# Patent

## Title
Patient-specific high tibia osteotomy

## Abstract

A surgical method for tibia osteotomy includes attaching a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is customized during a pre-operative planning stage and making a partial bone cut in the tibia through a planar slot of the alignment guide. The planar slot is oriented at a patient-specific angle relative to an anatomic axis of the patient and the angle is customized during the pre-operative planning stage. The method includes opening the bone cut to form an opening wedge, and inserting a patient-specific implantable wedge into the opening wedge.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No. 12/714,023 filed Feb. 26, 2010, which is a continuation-in-part of U.S. application Ser. No. 12/571,969, filed Oct. 1, 2009, which is a continuation-in-part of U.S. application Ser. No. 12/389,901, filed Feb. 20, 2009, which is a continuation-in-part of U.S. application Ser. No. 12/211,407, filed Sep. 16, 2008, which is a continuation-in-part of U.S. application Ser. No. 12/039,849, filed Feb. 29, 2008, which: (1) claims the benefit of U.S. Provisional Application No. 60/953,620, filed on Aug. 2, 2007, U.S. Provisional Application No. 60/947,813, filed on Jul. 3, 2007, U.S. Provisional Application No. 60/911,297, filed on Apr. 12, 2007, and U.S. Provisional Application No. 60/892,349, filed on Mar. 1, 2007; (2) is a continuation-in-part U.S. application Ser. No. 11/756,057, filed on May 31, 2007, which claims the benefit of U.S. Provisional Application No. 60/812,694, filed on Jun. 9, 2006; (3) is a continuation-in-part of U.S. application Ser. No. 11/971,390, filed on Jan. 9, 2008, which is a continuation-in-part of U.S. application Ser. No. 11/363,548, filed on Feb. 27, 2006; and (4) is a continuation-in-part of U.S. application Ser. No. 12/025,414, filed on Feb. 4, 2008, which claims the benefit of U.S. Provisional Application No. 60/953,637, filed on Aug. 2, 2007.
This application is also a continuation-in-part of U.S. application Ser. No. 12/103,834, filed Apr. 16, 2008, which claims the benefit of U.S. Provisional Application No. 60/912,178, filed Apr. 17, 2007.
This application is also a continuation-in-part of U.S. application Ser. No. 12/483,807, filed on Jun. 12, 2009, which is a continuation-in-part of U.S. application Ser. No. 12/371,096, filed on Feb. 13, 2009, which is a continuation-in-part of U.S. application Ser. No. 12/103,824, filed on Apr. 16, 2008, which claims the benefit of U.S. Provisional Application No. 60/912,178, filed on Apr. 17, 2007.


The disclosures of the above applications are incorporated herein by reference.
INTRODUCTION
Various knee osteotomies are performed to adjust or change the orientation of the tibia to correct various abnormalities caused by birth defects, trauma, or disease. High tibial osteotomies include open-wedge and closed-wedge osteotomies. Various cutting instruments and tools are used to perform such high tibial osteotomies.
The present teachings provide patient patient-specific surgical kits and methods for open-wedge or closed-wedge tibial osteotomies.
SUMMARY
The present teachings provide a surgical kit that includes a patient-specific alignment guide having a three-dimensional engagement surface custom-made by computer imaging to conform to a corresponding portion of a patient's tibial bone. The patient-specific alignment guide defines an elongated planar slot for guiding a blade. The planar slot is oriented at a selected angle and at a selected position relative to an anatomic axis of the patient when the engagement surface engages the corresponding portion of the tibial bone. The selected angle and selected position are determined during a pre-operative planning stage.
The present teachings also provide a surgical kit that includes a patient-specific implantable wedge for an open-wedge osteotomy, a patient-specific fixation plate and a patient-specific alignment guide. The implantable wedge includes first and second planar surfaces defining a patient-specific wedge angle, and a patient-specific outer surface opposite to the straight edge. The patient-specific fixation plate has a three-dimensional patient specific engagement surface for engaging the tibia and a surface engageable with the implantable wedge. The patient-specific alignment guide includes an engagement surface custom-made by computer imaging to conform to a corresponding portion of a patient's tibial bone. The patient-specific alignment guide defines an elongated planar slot for guiding a blade. The planar slot is oriented at a selected angle and at a selected position relative to an anatomic axis of the patient when the engagement surface engages the corresponding portion of the tibial bone. The selected angle and selected position are determined during a pre-operative planning stage.
The present teachings provide a surgical method including attaching a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is customized during a pre-operative planning stage and making a partial bone cut in the tibia through a planar slot of the alignment guide. The planar slot is oriented at a patient-specific angle relative to an anatomic axis of the patient and the angle is customized during the pre-operative planning stage. The method includes opening the bone cut to form an opening wedge, and inserting a patient-specific implantable wedge into the opening wedge.
The present teachings provide a surgical method including attaching a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is customized during pre-operative planning and making a first partial planar cut in the tibia through a first planar slot of the alignment guide. The first planar slot is oriented at a first patient-specific angle relative to an anatomic axis of the patient and the first angle customized during a pre-operative planning stage. A second partial planar cut is made in the tibia through a second planar slot of the alignment guide. The second planar slot is oriented at a second patient-specific angle relative to an anatomic axis of the patient and the second angle is customized during the pre-operative planning stage. The first and second planar cuts meet at an angle to define a bone wedge having a third patient-specific angle. The method includes removing the bone wedge to form a wedge opening and closing the wedge opening.
Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.



BRIEF DESCRIPTION OF THE DRAWINGS
The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a schematic illustration of a cut for open-wedge high tibial osteotomy in relation to the present teachings;
FIG. 1A is a schematic illustration of the geometry of an exemplary cut plane in relation to anatomic sagittal and transverse planes according to the present teachings;
FIG. 2 is a schematic illustration of opening the cut of FIG. 1 to form an wedge opening;
FIG. 3A is an environmental sectional view of a patient-specific wedge for the wedge opening of FIG. 2 according to the present teachings;
FIG. 3B is an environmental sectional view of a patient-specific plate and a patient-specific wedge of open-wedge high tibial osteotomy according to the present teachings;
FIG. 4 is a schematic illustration of removing a bone wedge for closed-wedge high tibial osteotomy in relation to the present teachings;
FIG. 5 is a schematic illustration of closing the wedge opening of FIG. 4 and attaching one fixation plate;
FIG. 5A is a schematic illustration of closing the wedge opening of FIG. 4 and attaching two fixation plates;
FIG. 6 is an environmental view of a patient-specific guide for an open-wedge high tibial osteotomy in relation to the present teachings;
FIG. 7 is an environmental view of a patient-specific guide for closed-wedge high tibial osteotomy in relation to the present teachings;
FIG. 8 is an environmental view of a patient-specific guide for an open-wedge high tibial osteotomy in relation to the present teachings;
FIG. 9 is an environmental view of a patient-specific guide for closed-wedge high tibial osteotomy in relation to the present teachings;
FIG. 10 is an isometric view of a patient-specific guide according to present teachings;
FIG. 11 is an environmental view of the patient-specific guide of FIG. 10 according to present teachings;
FIG. 12 is an isometric view of an exemplary implantable wedge according to present teachings;
FIG. 13 is an environmental view of the patient-specific wedge implant of FIG. 11 according to present teachings; and
FIGS. 14A and 14B are plan views of exemplary implantable wedges according to present teachings.



DESCRIPTION OF VARIOUS ASPECTS
The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses. For example, although the present teachings are illustrated for patient-specific instruments and implants for high tibial osteotomy, the present teachings can be used for other types of osteotomy procedures.
The present teachings generally provide patient-specific surgical kits that include alignment guides and associated implant components for use in osteotomy, such as high tibial osteotomy, for example. The patient-specific alignment guides can be used either with conventional or patient-specific implant components prepared with computer-assisted image methods. Computer modeling for obtaining three dimensional images of the patient's anatomy using MRI or CT scans of the patient's anatomy, the patient specific prosthesis components, and the patient-specific guides and templates can be provided by various CAD programs and/or software available, for example, by Materialise USA, Ann Arbor, Mich.
The patient-specific alignment guides and associated patient-specific implants disclosed herein can be generally formed using computer modeling based on the patient's 3-D anatomic image generated from image scans. The patient-specific alignment guides can have a three-dimensional engagement surface that is made to conformingly contact and match a three-dimensional image of the patient's bone surface (selectively with or without soft tissue), by the computer methods discussed above. The patient-specific alignment guides can include custom-made guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other instruments, such as drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan.
In various embodiments, the patient-specific alignment guide can include one or more patient-specific cutting guides for receiving and guiding a cutting blade at corresponding patient-specific cutting plane orientations relative to a selected anatomic axis for the specific patient. The patient-specific alignment guides can also include guiding formations for guiding the implantation of patient-specific or off-the-shelf implants associated with the osteotomy procedure, such as implantable wedges and implantable fixation plates. The geometry, shape and orientation of the various features of the patient-specific alignment guide, as well as various patient-specific implants and other patient-specific tools can be determined during the pre-operative planning stage of the procedure in connection with the computer-assisted modeling of the patient's anatomy. During the pre-operative planning stage, patient-specific alignment guides, implants and other tools, can be selected and manufactured for a specific-patient with input from a surgeon or other professional associated with the surgical procedure, as described in the commonly assigned and co-pending patent applications listed in the cross reference section and incorporated herein by reference.
In the following discussion, the terms “patient-specific”, “custom-made” or “customized” are defined to apply to components, including tools, implants, portions or combinations thereof, which include certain geometric features, including surfaces, curves, or other lines, and which are made to closely conform as mirror-images or negatives of corresponding geometric features of a patient's anatomy during a pre-operative planning stage based on 3-D computer images of the corresponding anatomy reconstructed from image scans of the patient by computer imaging methods. Further, patient specific guiding features, such as, guiding apertures and guiding slots, or other holes or openings that are included in alignment guides or in implants are defined as features that are made to have positions, orientations, dimensions, shapes and/or define cutting planes specific to the particular patient's anatomy based on the computer-assisted pre-operative plan associated with the patient.
A patient-specific osteotomy kit for an open-wedge osteotomy can include, according to the present teachings, a patient-specific alignment guide 200, as shown in FIG. 6, for example, a patient-specific implantable wedge (or wedge implant) 300, as shown in FIGS. 3A-3B, for example, and a patient-specific implantable fixation plate 400, as shown in FIG. 5, for example. The implantable wedge 300 and a patient-specific implantable fixation plate 400 can be modularly connected, or alternatively formed monolithically as a single integral structure. An off-the-shelf, i.e. non patient-specific implantable wedge or an off-the-shelf, i.e. non patient-specific implantable fixation plate can also be used optionally with the patient-specific alignment guide 200. For closed-wedge osteotomies, the implantable wedge 300 is omitted. It will be appreciated that the patient-specific alignment guides for open-wedge and closed-wedge osteotomies can include different features, as discussed below.
The patient-specific osteotomy kit can also include custom-made saw blades 500a, 500b having a predetermined cutting length corresponding to a patient-specific cutting depth. The cutting depth can be determined at the pre-operative planning stage. In various embodiments, the predetermined cutting length can be an actual dimension of the cutting edge of the blade 500b (see FIG. 9). In various other embodiments, the cutting depth can be adjustable and the blade 500a can include markings 502 indicating a patient-specific cutting depth. The cutting depth can also be constrained by a depth stop engaging the patient-specific alignment guide 200 at a patient-specific depth and preventing insertion of the cutting blade beyond the pre-determined length. A separate, commercially available depth gauge can also be used to mark and restrict cutting to a pre-determined patient-specific cutting depth.
Referring to FIGS. 1 and 2, an exemplary open-wedge high tibial osteotomy is illustrated in association with a knee joint 75 between a femur 70 and a tibia 80. A planar cut 90 at a selected angle β relative to a first reference axis A of the knee joint 75 can be made using the patient-specific kit of the present teachings. The first reference axis A can be a selected anatomic axis, such as, for example a mechanical axis of the joint or leg, a mechanical axis of the femoral bone, or a mechanical axis of the tibial bone, when different from the mechanical axis of the leg. Other anatomic axes, such as axes having significantly different orientations than the orientation of axis A illustrated in FIG. 1, can be used as reference axes, including, for example, an epicondylar axis, which can be substantially transverse to the axis A of FIG. 1. The angle β of the planar cut 90 relative to the reference axis A can be determined during the pre-operative planning stage of the osteotomy and in relation to the corresponding alignment guide 200.
The planar cut 90 can also be oriented at a patient-specific angle relative to second and third reference axes B1 and B2. A representative geometry illustrating the orientation of an exemplary cut plane P in relation to a sagittal plane S and a transverse plane T of the patient's anatomy is shown in FIG. 1A. In FIG. 1A, a first angle φ1 is defined between an axis N perpendicular to the cut plane P and an axis Z parallel to the first reference axis A, which extend superiorly-inferiorly on the sagittal plane. The first angle φ1 and angle β have a sum of 90 degrees. A second angle φ2 is defined between the axis N and an axis X parallel to the second reference axis B1, which extends medially-laterally on the transverse plane T. A third angle φ3 is defined between the axis N and an axis Y parallel to the third reference axis B2, which extends anteriorly-posteriorly on the transverse plane T. Medial-lateral, anterior-posterior and superior-inferior orientations of the cut plane P can be specified by selecting patient specific values for these angles, keeping in mind that only two of the three angles can be specified independently, while the third can be calculated from the relation that the sum of the squares of the cosines of the angles is equal to 1. In the following discussion, although patient-specific orientations of planar cuts and corresponding planar slots relative to the axis A will be described in detail, it will be understood that the planar cuts and planar slots can be additionally or alternatively be oriented at patient-specific angles about the axes B1 and B2.
Referring to FIGS. 1-3, the planar cut 90 is a partial cut, i.e., not a through cut, and can extend from a first boundary 92 at the intersection of the planar cut 90 with the outer surface of the tibia 80 to a second boundary 94 at the selected patient-specific cutting depth illustrated as distance L in FIG. 1. The first boundary 92 can be generally a curved line reflecting the curvature of the outer surface of the tibia 80. The second boundary 94 can be substantially a straight line as formed by the saw blade. The second boundary 94 can function as a hinge line (also referenced with numeral 94) for opening a wedge angle γ between first and second opposing faces 96, 98 of the cut 90, as illustrated by arrows C in FIG. 2. The wedge angle γ is patient-specific and can be selected during the pre-operative planning stage. The location of the first and second boundaries 92, 94, the angle β of the planar cut 90 relative to the reference axis A and the wedge angle γ can be determined during the pre-operative planning stage for correcting a condition of the particular patient, including conditions resulting from idiopathic bone misalignment, joint or bone disease, trauma, cancer or other therapeutic or corrective surgery. Similarly, the planar cut 90 can be oriented at a corresponding patient-specific angle φ2 relative to the medial-lateral axis B1, as illustrated in FIG. 1A.
Referring to FIGS. 1-3A, a patient-specific implantable wedge 300 having a corresponding wedge angle γ defined between first and second planar surfaces 302, 304 can be inserted and/or pushed between the first and second faces 96, 98 of the cut 90, while the cut 90 is partially open, i.e., while the first and second faces 96, 98 form an angle smaller than the angle γ, for guiding and facilitating the correct wedge opening to form the pre-selected angle γ. It will be appreciated, however, the cut 90 can be opened to an angle γ, using any other tool, such as trial wedge having the same angle γ.
With continued reference to FIGS. 1-3A, the first and second planar surfaces 302, 304 of the implantable wedge 300 can meet at a straight edge or truncated plane surface 306. Upon insertion of the implantable wedge 300, the cut 90 is opened and secured to the selected angle γ by the implantable wedge 300. The first and second planar surfaces 302, 304 of the implantable wedge 300 can abut against the first and second surfaces 96, 98 of the planar cut 90, and the edge 306 of the implantable wedge 300 can abut the second boundary 94 of the planar cut 90. The implantable wedge 300 can have a patient-specific boundary surface 308 opposite to the edge/surface 306. The boundary surface 308 is designed during the pre-operative planning stage as a continuous and smooth surface that provides a continuous contour relative to the contour of the tibia 80 on either side of the cut 90. The implantable wedge 300 can also be secured directly in the bone with sutures, pins, anchors or other fasteners.
Alternatively, and referring to FIGS. 3A and 3B, a patient-specific implantable fixation plate 400 can be used in combination with the patient-specific implantable wedge 300. The patient-specific implantable wedge 300 and the patient-specific fixation plate 400 can be modularly connected, as illustrated in FIG. 3B, or can be provided as a single monolithic and integrally formed component. A modular connection can include a dovetail connection illustrated at reference numerals 402 and 310 corresponding to opposing connection formations of the fixation plate 400 and implantable wedge 300. Other connection formations can include a taper lock connection, various groove and tongue connections, or connections with threadable fasteners or other biocompatible fasteners. The modular connection can be formed at a common boundary 404 between the fixation plate 400 and the implantable wedge 300.
The fixation plate 400 can include patient-specific surfaces 406a, 406b on either side the implantable wedge 300 and can be anchored to the tibia 80 using bone pins or other bone fasteners 450 that pass through corresponding apertures 408 of the fixation plate 400. The location and orientation of the apertures can also be patient-specific and determined during the pre-operative planning stage for the particular patient.
In various embodiments, and referring to FIG. 6, a patient-specific alignment guide 200 for an open-wedge osteotomy is illustrated. The alignment guide 200 can include a three-dimensional patient-specific engagement surface 202 made to conform to a corresponding outer surface of the tibia 80 by a computer-assisted method utilizing a 3-D image of the patient's tibia 80 during the pre-operative planning stage, as discussed above. The alignment guide 200 can include one or more guiding receptacles, the precise location of which is determined on the basis of a pre-operative surgical plan for locating alignment pins or other fasteners or for assisting in locating cutting blades or other cutting instruments for resecting the bone and/or shaping the bone for receiving an implant, as described in commonly-owned, co-pending in U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007, incorporated herein by reference. The alignment guide can be placed on and conform with the anterior/lateral surface of the tibia, for example.
Referring to FIG. 6, the alignment guide 200 can include a guiding receptacle in the form of a planar slot 206 oriented to define a patient-specific angle β relative to the anatomic axis A for guiding a blade 500a to form the planar cut 90. The blade 500a can include depth-control indicia 502 corresponding to the hinge line 94. The alignment guide 200 can also define one or more fixation apertures 204 for receiving bone fixation fasteners 250. Additional guiding receptacles, such as guiding apertures 208, can be provided for preparing fastener holes in the tibia 80 to receive the bone fixation fasteners 250 through the apertures 408 of the fixation plate 400. The location and orientation of the planar slot 206, the apertures 204 for the fasteners 250 and the guiding apertures 208 relative to alignment guide 200 can be determined during the pre-operative planning stage on a patient-specific (patient customized) basis. Similarly, the planar slot 206 can be oriented at a corresponding patient-specific angle φ2 relative to the medial-lateral axis B1, as illustrated in FIG. 1A.
Referring to FIG. 8, another alignment guide 200 for open-wedge osteotomy is illustrated. The alignment guide 200 can be placed on the anterior and/or lateral side of the proximal tibia 80, such that the three-dimensional patient-specific engagement surface 202 of the alignment guide 200 closely conforms to the corresponding portion of the tibia 80. The plane defined by the planar slot 206 is shown in phantom at a corresponding angle β=90−φ1 relative to the reference/anatomic axis A, as discussed above in connection with FIG. 6. A blade 500b can be used for the plane cut through the planar slot 206 having size that provides automatic control of the length of the cut.
Referring to FIGS. 4 and 5, an exemplary closed-wedge high tibial osteotomy is illustrated in association with a knee joint 75 between a femur 70 and a tibia 80. First and second partial planar cuts 90a, 90b at corresponding selected first and second angles β1 and β2 relative to a reference/anatomic axis A of the knee joint 75 can be made using a patient-specific kit of the present teachings. The first and second planar cuts 90a, 90b can intersect at a hinge line 94. The first and second angles β1 and β2 of the planar cuts 90a, 90b relative to the reference axis A can be determined during the pre-operative planning stage of the osteotomy and in relation to the corresponding alignment guide 200. Each of the first and second angles β1 and β2 is complementary of a corresponding angle φ1 shown in FIG. 1A (90−β1 and 90−β2). Similarly, the first and second cuts 90a, 90b can be oriented at corresponding and different angles φ2 relative to the medial-lateral axis B1, as illustrated in FIG. 1A. The first and second angles β1 and β2 of the planar cuts 90a, 90b define a bone wedge 91 of predetermined wedge angle γ=β1−β2. The bone wedge 91 can be removed and the corresponding wedge opening can be closed by bringing the surfaces of the first and second cuts 90a, 90b in contact by rotating about the hinge line 94. A first (or osteotomy-side) patient-specific fixation plate 400′ can be attached to the tibia 80 to secure the first and second cuts 90a, 90b in contact after the bone wedge 91 is removed. The first and second cuts 90a, 90b can also be secured by pins, sutures or other fasteners to the bone. In the fixation plate 400′ the same reference numerals are used to indicate features having the same functions as in the fixation plate 400. The fixation plate 400′ can include a patient-specific engagement surface 406 and apertures 408 at patient-specific positions and orientations for guiding bone fixation fasteners 250 through the apertures 408 and into the tibia 80.
Referring to FIGS. 5 and 5A, a second (or hinge-side) fixation plate 400′a can be used opposite the first or osteotomy-side fixation plate 400′ on the side of the osteotomy hinge. The second fixation plate 400′a can be a patient-specific fixation plate or an off-the shelf commercially available fixation plate. The second plate 400′a can be attached to the tibia with separate fasteners. Alternatively, the same fixation fasteners 250 can extend between both the first and second plates 400′ and 400′a. In such case, the guiding apertures 208 of the alignment guide 200′ can be used to drill guiding holes through the entire width of the tibia 80 for guiding the location of the first and second plates 400′ and 400′a and the common fixation fasteners 250 through the tibia and through the first and second plates 400′ and 400′a. 
Referring to FIG. 7, a patient-specific alignment guide 200′ for a closed-wedge osteotomy is illustrated. In alignment guide 200′ the same reference numerals are used to indicate features having the same functions as in alignment guide 200. The alignment guide 200′ can include a three-dimensional patient-specific engagement surface 202 made to conform to a corresponding outer surface of the tibia 80 by a computer-assisted method utilizing a 3-D image of the patient's tibia 80 during the pre-operative planning stage, as discussed above. The alignment guide 200′ can define first and second guiding receptacles in the form of first and second planar slots 206a, 206b oriented at selected first and second angles β1 and β2 relative to a reference/anatomic axis A for guiding a blade to form the planar cuts 90a, 90b of the removable bone wedge 91. The alignment guide 200′ can also define one or more apertures 204 receiving bone fixation fasteners 250. Additional guiding receptacles, such as guiding apertures 208 can be provided for drilling or otherwise preparing fastener holes in the tibia 80 corresponding to the apertures 408 of the fixation plate 400 for securing the fixation plate 400 to the tibia 80. The location and orientation of the first and second planar slots 206a, 206b, the apertures 204 and the guiding apertures 208 relative to alignment guide 200′ can be determined during the pre-operative planning stage on a patient-specific base. The alignment guide 200′ can be used with a blade 500a having depth indicia 502.
Referring to FIG. 9, another alignment guide 200′ for closed-wedge osteotomy is illustrated. The alignment guide 200′ can be placed on the anterior and/or lateral side of the proximal tibia 80, such that the patient-specific engagement surface 202 of the alignment guide 200′ closely conforms to the corresponding portion of the tibia 80. The planes defined by the first and second planar slots 206a, 206b are shown in phantom at corresponding first and second angles β1 and β2 (not shown) relative to the reference/anatomic axis A, as discussed above in connection with FIG. 7 and FIG. 1A. Additionally and optionally, each of the first and second angles β1 and β2 is complementary of a corresponding angle φ1 shown in FIG. 1A (90−β1 and 90−β2). Similarly, the planes defined by the first and second planar slots 206a, 206b can be oriented at corresponding and different angles φ2 relative to the medial-lateral axis B1, as illustrated in FIG. 1A.
Referring to FIGS. 10-13, another embodiment of a patient-specific alignment guide is illustrated at 600. As in the embodiments discussed above, the patient-specific alignment guide includes a three-dimensional patient-specific engagement surface 602, fixation apertures 604 for bone fixation fasteners 650 and guiding apertures 608 for drilling holes in the bone. In this embodiment, the alignment guide 600 includes a central cylindrical through-hole 611 passing through the center of a planar slot 606. The central hole 611, which has a diameter greater than the opening of the slot 606, can facilitate cutting with a blade along the slot 606 through either side of the central hole 611. Referring to FIG. 11, the central hole 611 of the alignment guide 600 can be used to drill a hole 93 in the bone 80 before the planar osteotomy cut 90 is performed at a selected patient-specific angle β, as shown in FIG. 11. The patient-specific guide 600 can include radiolucent markers 620, which are visible in radiographic images and can provide directional guidance during the surgical procedure. Similar markers in the form of lines or points/spots can also be provided on the patient-specific alignment guides 200, 200′ discussed above.
Referring to FIGS. 12 and 13, a patient-specific implantable wedge 700 can be inserted through the osteotomy cut to keep the osteotomy open. Similarly to the embodiments described above, the implantable wedge 700 can include a three-dimensional patient-specific surface 708 (best shown in FIG. 13), an elongated curved central portion 712 conforming to shape of the drilled hole 93 on the opposite surfaces of the planar cut 90. The elongated central portion 712 can be cylindrical or tapered (truncated cone or conical segment). A pair of planar portions 702, 704 extend radially from opposite sides of the central portion 712 from the patient specific surface 708 to an end surface 706 and define a wedge of angle γ. The central portion 712 can be aligned with the hole 93 and provide a guide for centering and inserting the implantable wedge 700 into the osteotomy cut 90. The central portion 712 can have greater thickness than and protrude away from and outside the planar portions 702, 704.
The various patient-specific implantable wedges 300, 700 for the open-wedge osteotomy can be made of various biocompatible materials including, for example, various metals or alloys, porous metal and porous metal alloys and bone-growth inducing materials, including Pro Osteon®, commercially available from Biomet, Inc., Warsaw, Ind., with or without a resorbable filler material. The implantable wedges 300, 700 can also be in the form of multiple-component wedges with or without interlocking connecting features. An exemplary illustration of a multiple-piece implantable wedge 800 is shown in FIGS. 14A and 14B. The implantable wedge 800 can extend from a first surface 808 to a second surface 807. The first surface 808 can be optionally patient-specific. The implantable wedge 800 can include a plurality of separate components 802. Two adjacent components 802 can be in contact at a common boundary 804. The adjacent components 802 can also be optionally interlocked with a connecting feature 806. The connecting feature 806 can be a single structural connector or a plurality of structural connectors, including tongue and groove, interdigitation, dovetail, threaded fasteners, etc.
The various fixation plates 400, 400′, 400′a can be made of similar materials. For open-wedge osteotomies, the fixation plate 400 can be integral to the implantable wedge 300, modularly coupled to the implantable wedge 300 via a connecting joint or fasteners, or directly coupled to the bone outside the implantable wedge 300. The various alignment guides 200, 200′, 600 can be made of any biocompatible material, including, polymer, ceramic, metal or combinations thereof.
As discussed above, a surgical kit for an open-wedge or a closed-wedge high tibial osteotomy can be provided on a patient-specific basis. The surgical kit can include a patient-specific alignment guide and, optionally, a patient-specific or an off-the-self fixation plate. For an open-wedge osteotomy, the surgical kit can include a patient-specific or an off-the-shelf implantable wedge. The patient-specific tools and implants are customized and prepared for the specific patient during a computer-assisted pre-operative planning stage in which the patient's anatomy is modeled in three dimensions from two-dimensional image scans. Patient-specific or customized blades can be included to provide adjustable depth control or automatic length. Other, non-customized blades can also be included.
The foregoing discussion discloses and describes merely exemplary arrangements of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein, so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings as defined in the following claims.

## Claims

1. A surgical method comprising:
attaching a three-dimensional engagement surface of a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is custom-made by computer imaging during a pre-operative planning stage, the three-dimensional engagement surface conforming as a negative surface to the corresponding surface of the patient's tibia;
making a partial bone cut in the tibia through a planar slot of the alignment guide, the planar slot oriented at a patient-specific angle relative to an anatomic axis of the patient, the angle custom-selected during the pre-operative planning stage for correcting the patient's anatomy;
opening the bone cut to form a wedge-shaped opening in the tibia; and
inserting a patient-specific implantable wedge into the wedge-shaped opening, the implantable wedge including first and second planar surfaces defining a wedge angle therebetween, the wedge angle custom-selected during pre-operative planning for correcting the patient's anatomy.

2. The surgical method of claim 1, further comprising removably attaching a patient-specific fixation plate to the implantable wedge, the patient-specific fixation plate having a custom made surface mating as a negative surface with a corresponding surface of the patient's tibia.

3. The surgical method of claim 2, further comprising drilling bone apertures for bone fasteners through patient-specific apertures of the alignment guide.

4. The surgical method of claim 2, wherein the planar slot defines a depth or length dimension of the cut.

5. The surgical method of claim 2, further comprising drilling a hole in the tibia through a central aperture intersecting the planar slot of the patient-specific alignment guide before making a bone cut through the planar slot.

6. The surgical method of claim 2, further comprising removably coupling the patient-specific fixation plate to the implantable wedge with a dovetail connection.

7. The surgical method of claim 2, wherein the implantable wedge includes a plurality of separate components.

8. The surgical method of claim 1, wherein inserting a patient-specific implantable wedge into the opening wedge includes attaching a patient-specific fixation plate monolithically formed with the implantable wedge, the patient-specific fixation plate having a custom made surface mating as a negative surface with a corresponding surface of the patient's tibia.

9. The surgical method of claim 1, further comprising drilling a guiding hole in the tibia through a central guiding aperture passing through the planar slot.

10. The surgical method of claim 9, wherein the implantable wedge includes an elongated curved central portion and pairs of planar surfaces extending radially from the central portion and defining the wedge angle therebetween, and wherein the central portion is configured to conform to a shape of the guiding hole drilled through the central guiding aperture of the patient-specific alignment guide.

11. A surgical method comprising:
attaching a three-dimensional engagement surface of a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is custom made by computer imaging during a pre-operative planning stage, the three-dimensional engagement surface conforming as a negative surface to the corresponding surface of a patient's tibial bone;
making a first partial planar cut in the tibia through a first planar slot of the alignment guide, the first planar slot oriented at a first patient-specific angle relative to an anatomic axis of the patient, the first patient-specific angle custom-selected for the patient during a pre-operative planning stage;
making a second partial planar cut in the tibia through a second planar slot of the alignment guide, the second planar slot oriented at a second patient-specific angle relative to an anatomic axis of the patient, the second patient-specific angle custom-selected during a pre-operative planning stage, the first and second planar cuts meeting at an angle to define a bone wedge having a third patient-specific angle;
removing the bone wedge to form a wedge-shaped opening; and
closing the wedge-shaped opening by bringing together corresponding first and second cut surfaces of the first and second planar cuts.

12. The surgical method of claim 11, further comprising attaching a three-dimensional patient-specific engagement surface of a patient-specific fixation plate over the tibia to secure the tibia after closing the wedge-shaped opening, the three-dimensional engagement surface conforming as a negative surface to the corresponding surface of the patient's tibia.

13. A surgical method comprising:
attaching a three-dimensional engagement surface of a patient-specific alignment guide to a corresponding surface of a tibia of a patient for whom the alignment guide is custom-made by computer imaging during a pre-operative planning stage, the three-dimensional engagement surface conforming as a negative surface to the corresponding surface of a patient's tibial bone;
drilling a hole in the tibia through a central aperture intersecting the planar slot of the patient-specific alignment guide;
making a partial bone cut in the tibia through the planar slot of the alignment guide, the planar slot oriented at a patient-specific angle relative to an anatomic axis of the patient, the angle custom-selected during the pre-operative planning stage for correcting the patient's anatomy;
opening the bone cut to form a wedge-shaped opening in the tibia; and
inserting a patient-specific implantable wedge into the wedge-shaped opening, the implantable wedge including first and second planar surfaces defining a wedge angle therebetween, the wedge angle custom-selected during pre-operative planning for correcting the patient's anatomy.

14. The surgical method of claim 13, wherein the implantable wedge includes an elongated curved central portion and pairs of planar surfaces extending radially from the central portion and defining the wedge angle therebetween, and wherein the central portion is configured to conform to a shape of the guiding hole drilled through the central guiding aperture of the patient-specific alignment guide.

15. The surgical method of claim 13, further comprising removably attaching a patient-specific fixation plate to the implantable wedge, the patient-specific fixation plate having a custom made surface mating as a negative surface with a corresponding surface of the patient's tibia.

16. The surgical method of claim 13, wherein inserting a patient-specific implantable wedge into the opening wedge includes attaching a patient-specific fixation plate monolithically formed with the implantable wedge, the patient-specific fixation plate having a custom made surface mating as a negative surface with a corresponding surface of the patient's tibia.

17. The surgical method of claim 13, further comprising removably coupling the patient-specific fixation plate to the implantable wedge with a dovetail connection.

18. The surgical method of claim 13, wherein the implantable wedge includes a plurality of separate components.

19. The surgical method of claim 13, further comprising drilling bone apertures for bone fasteners through patient-specific apertures of the alignment guide.

20. The surgical method of claim 13, wherein the planar slot defines a depth or length dimension of the cut.