includes a set of instructions to insert a cutting device in a desirable location, cutting the cement or any material around the implant, removing an implant from the bone, and intra-operative operational data for revising and/or cutting the bone for a new implant, such as a cut-file. The data generated from the planning computer 720 is readily transferred to the device computer 722 and/or tracking computer 724 through a wired or wirelessly connection in the operating room (OR); or transferred via a non-transient data storage medium (e.g., a compact disc (CD), a portable universal serial bus (USB) drive) if the planning computer 514 is located outside the OR.
The device computer 722 may be housed in the moveable base 708 and contain hardware, software, data and utilities that are primarily dedicated to the operation of the surgical robot 702. This may include surgical device control, robotic manipulator control, the processing of kinematic and inverse kinematic data, the execution of registration algorithms, the execution of calibration routines, the execution of surgical plan data, coordinate transformation processing, providing workflow instructions to a user, and utilizing position and orientation (POSE) data from the tracking system 706.
The tracking system 706 of the surgical system 700 includes two or more optical receivers 738 to detect the position of fiducial markers (e.g., retroreflective spheres, active light emitting diodes (LEDs)) uniquely arranged on rigid bodies. The fiducial markers arranged on a rigid body are collectively referred to as a fiducial marker array 740, where each fiducial marker array 740 has a unique arrangement of fiducial markers, or a unique transmitting wavelength/frequency if the markers are active LEDs. An example of an optical tracking system is described in U.S. Pat. No. 6,061,644. The tracking system 706 may be built into a surgical light 742, located on a boom, a stand, or built into the walls or ceilings of the OR. The tracking system computer 724 may include tracking hardware, software, data and utilities to determine the POSE of objects (e.g., bones B, surgical robot 702) in a local or global coordinate frame. The POSE of the objects is collectively referred to herein as POSE data, where this POSE data is readily communicated to the device computer 722 through a wired or wireless connection. Alternatively, the device computer 722 may determine the POSE data using the position of the fiducial markers detected from the optical receivers 738 directly.
The POSE data is determined using the position data detected from the optical receivers 738 and operations/processes such as image processing, image filtering, triangulation algorithms, geometric relationship processing, registration algorithms, calibration algorithms, and coordinate transformation processing. For example, the POSE of a digitizer probe 742 with an attached probe fiducial marker array 740b may be calibrated such that the probe tip is continuously known as described in U.S. Pat. No. 7,043,961. The POSE of the tool tip or tool axis of the tool 716 may be known with respect to a device fiducial marker array 740a using a calibration method as described in U.S. Prov. Pat. App. 62/128,857. The device fiducial marker 740a is depicted on the manipulator arm 710 but may also be positioned on the base 708 or the end-effector assembly 714. Registration algorithms are readily executed to determine the POSE and coordinate transforms between a bone B, a fiducial marker array 740, the surgical robot 702, the and the surgical plan, using registration methods known in the art, such as those described in U.S. Pat. No. 6,033,415, and 8,287,522.
The POSE data is used by the computing system 704 during the procedure to update the POSE and coordinate transforms between the bone B, the surgical robot 702, and the surgical plan to ensure the surgical robot 702 accurately executes the surgical plan on the bone B. It should be appreciated that in certain embodiments, other tracking systems may be incorporated with the surgical system 700 such as an electromagnetic field tracking system or a mechanical tracking system. An example of a mechanical tracking system is described in US Pat. No. 6,322,567. In a particular embodiment, the surgical system 700 does not include a tracking system 706 and a tracked digitizer probe 742, but instead employs a mechanical digitizer arm incorporated with the surgical robot 702 as described in U.S. Pat. No. 6,033,415, and a bone fixation and monitoring system that fixes the bone directly to the surgical robot 702 and monitors bone movement as described in U.S. Pat. No. 5,086,401, both of which are incorporated by reference herein in their entirety.
Intra-Operative ExecutionIntra-operatively, the bone is registered to the workspace of the robot (Block S240). Subsequently, the robotic milling of the target bone is provided at block S250. With reference back to
The robotic cutting of material 108 around the implant is provided at block S270. In various embodiments, with reference back to
After the user removes the implant, the surgical system 702 may prepare the bone to receive the revision components. During the pre-operative planning, the user may plan a desired POSE for the revision components based on the cavity that remains after the removal of the primary components. Because the geometry of the cutting device (300, 600) is known, particularly the thickness of the cutting device (300, 600), the geometry of the cavity after removal is also known. Therefore, the user can plan the placement of the new components based on the expected cavity dimensions. This is particularly advantageous because with traditional revision surgeries, the resulting cavity after removal of the primary implant is completely unknown and therefore pre-operatively planning the procedure is nearly impossible. Thus, the robotic system 700 allows a user to plan and precisely prepare a new cavity for the new components, greatly improving the stability and longevity of the revision components.
Claims
1. A cutting device comprising:
- a pair of cutting blades;
- a pivot point at which said pair of cutting blades are joined; and
- a flexible sheath, wherein at least a portion of the pair of cutting blades extend from said flexible sheath.
2. The cutting device of claim 1, further comprising a cam in mechanical communication with said pair of cutting blades.
3. The cutting device of claim 2, further comprising a clip to retain said cam intermediate between said pair of cutting blades and below said pivot point.
4. The cutting device of claim 3, wherein said clip is spring biased against rotation of said cam.
5. The cutting device of claim 2, wherein said cam is coupled to a drive shaft.
6. The cutting device of claim 5, wherein said clip has an opening through which said drive shaft passes.
7. The cutting device of claim 2, wherein said cam is intermediate between said pair of cutting blades and said spring bias bounds said pair of cutting blades.
8. The cutting device of claim 1, wherein said pair of cutting blades has a thickness of from 1 to 5 millimeters and a width of from 3 to 7 millimeters.
9. The cutting device of claim 1 wherein the cutting blades and flexible sheath flex to permit said pair of cutting blades and said flexible sheath to follow a surface of an implant installed in or on a bone.
10. The cutting device of claim 1 further comprising cutting teeth at a distal end of said pair of cutting blades, wherein the cutting teeth are angled to grab material.
11. A method for removing material underneath a surface of an implant installed on the bone comprising:
- driving the cutting blades of claim 1 to pivot about the pivot point; and
- translating the cutting device along a length of the bone to remove material underneath the surface of the implant installed on the bone.
12. The method of claim 11 further comprising removing the implant from the bone.
13. The method of claim 11 wherein said translating is along a curved path.
14. The method of claim 11, wherein the bone is a femur.
15. The method of claim 11, wherein the bone is a tibia
16. The method of claim 15, wherein the material removed is bone or bone cement.
17. A system for removing material from a target bone comprising:
- the cutting device of claim 1; and
- an actuator for driving the cutting blades.
18. The system of claim 19 further comprising a surgical robot controlling the cutting device of claim 1.
Type: Application
Filed: Oct 22, 2021
Publication Date: Feb 10, 2022
Applicant: Think Surgical, Inc. (Fremont, CA)
Inventor: Gibson Elliot (Fremont, CA)
Application Number: 17/508,316