Femoral acetabular impingement guide

[0001] This application is a continuation-in-part of U.S. application Ser. No. 12/888,005, filed Sep. 22, 2010, which is a continuation-in-part 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. 12/486,992, filed Jun. 18, 2009, and 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.

[0002] This application is continuation-in-part of U.S. application Ser. No. 12/872,663, filed on Aug. 31, 2010, which claims the benefit of U.S. Provisional Application No. 61/310,752 filed on Mar. 5, 2010.

[0003] This application is 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.

[0004] This application is also a continuation-in-part of U.S. application Ser. No. 12/103,834, filed on Apr. 16, 2008, which claims the benefit of U.S. Provisional Application No. 60/912,178, filed on Apr. 17, 2007.

[0005] The disclosures of the above applications are incorporated herein by reference.

[0006] The present teachings provide patient-specific guides for removing abnormality portions from a bone, such as, for example, femoral acetabular impingement portions.

[0007] The present teachings provide an orthopedic device for correcting a femoral bone abnormality. The orthopedic device includes a patient-specific three-dimensional shell and a patient-specific guiding feature. The shell has an outer surface and an inner bone engagement surface customized in a pre-operating planning stage by computer imaging to closely mate and conform to and substantially cover a femoral head of a patient in only one position. The guiding feature is pre-operatively planned relative to the shell such that when the shell is fitted over the femoral head, the guiding feature can guide a removal tool for removing an abnormality portion of the proximal femur of the patient.

[0008] In an exemplary embodiment, the orthopedic device includes a patient-specific three-dimensional shell, a customized arcuate bracket and a removal tool. The shell has an outer surface and an inner bone engagement surface customized in a pre-operating planning stage by computer imaging to closely mate and conform to a femoral head of a patient. The arcuate bracket extends from the outer surface of the shell and is pre-operatively planned relative to the shell such that when the shell is fitted over the femoral head, the arcuate bracket is adjacent to an abnormality portion of a proximal femur of the patient and can guide the removal tool for removing the abnormality portion. The removal tool includes a rotatable shaft, a cutting member coupled to the shaft and a bushing for coupling the shaft to the arcuate bracket to guide the cutting member to remove the abnormality portion.

[0009] The present teachings provide a method for correcting a femoral bone abnormality. The method includes positioning a three-dimensional shell over a femoral head of a patient, coupling a removal tool to a patient-specific guiding feature of the shell, and removing an abnormality portion from a proximal femur of the patient adjacent the guiding feature with a cutting member of the removal tool. The shell has an inner bone engagement surface customized in a pre-operating planning stage by computer imaging to closely mate and conform to the femoral head and at least a portion of a junction between the femoral head and a femoral neck of the patient in a unique position.

[0010] The present teachings further provide a patient-specific reamer for correcting a femoral bone abnormality. The reamer includes a rotatable cutting member having an outer cutting surface customized in a pre-operating planning stage by computer imaging to closely mate and conform to at least a portion of a junction between a femoral head and femoral neck of a specific patient. The reamer is customized for removing a femoral bone abnormality at the junction of the femoral head and femoral neck of the patient.

[0011] Further areas of applicability of the present invention 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 invention.

[0047] The following description is merely exemplary in nature and is in no way intended to limit the scope of the present teachings, applications, or uses.

[0048] The present teachings provide a method for preparing patient-specific instruments, including milling, reaming, cutting, alignment or other guides for use in orthopedic surgery for a joint, such as, for example, the hip joint. Conventional, not patient-specific, prosthesis components available in different sizes can be used with these patient-specific instruments, although patient-specific implant components prepared with computer-assisted image methods can also be used. Computer modeling for obtaining three-dimensional images of the patient's anatomy from MRI or CT scans of the patient's anatomy can be provided by various CAD programs and/or software available, for example, by Materialise USA, Ann Arbor, Mich. Such software can be used, according to the present teachings, to design patient-specific prosthesis components, patient-specific guides, templates and other instruments, and prepare a pre-operative plan for surgeon review.

[0049] Referring to FIG. 1, in preoperative planning, imaging data can be obtained of an entire leg including a joint to be reconstructed at a medical facility or doctor's office, at aspect 10. The imaging data can include a detailed scan of a hip, knee and ankle. The imaging data can be obtained using MRI, CT, X-Ray, ultrasound or any other imaging system. In some cases, the scan may be performed with the patient wearing an unloader brace to stress the ligaments. The scan data obtained can be sent to a manufacturer, at aspect 20. The scan data can be used by the manufacturer to construct a three-dimensional image of the joint. Generally, and depending on the procedure, an initial fitting and alignment protocol detailing the fit of any implant components and/or various alignment, milling, reaming and cutting instruments can be prepared. The fitting and alignment protocol can be stored in any computer storage medium, in a computer file form or any other computer or digital representation. The initial fitting and alignment protocol can be obtained using standard alignment methods or using alignment methods provided by or based on the preferences of individual surgeons.

[0050] As discussed above, in the preoperative planning stage of a surgical procedure, multiple image scans of portions of the patient's anatomy related to the procedure are obtained. Image markers visible in the scan can be placed on the patient's anatomy to allow image scaling and orientation. The obtained scans of the desired anatomy can be correlated to one another to reconstruct an image of the patient's specific anatomy in three-dimensions.

[0051] The outcome of the initial fitting is an initial surgical plan created at 25 that can be printed or represented in electronic form with corresponding viewing software. The initial surgical plan can be surgeon-specific, when using surgeon-specific alignment protocols. The initial surgical plan, in a computer file form associated with interactive software, can be sent to the surgeon, or other medical practitioner, for review, at 30. Using the interactive software, the surgeon can manipulate the position of images of various implant components (when used) and/or alignment/milling/reaming guides or other instruments relative to an image of the joint. The surgeon can modify the plan and send it to the manufacturer with recommendations or changes. The interactive review process can be repeated until a final, approved plan is sent to the manufacturer, at 40.

[0052] Various methods of sending the initial and final surgeon-approved surgical plans can be used. The surgical plans can be, for example, transferred to an electronic storage medium, such as CD, DVD, flash memory, which can then be mailed using regular posting methods. In various embodiments, the surgical plan can be e-mailed in electronic form or transmitted through the internet or other web-based service.

[0053] After the surgical plan is approved by the surgeon, patient-specific alignment/milling/reaming or other guides for the patient's joint can be developed using a CAD program or other three-dimensional modeling software, such as the software provided by Materialise, for example, according to the surgical plan, at 50. Patient-specific guides can then be manufactured and sterilized at 60. The guides can be manufactured by various stereolithography methods, selective laser sintering, fused deposition modeling or other rapid prototyping methods. In some embodiments, computer instructions of tool paths for machining the patient-specific guides can be generated and stored in a tool path data file. The tool path can be provided as input to a CNC mill or other automated machining system, and the alignment guides can be machined from polymer, ceramic, metal or other suitable material. The sterilized guides can be shipped to the surgeon or medical facility, at 70 for use during the surgical procedure. Patient-specific components or portions are defined as those constructed by a surgical plan approved by the doctor using three-dimensional images of the specific patient's anatomy and made to closely conform and mate substantially as a negative mold of corresponding portions of the patient's anatomy, including bone surfaces with or without associated soft tissue, such as articular cartilage, for example.

[0054] Images of the hip joint anatomy of the joint surface of the proximal femur with or without the associated soft tissues, such as articular cartilage, on the respective bone surfaces can be used in the alignment procedure. The alignment procedure can include, for example, the selection of an anteversion angle, a femoral neck angle and other orientations for positioning a femoral implant, such as a resurfacing component, without notching or impinging on the femoral neck. Multiple alignment procedures can be provided to accommodate the experience and preference of individual surgeons. For example, the alignment procedure can be based on the anatomic and mechanical axes. Further, the alignment procedure can be deformity-specific in relation, for example, to various deformities and/or malformations of the hip joint anatomy, articulation and orientation.

[0055] Referring to FIG. 2, an exemplary multiple-component femoral alignment guide 100 that can be manufactured using the method of FIG. 1 is illustrated. In this exemplary embodiment, the alignment guide 100 is shown with first and second adjacent components 102 and 104, although more than two components can be similarly included in the alignment guide 100. The first and second components 102, 104 can be movably and/or removably connected to one another with a coupling mechanism referenced at 120. The coupling mechanism 120 can be selected from a variety of mechanisms that provide easy intra-operative assembly. In various embodiments, for example, the coupling mechanism 120 can be a snap-on connection between the two components. In various embodiments, the coupling mechanism 120 can be an interlocking mechanism, such as a keyway-and-key mechanism, a dovetail mechanism, a puzzle-like interlocking mechanism, or any other interlocking mechanism. In various embodiments, the coupling mechanism 120 can include a permanent or temporary hinge or other pivotable structure that allows relative motion between the adjacent components, such that one component can be rotated relative to the other component for ease of positioning on the patient. The components can be permanently pivotably coupled with the hinge or can be detachable.

[0056] The exemplary alignment guide 100 can be configured as patient-specific for the femoral neck 86 of a proximal femur, as illustrated in FIG. 2. The alignment guide 100, when assembled, can wrap around and mate in three dimensions with the femoral neck 86 for assisting in the placement of an alignment pin for femoral head resurfacing. The first component 102 can include a guiding portion or formation 108 and a portion 112 having a first three-dimensional inner bone engagement surface 113 that can anatomically match or mate with a portion of the femoral neck 86 in three dimensions. The guiding formation 108 can be in the form of a sleeve including an inner guiding passage 109, a bore, a hole, or other opening through which an alignment pin or drill bit or other stool or fastener can be inserted. The second component 104 can be coupled to the first component 102 by the coupling mechanism 120. The second component 104 can include a second three-dimensional inner bone engagement surface 105 that can anatomically match and mate with substantially the remaining portion of the femoral neck 86 in three dimensions, without requiring other supports to retain the alignment guide 100 on the proximal femur.

[0057] FIGS. 3-5 illustrate various exemplary patient-specific, unitary or single-component alignment guides 100 for the patient's proximal femur. Same reference numbers are used to refer to similar parts or features throughout various embodiments. New or additional elements are identified with new reference numbers.

[0058] Referring to FIGS. 3 and 3A, a patient-specific alignment guide 100 according to the various embodiments can be constructed as a one-piece integral or monolithic component that has a three-dimensional inner patient-specific engagement surface 113 conforming to the corresponding anatomy of a specific patient, including subchondral bone with or without soft tissue. The alignment guide 100 can include first and second arms 130 that are patient-specific, curved and substantially concave toward the femoral neck 86 and extend anteriorly and posteriorly around the femoral neck 86 without, however, fully encircling the femoral neck 86. The alignment guide 100 can be generally saddle-shaped and can include a first portion 131 conforming to a portion of the femoral head 84. The first portion 131 can be patient-specific, curved and substantially concave toward the femoral head 84. A guiding portion 108 with an internal passage 109 can extend from the first portion 131 for guiding a pin, a drill bit or other tool. The alignment guide 100 can also include a second portion 132 extending from the first portion 131 along the femoral neck 86 and abutting the greater trochanter 76. The second portion 132 can be patient-specific, conforming to the anatomy of the femoral neck 86, such that the second portion 132 can be, for example, convex where the anatomy of the femoral neck 86 is concave. The first portion 131, the second portion 132 and the first and second arms 130 form the saddle shape of the alignment guide 100, as shown in FIG. 3. The engagement surface 113 includes the inner surfaces of the first portion 131, the second portion 132 and the first and second arms 130. The first and second arms 130 can be oriented substantially perpendicularly to the first and second portions 131, 132. The alignment guide 100 can be positioned superiorly relative to the femur, as shown in FIG. 3.

[0059] Referring to FIGS. 4 and 4A, an alignment guide 100 according to the various embodiments can include a second portion 132 that can abut the lesser trochanter 78 of the patient's femur. In the embodiment illustrated in FIG. 4, the alignment guide 100 can be positioned anteriorly or posteriorly relative to the femur and the first and second arms 130 can extend superiorly and inferiorly relative to the femur. The alignment guide 100 shown in FIG. 4 can be substantially saddle-shaped and patient-specific in three dimensions. The first portion 131 is patient-specific, curved and substantially concave inward and toward the femoral head 84. The second portion 132 is patient-specific, curved and substantially convex inward and toward the neck, and the first and second arms 130 are patient-specific, curved and substantially concave inward and toward the femoral neck 86. The engagement surface 113 includes the inner surfaces of the first portion 131, the second portion 132 and the first and second arms 130. The first and second arms 130 can be oriented substantially perpendicularly to the first and second portions 131, 132.

[0060] Referring to FIGS. 5 and 5A, an alignment guide 100 according to various embodiments can be positioned inferiorly relative to the femur and the first and second arms 130 can extend around the femoral neck 86 posteriorly and anteriorly relative to the femur. The alignment guide 100 shown in FIG. 5 is also saddle-shaped and patient-specific in three dimensions, with the first portion 131 being patient-specific, curved and substantially concave inward and toward the femoral head 84, the second portion 132 being patient-specific, curved and substantially convex inward and toward the neck, and the first and second arms 130 being curved and concave inward and toward the femoral neck 86. The engagement surface 113 includes the inner surfaces of the first portion 131, the second portion 132 and the first and second arms 130. The first and second arms 130 can be oriented substantially perpendicularly to the first and second portions 131, 132.

[0061] The alignment guides 100 shown in FIGS. 3A-5A can be made of biocompatible polymer or other material such that the first and second arms 130 that can flex to allow the alignment guide 100 to snap on and be held around the femoral neck 86 without any other temporary fixation. The alignment guide 100 can be also supported on the femur with removable fixators, such as pins.

[0062] Various additional exemplary alignment guides for femoral head resurfacing are shown in FIGS. 5B-5F. Referring to FIGS. 5B-5D, a patient-specific alignment guide 150 includes a tubular guiding portion 156 for guiding an alignment pin and an inner three-dimensional patient-specific engagement surface 154 for nesting and conforming to a complementary surface of the femoral head of a specific patient, such that the alignment guide 150 can fit only in one position on the femoral head 84 of the specific patient. The engagement surface 154 can include a plurality of patient-specific engagement pads 152 that are customized to conform and engage corresponding anatomic landmarks of the patient's proximal femur. For example, the engagement pad 152 that extends from a neck-engaging descending portion 158 of the alignment guide 150 is customized to abut and engage the lesser trochanter 78. Similarly, the other engagement pads are customized to conform to corresponding landmarks of the anatomy of the specific patient. Although three engagement pads 152 are illustrated, a lesser or greater number of pads can be used. The engagement pads 152 can provide additional stability, frictional resistance and customization for the alignment guide 150.

[0063] Referring to FIGS. 5E and 5F, an exemplary patient-specific alignment guide 160 includes a tubular guiding portion 166 for guiding an alignment pin and an inner three-dimensional patient-specific engagement surface 164 that is complementary to and nests uniquely on a corresponding surface of the femoral head 84 of the specific patient. The alignment guide 160 includes a neck-engaging descending portion 168 terminating at a patient-specific pad 162 that abuts the lesser trochanter 78 of the proximal femur. The alignment guide 160 includes an opening 167. The opening 167 can provide access to the femoral head during resurfacing, and can also reduce weight while providing additional structural stability and strength with a lightweight construction. The opening 167 can also be designed to be patient-specific for outlining a bone growth or other bone area to be removed by a tool, as described below in connection with FIGS. 10-12A.

[0064] In various embodiments, and referring to FIGS. 6, 6A and 6B, the alignment guide 100 can be in the form of a three-dimensional complete or partial shell encompassing the femoral head 84 and having a patient-specific three-dimensional inner engagement surface 113. The alignment guide 100 can include first and second components 102, 104 coupled with first and second connecting portions 140, 142 at a connection 141. In various embodiments, the first and second members 102, 104 can be flexible such that the alignment guide 100 can be mounted by opening up the connecting portions 140, 142 at one or more connections 141. In various embodiments, the first and second components 102, 104 can also include a hinge or a split connection (not shown) opposite to the connection 141. The first and second components 102, 104 can be patient-specific and curved, as shown in FIG. 6, with the inner engagement surface 113 closely conforming to the substantially convex surface of the femoral head 84 and to the substantially concave surface of the femoral neck 86. The first and second connecting portions 140, 142 can form a tongue and groove connection (142a, 140a) or a other clasp or snap-on connection (142b, 140b), as shown in the exemplary illustrations of FIGS. 6A and 6B.

[0065] It will be appreciated that other single or multiple-component guides can be similarly constructed for guiding and preparing other bone joints for receiving prosthetic components. Patient-specific guides can be, for example, constructed for the knee, the hip, the shoulder, etc., and can include two or more relatively movable and interconnected components. When more than two components are used, the same or different coupling mechanisms can be provided along the interfaces of the adjacent components. Each of the components can match a corresponding anatomic portion in three dimensions and can be configured for surgical placement on the patient and can include a guiding formation that is related to an axis associated with the anatomic portion. Such axes can be tangential or perpendicular or at other specified angle relative to the anatomic portion and relative to various anatomic axes of the joint, such as, for example, the mechanical axis, the epicondylar axis or other anatomic axis.

[0066] Referring to FIGS. 7-9, a patient-specific alignment guide 200 according to various embodiments is illustrated. The alignment guide 200 can include a frame 211 including a nut or other securing member 202, a body 213, a removable target member 212, and first and second arms 204, 206 movable between an open (non-engaging) and closed (engaging or clamping) configuration and pivotably coupled to the body 213 with pins or other pivots 207. The securing member 202 can be threadably connected to a threaded portion of a post 219 extending from the body 213. First and second tabs or extensions 208, 210 can extend from the corresponding first and second arms 204, 206 in the direction of the post 219. When the securing member 202 is fully threaded to the post 219, the securing member 202 pushes against the first and second extensions 208, 210 forcing and securing the first and second arms 204, 206 to the closed/clamping configuration around the patient's anatomy, as shown in FIG. 7. The post 219 can include a plurality of longitudinal passages 201 (shown in FIG. 8A) having different orientations relative to and converging toward a longitudinal axis A of the post 219, as shown in FIGS. 7 and 8A The passages 201 can be arranged to form a tool guide and can be used for passing guide wires, fixation pins, drills or other tools. The first and second arms 204, 206 can include patient-specific clamping portions 220, 222, as described below.

[0067] The frame 211 (excluding the patient-specific portions discussed below) can be any instrument guiding frame for femoral resurfacing procedures, such as, for example, the RECAP® KS Alignment Device, commercially available from Biomet, Inc. of Warsaw, Ind. Further details of a related frame can be found in WIPO publication WO 2008/040961, the disclosure of which is incorporated herein by reference. Other embodiments of a frame 211 according to the present teachings are discussed below.

[0068] Referring to FIGS. 7A and 7B, in various embodiments according to the present teachings, each clamping portion 220, 222 can be made to be patient-specific using the methods described above and can conform to the three-dimensional anatomy of the femoral neck 86 or a femoral head 84 of a specific patient, as shown in FIGS. 7A and 8E, for example. The clamping portions 220, 222 can be integral to the corresponding arms 206, 208 and made of the same material, such as a biocompatible metal. As illustrated in FIG. 7, the second arm 204 can include a pair of spaced-apart clamping portions 222 that are coupled to one another. It should be noted that one or both of the first and second arms 204, 206, can utilize this dual clamping configuration,

[0069] Referring to FIGS. 7B and 7C, in various embodiments according to the present teachings, the first and second arms 204, 206 can be modular, such that the corresponding patient-specific clamping portions 220, 222 can be removably coupled to the first and second arms 204, 206. The modular connection can be a groove-and-tab connection, as illustrated in FIG. 7B, which shows an exemplary groove/slot 230 and tab 231 in arm 206 and a corresponding tab/extension/hook 233 and groove/slot 232 associated with clamping portion 220. The tab 231 can be received in slot 232 while the tab 233 can be received in slot 230. It will be appreciated that the relative locations of the groove and tab can be reversed. Different types of removable connections can be used, including snap-on, dovetail, or other quick-coupling and de-coupling connections. The modular clamping portions 220, 222 can be of single-use, while the frame 211 can be sterilizable and reusable. In various embodiments, the modular clamping portions 220, 222 can be non patient-specific and provided in different sizes and/or in a kit form. Different biocompatible materials can be used for the modular clamping portions 220, 222 and the frame 211, such as metallic materials for the frame 211 and plastic materials for the modular clamping portions 220, 222, although other materials biocompatible materials can also be used.

[0070] Referring to FIG. 7D the clamping portions 220, 222 can be generic metallic portions, which can be fitted with patient-specific clamping covers 240. Each patient-specific cover 240 can include a three-dimensional patient specific surface 242. The patient-specific surface can be constructed from three-dimensional image data of the patient, as described above, and can closely match or conform, for example as negative mold, to a corresponding surface of the specific patient's femoral anatomy, such as the femoral neck 86, as shown in FIG. 7A or the femoral head 84, as shown in FIG. 8E. The patient specific cover 240 can include a groove or slot or opening 244 for fitting the cover 240 onto the corresponding clamping portion 220, 222. The covers 240 can be made of a compliant, soft and flexible material, such as a plastic, for easy fitting onto the clamping portions 220, 222 and can be single use or disposable covers that can be used with a sterilizable and reusable frame 211, such as a metallic frame. The covers 240 can also be provided in different sizes for non patient-specific uses.

[0071] Referring to FIGS. 8-8D, the patient-specific alignment guide 200 can be provided with more than two arms, such as first, second and third arms 204, 206, 205 with corresponding clamping portions 220. The first, second and third arms 204, 206, 205 can be arranged circumferentially at 120 degrees apart relative to the body 213. The clamping portions 220 can be patient specific for direct and full contact with the three-dimensional anatomy of the femoral neck 86, as shown in FIGS. 8B and 8C, or the three-dimensional anatomy of the femoral head 84, as shown in FIG. 8E, correspondingly providing curved surface contact with the femoral neck or femoral head. The clamping portions 220 can be modular, snap-on patient-specific components, such as those illustrated in FIG. 7B, or can be provided patient-specific disposable covers 240, such as those illustrated in FIG. 7D. In various embodiments, the clamping portions 220 can include pointed tips 221 for point-contact at relative distances determined for a specific patient, as shown in FIG. 8C. Instead of point tips 221, line edges can be used for patient-specific line contact in three dimensions.

[0072] In various embodiments, and referring to FIG. 9, the various clamping portions 220, 222 and patient-specific covers described above can be selectively used with a frame 211 in which the first and second arms 204, 206 can be spring-loaded at the pivot pins 207 and biased in the closed or clamping position around the femoral neck 86 or femoral head 84. The first and second arms 204, 206 can be released from the clamping position by applying pressure on corresponding first and second extensions 208, 210 in the direction of the arrows B shown in FIG. 9.

[0073] Referring to FIGS. 10-14, various patient-specific guides 300, 350, 380 are adapted for guiding a milling or other cutting instrument to remove a bony portion 90 of the proximal femur to correct a bone abnormality, such as, for example an abnormality that causes impingement, such as femoral acetabular impingement, including excessive acetabular over coverage and asymmetric femoral head/femoral neck junction. Other bone corrections can include, for example, removal of osteophytes, removal of various bone protrusions, corrections associated with CAM and Pincer impingements, including acetabular retroversion, coxa profunda, coxa vara, protrusio acetabuli, elliptical femoral head, slipped capital femoral epiphysis (SCFE), malunited femoral neck fractures and other bone abnormalities. The various patient-specific guides 300, 350, 380 for femoral acetabular correction are prepared based on pre-operative MRI, CT, or other radiographic scans, which also and image the proximal femur and identify an impingement or abnormality portion 90 (i.e., a portion that includes an abnormality or other defect). Using a commercially available software program, as discussed above, a three-dimensional image of the proximal femur and the impinging or other abnormality portion/area 90 can be reconstructed. Each of the patient-specific guides 300, 350, 380, can include a corresponding flexible or stretchable three-dimensional cap or shell 302, 352, 382 that forms a mold that can be fitted over the femoral head 84 and/or femoral neck 86 in a form-fitting manner, i.e., with an inner bone engagement surface 304, 354, 384 which is formed to closely mate and nest with the corresponding convex and/or concave portions of the surface of the femoral head 84 and/or femoral neck 86 in a unique position. The shell 302, 352, 382 can be made, for example, from a biocompatible plastic material. Each of the patient-specific guides 300, 350, 380 can include a guiding feature such as a guiding window 306, or a slot 360, or a bracket 386 or other structural element that is customized for the specific patient to accurately guide a milling/cutting/reaming removal tool to remove the impingement or abnormality portion 90 at a required depth of removal, as discussed below.

[0074] Referring to FIGS. 10 and 11, for example, an exemplary patient-specific guide 300 includes a patient-specific three-dimensional cap or shell 302 having an inner patient-specific bone engagement surface 304 that extends over and closely conforms and mates with a corresponding outer surface of the femoral head 84 and/or femoral neck 86 of the specific patient in only one nesting position. The patient-specific guide 300 can cover substantially the entire femoral head 84 or a portion thereof to provide adequate stability and secure the patient-specific guide 300 on the femoral head 84. The patient-specific guide 300 can include a guiding feature, such as an opening or guiding window 306 through which the impingement/abnormality portion 90 can be accessed and can protrude therefrom. The guiding window 306 includes a perimeter or boundary 308 that is customized during the pre-operative planning stage to circumscribe and identify a corresponding perimeter or boundary 92 of the impingement/abnormality portion 90 to be removed. A removal tool 330 can be guided by the guiding window 306 to remove the impingement/abnormality portion 90. The removal tool 330 can include a milling shaft 332 and a cutting portion 334 including cutting teeth or other cutting features extending from a distal end 336 of the milling shaft 332. The distal end 336 is designed to abut the outer surface of the shell 302 such that only the cutting portion 334 extends through the guiding window 306 to control the depth of milling. Accordingly, the distal end 336 of the removal tool 330 can provide a depth stop for removing only a required amount of the impingement/abnormality portion 90 as determined during the pre-operative planning stage. In one embodiment, the distal end 336 can be sized such that the entire area circumscribed by the guiding window 306 can be milled while the distal end 336 abuts the outer surface of the shell 302.

[0075] Referring to FIGS. 12, 12A and 13, another exemplary patient-specific guide 350 for femoral acetabular impingement/abnormality is illustrated. The patient-specific guide 350 can include a patient-specific three-dimensional cap or shell 352 having an inner patient-specific bone engagement surface 354 that extends over and closely conforms and mates with a corresponding and complementary outer surface of the femoral head 84 and/or femoral neck 86. The patient-specific guide 350 can include a patient-specific distal boundary surface 358 that can reach up to the proximal portion of the boundary 92 of the impingement/abnormality portion 90, such that the impingement/abnormality portion 90 extends outside the shell 352. The shell 352 defines a guiding feature in the form of patient-specific elongated arcuate guiding slot 360 for supporting a cutting/milling/reaming/burring removal tool 370. The guiding slot 360 can be a surface recess or a through slot and can have an arcuate shape extending in two dimensions over the surface of the shell 352 for guiding the removal tool 370, although in the exemplary embodiment of FIG. 13, the slot 360 is shown as arcuate along one arcuate dimension of the shell 352. The removal tool 370 includes a shaft 372 coupled to a cutting member 374 of the removal tool 370. The cutting member 374 can be a rotatable mill or reamer, for example. A collar or sleeve or a tubular bushing 376 can surround and slidably receive the shaft 372 to allow the shaft to be moved along a longitudinal axis T of the removal tool 370. The bushing 376 can also lock on the shaft 372 to prevent motion along the axis T by friction or a locking pin or other locking member (not shown). The bushing 376 can be coupled to a bar or other connecting member 378 that can be slidably received in the arcuate slot 360 for guiding the shaft 372 to move along the arcuate guiding slot 360, such that the cutting member 374 is guided over the impingement/abnormality portion 90 for removing the impingement/abnormality portion. The location, orientation, size and shape of the arcuate slot guiding 360 are customized during the pre-operative planning stage such the when the removal tool 370 is supported by the arcuate guiding slot 360, the cutting member 374 can engage and remove the impingement/abnormality portion 90.

[0076] Referring to FIG. 14, another exemplary patient-specific guide 380 for femoral acetabular impingement/abnormality is illustrated. The patient-specific guide 380 includes a patient-specific cap or shell 382 having an inner patient-specific bone engagement surface 384 that extends over and closely conforms and mates with a corresponding outer surface of the femoral head 84 and/or femoral neck 86. The patient-specific guide 380 includes a guiding feature in the form of a customized outer arcuate guiding bracket 386 sized and positioned to guide a removal tool 390 to remove an impingement/abnormality portion 90. The bracket is adjacent the impingement/abnormality portion 90 when the shell 382 is fitted over the femoral head 84. The removal tool 390 can include a shaft 392 coupled to a rotatable reamer/burr or other rotatable cutting member 394. The removal tool can also include a tubular sleeve or bushing 396 received around the shaft 392. The bushing 396 can include an extension 398 defining a groove 400 shaped to engage an arcuate ledge or tab 388 extending from and along the outer periphery bracket 386. The groove 400 and tab 388 can have complementary cross-sections, such as, for example, dovetail or T-shaped cross-sections. In one embodiment, the groove 400 and tab 388 lock such that the extension 398 does not slide relative to the tab 388. The rotatable cutting member 394 can be patient-specific with an outer surface designed during pre-operative planning to conform to at least a portion of the junction between the femoral head 84 and femoral neck 86 of the patient, such that it is be sized and shaped to remove the impingement/abnormality portion 90 only without moving along the arcuate tab 388. In alternative embodiments, the extension 398 of the bushing 396 can slide along the arcuate tab 388.

[0077] As discussed above, patient-specific guides for removing femoral acetabular impingement or other bone abnormality portions can be customized for a specific patient using MRI, CT or other scans of the patient's anatomy. The patient-specific guides are designed during a pre-operative planning stage using software that reconstructs a three-dimensional image of the patient's anatomy, such as, for example the acetabulum and the proximal femur and includes any femoral acetabular impingement/abnormality portions for removal by the patient-specific guides. Such impingement/abnormality removal guides can be accurately located on the patient's anatomy by including a patient-specific three-dimensional cap or shell that is shaped to fit over the proximal femoral anatomy including the femoral head and/or neck and portions thereof. The patient-specific shell can include one of various guiding features for guiding a removal tool to remove the impingement/abnormality portion when the shell is placed over the femoral head. The patient-specific guides can be made of biocompatible materials including, for example, polymers, and can be disposable. The materials can be selected such that in some embodiments the patient-specific guides can be structurally robust and yet deflectable. In other embodiments the patient-specific guides can be elastically flexible for easy placement over the femoral head. In yet other embodiments the patient-specific guides can be pliable and stretchable for mounting over the patient's anatomy. In some embodiments, pins or other temporary bone fasteners can be used to secure the patient specific guides on the femoral head.

[0078] 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, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings.