Patent ID: 12220137

DETAILED DESCRIPTION OF THE INVENTION

The present invention has utility as a system and method to aid a surgeon in efficiently and precisely aligning a cutting guide on a patient's bone. The system and method is especially advantageous for total knee arthroplasty and revision knee arthroplasty, however, it should be appreciated that other medical applications may exploit the subject matter disclosed herein such as high tibial osteotomies, spinal reconstruction surgery, and other procedures requiring the precise placement of a cutting guide to aid a surgeon in creating bone cuts.

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.

Embodiments of the present invention may be implemented with a surgical system. Examples of surgical systems used in embodiments of the invention illustratively include a 1-6 degree of freedom hand-held surgical system, a 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 U.S. Prov. App. No. 62/054,009. In a specific embodiment, the surgical system is a serial-chain manipulator system as described in U.S. Pat. No. 6,033,415 assigned to the assignee of the present application and incorporated by reference herein in its entirety. The manipulator system may provide autonomous, semi-autonomous, or haptic control and any combinations thereof. In a specific embodiment, a tool attached to the manipulator system may be manually maneuvered by a user while the system provides at least one of power, active or haptic control to the tool.

With reference to the figures,FIG.1illustrates a 2-degree-of-freedom (2-DOF) surgical system100. The 2-DOF surgical system100is generally described in PCT App. Num. US2015/051713, assigned to the assignee of the present application and incorporated by reference herein in its entirety. The 2-DOF surgical system100includes a computing system102, an articulating surgical device104, and a tracking system106. The surgical system100is able to guide and assist a user in accurately placing pins coincident with a virtual pin plane that is defined relative to a subject's bone. The virtual plane is defined in a surgical plan such that a cut 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.

Articulating Surgical Device

FIGS.2A and2Billustrate the articulating surgical device104of the 2-DOF surgical system100in more detail. The surgical device104includes a hand-held portion202and a working portion204. The hand-held portion202includes an outer casing203of ergonomic design to be held and manipulated by a user. The working portion204includes a tool206having a tool axis207. The tool206is readily attached to and driven by a motor205. The hand-held portion202and working portion204are connected by a front linear rail208aand a back linear rail208bthat are actuated by components in the hand-held portion202to control the pitch and translation of the working portion204relative to the hand-held portion202. A tracking array212, having three or more fiducial markers, is rigidly attached to the working portion142to permit a tracking system106to track the POSE of the working portion204. The fiducial markers may be active markers such as light emitting diodes (LEDs), or passive markers such as retroreflective spheres. An input/output port in some inventive embodiments provides power and/or control signals to the device104; or the device may receive power from batteries and control signals via a wireless connection alleviating the need for electrical wiring to be connected to the device104. In a particular embodiment, the device may receive wireless control signals via visible light communication as described in Int'l Pat. App. WO 2016/081931 assigned to the assignee of the present application and incorporated by reference herein in its entirety. The device104may further include one or more user input mechanisms such as a trigger214or a button.

Within the outer casing of the hand-held portion202are a front actuator210athat powers a front ball screw216aand a back actuator210bthat powers a back ball screw216b. The actuators (210a,210b) may be servo-motors that bi-directionally rotate the ball screws (216a,216b). A first end of the linear rails (208a,208b) are attached to the working portion204via hinges (220a,220b), where the hinges (220a,220b) allow the working portion204to pivot relative to the linear rails (208a,208b). Ball nuts (218a,218b) are attached at a second end of the linear rails (208a,208b). The ball nuts (218a,218b) are in mechanical communication with the ball screws (216a,216b). The actuators (210a,210b) power the ball screws (216a,216b) which cause the ball nuts (218a,218b) to translate along the axis of the ball screws (216a,216b). Accordingly, the translation ‘d’ and pitch ‘a’ of the working portion204may be adjusted depending on the position of each ball nut (218a,218b) on their corresponding ball screw (216a,216b). A linear guide222may further constrain and guide the motion of the linear rails (208a,208b) in the translational direction ‘d’.

Computing System and Tracking System

With reference back toFIG.1, the computing system102generally includes hardware and software for executing a surgical procedure. In particular embodiments, the computing system102provides actuation commands to the actuators (210a,210b) to control the position and orientation (POSE) of the tool206. The computing system102can thus maintain the tool axis207with a virtual plane defined in a surgical plan independent of the POSE of the hand-held portion202.

The computing system102in some inventive embodiments includes: a device computer108including a processor; a planning computer110including a processor; a tracking computer111including a processor, and peripheral devices. Processors operate in the computing system102to 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.

In particular inventive embodiments, the device computer108may include one or more processors, controllers, and any additional data storage medium such as RAM, ROM or other non-volatile or volatile memory to perform functions related to the operation of the surgical device104. For example, the device computer108may include software, data, and utilities to control the surgical device104such as the POSE of the working portion204, receive and process tracking data, control the speed of the motor205, 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.

The device computer108, the planning computer110, and the tracking computer111may 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 system100. For example, the tracking computer111may have operational data to control the device104without the need for a device computer108. Or, the device computer108may include operational data to plan to the surgical procedure with the need for the planning computer110. In any case, the peripheral devices allow a user to interface with the surgical system100and may include: one or more user interfaces, such as a display or monitor112; and various user input mechanisms, illustratively including a keyboard114, mouse122, pendent124, joystick126, foot pedal128, or the monitor112may have touchscreen capabilities.

The planning computer110is preferably dedicated to planning the procedure either pre-operatively or intra-operatively. For example, the planning computer110may contain hardware (e.g. processors, controllers, and memory), software, data, and utilities capable of receiving and 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 the implants relative to the bone, generating the surgical plan data for use with the system100, and providing other various functions to aid a user in planning the surgical procedure. The planning computer also contains software dedicated to defining virtual planes with regards to embodiments of the invention as further described below. The final surgical plan data may include an image data set of the bone, bone registration data, 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 device computer108and the planning computer110may be directly connected in the operating room, or may exist as separate entities. The final surgical plan is readily transferred to the device computer108and/or tracking computer111through 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 computer110is located outside the OR. As described above, the computing system102may act as a single entity, with multiple processors, capable of performing the functions of the device computer108, the tracking computer111, and the planning computer110.

The computing system102may accurately maintain the tool axis207in 3-D space based on POSE data from the tracking system106as shown inFIG.1. The tracking system106generally includes a detection device to determine the POSE of an object relative to the position of the detection device. In a particular embodiment, the tracking system106is an optical tracking system as described in U.S. Pat. No. 6,061,644, having two or more optical receivers116to detect the position of fiducial markers arranged on rigid bodies. Illustrative examples of the fiducial markers include: an active transmitter, such as an LED or electromagnetic radiation emitter; a passive reflector, such as a plastic sphere with a retro-reflective film; or a distinct pattern or sequence of shapes, lines or other characters. A set of fiducial markers arranged on a rigid body is referred to herein as a fiducial marker array (120a,120b,120c,212), where each fiducial marker array (120a,120b,120c,212) has a unique geometry/arrangement of fiducial markers, or a unique transmitting wavelength/frequency if the markers are active LEDS, such that the tracking system106can distinguish between each of the tracked objects. In a specific embodiment, the fiducial marker arrays (120a,120b,120c,212) include three or more active emitters or passive reflectors uniquely arranged in a known geometry on each rigid body.

The tracking system106may be built into a surgical light118, located on a boom, stand, or built into the walls or ceilings of the operating room. The tracking system computer111includes tracking hardware, software, data, and utilities to determine the POSE of objects (e.g. bones such as the femur F and tibia T, the surgical device104) in a local or global coordinate frame. The POSE of the objects is referred to herein as POSE data, where this POSE data is readily communicated to the device computer108through a wired or wireless connection. Alternatively, the device computer108may determine the POSE data using the position of the fiducial markers detected directly from the optical receivers116.

The POSE data is determined using the position of the fiducial markers detected from the optical receivers116and 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 system106is used by the computing system102to perform various functions. For example, the POSE of a digitizer probe130with an attached probe fiducial marker array120cmay be calibrated such that tip of the probe is continuously known as described in U.S. Pat. No. 7,043,961. The POSE of the tip or axis of the tool206may be known with respect to the device fiducial marker array212using a calibration method as described in Int'l Pat. App. No. WO 2016/141378. Registration algorithms are readily executed using the POSE data to determine the POSE and/or coordinate transforms between a bone, a surgical plan, and a surgical system. For example, in registration methods as described in U.S. Pat. Nos. 6,033,415 and 8,287,522, points on a patient's bone may be collected using a tracked digitizer probe to transform the coordinates of a surgical plan, coordinates of the bone, and the coordinates of a surgical device, The bone may also be registered using image registration as described in U.S. Pat. No. 5,951,475. The coordinate transformations may be continuously updated using the POSE data from a tracking system tracking the POSE of the bone post-registration and the surgical device.

It should be appreciated that in certain inventive embodiments, other tracking systems are incorporated with the surgical system100such as an electromagnetic field tracking system, ultrasound tracking systems, accelerometers and gyroscopes, or a mechanical tracking system. The replacement of a non-mechanical tracking system with other tracking systems 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.

In the surgical system100, an optical tracking system106with optical receivers116is used to collect POSE data of the femur and tibia during total knee arthroplasty. The distal femur F and proximal tibia T are exposed as in a typical TKA procedure. Tracking arrays120aand120bare attached thereto and the femur F and tibia T are subsequently digitized and registered to a surgical plan. The POSE of the femur F and tibia T are tracked in real-time by the tracking system106so the coordinate transformation between the surgical plan and the surgical device are updated as the bones and surgical device move in the operating space. Therefore, a relationship between the POSE of the tool206and the POSE of any coordinates defined in the surgical plan may be determined by the computing system102. In turn, the computing system102can supply actuation commands to the actuators (210a,210b) in real-time to accurately maintain the tool axis207to the defined coordinates.

Additionally, user input mechanisms, such as the trigger214or foot pedal128, may be used by the user to indicate to the computing system102that the tool axis207needs to be maintained to other coordinates defined in a surgical plan. For example, the tool axis207may be maintained in a first defined plane, and the user may step on the foot pedal128to relay to the computing system102that the tool axis207needs to be maintained in a second defined plane. Surgical Planning and Execution for a Total Knee Arthroplasty (TKA) Application

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 patient's bony anatomy from a computed tomography (CT), magnetic resonance imaging (MRI), x-ray, ultrasound image data set, or from a set of points collected on the bone intra-operatively. 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. For example, with reference toFIG.3, a 3-D model of the patient's distal femur302and a 3-D model of the femoral prosthesis304are shown. The final placement of the femoral prosthesis model304on the bone model302defines the bone cut planes (shaded regions of the bone model302) where the bone is cut intra-operatively to receive the prosthesis as desired. In TKA, the planned cut planes generally include the anterior cut plane306, anterior chamfer cut plane308, the distal cut plane310, the posterior chamfer cut plane312, the posterior cut plane314and the tibial cut plane (not shown).

The surgical plan contains the 3-D model of the patient's operative bone combined with the location of one or more virtual planes316. The location of the virtual plane(s)316is defined by the planning software using the position and orientation (POSE) of one or more planned cut planes and one or more dimensions of a cutting guide or alignment guide. Ultimately, the location of the virtual plane(s)316is defined to aid in the placement of a cutting guide such that one or more guide slots of the cutting guide are in the correct POSE to accurately guide a saw in creating the bone cuts. Embodiments of the various inventive cutting guides, alignment guides, defining of the virtual planes, and use of the bone pins are further described in detail below.

In general, embodiments of the inventive cutting guides and alignment guides disclosed herein may be made of a rigid or semi-rigid material, such as stainless steel, aluminum, titanium, polyetheretherketone (PEEK), polyphenylsulfone, acrylonitrile butadiene styrene (ABS), and the like. Embodiments of the cutting guides and alignment guides may be manufactured using appropriate machining tools known in the art.

Distal Cutting Guide, Alignment Guide and N-in-1 Cutting Block

A particular inventive embodiment of a cutting guide to accurately create the planned distal cut plane310is the universal distal cutting guide400as depicted inFIG.4AandFIG.4B. The distal cutting guide400includes a guide portion402and an attachment portion404. The guide portion402includes a guide slot406and a bottom surface410. The guide slot406is for guiding a surgical saw in creating the distal cut plane416on the femur. The bottom surface410abuts against one or more bone pins412that are placed on the bone. The attachment portion404and the guide portion402clamp to the bone pins412using fasteners408as shown inFIG.4BandFIG.4D.

With reference toFIGS.22A to22Din which like reference numerals have the meaning ascribed to that numeral with respect to the aforementioned figures, a particular embodiment of a cutting guide400′ is shown. The cutting guide400′ includes an attachment portion404(e.g., a first portion), and guide portion402(e.g., a second portion) having a guide slot406(e.g., an opening). The guide slot406is configured to receive and guide a cutting tool to form a cut plane (e.g., distal cut plane416) on the bone in the planned POSE. A space407is formed between the guide portion402and the attachment portion404having a height (i.e., a vertical dimension with respect to the orientation of the cutting guide400′ as shown inFIG.22A) and a width (i.e., a horizontal dimension with respect to the orientation of the cutting guide400′ as shown inFIG.22A), where the width is greater than the height. The space407is configured to receive a portion of one or more bone pins412therein and may facilitate the assembly of the cutting guide400′ to the bone pins412. Having the width of the space407greater than the height alleviates the need to place the bone pins in a specific POSE on the bones. Conventional cutting jigs typically have single holes for receiving screws in a single POSE on the bone to anchor the cutting jig to the bone. The space407of the cutting guide400′ allows the cutting guide400′ to be assembled on bone pins412that are placed at any distance apart or in-plane orientation (“in-plane” meaning coincident with the virtual plane), and as long as the bone pins412are accurately placed in the bone coincident with the virtual plane414(regardless of a specific in-plane position or in-plane orientation), the cutting guide400′ may be accurately positioned to align the guide slot406with a planned cut plane. This allows the user to place the bone pins412in the bone at any in-plane position or in-plane orientation and may allow the user to avoid in-plane anatomy (e.g., avoid an osteophyte located coincident with the virtual plane) or target in-plane anatomy (e.g., placing a pin coincident with the virtual plane at a position of denser bone).

In a specific embodiment, the cutting guide400′ further includes a fastener408to adjust the height of the space407to engage/disengage (e.g., clamp) the cutting guide400′ with the bone pins412. The fastener408may be rotated to move the guide portion402and attachment portion404with respect to one another to cause this height change of the space407. As best shown inFIGS.22C and22D, the fastener408may include a knob417coupled to a shaft418. The shaft418may fit through apertures (428,430) in the attachment portion404and the guide portion, respectively, to assemble the attachment portion404to the guide portion402. The aperture428in the guide portion402may be threaded to interact with threads located on a portion of the shaft418to securely assemble the guide portion402and the attachment portion404. Rotation of the knob417may therefore cause the attachment portion404to move with respect to the guide portion402and change the height of the space407. However, it should be appreciated that the configuration may be changed such that the rotation of the knob417causes the guide portion402to move with respect to the attachment portion404. The fastener408may further include a transverse hole420at an end of the shaft418for receiving a spring pin422. The guide portion402may include a recess409where the spring pin422resides when placed in the transverse hole420of the fastener408as best seen inFIG.22B. The spring pin422keeps the fastener408from being overly loosened to the point where the attachment portion404disassembles from the guide portion402. The fastener408may further include additional hardware (424,426) (e.g., washers, spacers, nuts) to assemble the attachment portion404to the guide portion402. In a specific embodiment, a bottom surface of the guide portion402and a top surface of the attachment portion404include grooves to increase the clamping pressure onto the bone pins. It is further contemplated, that the cutting guide400′ may not require a fastener408, where the space407has a fixed height sufficient to fit onto the bone pins412and hold the cutting guide400′ thereon. This fixed height may create an interaction fit or interference fit with the bone pins412, or may simply slide onto the bone pins without causing any substantial wobble between the cutting guide400′ and the bone pins (e.g., no more than 0.01 degrees to 1.0 degrees of wobble with respect to the virtual pin plane414). In some embodiments, the fixed height may be slightly larger than the portion of the bone pin412that is received in the space407to achieve this fit. For example, the fixed height may be 5.1 millimeters (mm) to slide onto a bone pin412having a 5 mm diameter. The fixed height may be anywhere from 0.1%-10% larger than the size of the portion of the bone pin412that is received in the space407.

A surgical system is used to place the longitudinal axis of the bone pins412on a virtual pin plane414. In a particular embodiment, the 2-DOF surgical system100is used, wherein the tool206of the surgical device104is a drill bit rotated by the drill205. As the user manipulates the surgical device104, the computing system supplies actuation commands to the actuators to align the tool axis207with the pin plane414.

The virtual pin plane414is defined in the surgical plan by the planning software using the POSE of the planned distal cut plane310, and the distance between the guide slot406and the bottom surface410of the guide portion402. The planning software may also use the known width of the bone pins412. For example, the pin plane414can be defined by proximally translating the planned distal cut plane310by the distance between the guide slot406and the bottom surface410of the distal cutting guide400. The software may further proximally translate the planned distal cut plane310by an additional half width of the pins412. Therefore, when the cutting guide400is clamped to the bone pins412, the guide slot406is aligned with the planned distal cut plane310.

The user or the computing system102may activate the drill when properly aligned with the pin plane414to drill pilot holes for the pins412. The pins412are then drilled into the pilot holes using a standard drill. In a specific embodiment, the tool206is the pin412, wherein the pin412is attached to the drill205of the surgical device104and drilled directly into the bone on the pin plane414. At least two bone pins412may be drilled on the pin plane414to constrain the distal cutting guide400in the proper position and orientation when clamped to the pins412however three or more bone pins412can be used for further stability.

There are multiple advantages to using the 2-DOF surgical system100to accurately place the bone pins412. For one, the surgical device104is actuating in real-time, therefore the user is actively guided to the POSE of the pin plane412. In addition, the correct position and orientation of the bone pins412is accurately maintained regardless of the surgeon's placement of the hand-held portion204of the 2-DOF surgical system100.

One main advantage of the cutting guide400is its universality because the cutting guide400may be used for any type of implant and any type of patient. This is particularly advantageous, because the universal distal cutting guide400can be sterilized and re-used for multiple surgeries, greatly reducing the cost of TKA, which otherwise requires either patient specific cutting guides or implant specific cutting guides for each surgery.

The advantageous part of using pin planes, rather than defining a specific location for the bone pins412, is the user can place the longitudinal axes of the pins in any arbitrary orientation and position on the plane414and still attach the cutting guide400such that the guide slot406is accurately aligned with the planned distal cut plane310. This greatly reduces the operational time of the procedure. In addition, the user can avoid any particular landmarks coincident with the virtual plane if so desired.

After the cutting guide400is assembled on the bone pins412, the user can saw the distal cut416on the femur F by guiding a surgical saw through the guide slot406. Subsequently, the bone pins412and cutting guide400are removed from the bone to create the remaining bone cuts.

In a particular embodiment, with respect toFIGS.5A-5D, a prior art 4-in-1 cutting block500is used to create the remaining bone cuts.FIG.5Ais a perspective view of the 4-in-1 cutting block,FIG.5Bis a side elevation view thereof,FIG.5Cis a top plan view thereof, andFIG.5Dis a bottom plan view thereof. The 4-in-1 cutting block500may be made of materials similar to that of the distal cutting guide400. The 4-in-1 cutting block500is manufactured to include a body502, a posterior guide slot504, a posterior chamfer guide slot506, an anterior chamfer guide slot508, and an anterior guide slot510. The cutting block500also includes two pegs512to fit into pilot holes to be drilled on the distal cut plane416, and two pin securing guides514to receive pins412′ to secure the cutting block500to the femur F. Although a 4-in-1 cutting block500is described herein, it should be appreciated that any N-in-1 cutting block for creating additional cut-planes on the bone may be aligned and assembled on the bone using the embodiments described herein. An N-in-1 cutting block can account for femoral prostheses having greater than 5 planar contact surfaces (for reference and clarity, the femoral prosthesis304shown inFIG.3has 5 planar contact surfaces including the posterior contact surface318that mates with the posterior cut plane314).

The 4-in-1 cutting block500may be aligned on the bone using an alignment guide. A particular embodiment of the alignment guide is a planar alignment guide600as shown inFIG.6AandFIG.6B.FIG.6Ais a perspective view of the planar alignment guide600, andFIG.6Bis a top plan view of thereof. The planar alignment guide600includes a body602, and two holes604integrated with the body602. The body602includes a bottom portion606adapted to fit in a channel800(shown inFIG.8A) to be milled on the distal cut plane416. The distance between the centers of the holes604correspond to the distance between the centers of the pegs512of the 4-in-1 block500.

With reference toFIGS.7A and7B, a particular embodiment of the alignment guide is an offset alignment guide700.FIG.7Ais a perspective view of the alignment guide700, andFIG.7Bis a bottom plan view thereof. The alignment guide700includes a body702, at least one ridge704at the edge and extending from the body702, and two holes604′ bored through the body702, where the two holes604′ are located a known distance from the ridge604. The distance between the centers of the two holes604′ correspond to the distance between the pegs512of the 4-in-1 cutting block500. The at least one ridge704is adapted to fit in a channel800(shown inFIG.8A) to be milled on the distal cut plane416.

The planned location for the pegs512on the planned distal cut plane310is determined based on the planned size and location of the prosthesis such that the guide slots of the 4-in-1 cutting block500align with the remaining bone cut planes. The planning software can define a virtual channel plane in the surgical plan, in which a channel800will be milled to receive the alignment guide (600,700). In a particular embodiment, the channel plane is defined by a plane that is perpendicular to the distal cut plane and aligned with the medial-lateral direction of the prosthesis. In another embodiment, the channel plane is defined based on the POSE of the planned anterior cut plane306or posterior cut plane314, and the location of the pegs required to align the guide slots for the remaining bone cuts. For example, if the planar alignment guide600is used, the planning software can define a virtual channel plane by anteriorly translating the planned posterior cut plane314to the location of the center of the pegs512of the 4-in-1 cutting block500. If the offset alignment guide700is used, then, the virtual channel plane is defined by anteriorly translating the planned posterior cut plane314to the location of the pegs512, and then posteriorly/anteriorly translating the planned plane by the known distance between the center of the holes604′ and the ridge704.

The virtual channel plane defined in the surgical plan is used to create a channel800on the distal cut plane416formed on the femur F with a surgical system as shown inFIGS.8A-8D. In a particular embodiment, the 2-DOF surgical system100is used wherein the tool206of the surgical device104is actuated such that the tool axis207remains substantially coincident with the channel plane. To mill the channel800, the tool206is a bone cutting tool such as an end mill, burr or a rotary cutter. The tool206may further include a sleeve to prevent the tool206from cutting the channel800too deep. After the channel800is milled, the alignment guide is placed in the channel, whereby the holes604′ are aligned with the position for the pegs512of the 4-in-1 cutting block500. When using the planar alignment guide600, the bottom portion606of the body602fits directly in the channel. When using the offset alignment guide700, the ridge704fits directly into the channel800as shown inFIGS.8C and8D. In both cases, a standard drill is then used to drill pilot holes for the pegs512by drilling through the holes604′ of the alignment guide.

After the holes for the pegs512have been drilled, the alignment guide is removed from the femur F. The 4-in-1 block500is attached to the femur F via the pegs512. The remaining four bone cuts on the femur F are created using a surgical saw guided by the guide slots of the 4-in-1 cutting block500. The 4-in-1 block500is then removed, and the femoral prosthesis can be fixed to the femur F in a conventional manner.

A particular advantage in using the offset alignment guide700as opposed to the planar alignment guide600, is the created channel800to receive the ridge704can be removed with one of the four planar cuts, depending on the distance between the ridge704and the holes604′. In general, the use of the channel plane with an alignment guide (600,700) is advantageous because position of the cutting block500in the medial-lateral direction does not need to be precise on the distal cut416as long as the guide slots of the 4-in-1 cutting block500span enough of the bone to create the remaining bone cuts. Additionally, by using a surgical system, the channel can be quickly and accurately created. In combination, all of these are highly advantageous over the traditional cutting alignment guides because there is no need to reference a monitor if passive navigation was otherwise used, there is no need to locate multiple anatomical landmarks to drill the holes for the pegs of a 4-in-1 block, and the overall surgical time is reduced.

Distal Cutting Guide with Alignment Guide

In a particular embodiment of the cutting guide, a distal cutting and alignment guide900is illustrated inFIG.9AandFIG.9B. A front perspective view of the distal cutting guide900is shown inFIG.9A, and a rear perspective view thereof is shown inFIG.9B. The distal cutting and alignment guide900includes a guide portion902and an attachment portion904. The guide portion902may be in the shape of an inverted “L”, with a distal guide slot906and a pair of holes908bored through. The distance between the centers of the two holes908correspond to the distance between the pegs512of the 4-in-1 block500. The guide portion902also includes an abutment face912adapted to abut against alignment pins914. The attachment portion904attaches to the guide portion902with fasteners910to clamp bone pins912to the distal cutting and alignment guide900.

The planning software defines two virtual planes to accurately place the cutting and alignment guide900to the femur F. A first pin plane is defined such that the guide slot906aligns with the planned distal cut plane310when the cutting guide900is assembled to the bone pins912. A second pin plane is defined such that when the face912abuts against the alignment pins914second pin plane, the holes908align with the POSE for the pegs512of the 4-in-1 cutting block500. For example, inFIG.9C, the first pin plane is defined for the bone pins912and the second pin plane is defined for the alignment pins914. The second pin plane is defined in the planning software as follows: 1) a plane is defined perpendicular to the planned distal cut plane310and parallel with the planned position for the pegs512, and 2) that plane is then posteriorly translated by the distance between the centers of the holes908and the face912of the distal cutting and alignment guide900. Therefore, when the face912abuts against the alignment pins914, the holes908are accurately aligned in the anterior/posterior direction and internal-external rotation.

The bone pins912and alignment pins914are accurately placed on the first and second pin planes using a surgical system as described above. The cutting guide900is then assembled to the femur F, wherein the face912abuts against the alignment pins914as shown inFIG.9D. Before the surgeon creates the distal cut416, two pilot holes are drilled through the holes908. The alignment pins914are removed and the distal cut416is made by guiding a surgical saw through the guide slot906. The cutting guide900is removed from the femur F, and the 4-in-1 guide block can be directly assembled in the pilot holes to aid in creating the remaining cuts.

Slot Alignment Guide

In a particular embodiment of the alignment guide, a slot alignment guide1000is shown inFIG.10AandFIG.10B.FIG.10Ais a perspective view of the slot alignment guide1000, andFIG.6Bis a top plan view thereof. The slot alignment guide1000includes two holes1002, and a pin receiving slot1004. The slot alignment guide1000may further include a lip1006. The distance between the centers of the two holes1002correspond to the distance between the pegs512of the 4-in-1 block500. The pin receiving slot1004is of sufficient width to be received on the bone pins1008. The distance between the center of the slot1004and the holes1002are known to define a virtual pin plane for the bone pins1008.

The slot alignment guide1000may be used if the cancellous bone on the distal surface416of the femur F is particularly soft, weak, or more flexible. In these cases, the planar alignment guide600or the offset alignment guide700in the channel800may become misaligned due to the flexible nature of this cancellous bone. Therefore, bone pins1008may be inserted on the channel plane as defined above. The bone pins1008are aligned and inserted on the channel plane using the methods previously described as shown inFIG.10C. A ring1010such as a washer or spacer may be placed on the bone pins1008to further protect the distal surface416of the femur F. The pin receiving slot1004of the slot alignment guide1000is placed on the bone pins1000. The lip1006may interact with the ring1010such that the alignment guide1000lies flat on the distal surface416of the femur F. A user may then drill pilot holes through the holes1002using a standard drill. The alignment guide1000and the bone pins1008are removed from the femur F and the pegs512of the 4-in-1 guide block500is assembled to the pilot holes to aid in creating the remaining bone cuts.

It should be appreciated that the 4-in-1 block may have other features, other than the pegs512, to interact and attach with the distal cut surface416of the femur F. The pegs512may instead be a body extruding from the bottom surface of the 4-in-1 block500and adapted to fit in a corresponding shape created on the distal cut surface416. The extruding body may have a variety of shapes including an extruded rectangle, triangle, the shapes manufactured for a keel of a tibial base plate implant, and any other extruding body/bodies. Therefore, the alignment guides described herein may have the same corresponding shape, instead of the holes (604,604′, and908), to guide a user in creating that shape on the distal cut surface416so the 4-in-1 block can be accurately placed thereon.

Clamp Alignment Guide

With reference toFIGS.16A-17C, a clamp alignment guide (1600,1700) is used to aid in the alignment of an N-in-1 cutting block on the femur. The clamp alignment guides (1600,1700) are configured to clamp onto their own set of pins in a POSE that permits a user to accurately create the pilot holes for the cutting block pegs512. In a particular embodiment, with reference toFIGS.16A-16E, a referencing clamp alignment guide1600and the use thereof is shown. The referencing clamp alignment guide1600includes a guide portion1602and a clamping portion1604. The guide portion1602has a pair of referencing feet1606that reference a top surface409of the universal distal cutting guide400′, and two or more holes1608spaced a distance apart corresponding to the distance between the pegs512of a cutting block.

In general, the virtual pin plane for the clamp alignment guides (1600,1700) is defined by: 1) defining a plane perpendicular to the planned distal cut plane310and parallel with the planned position for the pegs512; 2) posteriorly translating that plane by the known distance between the centers of the holes1608and a bottom surface1609of the alignment portion1602; and 3) further posteriorly translating that plane by an additional half-width of the pins1610.

Use of the reference clamp alignment guide1600is shown with respect toFIGS.16C and16D. A universal cut guide400′ is first assembled on the femur F as described above. The pins1610are positioned on the virtual pin plane using a surgical system, such as the 2-DOF surgical system100. The clamp guide1600is assembled on the pins1610with the feet1606referencing the top surface409of the universal cut guide400′. The user then drills the pilot holes for the cutting block pegs512using the holes1608as a guide. After which, the clamp alignment guide1600and pins1610are removed from the bone and the user creates the distal cut via the guide slot406. Subsequently, the distal cut guide400′ and distal pins412are removed from the bone, the cutting block pegs512are inserted in the pilot holes, and the remaining cut planes are created on the femur.

There is one issue a user may encounter when using the clamp alignment guides (1600,1700). The drill and drill bit for creating the N-in-1 pilot holes need to have sufficient clearance so as to not interfere with the placement of the pins1610, while also permitting the drill bit to traverse all of the bone distal to the distal cut plane and create a hole beyond the distal cut plane that is deep enough to fully receive the cutting block pegs512. In a particular embodiment, with reference toFIG.16E, this problem is solved using a stepped diameter drill bit1617.FIG.16Edepicts the distal cut guide400′ and reference clamp guide1600assembled on the bone, and a drill1618driving a stepped diameter drill bit1617through the guide holes1608. Because the exact distance between the planned distal cut plane1612and the top of the guide1614is known (this is geometrically known because the distance from i) the guide slot406and the distal guide's top surface409is known, and ii) the distance from the bottom of the referencing feet1606stabilized on the top surface409, to the top of the guide1614is also known, therefore i+ii=the distance between the top of the guide1614and the planned cut plane1612), a drill bit1617having a stepped diameter can simultaneously clear the length of the pins1610and also set the engagement in the bone beyond the distal cut plane1612so the user does not have to determine how deep to drill. Here the drill bit1617has a distal portion1619having a diameter less than a proximal portion1620. The distal portion1619has a diameter that fits through the guide holes1608and large enough to create a hole for receiving the cutting block pegs512. The distal portion1619has a length capable of traversing the bone distal of the distal cut plane1619and extend beyond the distal cut plane1612enough to create a pilot hole deep enough to fully receive the pegs512. The proximal portion1620has a diameter larger than the diameter of the guide holes1608and a length that ensures the bulky drill1618does not interfere with pins1610. In another embodiment, to solve this clearance issue, the drill1618is tracked by a tracking system and a monitor provides visual feedback to the user. When the tip of the drill extends beyond a certain depth (e.g. breaks the planned distal cut plane1612), the monitor displays this information and/or provides depth information.

In a specific embodiment, with reference toFIGS.17A-17C, a plane clamp alignment guide1700is used to aid in the creation of the pilot holes to receive the cutting block pegs512. The plane alignment guide1700is placed directly on the distal cut plane416and includes a guide portion1702and a clamping portion1704. The guide portion1700includes two or more holes1706similar to the reference alignment guide1600. The guide1700may further include a projection1708to increase the contact surface area between the guide1700and the distal cut surface416to increase the stability of the guide on the distal surface416. Accordingly, the bottom surface1712of the plane alignment guide1700is flat to mate with the planar distal cut surface416. Fasteners1710or a clamping mechanism allows the plane guide1700to assemble to the pins1714inserted on the bone.

The procedure for using the plane alignment guide1700is as follows. The user first creates the distal cut using a universal distal cutting guide400. The user then inserts pins1714on a virtual pin plane, where the virtual pin plane is defined as described above for the clamp alignment guides (1600,1700). The pins1714are inserted directly on the distal cut surface416. The plane alignment guide1700is then clamped to the pins1714where the bottom surface1712of the guide1700lies flush with the cut surface416. The user drills the pilot holes for the pegs512using the holes1706as a guide. Subsequently, the pins1714and the plane alignment guide1700are removed, the pegs512of an N-in-1 cutting block are placed in the pilot holes, and the remaining cut planes are created. The clearance issue described above for the reference alignment guide1600can be readily solved in a similar manner for the plane alignment guide1700.

5-DOF Chamfer Guide

In a specific embodiment of the cutting guide, a 5-DOF chamfer cutting guide1100is shown inFIGS.11A-11E.FIG.11Ais a perspective view of the top of the chamfer cutting guide1100,FIG.11Bis a perspective view of the bottom thereof,FIG.11Cis a top plan view,FIG.11Dis a front elevation view, andFIG.11Eis a side elevation view. The chamfer cutting guide1100includes a guide body1102in the shape of an inverted “L”. The guide body1102includes a first attachment slot1104a, a second attachment slot1104b, a distal guide slot1106, an anterior guide slot1108, and a chamfer guide slot1110. One side of the attachment slots1104is open, so the chamfer cutting guide1100can slide onto the bone pins. The attachment slot opening is best visualized inFIG.11Don the right side of the attachment slots1104.

The planning software defines the location of 5-DOF chamfer cutting guide1100in the location necessary to place the guide slots in the correct position and orientation to accurately execute the planned cut planes. The surgical plan also includes two pin planes (1202a,1202b, as shown inFIGS.12A-12B), on which bone pins (1204a,1204b) are placed that are defined relative to the cut planes; the two planes have an intersection axis that is parallel to all of the cut planes. The pin planes (1202a,1202b) may be defined using the known dimensions of the chamfer cutting guide1100, and the POSE of the planned cut planes. For example, the planning software knows the position and orientation of the attachment slots1104with respect to the guide slots. Using these dimensions the planning software may define a first pin plane1204aand a second pin plane1204b. By defining two pin planes with four or more pins, 5 degrees of freedom are constrained, which is sufficient to perform a TKA procedure using a surgical saw if the unconstrained degree of freedom is in the medial-lateral direction, which is parallel to all of the cut planes.

A surgical system, such as the one described above, is then used to place the bone pins (1204a.1204b) substantially coincident on the pin planes (1202a,1202b). Once again, the pins1204can be inserted at an arbitrary position and orientation on that plane. The attachment slots1104of the chamfer cutting guide1100slide over the bone pins (1204a.1204b) as shown inFIG.12C. The user then creates the distal cut plane, anterior cut plane, posterior cut plane, and the chamfer cut planes by guiding a surgical saw through the respective guide slots. The chamfer guide1100and the bone pins1204are then removed. A second cut guide (not shown), which fits against the distal and posterior cut surfaces can guide the anterior cut using similar embodiments of the cutting guides, pin planes, and bone pins as described herein.

Pin Alignment Guide

In a particular embodiment of the alignment guide, a pin alignment guide1300is shown inFIG.13AandFIG.13B. The pin alignment guide1300includes a tubular body1302and fins1304extruding outwardly from the tubular body1302. The pin alignment guide1300aids a user in aligning bone pins for use with a cutting guide that requires the bone pins to be placed a specific distance apart. For example, the cutting guide1400shown inFIGS.14A and14Bincludes a guide slot1402, and two holes1404that receive bone pins placed a specific distance apart.

To use the pin alignment guides1300, with respect toFIG.15A, at least two perpendicular channel planes are defined in the planning software. A first channel plane, to create a first channel1502on the bone, is defined as described above using the planned distal cut plane310and the distance between the guide slot1402and the center of the holes1404. A second channel plane, to create a second channel1504on the bone, is defined perpendicular to the first channel plane. A third channel plane is defined perpendicular to the first channel plane and medially/laterally translated by the distance between the centers of the holes1404of the cutting guide1400. The channels (1502,1504) are precisely milled on the bone using a surgical system as described above.

The intersection of the first channel1502and the second channel1504(shown at1506), receives the pin alignment guide1300as shown inFIG.15B, wherein the fins1304fit directly into the channels. A user can then drill a pilot hole, or a bone pin directly through the tubular body1302of the pin alignment guide1300. The procedure is repeated to place any additional bone pins on the bone. Subsequently, the holes1404of the cutting guide1400are placed on the bone pins, and the bone cut is created as planned. It should be appreciated that this technique can similarly be used for other cutting guides. For example, the pin alignment guide technique can be used to create pilot holes on the distal cut416of the femur F for the pegs512of a 4-in-1 block500.

Tibial Cut Plane

The tibial cut plane may be created using similar embodiments as described above and should be apparent to one skilled in the art after reading the subject matter herein.

In a particular embodiment, the tibial cut guide may be aligned invarus-valgus rotation, internal-external rotation, flexion-extension rotation, and proximal-distal position. The anterior-posterior position is not important. The tibial cut guide is positioned using two or more pins positioned on two planes that have an intersection axis that is aligned with the planned anterior-posterior direction. For example, two planes oriented ±45° invarus-valgus, such that when the guide is placed on the pins, all degrees of freedom except the anterior-posterior are constrained.

Example: Distal Cutting Guide, Alignment Guide and 4-In-1 Block

Testing was conducted on femoral and tibia saw bones using the 2-DOF surgical system100, the universal distal cutting guide400, the offset alignment guide700and the 4-in-1 block500. Artificial ligaments were attached between the saw bones to mimic the kinematics of the knee. The purpose of the testing was to assess the overall time required to create the planar cuts on the femoral saw bone, referred to hereafter as femur. The timing began prior to fixing the femoral tracking array120band ended once the last cut plane on the femur was completed.

To begin, the femoral tracking array120bwas fixed to the lateral side of the femur. A tracked digitizer probe was used to collect various points on the distal femoral surface. The collected points were used to register the POSE of the femur to a surgical plan. The 2-DOF surgical device104was used to drill two holes in the virtual pin plane414, the virtual pin plane414being defined in the planning software prior to testing. A standard drill was then used to insert pins412in the drilled holes. The universal distal cutting guide400was clamped to the pins412and the distal cut416was created using a surgical saw guided through the slot406of the distal cutting guide400. The distal cutting guide400and pins412were then removed from the femur.

The 2-DOF surgical device104was then used to mill a channel800on the distal cut surface416along the virtual channel plane, the virtual channel plane being defined in the planning software prior to testing. The ridge704of the offset alignment guide700was placed in the channel800and a standard drill was used to drill two holes on the distal surface416guided by the two holes604′ of the offset alignment guide700. The offset alignment guide700was removed from the channel800and the pegs512of the 4-in-1 block500were placed in the two drilled holes. The remaining four planar cuts were created using a surgical saw guided by the guide slots (504,506,508, and510) of the 4-in-1 block500. The recorded time from femoral tracking array120bfixation to the creation of the final cut plane was approximately 18 minutes.

It is worthy to note, that during testing the standard drill had lost power and required charging. The timing was not stopped during the charging step. It is presumed that an experienced surgeon could execute this testing procedure in approximately 10 to 15 minutes.

Articulating Pin-Driving Device

The articulating device204of the 2-DOF surgical system100described above can accurately align a tool/pin to be coincident with one or more virtual planes. However, the surgeon still has to manually advance the device204towards the bone to insert the pin or to create a pilot hole for the pin, which may be uncomfortable for the surgeon. In addition, it is possible that extreme or sudden movements by the surgeon or bone while operating the device may introduce small errors in the pin alignment. A contributing factor to the extreme or sudden movements may be a lacking of real-time information, during use, as to the articulating travel range, or workspace, in which the device operates204within.

To provide further control and feedback for the user, the 2-DOF surgical device104may be modified to include a third pin-driving degree-of-freedom, which will be referred to hereinafter as an articulating pin-driver device104′. With reference toFIGS.18A-18Cin which like reference numerals have the meaning ascribed to that numeral with respect to the aforementioned figures, a particular embodiment of the articulating pin driver device104′ is shown. In addition to the components of the 2-DOF surgical device104, the working portion204′ of the articulating pin driver device104′ further includes components configured to drive a pin206′ into a bone. Specifically, with reference toFIG.18C, the working portion204′ includes the motor205, a motor coupler1808, a pin-driving ball screw1804, a pin holder1806, and the pin206′. A specially adapted carriage1810is configured to support and carry the working portion204′ and may include mechanisms for actuating the pin. In some inventive embodiments, the carriage1810includes a pin-driving ball nut1812and connection members1814such as holes, bearings, or axle supports to receive a rod, a dowel, or an axel to act as the hinges (220a,220b) that are connected with the first end of the linear rails (208a,208b). The motor coupler1808couples the motor205with the pin-driving ball screw1804. The pin-driving ball screw1804is in mechanical communication with the pin-driving ball nut1812. The pin holder1806connects the pin-driving ball screw1804with the pin206′. The pin206′ is removably attached with the pin holder1806to allow the pin206′ to remain in the bone when inserted therein. The motor205may bi-rotationally drive the pin-driving ball screw1804and the pin206′ to advance and drive the pin206′ into a bone. The components may further include a motor carriage (not shown) operably connected with a motor linear rail (not shown). The motor carriage is secured to the motor205to keep the motor205from rotating while allowing the motor205to translate along the motor linear rail. The motor linear rail may extend from the carriage1810.FIG.18Aillustrates the pin206′ in a retracted state andFIG.18Billustrates the pin206′ in an extended state, where the pin206′ can translate a distance “d2”. An outer guard1802may be present to guard the user from the actuating mechanisms in the working portion204′. If an outer guard1802is present, the guard1802may be dimensioned to conceal the entire pin206′ when the pin206′ is in the retracted state, or the guard1802may only conceal a portion of the pin206′ to allow the user to visualize the tip of the pin206′ prior to bone insertion.

In a specific embodiment, the working portion204′ may include a first motor205for rotating the pin206′, and a second motor (not shown) for translationally driving the pin206′. The second motor may rotate a ball screw or a worm gear that is in communication with an opposing ball nut or gear rack configured with the first motor205. As the second motor bi-rotationally drives the ball screw or worm gear, the first motor205and the pin206′ translate accordingly.

The device computer108of the articulating pin driving device104′ may further include hardware and software to control the pin-driving action. In an embodiment, the device computer108includes two motor controllers for independently controlling the front actuator210aand back actuator210b, respectively, to maintain the POSE of the working portion (204,204′). A third motor controller may independently control the motor205for driving and rotating the pin206′ into the bone. In the specific embodiment where a first motor205rotates the pin206′ and a second motor (not shown) translates the pin206′, the device computer108may include two separate motor controllers to independently control the first motor205and the second motor.

In a specific embodiment, with reference toFIGS.19A-19B, the articulating device104′ includes a bone stabilizing member1902attached or integrated with the hand-held portion202. The bone stabilizing member1902includes bone contacting elements (1904a,1904b) which are configured to contact the bone and stabilize the hand-held portion202while the working portion204′ articulates. The bone contacting elements (222a,222b) may be a flat surface, a pointed protrusion, or a surface having jagged edges to interact with the bone and stabilize the hand-held portion202. The bone contacting element(s) (1904a,1904b) project just beyond the working portion204′ such that the element(s) (1904a,1904b) may contact the bone without negatively impacting how deep the pin206′ may be inserted in the bone. When the user is in the approximate region for driving the pin206′, the user may stabilize the hand-held portion202to the bone via the bone contacting elements (1904a,1904b). With the hand-held portion stabilized, the working portion204′ further articulates until the pin206′ is precisely coincident with a virtual pin plane. In a specific embodiment, once the pin206′ aligns with the virtual pin plane214, the system100automatically locks the actuators (210a,210b) and activates the motor205to drive the pin206′ into the bone. In another embodiment, the user activates a user input mechanism such as a trigger214or a button before the system100either locks the actuators (210a,210b), drives the pin206′, or both. Therefore, the user can anticipate and control when the pin206′ is driven into the bone. This user input mechanism may similarly be used by the user to control the amount of extension or retraction of the pin206′ in general.

In a particular embodiment, with reference toFIG.19A, one or more indicators1906, such as an LED or a display, is attached or integrated with the device104′. The indicator1906may be attached to the outer guard1802, the working portion204′, or the hand-held portion202for example. The indicator(s)1906provide feedback to the user as to a current position of the device104′ with respect to a desired position for the device104′. For example, the indicator1906may emit a red light to indicate that the device104′ is outside of the travel ranges of the three ball screws (216a,216b,1804). In other words, a red light is emitted when the working portion204′ and pin206′ can no longer be articulated to reach a desired position, orientation, or a desired depth to insert the pin206′. The indicator1906may emit a yellow light when the user is approaching the travel ranges and a green light when the pin206′ is aligned with a virtual pin plane. The indicator1906may further produce a blinking light that changes in blinking frequency based on how close the device104′ is to exceeding the travel range, or how close the pin206′ is to a virtual pin plane. The indicator1906may also indicate when the device104′ is ready to autonomously place the pin inside the bone. In a particular embodiment, the working portion204′ does not actuate until the indicator1906is in an active state, where the active state is triggered when the device104′ is within the travel limits of the ball screw. This data conveyed by the indicator1906is readily available based on either: a) local data collected directly from the device104′, such as the device kinematics; b) the tracking data collected from the tracking system106; c) a comparison of the POSE of the device104′ with the surgical plan; or d) a combination thereof.

In a specific embodiment, with reference toFIGS.20A and20B, the articulating device104′ includes a partial enclosure2002.FIG.20Ais perspective view of the articulating device104′ with the partial enclosure2002andFIG.6Bis a cross-section view thereof. The partial enclosure2002is attached to the hand-held portion202and partially encloses the working portion204′. The working portion204′ is able to articulate within the partial enclosure2002. The partial enclosure2002has an internal dimension (i.e. height or diameter) of ‘h’ that corresponds to the travel range of the working portion204′. This dimension ‘h’ may account for the translation ‘d’ of the working portion204′ and any additional height required to account for the pitch ‘a’ of the working portion204′. The advantage of the partial enclosure2002is to provide the user with a guide as to the workspace or travel range of the working portion204′. The user can simply place a front end of the partial enclosure2002on the bone to stabilize the hand-held portion202, at which time the working portion204′ can articulate to a virtual pin plane and drive the pin206′ into the bone. The user is no longer trying to aim the small pin206′ directly to a pin plane, but is rather using a larger guide, the partial enclosure2002, to get the pin206′ in the general vicinity of a pin plane and allowing the working portion204′ to perform the alignment. In addition, the user no longer has to worry about exceeding the travel limits of the working portion204′ while aligning the pin206′.

The front end of the partial enclosure2002may act as a bone contacting element (1904a,1904b) to stabilize the hand-held portion202and may further include features such as a jagged edge or one or more pointed protrusions.

The pin206′ extends beyond the partial enclosure2002in the extended state to allow the pin to be driven into the bone as shown inFIG.6B. When the pin206′ is in the retracted state, the pin206′ is enclosed within the partial enclosure2002.

The partial enclosure2002may further include the indicator1906to aid the user in positioning the device104′ to a desired pin plane as described above.

The partial enclosure2002is further configured to allow the tracking array212to attach with the working portion204′, or an outer guard1802′ of the working portion204′, to permit the tracking system106to track the POSE of the working portion204′ as it articulates.

In a particular embodiment, with reference toFIGS.21A and21B, the articulating device104′ includes a full enclosure2102.FIG.7Ais a perspective view of the articulating device102with the full enclosure2102andFIG.7Bis a cross-section view thereof. The full enclosure2102is configured with the same principles and has the same advantages as the partial enclosure2002, except the tracking array212is attached directly to the full enclosure2102. Since the tracking array212is attached to the full enclosure2102, the control scheme for controlling the working portion204′ must be modified, where the device kinematics are used to determine the POSE of the working portion204′. Particularly, the tracking system106tracks the hand-held portion202based on the geometric relationship between the array212and the hand-held portion202, and the actuator (210a,210b) positions (i.e. the rotational position of the actuators that corresponds to the position of the ball nuts (218a,218b) on the ball screws (216a,216b)) are used to determine the POSE of the working portion204′ with respect to the hand-held portion202. Therefore, the computing system102can determine new actuator positions to control and align the pin206′ with a virtual pin plane.

It should be appreciated that the partial enclosure2002and full enclosure2102may be sized and adapted for assembly to a hand-held system having greater than two degrees of freedom with similar advantages. For example, it is contemplated that the inner dimensions of the enclosure (226,228) may accommodate the travel limits of a device having an articulating portion that articulates in one or more translational directions, pitch, and yaw such as the system described in U.S. Pat. App. No. 20130060278. However, as the number of degrees of freedom increase, so does the size of the enclosure (226,228) which may impede the operating workspace.

It should be further appreciated that the embodiments of the bone stabilizing member1902, the indicator1906, the partial enclosure2002, and full enclosure2102, can all be adapted for use with the 2-DOF surgical device104as shown inFIGS.2A-2B.

Bi-Cortical Drilling

To further stabilize the bone pins in the bone it may be desirable to drill the pins through two cortical regions of the bone, also referred to as bi-cortical drilling. However, if a drill bit or a pin is drilled beyond the second cortical region and into the soft tissue, patient harm can occur. Therefore, it is proposed that the third pin-driving actuation axis can also be used to retract the drill bit/pin if the drill bit/pin breaks through the second cortical region.

In a particular embodiment, bone breakthrough is detected using an existing method, such as the method described in Taha, Zahari, A. Salah, and J. Lee. “Bone breakthrough detection for orthopedic robot-assisted surgery.” APIEMS 2008Proceedings of the9th Asia Pacific Industrial Engineering and Management Systems Conference.2008, which is hereby incorporated by reference in its entirety. The articulating pin-driving device104′ then automatically retracts the drill bit/pin at a constant optimal retraction speed relative to the bone, regardless of how the user is moving the hand-held portion202. This ensures that if the drill bit/pin breakthrough the second cortical region, that the drill bit/pin is retracted so as to not cause any patient harm. The retraction speed is a function of the optimal retraction speed combined with the current speed of the hand-held portion202.

The relative speed between the hand-held portion202and the bone can be measured several different ways. In one embodiment, the speed of the hand-held portion202relative to the bone is not detected and instead a speed is assumed. In another embodiment, a simple linear distance measuring tool is used, such as a laser distance measurement device. In a particular embodiment, the tracking system106is used to track both the bone and the hand-held portion202using one or more fiducial markers on each of the bone and the hand-held portion202.

One Bone Pin for Receiving a Cut Guide or Alignment Guide

With reference now toFIGS.23A to23C, a particular embodiment for aligning a cut guide or alignment guide with respect to a bone is shown, where only one bone pin412′ is inserted in the bone. The bone pin412′ may include a shaft450having a distal end452, a proximal end454, and a coupling portion456. The coupling portion456provides at least two contact points for assembling a cut guide or alignment guide onto the bone pin412′ and maintains the orientation of the cut guide or alignment guide with respect to the bone during use. The coupling portion456may be planar or extend laterally from the shaft450and provide the at least two contact points for assembly with a cut guide or alignment guide. The coupling portion456therefore alleviates the need for additional bone pins412, which reduces the overall surgical time.

When inserting a bone pin412′ having a coupling portion456into the bone, it is important that the final orientation (i.e., the orientation of the bone pin412′ when inserted in the bone as shown inFIG.23B) of the at least two contact points of the coupling portion456aligns parallel with the virtual pin plane414. This is to ensure that a cut guide or alignment guide when placed on the bone pin412′ is properly oriented with respect to a planned cut plane. A robotic system may assist in this alignment by determining an initial orientation of the bone pin412when first coupled to a robotic device and then tracking the orientation of the bone pin412′ (and more specifically the orientation of the coupling portion456) as the bone pin412′ is rotated by a motor (e.g., motor205as shown inFIG.2A). In a particular embodiment, the initial orientation of the bone pin412′ is determined using a robotic device (e.g., articulating hand-held device104) having a chuck or collet that resets to a “home” position prior to coupling the bone pin′412to the robotic device. With the chuck or collet in the ‘home’ position, a bone pin412′ is always coupled to the robotic device in the same initial orientation, where this initial orientation is stored in the system. In another embodiment, the initial orientation of the bone pin412′ is determined with a tracked digitizer or tracked calibration device by digitizing the bone pin412′ or assembling the tracked calibration device to the bone pin412′ and calculating the initial orientation of the bone pin412′. After the initial orientation is determined, the system may track the rotational orientation of the bone pin412′ as the bone pin412′ is rotated by a motor (e.g., motor205) based on: i) the initial orientation; and ii) the subsequent number of rotations (and/or amount of rotation) of the motor spindle. Then, the system may automatically shut off the motor, or signal the user (e.g., a visual or audible alert), when the orientation of the at least two contact points of the coupling portion456aligns parallel with the virtual pin plane414. The system may also account for the tracked depth of the bone pin412′ in the bone to ensure the automatic shut-off or signal only occurs when the bone pin412′ is sufficiently embedded in the bone. As a result, the final orientation of the coupling portion456when inserted in the bone is aligned parallel with the virtual pin plane414to receive a cut guide or alignment guide in the planned orientation.

Other Embodiments

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 can be made in the function and arrangements of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.

The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.