# Patent

## Title
Patient-specific hip joint devices

## Abstract

An implant for a femoral head of a patient. The implant includes a shell implantable on the femoral head of the patient and correcting a defect of the femoral head. The shell is designed preoperatively to have a patient-specific first surface for articulation with the patient's acetabulum and a patient-specific periphery mateable with a periphery of the defect. The shell caps the defect and the first surface of the shell is continuous to a remaining healthy surface of the femoral head. The defect can be a bone defect, a cartilage defect or a combination thereof.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No. 12/978,069 filed on Dec. 23, 2010, which is a continuation-in-part of U.S. application Ser. No. 12/973,214 filed on Dec. 20, 2010, which a continuation-in-part of U.S. application Ser. No. 12/955,361 filed on Nov. 29, 2010, which is a continuation-in-part of: (1.) U.S. application Ser. No. 12/938,905 filed on Nov. 3, 2010, and (2.) U.S. application Ser. No. 12/938,913 filed on Nov. 3, 2010, which is a continuation-in-part of U.S. application Ser. No. 12/893,306 filed on Sep. 29, 2010, which is a continuation-in-part of U.S. application Ser. No. 12/888,005 filed on Sep. 22, 2010, now U.S. Pat. No. 8,377,066 issued on Feb. 19, 2013, 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, which is a continuation-in-part of U.S. application Ser. No. 12/571,969 filed on Oct. 1, 2009, which is a continuation-in-part of: (1.) U.S. application Ser. No. 12/486,992 filed on Jun. 18, 2009, and (2.) U.S. application Ser. No. 12/389,901 filed on Feb. 20, 2009, now U.S. Pat. No. 8,133,234 issued on Mar. 13, 2012, which is a continuation-in-part of U.S. application Ser. No. 12/211,407 filed on Sep. 16, 2008, which is a continuation-in-part of U.S. application Ser. No. 12/039,849 filed on Feb. 29, 2008, now U.S. Pat. No. 8,282,646 issued on Oct. 9, 2012, which: (1.) claims the benefit of: (a.) U.S. Provisional Application No. 60/953,620 filed on Aug. 2, 2007, (b.) U.S. Provisional Application No. 60/947,813 filed on Jul. 3, 2007, (c.) U.S. Provisional Application No. 60/911,297 filed on Apr. 12, 2007, and (d.) 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, now U.S. Pat. No. 8,092,465 issued on Jan. 10, 2012, 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, now U.S. Pat. No. 8,070,752 issued on Dec. 6, 2011, which is a continuation-in-part of U.S. application Ser. No. 11/363,548 filed on Feb. 27, 2006, now U.S. Pat. No. 7,780,672 issued on Aug. 24, 2010; and (4) is a continuation-in-part of U.S. application Ser. No. 12/025,414 filed on Feb. 4, 2008, now U.S. Pat. No. 8,298,237 issued on Oct. 30, 2012, which claims the benefit of U.S. Provisional Application No. 60/953,637 filed on Aug. 2, 2007.
This application is a continuation-in-part of U.S. application Ser. No. 13/766,419 filed on Feb. 13, 2013, which is a divisional of U.S. application Ser. No. 12/872,663 filed on Aug. 31, 2010, now U.S. Pat. No. 8,407,067 issued on Mar. 26, 2013, which claims the benefit of U.S. Provisional Application No. 61/310,752 filed on Mar. 5, 2010.
This application is a divisional of U.S. application Ser. No. 12/978,069 filed on Dec. 23, 2010, which is also a continuation-in-part of U.S. application Ser. No. 12/483,807 filed on Jun. 12, 2009, now U.S. Pat. No. 8,473,305 issued on Jun. 25, 2013, 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, now abandoned, which claims the benefit of U.S. Provisional Application No. 60/912,178 filed on Apr. 17, 2007.
This application is a divisional of U.S. application Ser. No. 12/978,069 filed on Dec. 23, 2010, which is also a continuation-in-part of U.S. application Ser. No. 12/103,834 filed on Apr. 16, 2008, now U.S. Pat. No. 7,967,868 issued on Jun. 28, 2011, which claims the benefit of U.S. Provisional Application No. 60/912,178 filed on Apr. 17, 2007.
The disclosures of the above applications are incorporated herein by reference.


INTRODUCTION
The present teachings provide various patient-specific guides and related implants for the hip joint.
SUMMARY
The present teachings provide a hip-joint device that includes a patient-specific acetabular resection guide. The acetabular resection guide includes a dome-shaped surface bounded by a periphery. The dome-shaped surface is a three-dimensional patient-specific surface designed to anatomically match and be received into an acetabulum of the patient, based on a three-dimensional image of a hip joint of the patient reconstructed from a medical scan of the hip joint. The resection guide includes a plurality of guiding formations defined on the resection guide and having patient-specific shapes and orientations for guiding corresponding osteotomies relative to the acetabulum for correcting hip dysplasia.
In some embodiments, the acetabular resection guide include an annular flange extending from the periphery of the dome-shaped surface. The annular flange has a patient-specific surface engageable to a periacetabular area of the acetabulum of the patient. A plurality of elongated slots are defined by the flange and oriented around the periphery in a patient-specific orientation for guiding a cutting instrument to re-orient the acetabulum relative to the pelvis.
The present teachings also provide an implant for a femoral head of a patient. The implant includes a shell implantable on the femoral head of the patient and correcting a defect of the femoral head. The shell is designed preoperatively to have a patient-specific first surface for articulation with the patient's acetabulum and a patient-specific periphery mateable with a periphery of the defect. The shell caps the defect and the first surface of the shell is continuous to a remaining healthy surface of the femoral head. The defect can be a bone defect, a cartilage defect or a combination thereof.
The present teachings provide a method for repairing a hip-joint. The method includes engaging an acetabulum of a pelvis of a patient with a patient-specific resection guide and positioning a patient-specific dome-shaped surface of the resection guide into a complementary surface of the acetabulum. The method also includes guiding a cutting instrument through a first elongated slot of a flange surrounding the dome-shaped surface, performing a first osteotomy through the first elongated slot, and correcting an orientation of the acetabulum.
In another embodiment, the method includes determining a first patient-specific osteotomy for re-orienting a patient's acetabulum to correct hip dysplasia. The method also includes designing a patient-specific resection guide having a patient-specific dome-shaped surface complementary to the patient's acetabulum and a flange surrounding the dome shaped surface, and designing a first patient-specific slot for guiding the first-patient-specific osteotomy.
Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.



BRIEF DESCRIPTION OF THE DRAWINGS
The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is an exemplary illustration of a patient in preparation of an acetabular implant procedure;
FIG. 1A is a perspective view of an acetabular guide according to the present teachings, the acetabular guide shown in relation to a patient's anatomy;
FIG. 2 is an environmental perspective view of the acetabular guide of FIG. 1A shown with an acetabular inserter holding an acetabular implant according to the present teachings;
FIG. 3 is a perspective view of the acetabular inserter and acetabular implant of FIG. 2;
FIG. 3A is a perspective environmental view of an acetabular implant illustrating rotation about an anatomic axis A during insertion according to the present teachings;
FIG. 3B is a perspective environmental view of an acetabular implant illustrating rotation about an anatomic axis B during insertion according to the present teachings;
FIG. 4 is an exploded view of the acetabular inserter and acetabular implant of FIG. 3;
FIG. 5 is an environmental view of a patient-specific acetabular resection guide according to the present teachings;
FIG. 6 is a perspective view of a patient-specific acetabular resection guide according to the present teachings;
FIG. 6A is an anterior view of a hip joint illustrating an example of hip dysplasia;
FIG. 6B is an anterior view of a hip joint illustrating an example of a corrected hip dysplasia according to the present teachings;
FIG. 6C is an anterior view of a hip joint illustrating an example of planned osteotomies according to the present teachings;
FIG. 7 is a perspective view of an exemplary acetabular implant;
FIG. 8 is perspective view of a pelvis showing a defective region;
FIG. 8A is a perspective view of a patient-specific augment for use in relation to FIG. 8 according to the present teachings;
FIG. 8B is a perspective view of another patient-specific augment for use in relation to FIG. 8 according to the present teachings;
FIG. 9 is a perspective view of an exemplary acetabular implant with a patient-specific augment according to the present teachings;
FIG. 10 is perspective view of a femoral head showing a bony defect;
FIG. 11 an environmental view of an exemplary patient-specific implant for use in relation to FIG. 10 according to the present teachings;
FIG. 12 is perspective view of a femoral head showing a cartilage defect; and
FIG. 13 an environmental view of an exemplary patient-specific implant for use in relation to FIG. 12 according to 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.
The present teachings generally provide a patient-specific acetabular guide and associated inserter for use in orthopedic surgery, such as in joint replacement or revision surgery, 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, CT or Other medical scans of the patient's anatomy, the patient-specific prosthesis components, and the patient-specific guides and templates can be designed using various CAD programs and/or software available, for example, by Materialise USA, Ann Arbor, Mich.
Patient-specific alignment guides and implants are generally configured to match the anatomy of a specific patient. The patient-specific alignment guides are generally formed using computer modeling based on the patient's 3-D anatomic image and have an engagement surface that is made to conformingly contact and match a three-dimensional image of the patient's bone surface (with or without cartilage or other 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. The patient-specific alignment guides can be used in minimally invasive surgery, and in particular in surgery with multiple minimally-invasive incisions. Various alignment guides and preoperative planning procedures are disclosed in commonly assigned and co-pending U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007; U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008; U.S. patent application Ser. No. 11/971,390, filed on Jan. 9, 2008, U.S. patent application Ser. No. 11/363,548, filed on Feb. 27, 2006; and U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008. The disclosures of the above applications are incorporated herein by reference.
As disclosed, for example, in above-referenced U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007; in the preoperative planning stage for a joint replacement or revision procedure, an MRI scan or a series of CT scans of the relevant anatomy of the patient, such as, for example, the entire leg of the joint to be reconstructed, can be performed at a medical facility or doctor's office. The medical scan data obtained can be sent to a manufacturer. The medical scan data can be used to construct a three-dimensional image of the joint and provide an initial implant fitting and alignment in a computer file form or other computer representation. The initial implant fitting and alignment can be obtained using an alignment method, such as alignment protocols used by individual surgeons.
The outcome of the initial fitting is an initial surgical plan that can be printed or provided 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. The surgeon can incrementally manipulate the position of images of implant components in an interactive image of the joint. Additionally, the surgeon can select or modify resection planes, types of implants and orientations of implant insertion. For example, the surgeon may select patient-specific anteversion and abduction angles for acetabular implants, as discussed below. After the surgeon modifies and/or approves the surgical plan, the surgeon can send the final, approved plan to the manufacturer.
After the surgical plan is approved by the surgeon, patient-specific alignment guides can be developed using a CAD program or other imaging software, such as the software provided by Materialise, for example, according to the surgical plan. 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 alignment 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, and sterilized. The sterilized alignment guides can be shipped to the surgeon or medical facility, for use during the surgical procedure.
The present teachings provide a patient-specific acetabular guide and associated inserter for inserting an acetabular implant in the acetabulum of a patient's pelvis in a guided orientation at least about first and second non-parallel anatomic axes. Referring to FIGS. 1, 3A and 3B, the first anatomic axis indicated at “A”, passes through the acetabulum 82 of a patient's pelvis 80 (only half of the pelvis is shown) and is oriented generally in a superior/inferior direction relative to the patient. The second anatomic axis is indicated at “B” and is substantially perpendicular to the first axis A. As described below, the present teachings provide instruments and methods for guiding, orienting and positioning an acetabular implant 200 at a selected angle of anteversion relative to the axis A, as shown in FIG. 3A, and at a selected angle of abduction relative to the axis B, as also shown in FIG. 3B. The anteversion and abduction angles can be determined interactive or other surgeon input and can be patient-specific.
Referring to FIG. 1A, an exemplary acetabular guide 100 according to the present teachings can include a first surface 108 for engaging an area surrounding the acetabulum 82 and a second surface 110 opposite to the first surface 108. The acetabulum-engaging first surface 108 can be custom-made or patient-specific to conform and mirror an acetabular rim surface 84 around the acetabulum 82 of a specific patient by using three-dimensional image of the acetabulum and surrounding pelvic area of the patient, as described above. The first surface 108 enables the acetabular guide to nest or closely mate relative to the acetabulum 82 of the patient.
The acetabular guide 100 can be temporarily and removably attached to the pelvis 80 using temporary fasteners 120, such as bone nails or tacks, for example, passing through corresponding holes 104 through the acetabular guide 100. The acetabular guide 100 can be annular with an opening defined by an inner surface 102. The inner surface 102 can be, for example, a cylindrical surface. The inner surface 102 can be oriented relative to the first and second surfaces 108, 110 of the acetabular guide 100 to provide a selected anteversion angle about the first axis A and a selected abduction angle relative to the axis B, as shown in FIGS. 2, 3A and 3B. The anteversion and abduction angles can be surgeon-selected and patient-specific and can be determined with surgeon input during the preoperative planning for the specific patient. Anteversion angles can be, for example, in the range of about 10-20 degrees forward relative to the first axis A, and adduction angles can be in the range of about 40-50 degrees downward relative to the second axis B.
Referring to FIGS. 2-4, the acetabular guide 100 can be attached to the pelvis 80 around the acetabulum 72 after the acetabulum 82 has been reamed and prepared for receiving the acetabular implant 200, such as the MagnumTM acetabular cup commercially available from Biomet, Inc., Warsaw, Ind. The acetabular implant 200 can be inserted into the prepared acetabulum 82 using an inserter 300 according to the present teachings. The inserter 300, which can also function as an impactor, can include a handle 304 with a proximal impaction surface 318, a shaft 302 and a guide-engaging portion 310 having a surface with a flat or planar portion 320. The guide-engaging portion 310 can have an outer surface 312, which conforms to and is mateable with the inner surface 102 of the acetabular guide 100 for guiding the acetabular implant 200. The inner surface 102 and the outer surface 312 can be cylindrical.
Referring to FIG. 4, the inserter 300 can engage the acetabular implant 200 via an intermediate member 250, such as the intermediate member of the MagnumTM system, which is commercially available from Biomet, Inc., Warsaw, Ind. More specifically, the inserter 300 can include a distal portion 314, such as a ball-bearing bushing, which can be inserted and engage a receptacle 252 of the intermediate member 250. The acetabular implant 200 can be mounted on the intermediate member 250 by aligning a plurality of fingers 254 of the intermediate member 250 with corresponding cut-outs 202 on a peripheral edge of the acetabular implant 200. The fingers 254 of the intermediate member 250 securely engage the cut-outs 202 of the acetabular implant 200 when the distal portion/bushing 314 of the inserter 300 is pushed in and received in the receptacle 252 of the intermediate member 250.
Referring to FIG. 2, the inserter 300 with the acetabular implant 200 mounted thereon can be directed toward the acetabular guide 100. The outer surface 312 of the guide engaging portion 310 of the inserter 300 can be brought into contact with the inner surface 102 of the acetabular guide 100, guiding the acetabular implant 200 toward the selected anteversion and abduction orientation through the acetabular guide 100. The outer surface 312 of the guide engaging portion 310 can also provide an impaction-depth feedback by alignment with the inner surface 102 of the acetabular guide. Full impaction of the acetabular implant 200 into the acetabulum 82 can be indicated when planar portion 320 and/or outer surface 312 of the guide-engaging portion 310 of the inserter 300 are flush with and do not protrude over and above the second surface 110 of the acetabular guide 100. Depth indicia 322 can also be provided on the inserter shaft 302 or on the guide-engaging portion 310 of the inserter 300, as shown in FIG. 2.
After the acetabular implant 200 is fully seated in the acetabulum 82 in the selected anteversion and abduction orientations, the inserter 300 and intermediate member 250 can be removed. The temporary fasteners 120 can be removed and the acetabular guide released.
The acetabular guide 100 can be made of any biocompatible material, such as metal, ceramic or polymer. The acetabular guide 100 can be constructed by various manufacturing methods depending of the selected material, including, for example, machining, casting, molding, stereolithography or other layer deposition methods. In one aspect, the acetabular guide 100 can be made of disposable plastic material.
For certain patients, acetabular implants may be implanted after certain hip joint abnormalities are corrected, such as for example, after correcting developmental, congenital or other hip joint dysplasia or other misalignment between a femoral head 90 and the acetabulum 82 of the pelvis 80, as illustrated in FIG. 6A. In the exemplary illustration of FIG. 6A, the center axis of the femoral head D is misaligned relative to the center axis D′ of the acetabulum 82.
Hip dysplasia is a condition typically characterized by poor coverage of the superior and anterior surface of the femoral head, a shallow acetabulum and/or short femoral neck. Various surgical procedures have been developed to correct hip dysplasia, including periacetabular osteotomy methods, single open osteotomy, double osteotomy, and triple osteotomy. Various osteotomy methods are known by the names of the surgeons who developed the corrective surgical methods, such as, Salter, Bernese, and Gantz osteotomies, for example.
An exemplary surgical approach for correcting hip dysplasia includes performing a series of controlled osteotomies, such as osteotomies 86, 87, 88 around the acetabulum to separate the acetabulum from the pelvis, as illustrated in FIG. 6C. The surgeon can then re-orient or rotate the acetabulum 82 relative to the pelvis 80 and femoral head 90 to place the acetabulum 82 in a better position to cover and articulate with the femoral head 90. In some cases, correction of hip joint dysplasia may require a single osteotomy 86 at the iliac area, for example, such that the acetabulum 82 remains hinged to the pelvis at the ischial and/or pubic area and can be re-oriented with or without implantation of a wedge 450 to keep the osteotomy open, as illustrated in FIG. 6B. The wedge 450 can be a bone autograft or a bone allograft or biocompatible wedge implant made of metal or metal alloy, and can be designed as a patient-specific wedge implant, similar to those disclosed in commonly assigned U.S. application Ser. No. 12/714,023, filed Feb. 26, 2010, cross-referenced above and incorporated herein by reference. The acetabulum 82 can be secured to the pelvis using bone screws and/or plates, similar to those disclosed in the above-referenced U.S. application Ser. No. 12/714,023, filed Feb. 26, 2010.
During the corrective procedure for hip dysplasia, the surgeon typically determines the location and orientation of the desired osteotomies and performs the osteotomies substantial in a free-hand manner. The present teaching provide patient-specific acetabular resection guides with that can assist and guide the surgeon to perform the osteotomies according to a pre-operative plan of osteotomies designed for the particular patient. Referring to FIGS. 5 and 6, an exemplary patient-specific acetabular resection guide 400 can be used according to the present teachings to perform pre-planned osteotomies and correct developmental hip dysplasia or related conditions.
The acetabular resection guide 400 provides a patient-specific guide that is prepared during pre-operative planning for the surgical procedure based on a three-dimensional image of the hip joint of the patient. The three-dimensional image of the hip joint of the patient is developed by commercially available software, as discussed above, using MRI, CT, fluoroscopy, ultrasound, or other medical scans of the particular patient. Referring to FIGS. 5 and 6, the acetabular resection guide 400 includes a three-dimensional curved patient-specific engagement surface 402. The patient-specific engagement surface 402 is dome-shaped and has a complementary shape that matches the acetabulum socket of the pelvis 80 of the patient for nesting therein in only one position. An annular flange 404 extends from a periphery or rim 403 of the patient-specific engagement surface 402. The flange 404 has a substantially flat or planar upper surface 405 and an opposite lower surface 407 that can be patient-specific at least in some or all of the areas 409 that engage the periacetabular surface of the pelvis 80. The flange 404 of the acetabular resection guide 400 is designed during the pre-operative plan to define a plurality of elongated through-slots or other resection guiding formations collectively referenced as resection slots or guiding formations 406.
In one illustrative embodiment, resection slots 406a, 406b, 406c, 406d, 406e arranged peripherally around the periphery 403 for guiding a saw blade 430 or other cutting instrument to resect the periacetabular area to separate the acetabulum 82 from the pelvis 80 and enable relative rotation of the acetabulum 82 relative to the pelvis for correction the hip dysplasia using a periacetabular resection procedure. As can be seen in FIG. 5, some of the elongated slots (406a, 406b, 406c) may overlap or intersect one another such that after resection, the acetabulum can be rotated relative to the femoral head such that the orientation of the acetabulum is corrected. The orientation and location of the elongated slots 406 is patient-specific and is determined pre-operatively to match the acetabulum of the patient for enabling the acetabular resections.
The acetabular resection guide 400 can also include a straight elongated patient-specific resection slot 406′ for performing a single resection 86 for the procedure described in reference to FIG. 6B. For the single osteotomy procedure, the acetabulum remains hinged in the ischial and pubic region at a patient-specific location determined by the uncut region that remains in the acetabulum based on the location of the osteotomy 86 and the corresponding resection slot 406′. The osteotomy 86 can be opened to the extent required for improving the alignment between the femoral head 90 and the acetabulum 82 and an implant 450 can be inserted to keep the osteotomy 86 open, as described above.
The acetabular resection guide 400 can also include an arcuate or curved slot 406′′ that can be used optionally in other corrective procedures. The acetabular resection guide 400 can be provided with all or some of the above described slots 406, all of which can be designed pre-operatively to be patient-specific and provide the surgeon with more than one option of performing the procedure based on intra-operative considerations. The various options can be provided in a single acetabular resection guide 400, as illustrated in FIG. 5. Alternatively, more than one acetabular resection guide 400 can be provided for various combinations of slots 406. For example, one acetabular resection guide 400 can include only the slots 406a through 406e, while another acetabular resection guide 400 can include one or both the slots shown in phantom lines 406′ and 406′′.
In some instances acetabular dysplasia can be corrected solely by performing one or more osteotomies and re-orienting the acetabulum, as described above, or in combination with a total or partial hip replacement, or solely by a hip replacement. Referring to FIGS. 7-9, an acetabular implant 550 can be selected for implantation during the pre-operative stage, with or without re-orientation of the acetabulum depending on the patient's condition and the surgeon's preferences. The acetabular implant 550 can be patient-specific and designed during the pre-operative stage based on the three dimensional image of the hip joint of the patient such that an outer surface 560 of the acetabular implant 550 matches in a complementary manner with the patient's acetabulum and other patient-specific kinematic considerations. Alternatively, the acetabular implant 550 can be a commercially available implant, such as the Regenerex© Ringloc© Modular Acetabular System available from Biomet Manufacturing Corp, Warsaw, Ind. The acetabular implant 550 can include an outer acetabular cup or shell 552 and a liner cup 554 that includes an inner cavity 558 for articulating with a natural femoral head or a femoral head implant. The outer surface 560 of the acetabular shell 552 can be coated or otherwise covered with material promoting ingrowth, such a porous metal, including, for example, the Regenerex© porous titanium construct commercially available from Biomet Manufacturing Corp, Warsaw, Ind. The acetabular shell 552 can include a plurality of apertures 556 for use with fasteners to attach the acetabular shell 552 to the acetabulum 82 of the patient. The liner cup 554 can be made from a wear-resistant material, including, for example, polyethylene.
Other anatomic defects can also be associated with the patient's acetabulum and identified in the medical scans of the hip joint of the patient. Referring to FIG. 8, for example, a weakened or defective area 83 can extend from a periphery 85 of the acetabulum 82 of the patient. A patient-specific acetabular or periacetabular augment 500 (henceforth collectively acetabular augment 500) can be prepared during the preoperative plan to strengthen, fill or replace and generally correct the defective area 83 and be coupled with the acetabular shell 552, as illustrated in FIGS. 8-9. The acetabular augment 500 can include a three-dimensional curved outer patient-specific surface 502 to match and replace the defective area 83, with or without any prior milling, burring procedure, as selected by the surgeon during the pre-operative planning stage. The outer surface 502 of the acetabular augment 500 can be covered with ingrowth-promoting material, such as porous titanium, and include a plurality of through apertures 506 for fixation to the pelvis 80. In one embodiment, the apertures can be communicating or define a common elongated opening 508. The acetabular augment 500 can include an implant-coupling surface 504 shaped and sized to mate and be stacked onto the outer surface 560 of the acetabular shell 552, which, as discussed above, can be custom-made for specific patient or a standard non-custom acetabular shell 552. Additionally, the acetabular augment 500 can be secured to the acetabular shell 552 with fasteners.
Referring to FIGS. 10-13, anatomic defects identified in the medical scan of the hip joint of the patient may also include bone defects 92 associated with the femoral head 90 and/or cartilage defects 94 in the acetabulum of femoral head 90, or combinations thereof. Such defects can be corrected with patient-specific implants that can be designed and selected during the preoperative plan based on the three-dimensional image of the hip joint of the patient constructed from MRI or CT pr other medical scans of the patient, as discussed above.
Referring to FIGS. 10 and 11, a relatively small or superficial bone defect 92 bounded by a periphery 96 on the bone surface of the femoral head 90 can be corrected with a patient-specific femoral implant 600. The femoral implant 600 can be shaped as a cap or shell and can include a first or patient-specific three-dimensional curved articulating surface 606 that replaces the defective area of the bone defect 92 and is inset or continuous to a remaining healthy surface of the femoral head 90 for articulation with the acetabulum of the patient or with an acetabular implant. The first surface 606 can be bounded by a patient-specific periphery 608 that matches the periphery 96 of the bone defect 92. The periphery 96 of the bone defect 92 may be a periphery after the bone defect 92 is milled or burred to remove diseased or weak areas or other growths and abnormalities, as applicable for the particular patient and type of defect present. A recess may also be formed at the periphery 92 for nestingly receiving the femoral implant 600. The femoral implant 600 can include a second or bone engagement surface 602 opposite to the first surface 606. The bone engagement surface 602 can designed to fit a healthy area underlying the defect after the bone defect 92 has been removed or cleaned. The femoral implant 600 can be secured to the bone with pegs, keels, screws or other fixators 604, which can be either, monolithically attached and integral to the femoral implant or modularly coupled to the femoral implant 600. The femoral implant 600 can be made of any biocompatible material, including metal alloys, such as titanium alloys (Ti-6Al-4V), or cobalt-chromium alloys (Co—Cr—Mo) or ingrowth-promoting porous metal (Regenerex©) or plastic materials including Ultra High Molecular Weight Polyethylene (UHMWPE), PEEK, or other polymers.
Referring to FIGS. 12 and 13, a cartilage defect 94 bounded by a periphery 98 on the cartilage of the femoral head 90 can be corrected with a patient-specific femoral implant 650. The femoral implant 650 can be shaped as a cap or shell and can include a first or patient-specific three-dimensional curved articulating surface 656 that replaces the defective area of the cartilage defect 94 and is continuous to a remaining healthy surface of the articular cartilage of the femoral head 90. The articulating surface 656 can be bounded by a patient-specific periphery 658 that matches the periphery 98 of the cartilage defect 94 (the periphery 658 is shown as a regular shape in FIG. 13 for simplicity). The periphery 98 of the cartilage defect 94 may be a periphery defined after the cartilage defect 94 is trimmed or burred to remove diseased or weak areas or other abnormalities of the cartilage, as applicable for the particular patient and type of defect present, but it generally retains the shape of the defect 94. The femoral implant 650 can include a second or bone engagement surface 652 opposite to the articulating surface 656. The bone engagement surface 652 can be patient-specific and designed to fit a healthy area underlying the cartilage defect 94 after the cartilage defect 94 has been removed or cleaned. The femoral implant 650 can be secured to the bone with a stem, a peg, a keel or other fixation element 654, which can be either, monolithically attached and integral to the femoral implant or modularly coupled to the femoral implant 650. The femoral implant 650 can also be press-fitted or interference fitted or fitted with a cementing agent with or without biologic or other pharmacologic/antibiotic or ingrowth-promoting agents and implanted without the use of a fastening member 654. In other embodiments, the fixation element 654 can be resorbable. The femoral implant 650 can be made of pyrolytic carbon, ingrowth-promoting porous metal (Regenerex©), PEEK, or biocompatible metal alloys including titanium alloys (Ti-6Al-4V) and cobalt-chromium alloys (Co—Cr—Mo).
It should be appreciated that defects extending through the articular cartilage into the underlying subchondral bone, i.e., defects including cartilage and underlying bone, can be similarly corrected with femoral implant 600 or femoral implant 650.
The present teachings provide various patient-specific instruments, including alignment guides and resection guides for hip joint arthroplasty. The guides can be used with patient-specific implants or with standard, non custom implants. The present teachings also provide patient-specific implants for the acetabulum and femoral head for correcting bone and/or cartilage defects.
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 teachings of the invention without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings as defined in the following claims.

## Claims

1. An implant for a femoral head, the implant comprising:
a shell, having, a first surface configured to replace a defective area of a bone defect of a portion of an articulation surface of the femoral head, the first surface being patient-specific to the portion of the articulation surface of the femoral head and configured to conform with the patient's acetabulum for partial articulation thereon, wherein the patient-specific first surface is a three-dimensionally curved articulation surface that is configured to replace the defective area of the femoral head with a continuation of a healthy bone surface;
a patient-specific periphery mateable with a periphery of the bone defect, such that the first surface is configured to be continuous at the periphery of the bone defect to a remaining healthy surface of the articulation surface of the femoral head and the implant is configured to replace and correct the bone defect to allow for full articulation with the patient's acetabulum; and
a second surface opposite the first surface and configured to engage bone underlying the bone defect.

2. The implant of claim 1, further comprising a bone fixator extending from the second surface into the underlying bone.

3. The implant of claim 2, wherein the fixator is monolithically attached and integral to the implant.

4. The implant of claim 2, wherein the fixator is modularly attached to the implant.

5. The implant of claim 1, wherein the patient-specific periphery is configured to mate with a recess formed in the periphery of the bone defect.

6. The implant of claim 1, wherein the implant is shaped as a portion of a shell configured to be received in the defective area of the bone defect.

7. The implant of claim 1, wherein the second surface is configured to engage a healthy bone area exposed after the bone defect is cleaned or removed.

8. The implant of claim 1, wherein the second surface is patient-specific.

9. The implant of claim 1, wherein the second surface comprises a three-dimensionally curved surface that is configured to conform and mirror healthy bone area underlying the defect.

10. The implant of claim 2, wherein the bone fixator comprises a curved peg extending from a first end at the second surface to a narrower, second end extended away from the second surface.

11. An implant for a femoral head, the implant comprising:
a shell, having,
a first surface configured to replace a cartilage defect of a portion of an articulation surface of the femoral head, the first surface being patient-specific to the portion of the articulation surface of the femoral head and configured to conform with the patient's acetabulum for partial articulation thereon, wherein the patient-specific first surface is a three-dimensionally curved articulation surface that is configured to replace the cartilage defect of the femoral head with a continuation of a healthy bone surface;
a patient-specific periphery mateable with a periphery of the cartilage defect, such that the first surface is configured to be continuous at the periphery of the bone defect to a remaining healthy cartilage of the articulation surface of the femoral head and the implant is configured to replace and correct the cartilage defect such that the first surface and the remaining healthy cartilage of the articulation surface allow for full articulation of the femoral head with the patient's acetabulum; and
a second surface opposite the first surface, the second surface being patient-specific and configured to conform and engage a healthy area of the femoral head underlying the cartilage defect.

12. The implant of claim 11, wherein the implant is configured to be press-fitted into the healthy area underlying the cartilage defect.

13. The implant of claim 11, wherein the implant includes a fixation element extending from the second surface and configured to engage the healthy area of the femoral head underlying the cartilage defect.

14. The implant of claim 11, comprising pyrolytic carbon.

15. The implant of claim 11, comprising resorbable material.

16. The implant of claim 11, in combination with a cementing agent for securing the implant in the femoral head.