Patient specific high tibia osteotomy

A surgical kit 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.

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 teaching 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 teaching 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 teaching 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.

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 associate 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 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 guide200, as shown inFIG. 6, for example, a patient-specific implantable wedge (or wedge implant)300, as shown inFIGS. 3A-3B, for example, and a patient-specific implantable fixation plate400, as shown inFIG. 5, for example. The implantable wedge300and a patient-specific implantable fixation plate400can 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 guide200. For closed-wedge osteotomies, the implantable wedge300is 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 blades500a,500bhaving 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 blade500b(seeFIG. 9). In various other embodiments, the cutting depth can be adjustable and the blade500acan include markings502indicating a patient-specific cutting depth. The cutting depth can also be constrained by a depth stop engaging the patient-specific alignment guide200at 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 toFIGS. 1 and 2, an exemplary open-wedge high tibial osteotomy is illustrated in association with a knee joint75between a femur70and a tibia80. A planar cut90at a selected angle β relative to a first reference axis A of the knee joint75can 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 inFIG. 1, can be used as reference axes, including, for example, an epicondylar axis, which can be substantially transverse to the axis A ofFIG. 1. The angle β of the planar cut90relative to the reference axis A can be determined during the pre-operative planning stage of the osteotomy and in relation to the corresponding alignment guide200.

The planar cut90can also be oriented at a patient-specific angle relative to second and third reference axes B1and 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 inFIG. 1A. InFIG. 1A, a first angle φ1is 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 φ1and angle β have a sum of 90 degrees. A second angle φ2is 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 φ3is 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 B1and B2.

Referring toFIGS. 1-3, the planar cut90is a partial cut, i.e., not a through cut, and can extend from a first boundary92at the intersection of the planar cut90with the outer surface of the tibia80to a second boundary94at the selected patient-specific cutting depth illustrated as distance L inFIG. 1. The first boundary92can be generally a curved line reflecting the curvature of the outer surface of the tibia80. The second boundary94can be substantially a straight line as formed by the saw blade. The second boundary94can function as a hinge line (also referenced with numeral94) for opening a wedge angle γ between first and second opposing faces96,98of the cut90, as illustrated by arrows C inFIG. 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 boundaries92,94, the angle β of the planar cut90relative 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 cut90can be oriented at a corresponding patient-specific angle φ2relative to the medial-lateral axis B1, as illustrated inFIG. 1A.

Referring toFIGS. 1-3A, a patient-specific implantable wedge300having a corresponding wedge angle γ defined between first and second planar surfaces302,304can be inserted and/or pushed between the first and second faces96,98of the cut90, while the cut90is partially open, i.e., while the first and second faces96,98form 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 cut90can be opened to an angle γ, using any other tool, such as trial wedge having the same angle γ.

With continued reference toFIGS. 1-3A, the first and second first and second planar surfaces302,304of the implantable wedge300can meet at a straight edge or truncated plane surface306. Upon insertion of the implantable wedge300, the cut90is opened and secured to the selected angle γ by the implantable wedge300. The first and second planar surfaces302,304of the implantable wedge300can abut against the first and second surfaces96,98of the planar cut90, and the edge306of the implantable wedge300can abut the second boundary94of the planar cut90. The implantable wedge300can have a patient-specific boundary surface308opposite to the edge/surface306. The boundary surface308is designed during the pre-operative planning stage as a continuous and smooth surface that provides a continuous contour relative to the contour of the tibia80on either side of the cut90. The implantable wedge300can also be secured directly in the bone with sutures, pins, anchors or other fasteners.

Alternatively, and referring toFIGS. 3A and 3B, a patient-specific implantable fixation plate400can be used in combination with the patient-specific implantable wedge300. The patient-specific implantable wedge300and the patient-specific fixation plate400can be modularly connected, as illustrated inFIG. 3B, or can be provided as a single monolithic and integrally formed component. A modular connection can include a dovetail connection illustrated at reference numerals402and310corresponding to opposing connection formations of the fixation plate400and implantable wedge300. 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 boundary404between the fixation plate400and the implantable wedge300.

The fixation plate400can include patient-specific surfaces406a,406bon either side the implantable wedge300and can be anchored to the tibia80using bone pins or other bone fasteners450that pass through corresponding apertures408of the fixation plate400. 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 toFIG. 6, a patient-specific alignment guide200for an open-wedge osteotomy is illustrated. The alignment guide200can include a three-dimensional patient-specific engagement surface202made to conform to a corresponding outer surface of the tibia80by a computer-assisted method utilizing a 3-D image of the patient's tibia80during the pre-operative planning stage, as discussed above. The alignment guide200can 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 toFIG. 6, the alignment guide200can include a guiding receptacle in the form of a planar slot206oriented to define a patient-specific angle β relative to the anatomic axis A for guiding a blade500ato form the planar cut90. The blade500acan include depth-control indicia502corresponding to the hinge line94. The alignment guide200can also define one or more fixation apertures204for receiving bone fixation fasteners250. Additional guiding receptacles, such as guiding apertures208, can be provided for preparing fastener holes in the tibia80to receive the bone fixation fasteners250through the apertures408of the fixation plate400. The location and orientation of the planar slot206, the apertures204for the fasteners250and the guiding apertures208relative to alignment guide200can be determined during the pre-operative planning stage on a patient-specific (patient customized) basis. Similarly, the planar slot206can be oriented at a corresponding patient-specific angle φ2relative to the medial-lateral axis B1, as illustrated inFIG. 1A.

Referring toFIG. 8, another alignment guide200for open-wedge osteotomy is illustrated. The alignment guide200can be placed on the anterior and/or lateral side of the proximal tibia80, such that the three-dimensional patient-specific engagement surface202of the alignment guide200closely conforms to the corresponding portion of the tibia80. The plane defined by the planar slot206is shown in phantom at a corresponding angle β=90-φ1relative to the reference/anatomic axis A, as discussed above in connection withFIG. 6. A blade500bcan be used for the plane cut through the planar slot206having size that provides automatic control of the length of the cut.

Referring toFIGS. 4 and 5, an exemplary closed-wedge high tibial osteotomy is illustrated in association with a knee joint75between a femur70and a tibia80. First and second partial planar cuts90a,90bat corresponding selected first and second angles β1and β2relative to a reference/anatomic axis A of the knee joint75can be made using a patient-specific kit of the present teachings. The first and second planar cuts90a,90bcan intersect at a hinge line94. The first and second angles β1and β2of the planar cuts90a,90brelative to the reference axis A can be determined during the pre-operative planning stage of the osteotomy and in relation to the corresponding alignment guide200. Each of the first and second angles β1and β2is complementary of a corresponding angle φ1shown inFIG. 1A(90-β1and90-β2). Similarly, the first and second cuts90a,90bcan be oriented at corresponding and different angles φ2relative to the medial-lateral axis B1, as illustrated inFIG. 1A. The first and second angles β1and β2of the planar cuts90a,90bdefine a bone wedge91of predetermined wedge angle γ=β1-β2. The bone wedge91can be removed and the corresponding wedge opening can be closed by bringing the surfaces of the first and second cuts90a,90bin contact by rotating about the hinge line94. A first (or osteotomy-side) patient-specific fixation plate400′ can be attached to the tibia80to secure the first and second cuts90a,90bin contact after the bone wedge91is removed. The first and second cuts90a,90bcan also be secured by pins, sutures or other fasteners to the bone. In the fixation plate400′ the same reference numerals are used to indicate features having the same functions as in the fixation plate400. The fixation plate400′ can include a patient-specific engagement surface406and apertures408at patient-specific positions and orientations for guiding bone fixation fasteners250through the apertures408and into the tibia80.

Referring toFIGS. 5 and 5A, a second (or hinge-side) fixation plate400′acan be used opposite the first or osteotomy-side fixation plate400′ on the side of the osteotomy hinge. The second fixation plate400′acan be a patient-specific fixation plate or an off-the shelf commercially available fixation plate. The second plate400′acan be attached to the tibia with separate fasteners. Alternatively, the same fixation fasteners250can extend between both the first and second plates400′ and400′a. In such case, the guiding apertures208of the alignment guide200′ can be used to drill guiding holes through the entire width of the tibia80for guiding the location of the first and second plates400′ and400′aand the common fixation fasteners250through the tibia and through the first and second plates400′ and400′.

Referring toFIG. 7, a patient-specific alignment guide200′ for a closed-wedge osteotomy is illustrated. In alignment guide200′ the same reference numerals are used to indicate features having the same functions as in alignment guide200. The alignment guide200′ can include a three-dimensional patient-specific engagement surface202made to conform to a corresponding outer surface of the tibia80by a computer-assisted method utilizing a 3-D image of the patient's tibia80during the pre-operative planning stage, as discussed above. The alignment guide200′ can define first and second guiding receptacles in the form of first and second planar slots206a,206boriented at selected first and second angles β1and β2relative to a reference/anatomic axis A for guiding a blade to form the planar cuts90a,90bof the removable bone wedge91. The alignment guide200′ can also define one or more apertures204receiving bone fixation fasteners250. Additional guiding receptacles, such as guiding apertures208can be provided for drilling or otherwise preparing fastener holes in the tibia80corresponding to the apertures408of the fixation plate400for securing the fixation plate400to the tibia80. The location and orientation of the first and second planar slots206a,206b, the apertures204and the guiding apertures208relative to alignment guide200′ can be determined during the pre-operative planning stage on a patient-specific base. The alignment guide200′ can be used with a blade500ahaving depth indicia502.

Referring toFIG. 9, another alignment guide200′ for closed-wedge osteotomy is illustrated. The alignment guide200′ can be placed on the anterior and/or lateral side of the proximal tibia80, such that the patient-specific engagement surface202of the alignment guide200′ closely conforms to the corresponding portion of the tibia80. The planes defined by the first and second planar slots206a,206bare shown in phantom at corresponding first and second angles β1and β2(not shown) relative to the reference/anatomic axis A, as discussed above in connection withFIG. 7andFIG. 1A. Additionally and optionally, each of the first and second angles β1and β2is complementary of a corresponding angle φ1shown inFIG. 1A(90-β1and90-β2). Similarly, the planes defined by the first and second planar slots206a,206bcan be oriented at corresponding and different angles φ2relative to the medial-lateral axis B1, as illustrated inFIG. 1A.

Referring toFIGS. 10-13, another embodiment of a patient-specific alignment guide is illustrated at600. As in the embodiments discussed above, the patient-specific alignment guide includes a three-dimensional patient-specific engagement surface602, fixation apertures604for bone fixation fasteners650and guiding apertures608for drilling holes in the bone. In this embodiment, the alignment guide600includes a central cylindrical through-hole611passing through the center of a planar slot606. The central hole611, which has a diameter greater than the opening of the slot606, can facilitate cutting with a blade along the slot606through either side of the central hole611. Referring toFIG. 11, the central hole611of the alignment guide600can be used to drill a hole93in the bone80before the planar osteotomy cut90is performed at a selected patient-specific angle β, as shown inFIG. 11. The patient-specific guide600can include radiolucent markers620, 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 guides200,200′ discussed above.

Referring toFIGS. 12 and 13, a patient-specific implantable wedge700can be inserted through the osteotomy cut to keep the osteotomy open. Similarly to the embodiments described above, the implantable wedge700can include a three-dimensional patient-specific surface708(best shown inFIG. 13), an elongated curved central portion712conforming to shape of the drilled hole93on the opposite surfaces of the planar cut90. The elongated central portion712can be cylindrical or tapered (truncated cone or conical segment). A pair of planar portions702,704extend radially from opposite sides of the central portion712from the patient specific surface708to an end surface706and define a wedge of angle γ. The central portion712can be aligned with the hole93and provide a guide for centering and inserting the implantable wedge700into the osteotomy cut90. The central portion712can have greater thickness than and protrude away from and outside the planar portions702,704.

The various patient-specific implantable wedges300,700for 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 wedges300,700can also be in the form of multiple-component wedges with or without interlocking connecting features. An exemplary illustration of a multiple-piece implantable wedge800is shown inFIGS. 14A and 14B. The implantable wedge800can extend from a first surface808to a second surface807. The first surface808can be optionally patient-specific. The implantable wedge800can include a plurality of separate components802. Two adjacent components802can be in contact at a common boundary804. The adjacent components802can also be optionally interlocked with a connecting feature806. The connecting feature806can be a single structural connector or a plurality of structural connectors, including tongue and groove, interdigitation, dovetail, threaded fasteners, etc.

The various fixation plates400,400′,400′acan be made of similar materials. For open-wedge osteotomies, the fixation plate400can be integral to the implantable wedge300, modularly coupled to the implantable wedge300via a connecting joint or fasteners, or directly coupled to the bone outside the implantable wedge300. The various alignment guides200,200′,600can 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.