Patient-Specific Osteotomy Devices And Methods

[0001] This application is a divisional of U.S. application Ser. No. 13/106,295 filed on May 12, 2011, which is a continuation-in-part of U.S. application Ser. No. 12/714,023 filed on Feb. 26, 2010, now U.S. Pat. No. 8,241,293 issued on Aug. 14, 2012. The disclosures of the above applications are incorporated herein by reference.

[0002] 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.

[0003] The present teachings provide patient-specific osteotomy implants and surgical instruments and associated methods for tibial osteotomies.

[0004] The present teachings provide an osteotomy method and associated implants and instruments. The osteotomy method includes attaching a patient-specific osteotomy guide to a corresponding surface of a tibia of a patient and making an osteotomy at a patient-specific orientation through a resection slot of the osteotomy guide. The osteotomy guide is removed and first and second faces of the osteotomy are opened to form an implant insertion angle. The first and second faces of the osteotomy are secured at the implant insertion angle. An osteotomy implant having a patient-specific wedge angle that is smaller than the implant insertion angle is implanted. The first and second faces of the osteotomy are brought to the patient-specific wedge angle and in contact with the osteotomy implant.

[0005] The present teachings also provide an osteotomy surgical kit that includes a patient-specific osteotomy guide and a patient specific osteotomy implant. The osteotomy surgical kit can include a patient-specific spreader, a graduated osteotome and an osteotomy securing device for securing opposite faces of the osteotomy at a predetermined angle for implanting the osteotomy implant. The patient-specific osteotomy guide can include a patient-specific resection slot for guiding the resection and a drill support device for drilling a stress-relief hole at the edge of the osteotomy.

[0006] 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.

[0039] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0040] 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.

[0041] The present teachings generally provide patient-specific osteotomy 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, Plymouth, Mich.

[0042] 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.

[0043] 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 designed 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.

[0044] 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 and/or define cutting planes specific to the particular patient's anatomy based on the computer-assisted pre-operative plan associated with the patient.

[0045] 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.

[0046] 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 (see FIG. 6). 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.

[0047] 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 8 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.

[0048] 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.

[0049] 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 or osteotomy angle γ between first and second opposing faces 96, 98 of the cut 90, as illustrated by arrows C in FIG. 2. The osteotomy 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.

[0050] 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. In some embodiments, the cut 90 is opened at an angle greater than γ, as discussed below in connection with FIGS. 20-23.

[0051] 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 faces 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. In some embodiments, the implantable wedge can be cemented or coated with materials promoting bone in-growth.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 a size that provides automatic control of the length of the cut.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 radiopaque 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.

[0062] 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 extends radially from opposite sides of the central portion 712 from the patient specific surface 708 to an end surface 706 and defines 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.

[0063] The various patient-specific implantable wedges 300, 700 for the open-wedge osteotomy can be made of various biocompatible materials including, for example, various solid metals or alloys, solid PEEK, porous metal and porous metal alloys, porous thermoplastics, such as PEEK (polyether ether ketone), PEKK (polyether ketone ketone), osteoinductive or osteoconductive materials, including Pro Osteon®, commercially available from Biomet, Inc., Warsaw, Ind., with or without a resorbable filler material, and/or combinations thereof. 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.

[0064] 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.

[0065] As discussed above in connection with FIGS. 1-14B, 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.

[0066] Additional embodiments of patient-specific implants and instruments for performing open osteotomy are illustrated in FIGS. 15A-24. The instruments include a patient-specific resection/drill alignment guide (or osteotomy guide, for short) 900, a drill guide 920 (FIGS. 15A and 15B), patient-specific osteotomy implants 1000 and 1000A (FIGS. 16A-16C), a patient-specific osteotomy spreader 1100 (FIG. 17), a graduated osteotome 1100A (FIG. 21), an impactor assembly 1200 (FIG. 18), an osteotomy securing device 1300 (FIG. 20) and a fixation plate 1500 (FIG. 24). These instruments and implants can also be used to supplement and/or replace corresponding instruments and implants discussed above in connection with FIGS. 1-14B and can also be included in the surgical kit described above for a particular patient and surgeon as optional additional or interchangeable components.

[0067] Generally, medical scans of the patient's anatomy, including the proximal femur and tibia, are imported into a computer program, such as the software commercially available from Materialise USA, as discussed above. A virtual three-dimensional model of the patient's anatomy is reconstructed using the software. A surgeon's planned osteotomy, including osteotomy angle correction and extent can be virtually modeled and patient-specific guides and other instruments can be designed based on the virtual model. More specifically, the osteotomy guide 900 shown in FIGS. 15A and 15B, the osteotomy implants 1000 and 1000A shown in FIGS. 16A-16C and the osteotomy spreader 1100 shown in FIG. 17 can all be patient-specific and designed from the medical scans of the patient. The fixation plate 1500 can also be patient-specific, although a non-custom fixation plate can also be used. Before describing in further detail the various instruments and implants referenced above in connection with FIGS. 15A to 24, an exemplary procedure using these instruments and implants is described below.

[0068] Referring to FIG. 15A, the osteotomy guide 900 is mounted or nested in a unique (only one) position on a surface 82 of the tibia 80 according to the preoperative plan for the patient for performing an osteotomy to correct the patient's joint misalignment or other defect. Referring to FIG. 19A, a patient-specific osteotomy spreader 1100 is driven into the osteotomy 90 that has been previously cut using the osteotomy guide 900. The osteotomy 90 can be optionally opened further to allow for the insertion of the osteotomy implant 1000 or 1000A using the graduated osteotome 1100A of FIG. 21. The osteotomy securing device 1300 can be affixed across the osteotomy 90 to keep the osteotomy 90 open. The osteotomy spreader 1100 and the graduated osteotome 1100A, if used, can then be removed, as shown in FIGS. 22 and 23. The patient-specific osteotomy implant 1000 (or 1000A) can be implanted into the opened osteotomy 90 and a fixation plate 1500 can be affixed over the osteotomy 90 and the osteotomy implant 1000 (1000A), as shown in FIG. 24. These implants, instruments and procedures are described in further detail below.

[0069] Referring to FIGS. 15A and 15B, the osteotomy guide 900 includes an alignment portion 902, a resection (and drill) portion 908 for guiding a resection and drilling a hole through the alignment portion 902, a drill support 914 and a drill guide 920. The alignment portion 902, the resection portion 908 and the drill support 914 can be made as a one-piece integral (monolithic) unit. The drill guide 920 can be removably coupled to the drill support 914, as discussed below. The alignment portion 902 includes a patient-specific three-dimensional inner surface 904 that is designed and configured during the preoperative plan to be complementary and nestingly mate with a corresponding outer surface 82 (including patient-specific natural bone landmarks thereon, such as osteophytes, for example) of the patient's tibia 80 only in one position. The alignment portion 902 can also include two or more guiding formations 906 having through bores 907 for attaching the osteotomy guide 900 to the tibia 80 using K-wires, pins or other bone fasteners. Two guiding formations 906 are illustrated in FIG. 15A.

[0070] With continued reference to FIG. 15A, the resection portion 908 can include a resection slot 910 for guiding a cutting tool to perform the osteotomy 90 according to the preoperative plan for the patient. The resection slot 910 passes through the alignment portion 902 and is sized and oriented relative to the alignment portion 902 (and therefore relative to the tibia 80) according to preoperative patient-specific, surgeon-approved, selected anatomic considerations, and other considerations. In some embodiments, the resection portion 908 can include a unicortical or a longer bicortical 912 intersecting the resection slot 910 and configured for guiding the insertion of the osteotomy implants 1000, 1000A, as discussed below and drilled before initiating the resection procedure through the resection slot 910. A unicortical hole 912 is a blind hole that stops short of penetrating the cortical bone on the opposite side of the resection, while a bicortical hole 912 is a through hole, i.e., a hole long enough to penetrate the opposite side of the cortical bone. The drill hole 912 is illustrated in FIG. 15A. A corresponding pre-resection guiding bone hole, such as the bone hole 93 described above in the embodiments related to FIG. 11, is drilled through the drill hole 912 into the tibia 80 for guiding the implant.

[0071] With continued reference to FIG. 15A, the drill support 914 can include a curved rig or frame or other three-dimensional structure 913 extending from the alignment portion 902 having a guiding tube 916 with a through bore 918. The drill support 914 is sized and shaped such that the through bore 918 can orient the drill guide 920 to drill a stress-relief hole 95 at the sharp edge (end) of the osteotomy 90, as shown in FIG. 19A. The drill guide 920 can include a tubular shaft 923 that is removably inserted through the guide tube 916 and has a longitudinal opening 924 for stabilizing and guiding a drill bit to drill the stress-relief hole 95 along the edge of the osteotomy 90. The stress-relief hole 95 reduces crack initiation by rounding the sharp edge of the osteotomy 90 and reducing stress concentration. The drill guide 900 can also include a handle 922 for holding and stabilizing the drill guide 920 during use.

[0072] In some embodiments, before performing the osteotomy 90 through the resection slot 910 and before drilling the guiding hole 93 through the drill hole 912 of the osteotomy guide 900, a posterior blade guard 1600, shown in FIG. 25, can be used to protect nerve bundles and or other soft tissue in the posterior surface of the knee. The posterior blade guard 1600 has a thin, three-dimensionally ribbon-like body that includes a flat (substantially planar) distal portion 1602, a curved U-shape portion 1604, and a flat proximal portion 1606 from which a connector shaft 1610 extends. Intraoperatively, the distal portion 1602 is inserted against the posterior surface of the tibia 80 and functions as a blade stop to protect posterior nerve bundles, ligaments and other tissue from being inadvertently damaged during the osteotomy. The middle portion 1604 functions as a retractor of soft tissue about the incision for the procedure. The shaft 1610 can have an end portion 1614 configured for coupling with an osteotomy handle, such as, for example, the tip 1210 of the impactor assembly 1200. After resection using the osteotomy guide 900, an auxiliary osteotome 1650, shown in FIG. 26, can be used to finish the osteotomy 90, if not fully completed. The auxiliary osteotome 1650 includes a handle or shaft 1652 carrying a distal blade 1654 with a sharp distal edge 1656 and a proximal impactor surface 1658. The posterior blade guard 1600 and the auxiliary osteotome 1650 can also be included in the osteotomy kit.

[0073] Referring to FIGS. 16A-16C, exemplary embodiments of an osteotomy implant 1000 and 1000A are illustrated. The osteotomy implant 1000 is configured for a procedure using a unicortical drill hole 912 and includes a corresponding curved hump or protrusion or curved ridge 1014, as shown in FIGS. 16B and 16C. The curved ridge 1014 is configured to be received into the osteotomy hole 93 drilled through the drill hole 912 of the osteotomy guide of FIG. 15A. The osteotomy implant 1000A is configured for a procedure using a deeper, bicortical hole 912 and includes two corresponding protrusions or curved ridges 1014a, 1014b, as shown in FIG. 16A. The curved ridge 1014 or ridges 1014a, 1014b can help align and direct the osteotomy implant 1000 (100A) into the bone along an insertion axis coinciding with the longitudinal axis of the curved ridge 1014 (or common longitudinal axes of curved ridges 1014a, 1014b). In the osteotomy implant 1000A, the insertion orientation is along an anterior-posterior orientation. Other orientations for inserting the osteotomy implant 1000 can also be selected by changing the location and orientation of the curved ridge 1014, such as, for example, along a medial to lateral direction or from an anterior-medial position toward a posterior-media position, as illustrated by the different orientations of the curved ridge 1014 in FIGS. 16B and 16C. In other respects, the osteotomy implants 1000, 1000A are similar and same reference numbers are used to describe similar or common to features. The osteotomy implant 1000 or 1000A is wedge-shaped and also U-shaped or horseshoe-shaped. Specifically, the osteotomy implant 1000 (1000A) includes first and second surfaces 1002, 1004 forming a wedge with wedge angle equal to a patient-specific osteotomy angle γ designed to be received in the osteotomy 90 to correct the patient's joint misalignment, as determined during the preoperative plan.

[0074] The osteotomy implant 1000 (1000A) can have a horseshoe shape or a U shape or other open-channel shape that is formed by a peripheral surface between the first and second surfaces 1002, 1004 of the osteotomy implant 1000 (1000A). The peripheral surface includes an outer wall surface 1008, an inner wall surface 1006 and first and second end surfaces 1010, 1012. The inner wall surface 1006 defines an opening for allowing access to a stem or other component of a tibial implant, if a tibial implant is to be implanted at some later time. The outer wall surface 1008 is configured during the preoperative plan to match and be continuous with the outer surface of the tibia of the patient adjacent to the osteotomy 90. The first and second end surfaces 1010, 1012 are generally rounded or not sharp and are designed to end before the stress-relief hole 95.

[0075] As discussed above in connection with osteotomy implants 400, 700, the osteotomy implants 1000, 100 can be made of various biocompatible materials including, for example, various solid metals or alloys, solid PEEK, porous metal and porous metal alloys, porous thermoplastics, such as PEEK (polyether ether ketone), PEKK (polyether ketone ketone), osteoinductive or osteoconductive materials, including Pro Osteon®, commercially available from Biomet, Inc., Warsaw, Ind., with or without a resorbable filler material, and/or combinations thereof. In some embodiments, two or more different materials can be used in each implant 1000 (1000A). For example, the central curved portion of the implant 1000 (100A) can be made of a porous material (porous metal, porous PEEK or PEKK), while portions around and including the protrusions 1014, or 1014a, 1014b, as well and portions adjacent and including first and second end surfaces 10110, 1012 can be made of a solid material (solid metal, solid PEEK or PEKK).

[0076] Referring to FIGS. 17, 18, 19A, 19B and 21, after the osteotomy 90 is cut into the tibia 80 using the osteotomy guide 900 of FIG. 15A, the patient-specific osteotomy spreader 1100 can be used to open up the osteotomy 90 in preparation for receiving an osteotomy implant 1000 (1000A). The osteotomy spreader 1100 is wedge-shaped. The wedge is defined by first and second opposing surfaces 1102, 1104 intersecting at a sharp edge 1108 and forming an angle equal to the patient-specific angle γ of the osteotomy implant 1000 (1000A). The osteotomy spreader 1100 includes a peripheral surface 1106 which can also be designed during the preoperative plan to be patient-specific. The osteotomy spreader 1100 can also be used as a trial for the osteotomy implant 1000 (1000A). The osteotomy spreader 1100 can include a short tubular shaft 1110 with internal threads 1112 for connecting to an externally threaded tip 1210 of the impactor assembly 1200, shown in FIG. 18. In some embodiments, the external and internal threads in the osteotomy spreader 1100 and the threaded tip 1210 may be reversed. In other embodiments, the osteotomy spreader 1100 and the impactor assembly can be coupled by other connecting means, such as bayonet coupling, taper to taper connection, or other quick connect/disconnect couplings.

[0077] The impactor assembly 1200 includes an impactor plate 1204 having an impactor surface 1206, a handle 1202 coupled to the impactor plate 1204, and a shaft 1208 extending from the handle 1202 and terminating at the externally threaded tip 1210. The impactor assembly 1200 can be coupled to the osteotomy spreader 1100, which is then pushed against the osteotomy 90. Striking the impactor surface 1206 with a mallet opens the osteotomy 90, as shown in FIG. 19A. When the osteotomy spreader 1100 is fully driven into the osteotomy 90, the opposite faces 96, 98 of the osteotomy 90 form the predefined osteotomy angle γ. To allow for ease in the implantation of the osteotomy implant 1000 (1000A), the osteotomy 90 is further opened by an additional small amount, as shown in FIG. 19B. The impactor assembly 1200 is removed from the osteotomy spreader 1100 and is attached to the osteotome 1100A. The osteotome 1100A includes a tubular shaft 1110A with internal threads 1112A for threadably engaging the threaded tip 1210 of the shaft 1208 of the impactor assembly 1200. In some embodiments, the external and internal threads in the osteotome 1100A and the threaded tip 1210 may be reversed. Alternative, other types of connections can be used, such as bayonet coupling, taper to taper connection, or other quick connect/disconnect couplings.

[0078] The osteotome 1100A includes first and second surfaces 1102A, 1104A forming a wedge having a peripheral wall surface 1106A and a sharp edge 1108A. The osteotome 1100A includes a plurality of engraved or otherwise marked lines or gradation markings 1120 on the first surface 1102A corresponding to additional amount of osteotomy opening. The proximal end portion 1105A of the first surface 1102A can be parallel (not inclined relative) to the second surface 1104A, so that the proximal end portion 1105A can also serve as a stop for the osteotome 1100A.

[0079] Referring to FIGS. 19A and 20-23, the osteotome 1100A, coupled to the impactor assembly 1200, is stacked over the osteotomy spreader 1100 and driven into the osteotomy 90 up to a predetermined gradation marking 1120 to open up the osteotomy by an insertion angle γ′ slightly larger than the osteotomy angle γ. The opposite faces 96, 98 of the osteotomy 90 are secured at the insertion angle γ′ using the osteotomy securing device 1300, as shown in FIG. 22. The osteotomy securing device 1300 can be an adjustable offset tie rod structure that includes first and second members 1310, 1350. The first member 1310 includes first and second portions 1302, 1313 forming an L-shape. A block 1304 extends from the second portion 1313 and has a bone engagement surface 1314, shown in FIG. 20. One or more holes 1316 extend from an outer surface 1312 of the second portion 1313 to the bone engagement surface 1314 of the block 1304 of the first member 1310 for attaching the first member 1310 to the tibia 80 on a side of the osteotomy 90 adjacent to face 98 with pins or other bone fasteners 1370, as shown in FIG. 23. The first portion 1302 of the first member 1310 has an elongated cylindrical bore 1320 for adjustably coupling the first member 1310 to the second member 1350. The osteotomy securing device 1300 can also include an elongated handle 1360 for stabilizing the osteotomy securing device 1300 during attachment to the tibia 80. In some embodiments, the handle 1360 can be a shaft extending from the first member 1310 of the osteotomy securing device 1300.

[0080] With continued reference to FIGS. 19A and 20-23, the second member 1350 includes first and second portions 1352, 1353 forming an L-shape. A block 1355 extends from the second portion 1353 and has a bone engagement surface 1354. One or more holes 1356 extend through the second portion 1353 and the block 1355 of the second member 1350 for attaching the second member 1350 to the tibia 80 on a side of the osteotomy 90 adjacent to face 96 with pins or other bone fasteners 1370, as shown in FIG. 23. The first portion 1352 of the second member 1310 can be an elongated cylindrical shaft (1352) with a flat or planar cutout surface 1351. The cylindrical shaft 1352 is slidably received into the cylindrical bore 1320 of the first member 1310 and is adjustably coupled to the first member 1310 along an axis D, such that the osteotomy securing device 1300 can span the opened osteotomy 90, as shown in FIG. 22. The osteotomy securing device 1300 can include a wing nut, set screw or other locking member 1330 for locking and securing the relative position of the first and second member 1310, 1350 relative to one another to maintain the osteotomy opening at the insertion angle γ′, as shown in FIG. 22. The locking member 1330 can include a portion that threadably passes through the first portion 1302 and through the cylindrical bore 1320 of the first member 1310, presses against the planar surface 1351 of the cylindrical shaft 1352 and prevents sliding of the cylindrical shaft 1352 relative to the cylindrical bore 1320 when the locking member 1330 is threadably tightened, as shown in FIG. 20.

[0081] Referring to FIGS. 22-24, after the implant insertion angle γ′ is stabilized with the osteotomy securing device 1300, as discussed above, the osteotome 1100A and the osteotomy spreader 1000 can be removed, and the osteotomy implant 1000 (1000A) inserted into the osteotomy opening formed by the insertion angle γ′. After full insertion and implantation, the osteotomy securing device 1300 is removed and the first and second faces 96, 98 of the osteotomy 90 are brought into contact with the osteotomy implant 1000 (1000A) at the predetermined osteotomy angle γ (which is smaller than the implant insertion angle γ′, as discussed above).

[0082] The osteotomy implant 1000 (1000A) and the osteotomy correction can be further secured using the fixation plate/implant 1500. As discussed above, the fixation plate 1500 can be either patient-specific, i.e., configured during the preoperative plan to have a patient-specific inner surface that mates with a corresponding surface of the patient's tibia after implantation of the osteotomy implant 1000 (1000A), or a non-custom fixation plate. In the illustration of FIG. 24, the fixation plate 1500 includes first and second portions 1502, 1504 configured in a T-shape and having corresponding fixation holes 1508, 1506 for bone screws. Another embodiment of a patient-specific fixation plate 400 is discussed above in connection with FIG. 3B and can be used instead of the fixation plate 1500.

[0083] As discussed above, various patient-specific alignment guides, resection guides, osteotomy guides, osteotomy implants, fixation plates and other osteotomy instruments can be used for correcting a joint misalignment. The various implants and instruments are not limited to the specific configurations and embodiments described above. It is contemplated that the various instruments and implants discussed above can be used interchangeably, such that a surgical kit for a specific patient and specific surgeon can include more that one set of implants and instruments to provide intraoperative choice between different or alternative surgical procedures for the same patient.

[0084] 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.