PIN PLACEMENT HOLDER FOR SURGICAL PIN DRIVER

Abstract

A surgical device for pin insertion in a bone of a subject to aid in performing a bone cutting procedure is provided that includes a drive portion configured to drive a pin for insertion into the bone. The drive portion has a pin drive assembly with a shaft having a shaft proximal end. At least one magnet is associated with the shaft proximal end adapted for attraction and retention of the pin in the shaft proximal end. A spindle assembly is adapted to drive the shaft so as to rotate the pin into the bone to a degree of bone retention that overcomes the attraction and the retention of the pin in the shaft proximal end. An alignment system for surgical bone cutting procedures inclusive of the same is also provided along with a method for aligning a cutting guide on a subject's bone.

Claims

1. A surgical device for inserting a pin into a bone, comprising: a drive portion, comprising: a shaft having a shaft end; a magnet associated with the shaft end and exerting an attractive force on a pin when coupled to the shaft end; and a motor to drive the shaft so as to rotate the pin for insertion into the bone to at least a depth where the force required to pull the pin from the bone is greater than the attractive force exerted on the pin by the magnet.

2. The device of claim 1 wherein the shaft further comprises a socket at the shaft end to accept a proximal end of the pin.

3. The device of claim 2 wherein the magnet is situated in the shaft and proximal to the socket.

4. The device of claim 1 further comprising a pin guide having a first portion with an inner diameter that fits over a portion of the pin to constrain a rotational axis of the pin.

5. The device of claim 4 wherein the pin guide has a second portion with an inner diameter that fits over a portion of the shaft.

6. The device of claim 1 further comprising a coupler that couples the shaft to the motor.

7. The device of claim 1 wherein the drive portion further comprises three or more fiducial markers to permit a tracking system to track the surgical device.

8. The device of claim 1 further comprising a hand-held portion movably connected to the drive portion.

9. The device of claim 2 wherein the hand-held portion comprises components to adjust the working portion relative to the hand-held portion in response to commands from one or more computers.

10. A surgical system, comprising: the surgical device of claim 1, further comprising a hand-held portion movably connected to the drive portion; and components for moving the working portion relative to the hand-held portion; a tracking system to track a position and orientation (POSE) of the pin when coupled to the shaft end of the surgical device; and one or more computers to: determine a tracked relationship between the POSE of the pin and a predetermined location of a virtual plane, wherein the predetermined location of the virtual plane is defined with respect to a predetermined location for a cut surface to be created on the bone; and supply commands to the components corresponding to movement of at least one of the bone and the hand-held portion to maintain alignment of an axis of the pin coincident with the virtual plane.

11. The system of claim 10 further comprising a plurality of pins that are inserted coincident with the virtual plane using the surgical device.

12. The system of claim 11 further comprising a cutting guide to be assembled onto the plurality of pins.

13. The system of claim 10 wherein the tracking system is an optical tracking system.

14. The system of claim 10 wherein the one or more computers is a device computer.

15. The system of claim 14 further comprising a planning computer to plan the predetermined location for the cut surface to be created on the bone.

16. The system of claim 10 wherein the bone is subject to total knee arthroplasty or revision knee arthroplasty.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention is further detailed with respect to the following drawings that are intended to show certain aspects of the present of invention, but should not be construed as limit on the practice of the invention, wherein:

[0016] FIGS. 1A and 1B illustrate perspective views of a distal cutting guide;

[0017] FIG. 1C illustrates a set of pins driven coincident with a virtual pin plane in a femoral bone;

[0018] FIG. 1D illustrates the distal cutting guide of FIGS. 1A and 1B assembled to the pins of FIG. 1C;

[0019] FIG. 2 is a perspective view of a drive portion of a hand held end effector in accordance with embodiments of the invention;

[0020] FIG. 3 is a side view of the drive portion of a hand held end effector shown in FIG. 2 in accordance with embodiments of the invention;

[0021] FIG. 4 is a central longitudinal cross-sectional view of FIG. 3 in accordance with embodiments of the invention;

[0022] FIG. 5A is an exploded view of FIG. 3 in accordance with embodiments of the invention;

[0023] FIG. 5B is an exploded view of FIG. 4 in accordance with embodiments of the invention;

[0024] FIGS. 6A-6H are detailed individual perspective views of the major components that form the drive portion of a hand held end effector in accordance with embodiments of the invention;

[0025] FIG. 7A is a detailed side view of the pin drive assembly in accordance with embodiments of the invention;

[0026] FIG. 7B is a detailed exploded and central longitudinal cross-sectional side view of the pin drive assembly in accordance with embodiments of the invention; and

[0027] FIG. 8 illustrates a surgical system in the context of an operating room (OR) in accordance with embodiments of the invention.

DETAILED DESCRIPTION

[0028] The present invention has utility as a system and method to aid a surgeon in quickly and precisely aligning a guide pin on a bone of a subject, with the aid of a pin placement holder in a pin driver assembly. In contrast to other prior art mechanisms, the present invention does not require an operator to use two hands to load and secure a pin. Certain embodiments of the inventive pin driver assembly use a pin guide that aligns an inserted pin to a shaft, where the shaft has a hex socket to rotationally lock the pin to the rotation of the shaft. The shaft also houses two small magnets to attract and secure the inserted pin, the magnets taking the place of a conventional 3-jaw chuck, or a collet system to hold and secure the pin to the driving tool, and thereby eliminate the need for the operator to use both of their hands to secure the pin to the driving tool or rely on a second person to assist. The magnets pull the inserted pin into the hex socket and prevents the pin from falling out of the pin guide or the hex socket, the magnet or magnets have a limited Gauss strength balance to retain the pin prior to bone securement, yet release the pin upon securement. The operator or surgeon can freely articulate the tool in any angle without worry of the pin falling out of the device.

[0029] The system and method is especially advantageous for total knee arthroplasty and revision knee arthroplasty where the position and orientation (POSE) of the pins are used to assemble and align a cutting guide thereon to facilitate the creation of a desired cut plane. However, it should be appreciated that other medical applications may exploit the subject matter disclosed herein such as osteotomies and high tibial osteotomies, and the placement of screws for spinal fusions and spinal reconstruction, maxillofacial surgery, fractures, and other procedures requiring the precise placement of bone pins, screws, or nails. Similarly, embodiments of the invention described herein may be adapted for use in a non-medical setting wherever the precise placement of a screw, nail, or rivet is needed such as construction, aircraft assembly and carpentry with the proviso that at least a portion of the fasteners are ferromagnetic.

[0030] The following description of various embodiments of the invention is not intended to limit the invention to these specific embodiments, but rather to enable any person skilled in the art to make and use this invention through exemplary aspects thereof. As used herein, a patient, or synonymously a subject, is defined as a human, a non-human primate; or an animal of a horse, a cow, a sheep, a goat, a cat, a rodent and a bird; or a cadaver of any of the aforementioned.

[0031] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0032] Referring now to the figures, FIG. 2 is a perspective view of an inventive drive portion 30 of a hand held surgical device 102, also referred to herein as a pin-driver device (see FIG. 8). FIG. 3 is a side view of the drive portion 30, while FIG. 4 is a central plane, longitudinal cross-sectional view of FIG. 3. FIG. 5A is an exploded view of FIG. 3, and FIG. 5B is an exploded view of FIG. 4. FIGS. 6A-6H are detailed individual perspective views of the major components that form the drive portion 30. FIG. 7A is a detailed side view of the pin drive assembly 35, and FIG. 7B is a detailed exploded and central longitudinal cross-sectional side view of the pin drive assembly 35. It is noted that embodiments of the inventive pin driver assembly may also be used with end effectors for robots as well as hand held devices. The drive portion 30 has two major subassemblies a spindle assembly 33 and a pin drive assembly 35. The modular design of the spindle 33 allows for the changing and integration of several different parts. The spindle 33 has the following major subcomponents: a bearing cap 42, a bearing holder 44, a set of disk springs 58, a coupler 52, a motor holder 48, a motor 50, and a spindle cartridge 46. The bearing cap 42 squeezes the outer cage of the bearing to facilitate preloading on angular contact bearings. The bearing holder 44 holds an arrangement of bearings 54, and provides a modular connection to the spindle cartridge 46. The flange 45 is perpendicular to the bearing axis to guarantee perpendicularity to the spindle cartridge 46. It is appreciated that the major subcomponents of the spindle 33 may be exchanged with minimal effects or changes to the other parts. For example, the motor holder 48 is readily changed to accommodate many different size motors and still be capable of attachment to the spindle cartridge 46. The set of disk springs 58 reduce the impact and vibration forces between the bearings 54. The coupler 52 attaches the pin driver assembly shaft 38 to the motor shaft 51. The motor holder 48 holds the motor 50, provides room for the coupler 52, and has a flange 49 connection that attaches to the spindle cartridge 46. The flat side of the flange 49 guarantees that the motor axis is perpendicular to the spindle cartridge wall 47. In addition, the flange 49 has allowance to translationally move the motor axis shaft to decrease radial misalignment between the pin drive shaft 38 and the motor shaft 51.

[0033] The spindle cartridge 46 serves as the centerpiece of the spindle assembly 33. The spindle cartridge 46 has two parallel flange walls 47 to attach the bearing holder 44, and the motor holder 48 to facilitate a corridor or parallel shafts between the motor 50 and the pin driver assembly 33. The spindle cartridge 46 may also have a mechanism, such as a screw, clasp, or other fastener, to permit a fiducial marker array 32 to attach to the drive portion 30. In other embodiments, the fiducial marker array 32 or individual fiducial markers are an integral part of the drive portion 30. A hand-held attachment member 40 connects with the spindle cartridge 46 and is adapted to pivotally attach with the hand-held portion of the hand-held surgical device 102. The fiducial markers may be active markers such as light emitting diodes (LEDs), passive markers such as retroreflective spheres, or other tracking reference markers such as magnetic sensors, ultrasonic beacons, inertial measuring units, and combinations thereof.

[0034] The pin driver assembly 35 is designed to increase surgical usability and accuracy. The pin driver assembly 35 has the following major subcomponents: a spindle shaft 38, a pin guide 36, and a magnet 56. The pin driver assembly 35 assembles to the spindle assembly 33 by way of the spindle shaft 38, where the spindle shaft 38 runs through the spindle cartridge 46 via the bearing holder 44, and attaches to the motor 50 via the coupler 52. In operation, a surgeon places a pin P into the pin guide 36. At least one magnet 56, which is fixed in the shaft 38, snap a male hex end 64 of the pin P into a hex socket 59 of the shaft 38. In a specific embodiment of the present invention, the magnets 56 are adhesively bonded to the shaft 38 in a magnet holder 57 that is proximal to the hex socket 59. The magnet(s) 56 prevent the pin P from falling out of the pin guide 36 by keeping a magnetic attractive force on the magnetically attracted metallic pin P. The pin guide 36 has a distal end 37 and a proximal end 39. The inner diameter of the distal end 37 is tightly dimensioned to the outer diameter of the pin P, and fits over the pin P with a small amount of clearance that constrains the pin's rotational axis to the shaft's rotational axis with a very little amount of play. The pin guide proximal end 39 has an inner diameter larger than that of the distal end 37 and is tightly dimensioned to the outer diameter of a distal portion 66 of the shaft 38. The design of the pin guide 36 stabilizes the pin P and makes the pin P rotate concentrically about the longitudinal axis of the shaft as the motor 50 drives (i.e. rotates) the pin P. One may accomplish this stabilization and alignment by manufacturing the shaft 38 with a deeper hex socket; however there are manufacturing constraints and added costs to do so. Therefore, the pin guide 36 is advantageous from a manufacturing point of view.

[0035] The hex socket 59 on the spindle shaft 38 rotates the pin P, which causes the pin P to drill deep inside a subject bone, and the grooves 62 on the pin P firmly hold the pin P in place. Once the pin P is firmly placed inside the subject bone, the magnetic pull force on the pin P is overcome and the pin P releases from the pin driver assembly 35 as the surgeon removes the pin driver assembly 35. In a specific inventive embodiment, the pin P is made of magnetically attractive stainless steel and the pin guide 36 is made of aluminum.

[0036] FIG. 8 illustrates an inventive embodiment of a pin driving surgical system 100 in the context of an operating room (OR). The surgical system 100 generally includes an articulating surgical device 102 with embodiments of the drive portion 30, a computing system 104, and a tracking system 106. The surgical system 100 is able to guide and assist a user in accurately placing pins coincident with a virtual plane that is defined relative to a subject's bone. The virtual plane is defined in a surgical plan such that a cutting guide when assembled to the inserted pins align one or more guide slots with the bone cuts required to receive a prosthetic implant in a planned position and orientation.

Computing System and Tracking System

[0037] The pin-driver device 102 is controlled by commands from the computing system 104 to maintain the coincidence of the longitudinal axis of the pin P with a virtual plane defined in the surgical plan. The computing system 104 may include a planning computer 108 including a processor; a device computer 110 including a processor; a tracking computer 112 including a processor; and peripheral devices. Processors operate in the computing system 104 to perform computations associated with the inventive system and method. It is appreciated that processor functions are shared between computers, a remote server, a cloud computing facility, or combinations thereof.

[0038] In a particular embodiment, the device computer 110 may include one or more processors, controllers, and any additional data storage medium such as RAM, ROM or other non-volatile memory to perform functions related to the operation of the surgical device 102. For example, the device computer 110 may include software, data, and utilities to control the surgical device 102, receive and process tracking data, execute registration algorithms, execute calibration routines, provide workflow instructions to the user throughout a surgical procedure, as well as any other suitable software, data or utilities required to successfully perform the procedure in accordance with embodiments of the invention.

[0039] The planning computer 108, device computer 110, and tracking computer 112 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 100. For example, the tracking computer 112 may have the operational data to control the device 102 without the need for a device computer 110. Or, the device computer 110 may include operational data to plan the surgical procedure without the need for the planning computer 108. In any case, the peripheral devices allow a user to interface with the surgical system 100 and may include: one or more user-interfaces, such as a display or monitor 114; and user-input mechanisms, such as a keyboard 116, mouse 118, pendent 120, joystick 122, foot pedal 124, or the monitor 114 may have touchscreen capabilities.

[0040] The planning computer 108 contains hardware (e.g., processors, controllers, and memory), software, data and utilities that are dedicated to aid a user in planning a surgical procedure, either pre-operatively or intra-operatively. This may include reading medical imaging data, segmenting imaging data, constructing and manipulating three-dimensional (3D) virtual models, storing and providing computer-aided design (CAD) files, planning the POSE of implants relative to the bone, defining virtual pin planes, and generating the surgical plan data for use with the system 100. The final surgical plan data may include an image data set of the bone, bone registration data points, subject identification information, the POSE of the implants relative to the bone, the POSE of one or more virtual planes defined relative to the bone, and any tissue modification instructions. The final surgical plan is readily transferred to the device computer 110 and/or tracking computer 112 through a wired or wireless 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 108 is located outside the OR.

[0041] The device computer 110 contains hardware, software, data and utilities that are primarily dedicated to the operation of the articulating device 102. This may include controlling the position and/or orientation (POSE) of the pin P, controlling the speed of the motor 50, the processing of kinematic and inverse kinematic data of the device 102, the execution of registration algorithms, the execution of calibration routines, the execution of surgical plan data, coordinate transformation processing, providing workflow instructions to the user, and utilizing POSE data from the tracking system 106.

[0042] The tracking system 106 includes two or more optical receivers 126 to detect the position of fiducial markers. A set of fiducial markers uniquely arranged on a rigid body is referred to herein as a fiducial marker array (32, 130a, 130b). Illustrative examples of the fiducial markers may include: an active transmitter, such as an LED or electromagnetic emitter; a passive reflector, such as a plastic sphere with a retro-reflective film; a distinct pattern or sequence of shapes, lines or other characters. An example of an optical tracking system is described in U.S. Pat. No. 6,061,644. The tracking system 106 may be built into a surgical light 128, located on a boom, a stand, or built into the walls or ceilings of the OR. The tracking system computer 112 may include tracking hardware, software, data and utilities to determine the POSE of objects (e.g., bones B, the articulating device 102) in a local or global coordinate frame. The POSE of the objects is also referred to herein as POSE data, where this POSE data is readily communicated to the device computer 110 through a wired or wireless connection. Alternatively, the device computer 110 may determine the POSE data using the position of the fiducial markers detected directly from the optical receivers 126.

[0043] The POSE data is determined using the position of the fiducial markers (130a, 130b, 130c) detected from the optical receivers 126 and operations/processes such as image processing, image filtering, triangulation algorithms, geometric relationship processing, registration algorithms, calibration algorithms, and coordinate transformation processing. POSE data from the tracking system 106 is used by the computing system 104 to perform various functions. For example, the POSE of a digitizer probe 132 with an attached probe fiducial marker array 130b 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 tip or axis of the pin P may be known with respect to a device fiducial marker array 32 using a calibration method as described in U.S. Prov. Pat. App. 62/128,857. Registration algorithms are readily executed to determine the POSE and/or coordinate transforms between a bone B and the surgical plan, using the registration methods described in U.S. Pat. Nos. 6,033,415, and 8,287,522. For example, in a registration method, points on a patient bone may be collected from a tracked digitizer probe 132 to transform the coordinates of a surgical plan to the coordinates of the bone.

[0044] It should be appreciated that in certain embodiments, other tracking systems may be incorporated with the surgical system 100 such as an electromagnetic field tracking system, a mechanical tracking system or other tracking systems that utilize acoustic emitters or reflectors; magnetic emitters or reflectors; accelerometers; gyroscopes; and the like or any combinations thereof. In particular inventive embodiments, mechanical tracking systems may be used. The replacement of a non-mechanical tracking system with a mechanical tracking system should be apparent to one skilled in the art. In specific embodiments, the use of a mechanical tracking system may be advantageous depending on the type of surgical system used such as the one described in U.S. Pat. No. 6,322,567 assigned to the assignee of the present application and incorporated by reference in its entirety.

Surgical Planning and Execution for a Total Knee Arthroplasty (TKA) Application

[0045] The surgical plan is created, either pre-operatively or intra-operatively, by a user using planning software. The planning software may be used to a generate three-dimensional (3-D) models of the subject's bony anatomy from a computed tomography (CT), magnetic resonance imaging (MRI), x-ray, or ultrasound image data set. Alternatively, the surgical plan is created using data collected directly from the patient intraoperatively (e.g. digitized points, kinematic femoral head center, ankle center, statistical bone morphing) such as with typical imageless navigation systems rather than using a per-operative image data set. A set of 3-D computer aided design (CAD) models of the manufacturer's prosthesis are pre-loaded in the software that allows the user to place the components of a desired prosthesis to the 3-D model of the boney anatomy to designate the best fit, position and orientation of the implant to the bone.

[0046] The surgical plan contains the 3-D model of the patient's operative bone combined with the location of one or more virtual pin planes. The location of the virtual pin plane(s) is defined by the planning software using the POSE of one or more planned cut planes and one or more dimensions of a cutting guide.

[0047] Intra-operatively, the surgical plan is registered to the bone. The surgical device 102 then articulates the pin in one-or-more degrees of freedom to align the pin P with a virtual pin plane. Once aligned, the user may command the device 102, via a trigger, to drive (e.g., rotate) the pin P, while manually advancing the pin P into the bone coincident with the virtual pin plane. In some embodiments, the pin P is automatically advanced into the bone with components associated with the surgical device 102. The pin P is inserted into the bone to a degree of bone retention that overcomes the attraction of the pin P to the magnet 56. Therefore, the surgical device 102 may be easily removed from the pin P to assemble and install subsequent pins. Cutting guides are then assembled to the pins to facilitate the creation of the planar cuts that receive the knee prosthesis.

Other Embodiments

[0048] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the described embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes may be made in the function and arrangement of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.