# Patent

## Title
Patient-specific femoral version guide

## Abstract

An orthopedic device includes a monolithic patient-specific guide. The patient-specific guide includes a three-dimensional contact surface preoperatively configured from medical scans of a specific patient as a negative surface of a medial portion of a proximal femoral bone of the patient according to a preoperative surgical plan for the patient. The guide also includes a proximal planar surface configured for guiding a resection of a femoral neck of the patient, and a scale formed on the planar surface. The scale is configured for indicating a preoperatively planned femoral version of a femoral stem implant and deviations therefrom.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 13/041,883 filed Mar. 7, 2011.
This application is also a non-provisional of U.S. patent application Ser. No. 61/569,924 filed Dec. 13, 2011.
The disclosures of the above applications are incorporated herein by reference.


FIELD OF INVENTION AND INTRODUCTION
The present teachings provide various patient-specific guides and other instruments for femoral hip arthroplasty. A femoral patient-specific guide with femoral version control is provided. The patient-specific guide is designed and constructed preoperatively based on three-dimensional digital images of the patient's hip joint. The digital images of the patient's hip joint can be reconstructed from medical scans of the patient (MRI, CT, X-ray, etc.) using commercially available CAD (Computer Aided Design) and/or other imaging software.
SUMMARY
The present teachings provide an orthopedic device that includes a monolithic patient-specific guide. The patient-specific guide includes a three-dimensional contact surface preoperatively configured from medical scans of a specific patient as a negative surface of a medial portion of a proximal femoral bone of the patient according to a preoperative surgical plan for the patient. The patient-specific guide also includes a proximal planar surface configured for guiding a resection of a femoral neck of the patient, and a scale formed on the planar surface. The scale is configured for indicating a preoperatively planned femoral version of a femoral stem implant and deviations therefrom.
In some embodiments, the orthopedic device includes a version assembly and a broach for a femoral stem implant. The version assembly has a body with an inner bore configured to receive a post extending from a proximal surface of the broach. A pointer element is attached to the body of the version assembly and can rotate with the broach when the version assembly is coupled to the broach. The pointer element is configured to indicate on the scale of the patient-specific guide an actual femoral version that is determined by the broach when the pointer element is coupled to the broach.
The present teachings also provide a method for hip arthroplasty. A patient-specific guide is mounted around a medial portion of a proximal femoral bone of a hip joint of a patient. A contact surface of the patient-specific guide is uniquely registered onto the medial portion. The contact surface is preoperatively configured as a negative of the medial portion from medical scans of the patient. A femoral neck of the femoral bone is resected along a planar resection guiding surface of the patient-specific guide. An intramedullary canal of the femoral bone is prepared using a broach through the resected femoral neck. A pointer element is coupled to the broach and indicates an actual femoral version angle on a scale of the patient-specific guide.
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 drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
FIG. 1 is an environmental perspective view of a patient-specific guide shown on a femoral neck of a patient according to the present teachings;
FIG. 1A is a perspective view of the patient-specific guide of FIG. 1;
FIG. 1B is an exploded view of FIG. 1;
FIG. 2 is a side view illustrating a neck resection made with the patient-specific guide of FIG. 1;
FIG. 3 is an environmental view of a broach for a femoral stem implant introduced into the intramedullary canal of the femoral bone after the femoral neck is resected and shown with a trial trunnion and trial femoral head;
FIG. 4 is an environmental view of the femoral guide of FIG. 1 shown with a version assembly according to the present teachings;
FIG. 5 is a plan view of FIG. 4; and
FIG. 6 is an environmental view illustrating total hip replacement implants.



Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
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 provide a patient-specific guide for a hip joint of a specific patient. The patient-specific guide is configured to mate to a medial portion of the femoral neck of the patient and indicate preoperatively selected femoral and acetabular version angles for the patient. Further, the femoral alignment guide can guide the neck resection and, combined with a pointer element, indicate intraoperatively the actual femoral version after the intramedullary canal is prepared for receiving a femoral stem implant. Based on the actual femoral version, the acetabular version can be adjusted intraoperatively to obtain an optimum combined version for the patient.
In the context of the present teachings, patient-specific guides, including alignment and/or resection guides are generally configured to match the anatomy of a specific patient in one or more respects. Each patient-specific guide has a three-dimensional patient-specific anatomy-engaging or contact surface that is configured as a mirror or negative or complementary surface that can conformingly contact and match a corresponding bone surface of the patient (with or without cartilage or other soft tissue).
In this respect, the patient-specific guide can nestingly mate and register in only one position with the corresponding joint surface (with or without articular cartilage) of the specific patient replicating complementarily at least a portion of the joint surface. A patient-specific guide can include custom-made (patient-specific) guiding formations, such as, for example, guiding holes for sutures or K-wires or for inserting pins or other fasteners in configurations determined by a surgeon-approved pre-operative plan. In some embodiments, patient-specific guides can also include patient-specific cutting guide surfaces, such as cutting slots, edges or other guiding formations for guiding a cutting tool to perform preoperatively planned resections of the joint.
The patient-specific guides can be designed preoperatively using computer-assisted image methods based on three-dimensional images of the patient's joint or other anatomy reconstructed from MRI, CT, ultrasound, X-ray, or other three- or two-dimensional medical scans of the patient's anatomy and in some cases complemented with digital photography methods and/or anthropometry databases. Various CAD programs and/or software can be utilized for three-dimensional image reconstruction, such as software commercially available, for example, by Materialise US, Plymouth, Mich.
In the preoperative planning stage for arthroplasty, imaging data of the relevant anatomy of a patient can be obtained at a medical facility or doctor's office, using one or more of the medical imaging methods described above. The imaging data can include various medical scans of a relevant portion of the patient's anatomy, as needed for joint modeling. An initial preoperative plan can be prepared for the patient in image space and can include planning and determination for joint resections, custom implant design or non-custom implant selection, sizing, fitting and designing patient-specific alignment and/or resection guides and other instruments for guiding the joint resections, drilling holes for locating pins or other fasteners and for other guidance during the surgical procedure.
Various patient-specific guides or other instruments and pre-operative planning procedures are descried in commonly assigned U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007, now U.S. Patent Publication No. 2007/0288030; U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008, now U.S. Patent Publication No. 2009/0024131; U.S. patent application Ser. No. 11/971,390, filed on Jan. 9, 2008, now U.S. Patent Publication No. 2008/0312659; U.S. patent application Ser. No. 11/363,548, filed on Feb. 27, 2006, now U.S. Pat. No. 7,780,672; U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008, now U.S. Patent Publication No. 2008/0114370; U.S. patent application Ser. No. 12/571,969, filed Oct. 1, 2009, now U.S. Patent Publication No. 2010/0087829, U.S. patent application Ser. No. 12/955,361, filed Nov. 29, 2010, now U.S. Patent Publication No. 2011/0071533, U.S. patent application Ser. No. 12/486,962, filed Jun. 18, 2009, now U.S. Patent Publication No. 2009/0250413, U.S. patent application Ser. No. 12/893,306, filed Sep. 29, 2010, now U.S. Patent Publication No. 2011/0015639, and U.S. patent application Ser. No. 13/041,883, filed Mar. 7, 2011, now U.S. Patent Publication No. 2011/0160736. The disclosures of the above applications are incorporated herein by reference.
The patient-specific guides of the present teachings can be made of any biocompatible material, including metal or plastic. Generally, the patient-specific alignment and/or resection guides can be single use, disposable instruments made of lightweight materials, including polymers. The patient-specific guides can be manufactured by machining or 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 data can be provided as input to a CNC mill or other automated machining system.
Briefly, a patient-specific guide 100 for hip arthroplasty is illustrated in FIGS. 1, 1A and 1B. A femoral version assembly 200 configured for use with the patient-specific guide 100 and a broach 300 is illustrated in FIGS. 3 and 4. The version assembly 200 is used for determining the version of a femoral stem after the intramedullary femoral canal of the patient has been prepared using the broach 300. An environmental view of an exemplary total hip replacement 400 is illustrated in FIG. 6. The total hip replacement 400 includes a femoral stem 410 implanted into an intramedullary canal 83 of the femoral bone 80, a femoral head 420 coupled to the femoral stem 410 and an acetabular component 430 received in an acetabulum 72 of the pelvis 70 of the patient.
Referring to FIG. 1, a patient-specific guide 100 is shown mounted on a medial portion 81 of a proximal femoral bone 80 of the specific patient for whom the patient-specific guide 100 was preoperatively configured. In this respect, the patient-specific guide 100 has an interior three-dimensional contact surface 102 preoperatively configured as a negative or mirror image of a corresponding surface of the medial portion of the femoral bone 80. The contact surface 102 is configured and manufactured based on a three-dimensional image of the proximal femoral bone and hip joint that are digitally reconstructed from medical scans of the patient, as discussed above. The medial portion 81 can include the lesser trochanter of the femoral bone and surface portions surrounding the lesser trochanter and adjacent to the femoral neck 84 of the femoral bone 80 of the patient. Accordingly, the patient-specific guide 100 can nest and mate with the medial portion 81 (including associated bone or other tissue landmarks, such as the lesser trochanter) of the femoral bone 80 only in one position, such that intraoperative registration to the patient's anatomy using computer or other intraoperative navigation is unnecessary and can be avoided. In the illustration of FIG. 1, the femoral neck 84, the femoral head 86, the great trochanter 82 and the medial portion 81 with the lesser trochanter are indicated.
Referring to FIGS. 1, 1A and 1B, the patient-specific guide 100 can include a proximal planar guiding surface 110 preoperatively configured for guiding a resection of the femoral neck 84 at a position and angle determined for the specific patient by the surgeon as part of the preoperative surgical plan and the three-dimensional image of the hip joint of the patient. The planar guiding surface 110 includes a rotational or angular scale (or version scale) 112 that can measure the version angle of a fully seated broach 300 shown FIG. 3 (and of a corresponding femoral stem 410, shown in FIG. 6). The version scale 112 is calibrated to show a zero degree (0°) version angle corresponding to a preoperatively selected (“ideal”) femoral version for the femoral stem 410, when the patient-specific guide 100 is mounted on the femoral bone 80 and coupled to the version assembly 200, as discussed below. The patient-specific guide 100, the proximal planar guiding surface 110 and the version scale 112 can be configured as a monolithic (integral, unitary or single-piece) component, as shown in FIG. 1A.
Referring to FIGS. 1-3, after a planar neck resection 88 guided by the resection guiding surface 110 is made, the patient-specific guide 100 can be removed. The surgeon can optionally make by hand (unguided) another resection 90, such as a vertical resection or a resection orthogonal to the neck resection 88. A broach 300 can be inserted through the neck resection 88 to prepare the intramedullary canal 83 for receiving a femoral stem 410 (see FIG. 6), as shown in FIG. 3 with the broach 300 in the fully seated position. At this stage, a magnetic neck trunnion 350 can be selected from a plurality of trunnions of different sizes and neck offsets and placed over a post 310 of the broach 300. A trial femoral head 370 can be selected from a plurality of trial femoral heads based on neck length and/or offset. Various femoral stem broaches, broach insertion tools, trunnions, trial femoral heads and total hip replacement implants are commercially available from Biomet Manufacturing Corp., Warsaw, Ind.
Referring to FIGS. 4 and 5, after the intramedullary canal 83 has been prepared and the broach 300 is fully seated in the intramedullary canal 83, the patient-specific guide 100 can be again mounted on the femoral bone 80, and the version assembly 200 can be placed over the broach 300. The version assembly 200 includes a body 202 with an inner bore 210 configured to receive the post 310 of the broach 300 in a keyed manner. The version assembly 200 also includes a pointer element 220 that is attached around a perimeter (or groove) 222 of the body 202 and configured during the preoperative plan to point at the zero marking of the version scale 112 when the broach 300 is accurately seated according to a preoperatively determined orientation and path. The body 202 and pointer element 220 can rotate with the broach 300 when coupled to the broach 300. If the broach 300 has deviated somewhat from the preoperatively determined orientation and path, as it can happen during broaching, then the pointer element 220 points to a different version angle deviating by an amount A from the preoperatively determined femoral version at the zero marking of the version scale 112, as shown in FIG. 5. Based on the femoral version deviation A, the acetabular version (the version of the acetabular component 430 in the acetabulum 72) can be adjusted intraoperatively such that the femoral and acetabular versions match when the total hip replacement 400 is implanted, as shown in FIG. 6.
Summarizing, the present teachings provide patient-specific and preoperative constructed instruments that can be uniquely registered to the specific patient without intraoperative computer-assisted navigation during a hip replacement procedure. In particular, the instruments provide a patient-specific guide and a version assembly that can indicate intraoperatively the preoperatively selected femoral version angle for the patient. Additionally, the instruments can measure the actual intraoperative femoral version angle, thereby allowing intraoperative adjustment for optimal fit of femoral and acetabular versions based on the encountered intraoperative conditions.
Example embodiments are provided so that this disclosure is thorough, and fully conveys the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure.
It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Accordingly, individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

## Claims

1. An orthopedic device comprising:
a patient-specific guide having:
a three-dimensional contact surface preoperatively configured from medical scans of a specific patient as a negative surface of a medial portion of a proximal femoral bone of the patient according to a preoperative surgical plan for the patient;
a proximal planar surface configured for guiding a resection of a femoral neck of the patient; and
a scale on the planar surface, the scale configured for indicating a preoperatively planned femoral version of a femoral stem implant and deviations therefrom.

2. The orthopedic device of claim 1, further comprising a version assembly including a body and a pointer element, the version assembly configured to indicate intraoperatively an actual femoral stem version on the scale of the patient specific guide when the version assembly is coupled to a fully seated broach for a femoral stem implant.

3. The orthopedic device of claim 2, wherein the body of the version assembly includes an internal bore configured to receive a proximal post of a broach for a femoral stem implant.

4. The orthopedic device of claim 3 in combination with a broach for the femoral stem.

5. The orthopedic device of claim 4, further comprising a trial trunnion for the broach and a trial femoral head for the trunnion.

6. The orthopedic device of claim 5, in combination with a hip replacement implant.

7. The orthopedic device of claim 1, wherein the medial portion includes a lesser trochanter and the contact surface is configured to include a portion negative of the lesser trochanter, wherein the patient-specific guide is monolithic.

8. An orthopedic device comprising:
a patient-specific guide having a three-dimensional contact surface preoperatively configured from medical scans of a specific patient as a negative surface of a medial portion of a proximal femoral bone of the patient according to a preoperative surgical plan for the patient, the medial portion including a lesser trochanter, the patient specific guide having a proximal planar surface configured for guiding a resection of a femoral neck of the patient and a scale on the planar surface, the scale configured for indicating a preoperatively planned femoral version of a femoral stem implant and deviations therefrom;
a broach for a femoral stem implant, the broach having a proximal post; and
a version assembly having a body with an inner bore receiving the post of the broach and a pointer element attached to the body and rotatable with the broach, the pointer element indicating on the scale a femoral version determined by the broach.

9. The orthopedic device of claim 8, wherein the patient-specific guide is disposable and monolithic.

10. The orthopedic device of claim 8, in combination with a plurality of trunnions and a plurality of trial femoral heads.

11. The orthopedic device of claim 8, in combination with a hip replacement implant.