Smith & Nephew Ex. 1075
`IPR Petition - USP 8,657,827
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`2960/146
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`[0004] U.S. Ser. No. 11/671,745 is also a continuation-in-part of U.S. Ser. No. 10/728,731,
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`entitled “FUSION OF MULTIPLE IMAGING PLANES FOR ISOTROPIC IMAGING IN MRI AND
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`QUANTITATIVE IMAGE ANALYSIS USING ISOTROPIC OR NEAR—ISOTROPIC IMAGING,” filed
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`December 4, 2003, which claims the benefit of U.S. Ser. No. 60/431,176, entitled “FUSION
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`OF MULTIPLE IMAGING PLANES FOR ISOTROPIC IMAGING IN MRI AND QUANTITATIVE IMAGE
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`ANALYSIS USING ISOTROPIC OR NEAR ISOTROPIC IMAGING,” filed December 4, 2002.
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`[0005] U.S. Ser. No. 11/671,745 is also a continuation-in-part of U.S. Ser. No. 10/681,750,
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`entitled “MINIMALLY INvASIvE JOINT IMPLANT WITH 3-DIMENSIONAL GEOMETRY MATCHING
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`THE ARTICULAR SURFACES,” filed October 7, 2003, which claims the benefit of U.S. Ser. No.
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`60/467,686, entitled “JOINT IMPLANTS,” filed May 2, 2003 and U.S. Ser. No. 60/416,601,
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`entitled “MINIMALLY INvASIvE JOINT IMPLANT WITH 3-DIMENSIONAL GEOMETRY MATCHING
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`THE ARTICULAR SURFACES,” filed October 7, 2002.
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`[0006] Each of the above-described applications are hereby incorporated by reference in
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`their entirety.
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`Technical Field
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`[0007] The present invention relates to orthopedic methods, systems and prosthetic devices
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`and more particularly relates to methods, systems and devices for articular resurfacing. The
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`present invention also includes surgical molds designed to achieve optimal cut planes in a
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`joint in preparation for installation of a joint implant.
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`Background Art
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`[0007] A variety of tools are available to assist surgeons in performing joint surgery. In the
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`knee, for example, U.S. Pat. No. 4,501, 266 to McDaniel issued Feb. 26, 1985 discloses a
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`knee distraction device that facilitates knee arthroplasty. The device has an adjustable force
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`calibration mechanism that enables the device to accommodate controlled selection of the
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`ligament-tensioning force to be applied to the respective, opposing sides of the knee. U.S.
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`Pat. No. 5,002,547 to Poggie et al. issued Mar. 26, 1991 discloses a modular apparatus for
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`use in preparing the bone surface for implantation of a modular total knee prosthesis. The
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`apparatus has cutting guides, templates, alignment devices along with a distractor and
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`clamping instruments that provide modularity and facilitate bone resection and prosthesis
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`implantation. U.S. Pat. No. 5,250,050 to Poggie et al. issued Oct. 5, 1993 is also directed to a
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`modular apparatus for use in preparing a bone surface for the implantation of a modular total
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`knee prosthesis. U.S. Pat. No. 5,387,216 to Thornhill et al. issued Feb. 7, 1995 discloses
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`instrumentation for use in knee revision surgery. A bearing sleeve is provided that is inserted
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`into the damaged canal in order to take up additional volume. The rod passes through the
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`sleeve and is positioned to meet the natural canal of the bone. The rod is then held in a fixed
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`position by the bearing sleeve. A cutting guide can then be mounted on the rod for cutting
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`the bone and to provide a mounting surface for the implant. U.S. Pat. No. 6,056,756 to Eng
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`et al. issued May 2, 2000 discloses a tool for preparing the distal femoral end for a prosthetic
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`implant. The tool lays out the resection for prosthetic replacement and includes a jack for
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`pivotally supporting an opposing bone such that the jack raises the opposing bone in flexion
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`to the spacing of the intended prosthesis. U.S. Pat. No. 6,106,529 to Techiera issued Aug. 22,
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`2000 discloses an epicondylar axis referencing drill guide for use in resection to prepare a
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`bone end for prosthetic joint replacement. U.S. Pat. No. 6,296,646 to Williamson issued Oct.
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`2, 2001 discloses a system that allows a practitioner to position the leg in the alignment that
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`is directed at the end of the implant procedure and to cut both the femur and tibia while the
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`leg is fixed in alignment. U.S. Pat. No. 6,620,168 to Lombardi et al. issued Sep. 16, 2003
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`discloses a tool for interrnedullary revision surgery along with tibial components.
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`[0008] U.S. Pat. No. 5,578,037 to Sanders et al. issued Nov. 26, 1996 discloses a surgical
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`guide for femoral resection. The guide enables a surgeon to resect a femoral neck during a
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`hip arthroplasty procedure so that the femoral prosthesis can be implanted to preserve or
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`closely approximate the anatomic center of rotation of the hip.
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`[0009] Currently available tools do not always enable the surgeon to make the most accurate
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`cuts on the bone surface in preparing the target joint for implantation.
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`[0010] Thus, there remains a need for tools that improve the accuracy of the joint resurfacing
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`process.
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`Summary of the Invention
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`[0011] In accordance with a first embodiment of the invention, a surgical tool includes a
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`plurality of components including a first component engaging a second component via an
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`interlock mechanism. The plurality of components includes a surface for engaging a joint
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`surface, the surface being a mirror image of the joint surface. At least one guide aperture for
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`directs movement of a surgical instrument.
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`[0012] In accordance with related embodiments of the invention, the shape and/or position of
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`the guide aperture may be based, at least in part, on one or more axes related to said joint.
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`The interlock mechanism may include a screw, a pin, a thread, a ratchet-like mechanism, a
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`hinge-like mechanism, and/or a press-fit mechanism. One or more of the plurality of
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`components may be at least one of expandable and collapsible, and may be, for example, a
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`balloon and/or include a hydraulic mechanism, an electronic mechanism, and/or a
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`mechanical mechanism. At least one of the plurality of components may include a
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`passageway for inserting a guide wire. The surgical tool may further include an arthroscopic
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`instrument that includes a portal, the plurality of components capable of being deployed
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`through the arthroscopic portal.
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`[0013] In accordance with further related embodiments, the plurality of components may
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`include a first template having a first template surface for engaging a first joint surface, the
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`first template surface being a mirror image of the first joint surface. A second template has a
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`second template surface for engaging a second joint surface, the second template surface
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`being a mirror image of the second joint surface. A linkage cross-references the first
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`template to the second template. At least one of the first template and the second template
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`may include one or more guide apertures for directing movement of a surgical instrument.
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`[0014] The linkage may cross-reference the first template to the second template relative to
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`one of an anatomical and a biomechanical axis.
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`[00l5] In accordance with still further embodiments of the invention, the surgical tool may
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`be configured to be used in at least one of hip, knee, ankle, shoulder, elbow and wrist.
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`[00l6] In accordance with another embodiment of the invention, a patellar 3-D guidance tool
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`includes a template. The template includes at least one contact surface for engaging a
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`surface of the patella. The at least one contact surface substantially conforms with the
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`surface associated with the patellar. At least one guide aperture directs movement of a
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`surgical instrument, wherein the shape and/or position of the guide aperture is based, at least
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`in part, on three or more anatomic reference points associated with the patellar.
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`[0017] In accordance with related embodiments of the invention, the three or more anatomic
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`reference surfaces include a medial osteochondral junction, a lateral osteochondral junction,
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`an inferior tubercle of the patellar, and/or the attachment surface of the quadriceps tendon.
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`The surface associated with the patellar may be an articular cartilage surface and/or a bone
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`surface. The template may include a mold. The template may include at least two
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`components, the at least two pieces including a first component including one or more of the
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`at least one contact surfaces, the second component including one or more of the at least one
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`guide apertures. At least one contact surface may include a plurality of discrete contact
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`surfaces. The shape and/or position of the guide aperture may be further based, at least in
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`part, on one or more axes related to said joint. The guide aperture may define a cut plane
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`that extends through the three or more anatomical reference points when the at least one
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`contact surface engages the surface of the patellar. The shape and/or position of the guide
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`aperture may be further adapted, at least in part, to optimized tracking of the patellar with the
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`femoral trochlea.
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`[00l8] In accordance with another embodiment of the invention, a patellar template includes
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`a plurality of discrete contact surfaces for engaging an articular surface of the patella. The
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`plurality of contact surfaces substantially conform with the articular surface of the patella. At
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`least one guide directs movement of a surgical instrument.
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`[0019] In accordance with related embodiments of the invention, the template may include
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`sidewalls defining an inner periphery that matches a circumference of the patella. The inner
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`periphery of the sidewalls may contact the circumference of the patella and substantially
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`prevent rotation of the patella. The inner periphery of the sidewalls may contact a non-
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`articulating circumference of the patella. The at least one guide may be positioned on the
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`sidewalls. The sidewalls may define a cup-shaped chamber having the inner periphery, an
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`open end for inserting the patella, and a bottom surface that includes the discrete contact
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`surfaces.
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`[0020] In accordance with further related embodiments of the invention, the plurality of
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`discrete contact points may include at least three spikes. The plurality of contact surfaces
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`may be hollow so as to allow passage of at least one of a drill a pin, a marking instrument..
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`At least one of the contact surfaces may reference subchondral bone. At least one of the
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`contact surfaces may reference cartilage. The articular surface may be at least one of an
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`articular cartilage surface and a bone surface.
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`[0021] In accordance with still further related embodiments of the invention, the at least one
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`guide may be positioned relative to the plurality of contact surfaces so as to guide a cut plane
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`through one or more anatomical landmarks on the patella. The guide may define a cut plane
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`that extends through three or more anatomical reference points when the at least one contact
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`surface engages the surface of the patellar. The anatomical landmarks may include at least
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`one of a medial junction, a lateral junction, a medial osteochondral junction, a lateral
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`osteochondral junction, an inferior tubercle of the patellar, and the attachment surface of the
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`quadriceps tendon. The template may include at least two components, the at least two
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`components including a first component including the plurality of contact surfaces, the
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`second component including one or more of the at least one guide apertures. The shape
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`and/or position of the guide may be based, at least in part, on one or more axes related to said
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`joint. The shape and/or position of the guide aperture may be adapted, at least in part, to
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`optimized tracking of the patellar with the femoral trochlea. The guide may include at least
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`one of an aperture and an outer cutting surface.
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`[0022] In accordance with another embodiment of the invention, a method of preparing a
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`patella using a template is presented. The template includes a plurality of discrete contact
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`surfaces for engaging an articular surface of the patella. The plurality of contact surfaces
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`substantially conform with the articular surface of the patella. The template further includes
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`at least one guide for directing movement of a surgical instrument. The method includes
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`positioning the template such that the plurality of discrete contact surfaces contact the
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`articular surface of the patella. A surgical instrument is guided via the at least one guide so
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`as to modify the patella.
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`[0023] In accordance with related embodiments of the invention, the template may include
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`sidewalls that define an inner periphery. The method may further include inserting the
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`patella into the inner periphery such that at least a portion of the inner periphery of the
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`chamber contacts an outer circumference of the patella, and the discrete contact surfaces
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`contact the articulating side of the patella. Locations on the patella which engage the contact
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`surfaces are marked. The patella is removed from the inner periphery. Cartilage at the
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`marked locations are excised so as to leave subchondral bone. Positioning the template
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`includes placing the plurality of discrete contacts surfaces in contact with the subchondral
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`bone at the excised locations.
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`[0024] In accordance with further related embodiments of the invention, the discrete contact
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`surfaces may be spikes, wherein marking locations on the patella includes pushing the spikes
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`into cartilage on the patella. The discrete contact surfaces may be hollow spikes, wherein
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`marking locations on the patella includes placing, for example, a drill or pin through the
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`hollow spikes to mark locations on the patella. The template may be a cup-shaped chamber
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`having the sidewalls that define the inner periphery, an open end for inserting the patella, and
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`a bottom surface that includes the discrete contact surfaces.
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`[0025] In accordance with still further related embodiments of the invention, guiding a
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`surgical instrument via the at least one guide may include performing a cut on the patella.
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`The cut may extend through three or more anatomical reference points. The anatomical
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`landmarks may include a medial junction, a lateral junction, a medial osteochondral junction,
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`a lateral osteochondral junction, an inferior tubercle of the patellar, and/or the attachment
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`surface of the quadriceps tendon.
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`[0026] In accordance with yet further related embodiments of the invention, the template
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`includes sidewalls that define an inner periphery, wherein positioning the template includes
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`inserting the patella into the inner periphery such that at least a portion of the inner periphery
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`of the chamber contacts an outer circumference of the patella, and the discrete contact
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`surfaces contact the cartilage on the patella. The template may be a cup-shaped chamber
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`having the sidewalls that define the inner periphery, an open end for inserting the patella, and
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`a bottom surface that includes the discrete contact surfaces.
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`[0027] In accordance with other related embodiments of the invention, the method may
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`further include obtaining an image of the patella,; and determining the shape, orientation
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`and/or position of at least one of the guides and the plurality of contact surfaces based, at
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`least in part, on the image. Obtaining the image may includes performing a CT, the method
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`further including segmenting bony margins of the patella from the image. Obtaining the
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`mage may include MRI, CT, ultrasound, x-ray technology, digital tomosynthesis, and optical
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`coherence tomography. For example, obtaining the image may includes performing a CT, the
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`method further including segmenting bony margins of the patella from the image.
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`Brief Description of the Drawings
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`[0028] The foregoing features of the invention will be more readily understood by reference
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`to the following detailed description, taken with reference to the accompanying drawings, in
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`which:
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`[0029] FIG. 1A illustrates a femur, tibia and fibula along with the mechanical and anatomic
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`axes. FIGS. lB-E illustrate the tibia with the anatomic and mechanical axis used to create a
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`cutting plane along with a cut femur and tibia. FIG. lF illustrates the proximal end of the
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`femur including the head of the femur.
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`[0030] FIG. 2 shows an example of a surgical tool having one surface matching the
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`geometry of an articular surface of the joint, in accordance with an embodiment of the
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`invention. Also shown is an aperture in the tool capable of controlling drill depth and width
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`of the hole and allowing implantation of an insertion of implant having a press-fit design.
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`[0031] FIG. 3 is a flow chart depicting various methods of the invention used to create a
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`mold for preparing a patient's joint for arthroscopic surgery, , in accordance with an
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`embodiment of the invention.
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`[0032] FIG. 4A depicts, in cross-section, an example of a surgical tool containing an
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`aperture through which a surgical drill or saw can fit, in accordance with an embodiment of
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`the invention. The aperture guides the drill or saw to make the proper hole or cut in the
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`underlying bone. Dotted lines represent where the cut corresponding to the aperture will be
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`made in bone. FIG. 4B depicts, in cross-section, an example of a surgical tool containing
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`apertures through which a surgical drill or saw can fit and which guide the drill or saw to
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`make cuts or holes in the bone, in accordance with an embodiment of the invention. Dotted
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`lines represent where the cuts corresponding to the apertures will be made in bone.
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`[0033] FIGS. SA-Q illustrate tibial cutting blocks and molds used to create a surface
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`perpendicular to the anatomic axis for receiving the tibial portion of a knee implant, in
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`accordance with an embodiment of the invention.
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`[0034] FIGS. 6A-O illustrate femur cutting blocks and molds used to create a surface for
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`receiving the femoral portion of a knee implant, in accordance with an embodiment of the
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`invention.
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`[0035] FIG. 7A-G illustrate patellar cutting blocks and molds used to prepare the patella for
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`receiving a portion of a knee implant, in accordance with an embodiment of the invention.
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`[0036] FIG. 8A-H illustrate femoral head cutting blocks and molds used to create a surface
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`for receiving the femoral portion of a knee implant, in accordance with an embodiment of the
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`invention.
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`[0037] FIG. 9A-D illustrate acetabulum cutting blocks and molds used to create a surface for
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`a hip implant, in accordance with an embodiment of the invention.
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`[0038] FIG. l0A illustrates a patella modeled from CT data, in accordance with an
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`embodiment of the invention. FIGS. l0B-D illustrate a mold guide, and then the mold guide
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`placed on an articular surface of the patella, in accordance with an embodiment of the
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`invention. FIG. l0E illustrates a drill placed into a patella through mold drill guide, in
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`accordance with an embodiment of the invention. FIG. l0F illustrates a reamer used to
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`prepare the patella, in accordance with an embodiment of the invention.
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`[0039] FIG. llA illustrates a reamer made for each patella size. FIG. llB illustrates a
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`reamed patella ready for patella implantation, in accordance with an embodiment of the
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`invention.
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`[0040] FIG. l2A-F illustrate a recessed patella implanted on a patella, in accordance with an
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`embodiment of the invention.
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`[0041] FIGS. l3A-D show a patellar template, in accordance with an embodiment of the
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`invention.
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`[0042] FIG. l4 shows the patella after modifications are made using the template of Fig.
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`l3A-D, in accordance with an embodiment of the invention.
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`[0043] FIG. l5 shows the underside of a patella implant that may be used in conjunction
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`with the modifications to the patella shown in FIG. l4, in accordance with an embodiment of
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`[0044] FIGS. 16A and 16B show the implant of Fig. 15 attached to the patella, in accordance
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`with an embodiment of the invention.
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`[0045] Fig. 17A shows a template that includes spikes, in accordance with an embodiment of
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`the invention. Fig. l7B shows a template that includes hollow spikes, in accordance with an
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`embodiment of the invention.
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`[0046] FIG. 18 shows a template that includes at least two components, in accordance with
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`an embodiment of the invention.
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`Detailed Description of Specific Embodiments
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`[0047] The following description is presented to enable any person skilled in the art to make
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`and use the invention. Various modifications to the embodiments described will be readily
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`apparent to those skilled in the art, and the generic principles defined herein can be applied to
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`other embodiments and applications without departing from the spirit and scope of the
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`present invention as defined by the appended claims. Thus, the present invention is not
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`intended to be limited to the embodiments shown, but is to be accorded the widest scope
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`consistent with the principles and features disclosed herein. To the extent necessary to
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`achieve a complete understanding of the invention disclosed, the specification and drawings
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`of all issued patents, patent publications, and patent applications cited in this application are
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`incorporated herein by reference.
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`[0048] 3D guidance surgical tools, referred to herein as a 3D guidance surgical templates,
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`that may be used for surgical assistance may include, without limitation, using templates, jigs
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`and/or molds, including 3D guidance molds. It is to be understood that the terms “template,”
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`“jig, mold,” “3D guidance mold,” and “3D guidance template,” shall be used
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`interchangeably within the detailed description and appended claims to describe the tool
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`unless the context indicates otherwise.
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`[0049] 3D guidance surgical tools that may be used may include guide apertures. It is to be
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`understood that the term guide aperture shall be used interchangeably within the detailed
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`description and appended claims to describe both guide surface and guide elements.
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`[0050] As will be appreciated by those of skill in the art, the practice of the present invention
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`employs, unless otherwise indicated, conventional methods of x-ray imaging and processing,
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`x-ray tomosynthesis, ultrasound including A-scan, B-scan and C-scan, computed
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`tomography (CT scan), magnetic resonance imaging (MRI), optical coherence tomography,
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`single photon emission tomography (SPECT) and positron emission tomography (PET)
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`within the skill of the art. Such techniques are explained fully in the literature and need not
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`be described herein. See, e.g., X-Ray Structure Determination: A Practical Guide, 2nd
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`Edition, editors Stout and Jensen, 1989, John Wiley & Sons, publisher; Body CT: A Practical
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`Approach, editor Slone, l999, McGraw-Hill publisher; X-ray Diagnosis: A Physician's
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`Approach, editor Lam, l998 Springer-Verlag, publisher; and Dental Radiology:
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`Understanding the X-Ray Image, editor Laetitia Brocklebank 1997, Oxford University Press
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`publisher. See also, The Essential Physics of Medical Imaging (2nd Ed.), Jerrold T. Bushberg,
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`et al.
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`[005 1] As described herein, repair systems, including surgical instruments, guides and
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`molds, of various sizes, curvatures and thicknesses can be obtained. These repair systems,
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`including surgical instruments, guides and molds, can be catalogued and stored to create a
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`library of systems from which an appropriate system for an individual patient can then be
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`selected. In other words, a defect, or an articular surface, is assessed in a particular subject
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`and a pre-existing repair system, including surgical instruments, guides and molds, having a
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`suitable shape and size is selected from the library for further manipulation (e.g., shaping)
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`and implantation.
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`[0052] Performing a total knee arthroplasty is a complicated procedure. In replacing the knee
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`with an artificial knee, it is important to get the anatomical and mechanical axes of the lower
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`extremity aligned correctly to ensure optimal functioning of the implanted knee.
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`[0053] As shown in FIG. 1A, the center of the hip 102 (located at the head 130 of the femur
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`132), the center of the knee 104 (located at the notch where the intercondular tubercle 134 of
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`the tibia 136 meet the femur) and ankle 106 lie approximately in a straight line 110 which
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`defines the mechanical axis of the lower extremity. The anatomic axis 120 aligns 5-7° offset
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`0 from the mechanical axis in the valgus, or outward, direction.
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`[0054] The long axis of the tibia 136 is collinear with the mechanical axis of the lower
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`extremity 110. From a three-dimensional perspective, the lower extremity of the body ideally
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`functions within a single plane known as the median anterior-posterior plane (MAP-plane)
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`throughout the flexion-extension arc. In order to accomplish this, the femoral head 130, the
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`mechanical axis of the femur, the patellar groove, the intercondylar notch, the patellar
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`articular crest, the tibia and the ankle remain within the MAP-plane during the flexion-
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`extension movement. During movement, the tibia rotates as the knee flexes and extends in
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`the epicondylar axis which is perpendicular to the MAP-plane.
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`[0055] A variety of image slices can be taken at each individual joint, e.g., the knee joint
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`150-1501,, and the hip joint 152-150,1. These image slices can be used as described above in
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`Section I along with an image of the full leg to ascertain the axis.
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`[005 6] With disease and malfunction of the knee, alignment of the anatomic axis is altered.
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`Performing a total knee arthroplasty is one solution for correcting a diseased knee.
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`Implanting a total knee joint, such as the PFC Sigma RP Knee System by Johnson &
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`Johnson, requires that a series of resections be made to the surfaces forming the knee joint in
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`order to facilitate installation of the artificial knee. The resections should be made to enable
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`the installed artificial knee to achieve flexion-extension movement within the MAP-plane
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`and to optimize the patient's anatomical and mechanical axis of the lower extremity.
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`[0057] First, the tibia 130 is resected to create a flat surface to accept the tibial component of
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`the implant. In most cases, the tibial surface is resected perpendicular to the long axis of the
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`tibia in the coronal plane, but is typically sloped 4-7° posteriorly in the sagittal plane to
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`match the normal slope of the tibia. As will be appreciated by those of skill in the art, the
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`sagittal slope can be 0° where the device to be implanted does not require a sloped tibial cut.
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`The resection line 158 is perpendicular to the mechanical axis 110, but the angle between the
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`resection line and the surface plane of the plateau 160 varies depending on the amount of
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`damage to the knee.
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`[0058] FIGS. 1B-D illustrate an anterior View of a resection of an anatomically normal tibial
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`component, a tibial component in a varus knee, and a tibial component in a valgus knee,
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`respectively. In each figure, the mechanical axis 110 extends vertically through the bone and
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`the resection line 158 is perpendicular to the mechanical axis 110 in the coronal plane,
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`varying from the surface line formed by the joint depending on the amount of damage to the
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`joint. FIG. 1B illustrates a normal knee wherein the line corresponding to the surface of the
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`joint 160 is parallel to the resection line 158. FIG. 1C illustrates a varus knee wherein the
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`line corresponding to the surface of the joint 160 is not parallel to the resection line 158. FIG.
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`lD illustrates a valgus knee wherein the line corresponding to the surface of the joint 160 is
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`not parallel to the resection line 158.
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`[0059] Once the tibial surface has been prepared, the surgeon turns to preparing the femoral
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`condyle.
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`[0060] The plateau of the femur 170 is resected to provide flat surfaces that communicate
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`with the interior of the femoral prosthesis. The cuts made to the femur are based on the
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`overall height of the gap to be created between the tibia and the femur. Typically, a 20 mm
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`gap is desirable to provide the implanted prosthesis adequate room to achieve full range of
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`motion. The bone is resected at a 5-7° angle valgus to the mechanical axis of the femur.
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`Resected surface 172 forms a flat plane with an angular relationship to adjoining surfaces
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`174, 176. The angle 0', 0" between the surfaces 172-174, and 172-176 varies according to the
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`design of the implant.
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`[0061] As illustrated in FIG. 1F, the external geometry of the proximal femur includes the
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`head 180, the neck 182, the lesser trochanter 184, the greater trochanter 186 and the proximal
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`femoral diaphysis. The relative positions of the trochanters 184, 186, the femoral head center
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`102 and the femoral shaft 188 are correlated with the inclination of the neck-shaft angle. The
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`mechanical axis 110 and anatomic axis 120 are also shown. Assessment of these
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`relationships can change the reaming direction to achieve neutral alignment of the prosthesis
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`with the femoral canal.
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`[0062] Using anteroposterior and lateral radiographs, measurements are made of the
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`proximal and distal geometry to determine the size and optimal design of the implant.
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`[0063] Typically, after obtaining surgical access to the hip joint, the femoral neck 182 is
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`resected, e.g. along the line 190. Once the neck is resected, the medullary canal is reamed.
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`Reaming can be accomplished, for example, with a conical or straight reamer, or a flexible
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`reamer. The depth of reaming is dictated by the specific design of the implant. Once the
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`canal has been reamed, the proximal reamer is prepared by serial rasping, with the rasp
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`directed down into the canal.
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`[0064] Further, surgical assistance can be provided by using a device applied to the outer
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`surface of the articular cartilage or the bone, including the subchondral bone, in order to
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`match the alignment of the articular repair system and the recipient site or the joint. The
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`device can be round, circular, oval, ellipsoid, curved or irregular in shape. The shape can be
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`selected or adjusted to match or enclose an area of diseased cartilage or an area slightly
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`larger than the area of diseased cartilage or substantially larger than the diseased cartilage.
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`The area can encompass the entire articular surface or the weight bearing surface. Such
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`devices are typically preferred when replacement of a majority or an entire articular surface
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`is contemplated.
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`[0065] Mechanical devices can be used for surgical assistance (e. g., surgical tools), for
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`example using gels, molds, plastics or metal. One or more electronic images or intraoperative
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`measurements can be obtained providing object coordinates that define the articular and/or
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`bone surface and shape. These obj ects' coordinates can be utilized to either shape the device,
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`e.g. using a CAD/CAM technique, to be adapted to a patient's articular anatomy or,
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`alternatively, to select a typically pre-made device that has a good fit with a patient's articular
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`anatomy. The device can have a surface and shape that will match all or portions of the
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`articular or bone surface and shape, e.g. similar to a "mirror image.” The device can include
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`apertures, slots and/or holes to accommodate surgical instruments such as drills, reamers,
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`curettes, k-wires, screws and saws.
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`[0066] Typically, a position will be chosen that will result in an anatomically desirable cut
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`plane, drill hole, or general instrument orientation for subsequent placement of an articular
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`repair system or for facilitating placement of the articular repair system. Moreover, the
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`device can be designed so that the depth of the drill, reamer or other surgical instrument can
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`be controlled, e.g., the drill cannot go any deeper into the tissue than defined by the device,
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`and the size of the hole in the block can be designed to essentially match the size of the
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`implant. Information about other joints or axis and alignment information of a joint or
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`extremity can be included when selecting the position of these slots or holes. Alternatively,
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`the openings in the device can be made larger than needed to accommodate these
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`instruments. The device can also be configured to conform to the articular shape. The
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`apertures, or openings, provided can be wide enough to allow for varying the position or
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`angle of the surgical instrument, e.g., reamers, saws, drills, curettes and other surgical
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`instruments. An instrument guide, typically comprised of a relatively hard material, can then
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`be applied to the device. The device helps orient the instrument guide relative to the three-
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`dimensional anatomy of the joint.
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`[0067] The surgeon can, optionally, make fine adjustments between the alignment device
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`and the instrument guide. In this manner, an opti