U.S. patent application number 13/960498 was filed with the patent office on 2014-09-18 for customized acetabular cup positioning guide and system and method of generating and employing such a guide.
This patent application is currently assigned to OtisMed Corporation. The applicant listed for this patent is OtisMed Corporation. Invention is credited to Keun Song.
Application Number | 20140276872 13/960498 |
Document ID | / |
Family ID | 51530969 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140276872 |
Kind Code |
A1 |
Song; Keun |
September 18, 2014 |
CUSTOMIZED ACETABULAR CUP POSITIONING GUIDE AND SYSTEM AND METHOD
OF GENERATING AND EMPLOYING SUCH A GUIDE
Abstract
Implementations described and claimed herein provide an
arthroplasty system positioning an acetabular cup implant. In one
implementation, the system includes a shape-match hip guide having
a patient specific mating region that is a negative of the surface
contour of the inside surface of the patient's acetabular cup, and
a directional rod that extends generally along the axis of the
patient's femoral head and femoral neck. They system can
additionally include an outrigger or silo device to aid in the
alignment of surgical tools for preparing and implanting of the
prosthetic acetabular cup in the patient's acetabular cup. Related
methods are also disclosed herein for generating a shape-match
guide and implanting an acetabular cup with the guide.
Inventors: |
Song; Keun; (Palo Alto,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OtisMed Corporation |
Alameda |
CA |
US |
|
|
Assignee: |
OtisMed Corporation
Alameda
CA
|
Family ID: |
51530969 |
Appl. No.: |
13/960498 |
Filed: |
August 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61794662 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
606/91 ;
29/592.1 |
Current CPC
Class: |
H05K 999/99 20130101;
A61F 2/4609 20130101; A61F 2002/4681 20130101; A61F 2002/4687
20130101; Y10T 29/49002 20150115; A61F 2002/30948 20130101; A61F
2002/30952 20130101; A61F 2/30942 20130101 |
Class at
Publication: |
606/91 ;
29/592.1 |
International
Class: |
A61F 2/46 20060101
A61F002/46 |
Claims
1. A method of manufacturing a custom acetabular cup positioning
guide for use in an arthroplasty procedure on a portion of a hip
region of a patient's body, wherein the portion of the hip region
includes a patient's acetabular cup, the method of manufacturing
comprising: generating a plurality of two dimensional medical
images of the portion of the hip region of the patient's body to
undergo the arthroplasty procedure; identifying landmarks on bone
boundaries in the two dimensional medical images; identifying a hip
axis line by triangulating a plurality of the landmarks in the two
dimensional medical images; using a computer processor to generate
a three dimensional bone model of the portion of the hip region of
the patient's body to undergo the arthroplasty procedure from the
plurality of two dimensional medical images, wherein the three
dimensional bone model includes a three dimensional model of the
patient's acetabular cup; shape-matching an inside surface of the
three dimensional model of the patient's acetabular cup relative to
the hip axis line; generating the custom acetabular positioning
guide based upon the identification of the hip axis line and a
negative contour of the inside surface of the three dimensional
model of the patient's acetabular cup.
2. The method of claim 1, wherein the custom positioning guide
comprises a directional rod that extends generally along the hip
axis line when the custom positioning guide matingly interdigitates
with an inside surface of the patient's acetabular cup.
3. The method of claim 1, further comprising generating a three
dimensional acetabular cup positioning guide model from the three
dimensional bone model.
4. The method of claim 1, wherein the plurality of medical images
are generated from MRI slices or CT slices.
5. The method of claim 1, wherein identifying landmarks on bone
boundaries include a user at a user interface employing at least
one of a mouse, keyboard, pen-and-tablet system, touch screen
system, or spatial input device to place landmark points.
6. The method of claim 1, wherein the landmarks identified on the
bone boundaries in the two dimensional images comprise a left
teardrop and a right teardrop of a pelvis, a right
anterior-superior ilium symphysis ("ASIS-R"), a left
anterior-superior ilium symphysis ("ASIS-L"), and a pubic
symphysis.
7. The method of claim 6, wherein the landmarks are identified in a
coronal image slice.
8. The method of claim 6 or 7, wherein the plurality of landmarks
used in triangulation in the two dimensional images include the
ASIS-R, the ASIS-L, and the pubic symphysis.
9. The method of claim 8, wherein identifying the hip axis line
further comprises identifying a pelvic axis line in the two
dimensional images that extends through the left teardrop and the
right teardrop of the pelvis.
10. The method of claim 9, further comprising determining an acute
first angle between the pelvic axis line and a first line that
extends through the pubic symphysis and either the ASIS-R or
ASIS-L, wherein the first line will extend through the ASIS-R if a
right hip region is to undergo the arthroplasty procedure and the
first line will extend through the ASIS-L if a left hip region is
to undergo the arthroplasty procedure.
11. The method of claim 10, further comprising identifying a second
angle by increasing the first angle by a surgically prescribed
degree, rotated downward from the first line, wherein the second
angle is coextensive with a hip axis angle, whereby the hip axis
angle is defined between the first line and the hip axis line.
12. The method of claim 11, wherein the surgically prescribed
degree is about forty-five degrees.
13. A custom acetabular cup positioning guide for use in an
arthroplasty procedure on a portion of a hip region of a patient's
body, wherein the portion of the hip region includes a patient's
acetabular cup, femoral head and femoral neck, the guide
comprising: a directional rod extending from a semi-hemispherical
mold, wherein the mold includes a hemispherical surface that is
generally a surface negative of a surface contour of an inside
surface of the patient's acetabular cup, whereby when the mold
interdigitates with the surface contour of the inside surface of
the patient's acetabular cup the directional rod extends along a
hip axis line, wherein the hip axis line generally extends along an
axis collinear with a preoperative orientation of the femoral head
and the femoral neck.
14. The custom guide of claim 13, further comprising an outrigger
positioning device, the outrigger positioning device comprising a
first and a second coupler, the first coupler configured to couple
with a portion of the directional rod, the second coupler
configured to couple with the first coupler and couple with a
portion of a reference rod, the reference rod configured to imbed
or anchor in a portion of a superior hip region of a patient's
body.
15. The custom guide of claim 14, wherein the reference rod extends
generally parallel with the directional rod, thereby providing a
correlating reference to the hip axis line.
16. The custom guide of claim 14, wherein the directional rod
extends through a portion of the first coupler and wherein the
reference rod extends through a portion of the second coupler.
17. The custom guide of claim 16, wherein the first coupler
matingly interdigitates with the second coupler.
18. The custom guide of claim 17, wherein the first and the second
coupler matingly interdigitate along corresponding planar
surfaces.
19. The custom guide of claim 16, wherein the first coupler is
configured for the removal of the directional rod while maintaining
orientation relative to the hip axis line, thereby allowing a shaft
of a surgical tool to be received in the first coupler such that
the shaft is generally collinear with the hip axis line.
20. The custom guide of claim 19, wherein the first coupler is
configured to allow translational movement of the shaft of the
surgical tool generally along the hip axis line.
21. A method of manufacturing a custom acetabular cup positioning
guide for use in an arthroplasty procedure involving a hip region
of a patient's body, wherein the hip region includes the patient's
femoral head, femoral neck and acetabular cup, the guide including
a mating region configured to matingly receive a portion of the
patient's acetabular cup, the mating region including a surface
contour that is generally a negative of a surface contour of the
patient's acetabular cup, the surface contour of the mating region
being configured to mate with the surface contour of the patient's
acetabular cup in a generally matching or interdigitating manner
when the patient's acetabular cup is matingly received by the
mating region, the method of manufacture comprising: a) generating
medical imaging slices of the portion of the patient bone; b)
identifying landmarks on bone boundaries in the medical imaging
slices; c) identifying a hip axis line, the hip axis line being
generally collinear with an axis of the patient's femoral head and
femoral neck in a preoperative state; d) using a computer processor
to generate a three dimensional bone model of the patient's
acetabular cup; e) shape-matching an inner surface of the three
dimensional bone model of the patient's acetabular cup relative to
the bone axis line; f) using data associated with the inner surface
of the three dimensional model of the patient's acetabular cup to
manufacture the custom acetabular cup positioning guide.
22. The method of claim 21, wherein the identifying a hip axis line
further comprises triangulating landmarks on the bone boundaries in
the medical imaging slices.
23. The method of claim 21, wherein the medical imaging slices are
generated from MRI slices or CT slices.
24. The method of claim 22, wherein the landmarks identified on the
bone boundaries in the medical imaging slices include a left
teardrop and a right teardrop of a pelvis, a right
anterior-superior ilium symphysis ("ASIS-R"), a left
anterior-superior ilium symphysis ("ASIS-L"), and a pubic
symphysis.
25. The method of claim 24, wherein the landmarks are identified in
a coronal image slice.
26. The method of claim 24, wherein the landmarks used in
triangulation in the two dimensional images include the ASIS-R, the
ASIS-L, and the pubic symphysis.
27. The method of claim 26, wherein identifying the hip axis line
further comprises identifying a pelvic axis line in the two
dimensional images that extends through the left teardrop and the
right teardrop of the pelvis.
28. The method of claim 27, further comprising determining an acute
first angle between the pelvic axis line and a first line that
extends through the pubic symphysis and either the ASIS-R or
ASIS-L, wherein the first line will extend through the ASIS-R if a
right hip region is to undergo the arthroplasty procedure and the
first line will extend through the ASIS-L if a left hip region is
to undergo the arthroplasty procedure.
29. The method of claim 28, further comprising identifying a second
angle by increasing the first angle by a surgically prescribed
degree, rotated downward from the first line, wherein the second
angle is coextensive with a hip axis angle, whereby the hip axis
angle is defined between the first line and the hip axis line.
30. The method of claim 29, wherein the surgically prescribed
degree is about forty-five degrees.
31. A method of performing an arthroplasty procedure on a hip
region of a patient's body, the arthroplasty procedure involving
implanting a prosthetic acetabular cup into a patient's acetabular
cup, the method comprising: preparing the hip region of a patient's
body to undergo the arthroplasty procedure, wherein preparing the
hip region includes accessing the patient's acetabular cup;
matingly interdigitating a shape-match hip guide with the patient's
acetabular cup, the shape-match hip guide comprising a directional
rod and a mating head with a mating surface that is generally a
surface negative of a surface contour of the patient's acetabular
cup; identifying a hip axis line that is generally collinear with a
longitudinal axis defined along the directional rod when the mating
surface of the mating head matingly interdigitates with the
patient's acetabular cup, the hip axis line extending generally
collinear with an axis of the patient's femoral head and femoral
neck in a preoperative state; preparing of the patient's acetabular
cup to receive the prosthetic acetabular cup; and implanting the
prosthetic acetabular cup into the patient's acetabular cup along
the hip axis line in order to replicate the preoperative state.
32. The method of claim 31, wherein preparing of the patient's
acetabular cup comprises reaming.
33. The method of claim 31, further comprising removing of the
shape-match hip guide from the patient's acetabular cup before the
preparing of the patient's acetabular cup to receive the prosthetic
acetabular cup.
34. The method of claim 31, wherein implanting the prosthetic cup
comprises driving of the prosthetic acetabular cup into the
patient's acetabular cup.
35. The method of claim 31, further comprising: coupling the
shape-match hip guide to a reference rod, the reference rod being
generally parallel to the directional rod and configured to imbed
in the hip region of a patient's body; decoupling the shape-match
hip guide from the reference rod; removing the shape-match hip
guide from the patient's acetabular cup; slideably coupling an
impactor rod to the reference rod, wherein the impactor rod is
configured to impact and seat the prosthetic acetabular cup into
the patient's acetabular cup; driving of the prosthetic acetabular
cup into the patient's acetabular cup along the hip axis line; and
removing the impactor rod and the reference rod from the hip region
of the patient's body.
36. The method of claim 35, wherein coupling to the reference rod
occurs via a pair of couplers.
37. The method of claim 36, further comprising: slideably coupling
a reamer to the reference rod; reaming the patient's acetabular cup
along the hip axis line; and decoupling and removing the reamer
from the reference rod.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to U.S. provisional patent application 61/794,662, which
was filed Mar. 15, 2013, entitled "ACETABULAR CUP POSITIONING," and
is hereby incorporated by reference in its entirety into the
present application.
FIELD OF THE INVENTION
[0002] Aspects of the presently disclosed technology relate to
medical apparatuses, systems, and methods. More specifically, the
presently disclosed technology relates to a customized acetabular
cup positioning guide and surgical systems and methods for
generating and employing the guide and implanting an acetabular cup
with the guide.
BACKGROUND OF THE INVENTION
[0003] Over time and through repeated use, bones and joints can
become damaged or worn. For example, repetitive strain on bones and
joints (e.g., through athletic activity), traumatic events, and
certain diseases (e.g., osteoarthritis) can cause cartilage in
joint areas, which normally provides a cushioning effect, to wear
down. When the cartilage wears down, fluid can accumulate in the
joint areas, resulting in pain, stiffness, and decreased
mobility.
[0004] Arthroplasty procedures can be used to repair damaged
joints. During a typical arthroplasty procedure, an arthritic or
otherwise dysfunctional joint can be remodeled or realigned or an
implant can be implanted into the damaged region. Arthroplasty
procedures may take place in any of a number of different regions
of the body, such as a knee, a hip, a shoulder, or an elbow.
[0005] One type of arthroplasty procedure is a total hip
arthroplasty ("THA") procedure, which consists of replacing both
the acetabulum, also known as acetabular cup, and the femoral head
with prosthetic implants. Another type of arthroplasty procedure is
a hemi or half hip replacement, which consists of replacing just
the femoral head with a prosthetic implant. The hip joint may have
been damaged by, for example, arthritis (e.g., severe
osteoarthritis or degenerative arthritis), trauma, or a rare
destructive joint disease. Typically, a THA procedure is conducted
to relieve pain due to osteoarthritis or to remedy severe joint
damage as part of hip fracture treatment.
[0006] The hip is one of the largest joints in the human body. The
hip consists of a ball and socket, wherein the socket is formed by
the acetabulum, which is part of the pelvis bone. The ball, in the
ball and socket system, is the femoral head, which is at the
proximal end of the femur. The surfaces of the ball and socket are
covered with articular cartilage, a smooth tissue that cushions the
ends of the bones and enables femoral head and the acetabulum to
move easily. A thin tissue called synovial membrane surrounds the
hip joint. In an otherwise healthy hip joint, this membrane makes a
small amount of fluid that lubricates the cartilage and eliminates
almost all friction during hip movement. Bands of ligaments connect
the ball to the socket and provide stability to the joint.
[0007] During a THA procedure, a damaged portion of bone in the
femoral head may be removed and replaced with a femoral prosthesis
or implant, and a damaged portion of the bone and cartilage in the
acetabulum may be removed by reaming, scraping, cleaning or
otherwise preparing of the acetabular surface to receive an
implanted prosthesis, such as a prosthetic acetabular cup. After
the damaged portion of the femoral head is removed, the femoral
prosthesis, which includes a stem, may be cemented or simply press
fitted into the patient's femur. Similarly, the acetabular cup may
be screwed, pinned, cemented, or otherwise coupled to the patient's
acetabulum. The acetabular cup can additionally include an
osseointegrated surface to enhance the fusion of the bone to the
implant. The interface between the acetabular cup and the femoral
prosthesis is the ball and socket joint, or the articular
interface. The specifications for the articular interface (e.g.,
make, model, size, material) vary depending on the patient's bony
anatomy, health, activity level, and associated risks involved with
the procedure.
[0008] Implants that are implanted into a damaged region may
provide support and structure to the damaged region and may help to
restore the damaged region, thereby enhancing its functionality.
Prior to implantation of an implant in a damaged region, the
damaged region is prepared to receive the implant. For example, in
a hip arthroplasty procedure, one or more of the bones in the hip
area, such as the femur and/or the acetabulum, may be treated
(e.g., cut, drilled, reamed, and/or resurfaced) to provide one or
more surfaces that can align with the implant and thereby
accommodate the implant.
[0009] Accuracy in implant alignment is an important factor to the
success of a THA procedure. Preparing a patient's acetabulum for
implanting of a prosthetic acetabular cup can be challenging
because of the unique contouring shape of the patient's acetabulum,
and because the pelvic bone does not easily lend itself to
resections, as in an arthroplasty procedure involving inplants to
the femur or tibia. These factors underscore the importance of
properly preparing the acetabulum prior to a THA procedure and
properly aligning the acetabular cup to the acetabulum. A one to
two millimeter translational misalignment may result in imbalanced
ligaments and thus may significantly affect the outcome of the
procedure. For example, implant misalignment may result in
intolerable post-surgery pain and also may prevent the patient from
having stable leg flexion. In particular, the patient's joint may
not be restored to its natural alignment with respect to the knee
and ankle centers, which can result in pain and difficulty in
adjustment to the new alignment.
[0010] To achieve accurate implant alignment, prior to treating
(e.g., cut, drilled, reamed, and/or resurfaced) any regions of a
bone, it is important to correctly determine the location at which
the treatment will take place and how the treatment will be
oriented. In some methods, an arthroplasty guide may be used to
position and orient a resection, sawing, or implantation
instrument, such as a cutting, drilling, reaming, resurfacing, or
impacting instrument on the regions of the bone. The arthroplasty
guide may, for example, include referencing rods and one or more
apertures and/or slots that are configured to accept such an
instrument. However, under some methods, it is difficult to
determine the proper orientation of an arthroplasty guide and
ultimately of the positioning and alignment of an acetabular cup
implant. Some methods utilize arthroplasty guides to provide
orientation of the treatment relative to the regions of the bone.
However, such guides often rely on a human to subjectively
determine or "eyeball" rotational angles and the extent of the
treatment. For example, when performing an acetabular cup
implantation into the hip region of a patient, many guides rely on
a surgeon to determine the proper orientation of the guide as well
as how much of the bone to remove when mating the implanted
prosthesis to the bone. More particularly, once a surgeon has begun
reaming a patient's acetabulum or impacting/implanting the
acetabular cup, it can be difficult and damaging to accurately stop
the reaming or impacting/implanting and start anew.
[0011] Accordingly, there is a need in the art for a customized
arthroplasty acetabular cup positioning guide, and surgical systems
and methods for generating and employing the acetabular cup
positioning guide that increases the accuracy of arthroplasty
procedures.
SUMMARY OF THE INVENTION
[0012] Implementations described and claimed herein address the
foregoing problems by providing a customized acetabular cup
positioning guide as well as systems and methods for generating and
employing the acetabular cup positioning guide for use in a hip
replacement arthroplasty procedure.
[0013] A custom acetabular positioning guide and method of
manufacturing and employing the guide are disclosed herein. In one
implementation, the acetabular cup positioning guide includes: a
directional rod extending from a semi-hemispherical blank or mold,
which has a hemispherical surface that is a negative of the surface
contour of the inside surface of the patient's acetabulum. The
manufactured shape-match hemispherical surface of the hip guide
matingly interdigitates with the corresponding inner surface of the
patient's acetabulum and causes the directional rod to extend along
a directional line that mimics a preoperatively planned axis. The
axis defined by the directional rod is then used as a guide for
implanting the prosthetic cup with an impactor shaft. While using
the impactor shaft to drive the prosthetic cup into the acetabular
cup of the patient, the surgeon tries to replicate the same
orientation of the directional rod with the impactor rod.
[0014] In another implementation, the acetabular cup positioning
guide includes a shape-match hip guide, which includes the
directional rod and semi-hemispherical blank with a hemispherical
surface that is a negative contour of the inside surface of the
patient's acetabular cup, as described in the previous
implementation. In addition, the positioning guide includes a first
coupler half of an outrigger device that extends over the
directional rod. A second coupler half of the outrigger device is
coupled to the first coupler half as well as a reference rod that
extends through the second coupler half to be imbedded in the bone
of the hip region. The reference rod is held parallel to the
directional rod by the outrigger device. The cup guide and
directional rod are removed from the outrigger device, which stays
implanted into the hip region of the patient in the original
orientation. Subsequent to reaming the acetabular cup, wherein the
reaming angle of the reamer may be guided by the coupler, which
attaches the first coupler to the directional rod or like device,
the prosthetic acetabular cup is then placed in the patient's
acetabular cup. The outrigger device provides one angle (i.e.,
inclination angle), whereby the surgeon "eyeballs" the other angle
(i.e., aversion angle).
[0015] In another implementation, the acetabular cup positioning
guide includes a shape-match hip guide, which includes the
directional rod and semi-hemispherical blank with a hemispherical
surface that is a negative contour of the inside surface of the
patient's acetabular cup, as described in the previous
implementation. In addition, the positioning guide includes a silo
device, which includes a barrel with a guide hole that slideably
receives the directional rod. The silo device also includes a
plurality of silo legs that extend from the barrel and are adapted
for anchoring to the bone of the patient's hip region. The silo
legs can be anchored to the hip region by pins, screws, or other
devices. Once anchored to the hip region, the shape-match hip guide
can be removed from the patient's acetabulum and thus the silo
device. The patient's acetabulum is reamed in preparation for
implantation of the prosthetic acetabular cup. The prosthetic
acetabular cup is then inserted into the patient's acetabulum or
acetabular cup and an impactor is inserted into the guide hole of
the silo barrel via an access slot and is held in place against the
prosthetic cup by reinstallation of a keyed side portion into the
slot. As a result, the impactor is held against the prosthetic cup
in proper alignment as established by the rod of the shape-match
hip guide. The impactor, which is slidingly retained in the guide
hole, may then be impacted against the prosthetic cup to seat the
cup in the patient's acetabular cup. The silo and impactor can then
be removed, leaving behind the implanted prosthetic acetabular
cup.
[0016] Other implementations described and claimed herein provide a
method of manufacturing the custom acetabular cup positioning
guide. In one embodiment, the method of manufacturing the custom
guide includes generating a plurality of MRI slices, CT slices, or
other suitable medical images of a portion of a patient's bone to
undergo an arthroplasty procedure. These images are used in the
pre-operative planning phase of the procedure and can include
medical imaging in axial, coronal, and sagittal planes.
[0017] In one embodiment of the method of manufacturing the custom
acetabular cup positioning guide, the operation includes placing
anatomical landmarks around the bone boundaries in the medical
image slices. For example, placing the landmark points may include
a user at a user interface employing at least one of a mouse,
keyboard, pen-and-tablet system, touch screen system, or spatial
input device to place landmark points. The bone boundaries may
include lines representative in the medical imaging slices of
acetabular cup boundaries, among others.
[0018] In one embodiment of the method of manufacturing the custom
acetabular cup positioning guide, the operation includes defining a
triangle in a coronal image slice of the hip region of the patient
that extends between certain landmarks. The triangle can be defined
across the patient's anterior pelvic area, wherein the triangle's
three corners are respectively located at the right
anterior-superior ilium symphysis ("ASIS-R"), the left
anterior-superior ilium symphysis ("ASIS-L"), and the pubic
symphysis. A pelvic axis line is defined to extend across the right
teardrop and the left teardrop of the pelvis. Both legs of the
triangle can be seen to extend immediately adjacent a proximal
point of the acetabular cup. The triangle can additionally include
a frontal axis that divides the triangle at its height by extending
between a midpoint of the base line of the triangle that extends
between the ASIS-R and the ASIS-L. The frontal axis is used to
check for pelvic tilt. A "check" can be made that the frontal axis
is perpendicular to the pelvic axis. Additional measurements can be
taken with respect to the triangle; the measurements can include
determining the angle between the pelvic axis and the target side
line, wherein the target side line is the leg of the triangle that
extends between the pubic symphysis and the anterior-superior ilium
symphysis on the surgical target side (i.e., ASIS-R or ASIS-L). A
45 degree angle or any value that is required as a surgical goal
prescribed by the surgeon can also be defined between an axis line
and the pelvic axis, wherein the intersection of the axis line and
the pelvic axis is about the teardrop of the pelvis on the surgical
target side. The 45 degree angle that was just described can be
moved to intersect the target side line in such a manner that the
axis line projects generally along the axis of the femoral head and
the femoral neck of the surgical target side. The axis line now
generally defines a hip guide pin axis, which defines the
inclination of the prosthetic acetabular cup.
[0019] In one embodiment of the method of manufacturing the custom
acetabular cup positioning guide, the operation includes converting
the MRI slices, CT slices, or similar medical images into at least
one three dimensional model that represents the portion of the
patient's body to undergo an arthroplasty procedure. The three
dimensional model can include a portion of the pelvis and the
contour surface of the acetabular cup, the contour surface being a
generally identical replication of the inner surface of the
patient's acetabular cup or acetabulum. The pre-operative planning
process explained with respect to the two dimensional medical
slices is replicated with respect to the three dimensional model. A
plane connects the proximal point of the public symphysis with a
proximal point of the acetabular cup. A second plane is provided
such that it intersects the first plane at the proximal point of
the acetabular cup. The second plane, also referred to as an
inclination plane, extends through the center point of the
acetabular cup. A third plane, referred to as an anteversion plane,
is positioned to evenly divide the anterior and posterior walls of
the acetabular cup and also pass through the center of the
acetabular cup. The anteversion plane is perpendicular to the
inclination plane and it divides the acetabular cup in half. The
intersection of the two planes defines an axis line that
approximates a center axis of the acetabular cup.
[0020] In one embodiment of the method of manufacturing the custom
acetabular cup positioning guide, the operation includes a three
dimensional model of a candidate prosthetic acetabular cup
occupying the acetabular cup of the three dimensional surface
model. The prosthetic cup is positioned relative to the inclination
and anteversion planes such that a center axis of the cup is
coaxial with the axis defined by the intersection of the planes. A
three dimensional model of a directional rod can be included,
wherein the directional rod is positioned so as to be coaxial with
the axis defined by the intersection of the planes.
[0021] In one embodiment of the method of manufacturing the custom
acetabular cup positioning guide, the operation includes replacing
the three dimensional model candidate prosthetic cup with a three
dimensional model of a semi-hemispherical blank or mold, while
maintaining the directional rod in its orientation relative to the
intersection of the inclination and anteversion planes. The
hemispherical surface of the semi-hemispherical blank or mold
extends along the surface contour of the inside surface of the
acetabular cup of the three dimensional surface model. As a result,
the blank or mold is caused to assume a surface contour that is a
negative of the surface contour of the inside surface of the
acetabular cup of the three dimensional surface model.
[0022] Other implementations are also described and recited herein.
Further, while multiple implementations are disclosed, still other
implementations of the presently disclosed technology will become
apparent to those skilled in the art from the following detailed
description, which shows and describes illustrative implementations
of the presently disclosed technology. As will be realized, the
presently disclosed technology is capable of modifications in
various aspects, all without departing from the spirit and scope of
the presently disclosed technology. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A is a schematic diagram of a system for employing the
customized acetabular cup guide production method disclosed
herein.
[0024] FIGS. 1B-1E are flow chart diagrams outlining the acetabular
cup positioning guide production method disclosed herein.
[0025] FIGS. 1F-1G are flow chart diagrams outlining the surgical
method of employing the acetabular cup positioning guide.
[0026] FIGS. 1H-1I are flow chart diagrams outlining the surgical
method of employing the acetabular cup positioning guide with an
outrigger device.
[0027] FIGS. 1J-1K are flow chart diagrams outlining the surgical
method of employing the acetabular cup positioning guide with a
silo device.
[0028] FIG. 2A illustrates a series of medical imaging scan slices
generated via MRI, CT or other medical imaging techniques.
[0029] FIG. 2B is a table of MRI scanning parameters used in the
generation of the medical image slices depicted in FIG. 2A.
[0030] FIGS. 3A and 3B are, respectively, axial and sagittal plane
medical image slices of the patient's acetabular cup.
[0031] FIG. 4 is an axial plane medical image slice exemplary of
the image contrast in the various image slices.
[0032] FIG. 5 is a coronal plane medical image slice of the entire
hip region used in the preoperative planning stages of a hip
replacement procedure.
[0033] FIGS. 6A-6F are coronal image slices depicting various
landmarks and parameters used in the preoperative planning stages
of a hip replacement procedure to determine a hip guide pin axis
that extends generally along the axis of the femoral head and the
femoral neck on the surgical target side of a patient.
[0034] FIG. 7 is an axial plane medical image slice segmented with
a spline along the inner surface of the acetabular cup.
[0035] FIG. 8 is another example of a medical image slice segmented
with a spline along the inner surface of the acetabular cup.
[0036] FIG. 9 is a computer generated three dimensional surface
model of a patient's acetabular cup compiled from various
splines.
[0037] FIG. 10 is an enlarged view of the acetabular cup of the
three dimensional model of a patient's acetabular cup.
[0038] FIG. 11 is an enlarged view of the acetabular cup of the
three dimensional model that depicts possible inaccurate areas that
form when converting two dimensional medical images into three
dimensional models.
[0039] FIGS. 12A-12D are three dimensional surface models of a
patient's acetabular cup in a coronal plane, with similar landmarks
and parameters employed in FIGS. 6A-6F in determining a hip guide
pin axis that extends generally along the axis of the femoral head
and the femoral neck on the surgical target side of a patient.
[0040] FIGS. 13A-13B are three dimensional surface models of a
patient's acetabular cup wherein a candidate prosthetic acetabular
cup without and with a directional rod extending along the hip
guide pin axis occupies the acetabular cup of the three dimensional
surface model.
[0041] FIG. 14 is a three dimensional surface model of a patient's
acetabular cup, similar to FIG. 13, wherein the candidate
prosthetic acetabular cup is replaced in the acetabular cup of the
3D surface model by a 3D model of a semi-hemispherical blank or
mold.
[0042] FIG. 15 is a 3D model of a shape-match hip guide that
includes a directional rod extending from a semi-hemispherical
blank or mold, which has the hemispherical surface that is a
negative of the surface contour of the inside surface of the
acetabular cup of the 3D surface model.
[0043] FIGS. 16A-16B are views of a patient's actual hip region
including the acetabular cup in the process of receiving an actual
prosthetic acetabular cup via a shape-match hip guide.
[0044] FIGS. 17A-17G are views of a patient's actual hip region
including the acetabular cup in the process of receiving an actual
prosthetic acetabular cup via a shape-match hip guide and an
outrigger device used in aligning the reaming of the patient's
acetabular cup and/or implantation of a prosthetic acetabular
cup.
[0045] FIG. 18A-18G are views of a patient's actual hip region
including the acetabular cup in the process of receiving an actual
prosthetic acetabular cup via a shape-match hip guide and a silo
device used in aligning the reaming of the patient's acetabular cup
and/or implantation of a prosthetic acetabular cup.
[0046] FIG. 19 illustrates three different embodiments of the
custom fit mating head of the hip guide described herein.
[0047] FIG. 20 depicts four different potential mating surface
regions that may or may not be integrated into the mating surface
of the head of the hip guide described herein.
DETAILED DESCRIPTION
[0048] Aspects of the presently disclosed technology involve
customized acetabular cup guides 252, systems 3, and methods of
using the same during arthroplasty procedures. In one aspect, the
guides 252 are customized to fit specific bone surfaces of a hip
joint 12 of a specific patient 11 to treat (e.g., cut, drilled,
reamed, and/or resurfaced) the bone to provide one or more surfaces
that can align with an implant and thereby accommodate the
implant.
[0049] For an overview discussion of the systems 3 for, and methods
of producing the customized acetabular cup positioning guides 252,
reference is made to FIG. 1A. FIG. 1A is a schematic diagram of a
system 3 for employing the customized acetabular cup guides
production method disclosed herein. FIGS. 1B-1E are flow chart
diagrams outlining the acetabular cup positioning guide production
method disclosed herein. The following overview discussion can be
broken down into four sections.
[0050] The first section, which is discussed with respect to FIGS.
1A-1C, pertains to an example method of determining, from two
dimensional (2D) medical images, a hip guide pin axis line for use
in the preoperative planning stages of an arthroplasty procedure.
The hip guide pin axis line generally extends along the patient
specific axis of the femoral head and femoral neck, wherein a
prosthesis that is implanted with respect to the hip guide pin axis
line will restore the patient's joint to its pre-degenerative
orientation. In other words, in some embodiments, the patient's
joint may be restored to its natural alignment, whether valgus,
varus or neutral.
[0051] The system 3 for producing the customized guide 252 may be
such that the system 3 initially generates the preoperative
planning ("POP") associated with the jig in the context of the POP
resulting in the patient's hip being restored to its natural
alignment. The disclosure, however, should not be limited to
methods resulting in natural alignment only, but should, where
appropriate, be considered as applicable to methods resulting in
alignments other than a natural alignment.
[0052] The second section, which is discussed with respect to FIGS.
1A and 1D-1E, pertains to an example method of generating a three
dimensional (3D) bone model of a portion of a patient's body to
undergo a hip replacement procedure, in particular a patient's
acetabular cup, and generating a 3D shape-match hip guide model
with a head that is a negative of the surface contour of a
patient's acetabular cup and a directional rod that aligns with the
hip guide pin axis line when the head matingly interdigitates with
the patient's acetabular cup. The 3D shape-match hip guide model
can then be machined in a CNC machine 13 or other suitable rapid
prototype machine to produce a custom guide 252, which is sent to
the surgeon, and employed in an arthroplasty surgical
procedure.
[0053] The third section, which is discussed with respect to FIGS.
1A and 1F-1K, pertains to a method of employing the shape-match
guide in a surgical procedure. In certain embodiments, the
shape-match hip guide is employed by itself and in certain
embodiments the shape-match hip guide is employed in conjunction
with an outrigger or silo alignment device.
[0054] The fourth section, which is discussed with respect to FIGS.
19-20, pertains to the mating head surface of the custom acetabular
hip guide 252 as it relates to placement in a patient's acetabular
cup.
[0055] I. POP with 2D Medical Images.
[0056] The system 3 in FIG. 1A includes a computer 4 having a CPU
5, a monitor or screen 1 and operator interface controls 6. The
computer 4 is linked to a medical imaging system 7, such as a CT or
MRI machine 7, and a computer controlled machining system 13, such
as a CNC milling machine 13 or other rapid prototype machine (e.g.,
stereolithography apparatus ["SLA" Machine]). As indicated in FIG.
1A, a patient 11 has a hip joint 12 to be replaced. The patient 11
has the joint 12 scanned in the imaging machine 7. The imaging
machine 7 makes a plurality of scans 10 of the joint 12, wherein
each scan pertains to a thin slice of the joint 12.
[0057] As can be understood from FIGS. 1B and 2A the plurality of
scans 10 is used to generate a plurality of 2D images of the joint
[BLOCK 100]. Where, for example, the joint is a hip 12, the 2D
images will include the femur, acetabular cup, and pelvic area
generally. The imaging may be performed via CT or MRI 7.
[0058] As can be understood from FIGS. 1A and 1D, the 2D images
[BLOCK 100] are sent to the computer 4 for creating computer
generated 3D models [BLOCK 150], which are used to generate a 3D
shape-match hip guide model 240. FIG. 2A illustrates a series of
medical imaging scan slices 10 generated via MRI, CT 7 or other
medical imaging techniques. These image slices 10 are employed in
the preoperative planning and shape-match hip guide designing
methodology discussed in the following pages.
[0059] FIG. 2B is a table of MRI scanning parameters used in the
generation of the image slices 10 depicted in FIG. 1A.
[0060] FIGS. 3A and 3B are, respectively, axial and sagittal MRI
image slices 10 of the patient's acetabular cup 30 at the most
axial and sagittal representative cross section of the cup 30. In
other words, the images slices 10 of FIGS. 3A and 3B are at those
axial and sagittal cross sections that show the cup 30 at its
largest diameter and most rounded point as viewed axially and
sagittally, respectively. The boundary of the cup 30 can be
determined in the axial and sagittal cross-sectional slices
illustrated in FIGS. 3A and 3B [BLOCK 105]. The bone boundaries are
segmented to create bone contour lines. FIG. 7 illustrates an
example of how each of the MRI image slices 10 is segmented with a
spline 120 along the inner surface 40 of the acetabular cup 30. The
spline 120 includes control points 122.
[0061] As shown in FIGS. 3A and 3B, a MRI locator or reference line
32 is positioned so as to extend across a widest part of the cup 30
at the articular edges 34 of the cup 30. A coronal scan angle,
which is indicated by the multiple parallel scan lines 36 in each
of the axial and sagittal image slices 10, is set to be
perpendicular to each of the axial and sagittal MRI locator lines
32 in the respective axial and sagittal MRI image slices 10
depicted in FIGS. 3A and 3B. Thus, the coronal scan angle is set to
be perpendicular to each of the axial and sagittal reference lines
32 that connect the articulate edges 34 in the most representative
cross section of the cup 30. The fovea 38 and femoral head 39 can
be seen clearly in FIG. 3A. The fovea 38 is the recess or
non-spherical area of the cup 30 and is the part of the cup 30 that
gives a tactile feel and prevents displacement of the mating
surface 232 (shown in FIG. 15) of the shape-match hip guide 240
when the surface 232 is in mating surface contact with the cup 30,
as described in the following pages.
[0062] FIG. 4 illustrates a MRI image slice 10 exemplary of the
image contrast in the various image slices. The MRI imaging
parameters, including TR and TE values are set to make the ideal
contrast for the anatomical details of the inner surface 40 of the
cup 30 and, especially, the fovea 38.
[0063] As indicated in FIG. 1B, landmarks are identified on the 2D
medical images [BLOCK 110]. FIG. 5 illustrates a coronal CT image
slice 50 of the entire hip area 52 of the patient. This coronal
view of the entire hip area 52 is used for preoperative planning,
as described as follows. The acetabular cups 30 and the femoral
heads 39, along with other useful anatomical landmarks are clearly
visible in the CT image slice 50. The landmarks are identified and
used to determine a hip axis guide line that will be used in
conjunction with the 3D bone model in generating a 3D shape-match
hip guide model.
[0064] FIG. 6A is the same coronal CT image slice 50 of FIG. 5,
except a triangle 60 has been defined thereon extending between
certain landmarks [BLOCK 115]. Specifically, the preoperative
planning methodology begins by defining the triangle 60 across the
patient's anterior pelvic area. The triangle's three corners are
respectively located at the right anterior-superior ilium symphysis
("ASIS-R") 62, the left anterior-superior ilium symphysis
("ASIS-L") 64, and the pubic symphysis 66. Further, a pelvic axis
line 67 is defined to extend across the right teardrop 68 and the
left teardrop 69 of the pelvis [BLOCK 120]. Both legs of the
triangle 60 (i.e., the sides of the triangle 60 extending between
the pubic symphysis and a respective ASIS) can be seen to extend
immediately adjacent a proximal point 63 of the acetablular cup
30.
[0065] FIG. 6B is the same coronal CT image slice 50 of FIG. 6A,
except the triangle 60 has been divided at its height by a frontal
axis 70 [BLOCK 125]. As illustrated in FIG. 7, the frontal axis 70
extends between a midpoint 71 of the base line 72 of the triangle
60 that extends between the ASIS-R 62 and ASIS-L 64. The steps of
the preoperative planning described with respect to FIGS. 6 and 7
is used to check for pelvic tilt. For example, if the hip joint
cartilage is damaged, there will be pelvic tilt such that the
pelvic axis 67 and base line (the topmost line) 72 of the triangle
60 will not be substantially parallel.
[0066] FIG. 6C is the same coronal CT image slice 50 of FIG. 6B,
except a check is made to see if the frontal axis 70 and the pelvic
axis 67 are perpendicular to each other [BLOCK 130].
[0067] FIG. 6D is the same coronal CT image slice 50 of FIG. 6C,
except a measurement is conducted on the patient's surgical target
side 90 to determine the angle 92 between the target side line 94
and the pelvic axis 67 [BLOCK 135]. The target side line 94 is the
leg of the triangle 60 that extends between the pubic symphysis 66
and the anterior-superior ilium symphysis on the surgical target
side 90. Thus, since the surgical target side 90 in the example
provided in FIG. 6D is the left side of the patient, the target
side line 94 extends between the pubic symphysis 66 and the ASIS-L
64. As indicated in FIG. 6D, the triangle point at the pubic
symphysis 66 can be at the superior extent 66 of the pubic
symphysis in one embodiment. In other embodiments, the triangle
point at the pubic symphysis 66A can be at the inferior extent 66A
of the pubic symphysis. In one embodiment, what is considered an
appropriate value for the angle 92 in a healthy patient may be a
value provided by the surgeon based on the surgeon's examination of
the patient and medical images of the patient. In other
embodiments, the triangle point at the pubic symphysis 66A can be
at the inferior extent 66A of the pubic symphysis. In another
embodiment, what is considered an appropriate value for the angle
92 in a healthy patient may be a value provided by medical texts or
experts.
[0068] FIG. 6E is the same coronal CT image slice 50 of FIG. 6D,
except a 45 degree angle 100 is defined between an axis line 102
and the pelvic axis 67, the intersection of the axis line 100 and
the pelvic axis 67 being at the teardrop of the pelvis on the
surgical target side 90 [BLOCK 140]. Since the surgical target side
90 is on the patient's left side in this example, the left teardrop
69 is the intersection of the axis line 102 and the pelvic axis
67.
[0069] FIG. 6F is the same coronal CT image slice 50 of FIG. 6E,
except the 45 degree angle 100 has been added to the angle 92
defined in FIG. 6D and the axis line 102 has been moved to
intersect the target side line 94 in such a manner that the axis
line 102 projects generally along the axis of the femoral head 39
and the femoral neck on the surgical target side 90 [BLOCK 145].
The axis line 102 now generally defines a hip guide pin axis 202 as
detailed in the following discussion pertaining to FIGS. 13A and
13B. This hip guide pin axis 202 defines the inclination of the
prosthetic acetabular cup 210 as described in the following
discussion pertaining to FIGS. 13A and 13B.
[0070] II. POP with 3D Bone Model.
[0071] The 2D medical images can be used to generate a 3D bone
model of the area of the patient to undergo an arthroplasty
procedure. As shown in FIG. 7, the MRI image slices 10 are
segmented with a spline 120 along the inner surface 40 of the
acetabular cup 30, wherein the spline 120 includes control points
122. The segmented 2D images and the associated splines 120 and
control points 122 are used to generate a 3D bone model. The 3D
bone model depicts the bones in the present deteriorated condition
with their respective degenerated joint surfaces, which may be a
result of osteoarthritis, injury, a combination thereof, etc. FIG.
8 illustrates how the MRI image slices 10 are segmented with a
spline 120 that includes control points 122 at the inner surface 40
of the acetabular cup 30, near the anterior and the posterior
walls.
[0072] Computer programs for creating 3D computer generated bone
models from segmented 2D images include: Analyze from
AnalyzeDirect, Inc., Overland Park, Kans.; Insight Toolkit, an
open-source software available from the National Liabrary of
Medicine Insight Segmentation and Registration Toolkit ("ITK"),
www.itk.org; 3D Slicer, an open-source software available from
www.slicer.org; Mimics from Materialise, Ann Arbor, Mich.; and
Paraview available at www.paraview.org. Further, some embodiments
may use customized software such as OMSegmentation (renamed
"PerForm" in later versions), developed by OtisMed, Inc. The
OMSegmentation (or PerForm) software may extensively use "ITK"
and/or "VTK" (Visualization Toolkit from Kitware, Inc., available
at www.vtk.org). Some embodiments may include using a prototype of
OMSegmentation, and such may utilize InsightSNAP software.
[0073] As indicated in FIG. 1D, the 3D computer bone models are
generated from 2D medical images in the preoperative planning
stages of an arthroplasty procedure [BLOCK 150]. FIG. 9 depicts a
computer generated three dimensional surface model 130 compiled
from the various splines 120. The 3D surface model 130 includes a
portion of the pelvis and the contour surface 132 of the acetabular
cup 30, the contour surface 132 being a generally identical
replication of the inner surface 40 of the patient's acetabular cup
30.
[0074] FIG. 10 is an enlarged view of the acetabular cup 30 of the
3D surface model 130 of FIG. 13, wherein the fovea 38 is more
clearly depicted. As already noted, the fovea 38 is the recess or
non-spherical area of the inner surface 40 of the cup 30 and is the
part of the cup 30 that gives a tactile feel and prevents
displacement of the mating surface 232 (shown in FIG. 15) of the
shape-match hip guide 252 when the surface 232 is in mating surface
contact with the cup 30, as described in the following paragraphs.
In one embodiment, the methodology includes checking the surface
features of the fovea 38 to see if the trending of the outlines are
consistent based on the MRI image analysis.
[0075] As can be understood from FIG. 8, the medical imaging scan
angle described in FIGS. 3A and 3B can limit the accuracy of the
anterior and posterior wall segmentation. As a result, the
corresponding 3D model 130 has inaccuracies in the anterior and
posterior regions of the cup 30. These inaccurate areas of the 3D
model 130 are enclosed by the rectangles 160, 161 in FIG. 11, which
is the same enlarged view of the cup 30 of the 3D model 130 of FIG.
10. These inaccurate areas may be subjected to an "overestimation"
process as described in U.S. patent application Ser. No.
12/505,056, filed Jul. 17, 2009 and hereby incorporated by
reference in its entirety into the present application. By
overestimating the inaccurate areas, the portions of the mating
surface 232 of the shape-match hip guide 252 corresponding to the
inaccurate areas will not make surface contact the patient's cup
inner surface corresponding to the inaccurate regions when the
mating surface 232 matingly engages other portions of the patient's
inner cup surface [BLOCK 155].
[0076] FIG. 12A is the 3D surface model 130 of FIG. 9 shown in the
same coronal view used in FIGS. 6A-6F. The planning process
explained with respect to the coronal CT scan 50 of FIGS. 6A-6F
will now be replicated with respect to the 3D model 130. Thus, as
shown in FIG. 12A, a plane 170 connects the proximal point of the
pubic symphysis 66 with a proximal point 63 of the acetablular cup
30 [BLOCK 165]. Thus, the plane extends from the pubic symphysis 66
to a point 63 near the fovea, thereby replicating the geometry of
the planning step described with respect to FIG. 6A.
[0077] FIG. 12B is the 3D surface model 130 of FIG. 12A further
along in the planning process replication. As shown in FIG. 12B, a
second plane 180 is provided such that the second plane 180
intersects the first plane 170 at the proximal point 63 of the
acetablular cup 30 [BLOCK 170]. Thus, the second plane 180 is
oriented to mimic the trajectory of the axis 102 of FIG. 6F,
thereby replicating the geometry of the planning step described
with respect to FIG. 6F.
[0078] FIG. 12C is the 3D surface model 130 of FIG. 12B with the
same planes 170, 180, but rotated so as to show the model 130 from
a more inferior and lateral perspective. As illustrated in FIG.
12C, the second plane 180, which may be called an inclination plane
180, extends through the center point of the acetabular cup 30. In
one embodiment, the view of the model 130 provided in FIG. 12C may
be considered perpendicular to the coronal view depicted in FIG.
12B.
[0079] FIG. 12D is the 3D surface model 130 of FIG. 12C with the
same planes 170, 180 and further including a third plane 200, which
may be called the anteversion plane 200 [BLOCK 175]. As illustrated
in FIG. 12D, the anteversion plane 200 is positioned to evenly
divide the anterior and posterior walls of the acetabular cup 30
and also pass through the center of the acetabular cup 30. The
anteversion plane 200 is perpendicular to the 45 degree line plane
(i.e., the inclination plane 180). Also, the anteversion plane 200
divides the inclination plane 180 in half. The intersection of the
two planes 180, 200 defines an axis line 202 that approximates a
center axis of the acetabular cup 30.
[0080] FIG. 13A illustrates the 3D surface model 130 of FIG. 12D
further rotated with the same planes 170, 180, 190 and further
including a 3D model of a candidate prosthetic acetabular cup 210
occupying the acetabular cup 30 of the 3D surface model 130 [BLOCK
180]. The prosthetic cup 210 is positioned relative to the
inclination and anteversion planes 180, 200 such that a center axis
of the cup is coaxial with the axis 202 defined by the intersection
of the planes 180, 200. Thus, the placement of the 3D model of the
prosthetic cup 210 in the cup 30 of the 3D surface model 130
relative to the axis 202 results in the preoperative planning of
the surgical placement of an actual prosthetic acetabular cup in
the actual acetabular cup of the patient.
[0081] FIG. 13B illustrates the 3D surface model 130 of FIG. 13A
wherein the planes 180, 190 have been removed and a 3D model of a
directional rod 220 has been coupled to the interior surface of the
3D model of the candidate prosthetic acetabular cup 210 occupying
the acetabular cup 30 of the 3D surface model 130. The directional
rod 220 is positioned so as to be coaxial with the axis 202 defined
by the intersection of the planes 180, 200 in FIG. 13A. Thus, the
placement of the 3D model of the directional rod 220 to be coaxial
with the axis 202 defined by the intersection of the planes 180,
200 in FIG. 13A replicates the inclination angle from the
preoperative planning depicted in FIG. 6F.
[0082] FIG. 14 illustrates the 3D surface model 130 of FIG. 13B
wherein all the planes 170, 180, 190 have been removed, the 3D
model of the directional rod 220 is still coaxially positioned
relative to the axis 202 as described with respect to FIG. 13B and
the 3D model of the candidate prosthetic acetabular cup 210 has
been replaced in the acetabular cup 30 of the 3D surface model 130
by a 3D model of a semi-hemispherical blank or mold 230 [BLOCK
185]. The hemispherical surface 232 of the semi-hemispherical blank
or mold 230 extends along the surface contour of the inside surface
of the acetabular cup 30 of the 3D surface model 130. As a result,
the hemispherical surface 232 of the semi-hemispherical blank or
mold 230 is caused to assume a surface contour that is a negative
of the surface contour of the inside surface of the acetabular cup
30 of the 3D surface model 130.
[0083] FIG. 15 illustrates the completed 3D model of a shape-match
hip guide 240 including the directional rod 220 extending from the
semi-hemispherical blank or mold 230, which has the hemispherical
surface 232 that is a negative of the surface contour of the inside
surface of the acetabular cup 30 of the 3D surface model 130. Thus,
when an actual shape-match hip guide 252 is manufactured to match
the model guide 240, the shape-match hemispherical surface of the
actual hip guide 252 will matingly interdigitate with the
corresponding inner surface of the patient's acetabular cup and
cause the directional rod 220 to be extend along a directional line
that mimics the axis 202 preoperatively planned according to the
steps outlined in FIGS. 6A-6F and 12A-14.
[0084] As illustrated in FIG. 1E, the 3D model shape-match hip
guide 240 is sent to a CNC machine 13 or other suitable prototyping
machine in order to machine or produce a physical shape-match hip
guide 252 [BLOCK 195-200]. Data associated with the 3D model
shape-match hip guide 240 can be transferred to a storage medium
(e.g., compact disc, digital video disc, flash drive) and
physically delivered to a manufacturer or the data can be
electronically sent via a network connection to a manufacturer.
Alternatively, the computer that generates the 3D model shape-match
hip guide 240 can be directly connected to a CNC machine 13 for
machining of the physical shape-match guide 252. The mating surface
232 of the hip guide 252 can be machined by an additive process,
such as by a rapid prototyping machine, or by a reductive process,
such as by machining in a CNC machine 13. In the case of a
machining process in a CNC machine 13 or similar device, a guide
blank 51 will be inputted into the CNC machine 13 and the machine
will generate the customized mating surface 232 of the blank or
mold 51.
[0085] In one embodiment, the POP procedure is a manual process,
wherein computer generated 3D bone models are manually manipulated
by a person sitting in front of a computer and visually observing
the bone model and the generation of the model shape-match hip
guide 240 via the computer controls. In one embodiment, the bone
modeling process is generally or completely automated. In other
words, a computer program may analyze the bone models and their
degenerated surface to determine the steps involved in the
preoperative planning process of the procedure (e.g., a computer
may perform the "overestimation" process and generate an
appropriate bone model).
[0086] III. Operating Procedure.
[0087] Once the POP phase of the procedure is complete and a
physical shape-match guide 252 is generated, a surgeon can perform
the arthroplasty procedure with the shape-match guide 252.
[0088] A. Employing the Shape-Match Hip Guide.
[0089] A first embodiment of a method of employing the guide 252
will now be discussed. In preparation for the arthroplasty
procedure, the region of a patient's body to undergo the procedure
is prepared for surgery [BLOCK 205]. The preparation can include a
surgeon or a surgical assistant making the appropriate incisions
into the target area of the patient's body 12. Once the target area
12 is accessible for the procedure, the actual shape-match hip
guide 252 is matingly received in the patient's acetabular cup
[BLOCK 210]. FIGS. 16A and 16B are inferior-lateral views of a
patient's actual hip region 250 including the surgical target
acetabular cup 251 in the process of receiving an actual prosthetic
acetabular cup 260. As shown in FIG. 16A, an actual shape-match hip
guide 252 is matingly received in the acetabular cup 251. The hip
guide 252 includes a directional rod 253 extending from a
semi-hemispherical head 254 having a hemispherical surface that is
a surface negative of the surface contour of the inside surface of
the surgical target acetabular cup 251. The guide 252 is
manufactured to be generally an exact physical replica of the
preoperatively planned 3D model guide 240 of FIG. 15.
[0090] As can be understood from FIGS. 16A and 16B, the mating
surface of the head 254 of the guide 252 is interdigitated with the
inner surface of the acetabular cup 251 to matingly engage with the
inner surface such that the rod 253 extends from the cup 251 as
preoperatively planned and discussed with respect to FIG. 15. The
surgeon estimates the orientation of the rod 253 as depicted in
FIG. 16A and then removes the guide 252 from the cup 251 [BLOCK
215]. The surgeon then reams the acetabular cup 251 [BLOCK 220].
The surgeon tries to replicate the same orientation of the rod 253
shown in FIG. 16A with the reamer [BLOCK 225].
[0091] As can be understood from FIG. 16B, once the reaming is
complete, the surgeon then inserts the prosthetic cup 260 into the
acetabular cup 251 via an impactor shaft 262 supporting the cup 260
[BLOCK 230]. While using the shaft 262 to drive the prosthetic cup
260 into the acetabular cup 251, the surgeon tries to replicate the
same orientation of the rod 253 shown in FIG. 16A with the impactor
rod 262 used in FIG. 16B [BLOCK 235]. The surgeon then removes the
impactor from the target area [BLOCK 236].
[0092] B. Employing the Shape-Match Hip Guide with an Outrigger
Alignment Device.
[0093] A second embodiment of a method employing the guide 252 will
now be discussed. In preparation for the arthroplasty procedure,
the region of a patient's body to undergo the procedure is prepared
for surgery [BLOCK 240]. The preparation can include a surgeon
making the appropriate incisions into the target area of the
patient's body. Once the target area is accessible for the
procedure, the actual shape-match hip guide 252 is matingly
received in the patient's acetabular cup [BLOCK 245]. FIGS. 17A and
17B are views of the patient's actual hip region 250 including the
surgical target acetabular cup 251 in the process of receiving an
actual prosthetic acetabular cup via another method in conjunction
with an outrigger device for employing the actual shape-match hip
guide 252. As shown in FIGS. 17A and 17B, the actual shape-match
hip guide 252 is matingly received in the acetabular cup 251 as
described with respect to FIG. 16A, and a first coupler half 270 of
the outrigger device extends over the rod 253.
[0094] FIGS. 17C and 17D are views of the patient's actual hip
region 250 further illustrating the process of employing the
outrigger device 300 with the shape-match hip guide 252. As shown
in FIGS. 17C and 17D, a second coupler half 290 is coupled to the
first coupler half 270, and a reference rod 292 extends through the
second coupler half 290 to be imbedded in the bone of the superior
hip region 250 [BLOCK 250-255]. The first and second coupler halves
270, 290 and the reference rod 292 are the major components of the
outrigger device 300. The reference rod 292 is held parallel to the
rod 253 of the guide 252 by the outrigger device 300 [BLOCK
255].
[0095] FIG. 17E is a view of the patient's actual hip region 250
further illustrating the process of employing the outrigger device
300 with the shape-match hip guide 252. As shown in FIG. 17E, the
hip guide 252 is removed from the acetabular cup 251 and the
outrigger device 300 while maintaining the outrigger device 300 in
the same orientation and location shown in FIG. 17E via the
reference rod 292 being imbedded in the bone of the patient's hip
region 250 [BLOCK 260]. Subsequent to reaming the acetabular cup
251 wherein the reaming angle of the reamer may be guided by the
coupler 270, the prosthetic acetabular cup 260 is then placed in
the patient's acetabular cup 251 [BLOCK 265-270]. The outrigger
device 300 only provides one angle (i.e., the inclination angle),
the surgeon having to determine the other angle (i.e., the
anteversion angle).
[0096] FIG. 17F is a view of the patient's actual hip region 250
further illustrating the process of employing the outrigger device
300 with the shape-match hip guide 252. As shown in FIG. 17F, the
impactor rod 262 is placed against the inside of the prosthetic cup
260 and received in the first coupler half 270 previous occupied by
the rod 253 of the hip guide 252 as discussed with respect to FIGS.
17A and 17B [BLOCK 275]. The outrigger device 300 maintains the
impactor rod 262 in the same orientation and location of the rod
253 of the hip guide 252 on account of the reference rod 292 being
imbedded in the bone of the patient's hip region 250. As already
noted, the outrigger device 300 only provides one angle (i.e., the
inclination angle), the surgeon having to eyeball the other angle
(i.e., the anteversion angle).
[0097] FIG. 17G is a view of the patient's actual hip region 250
illustrating the impactor rod 262 ready for impaction of the
prosthetic cup 260 into the patient's acetabular cup 251 after
removal of the outrigger device 300 from the impactor rod 262 after
the outrigger device 300 was used to align the impactor rod 262 as
described with respect to FIG. 17F. The prostethic acetabular cup
is impacted into the patient's acetabular cup [BLOCK 280].
Following impaction, the impactor and outrigger device are removed
from the patient's acetabulum [BLOCK 281].
[0098] C. Employing the Shape-Match Hip Guide with a Silo Alignment
Device.
[0099] A third embodiment of a method employing the guide 252 will
now be discussed. FIGS. 18A and 18B are views of the patient's
actual hip region 250 illustrating the process of employing a silo
device 350 with the shape-match hip guide 252. In preparation for
the surgical procedure, a surgeon or a surgeon's assistant will
prepare the hip region of the patient for the procedure [BLOCK
285]. The preparation may include making an incision and generally
preparing the patient's acetabulum to receive a prosthetic
shape-match hip guide. As shown in FIG. 18A, the shape-match hip
guide 252 is first matingly engaged with the patient's acetabular
cup 251 as previously described herein [BLOCK 290]. As indicated in
FIG. 18B, the barrel 351 of the preassembled silo 350 is slid over
the rod 253 of the guide 252, and the three silo legs 350A-C
extending from the silo barrel 351 are positioned for anchoring to
the bone of the patient's hip region 250 [BLOCK 295].
[0100] FIGS. 18C and 18D are views of the patient's actual hip
region 250 further illustrating the process of employing a silo
device 350 with the shape-match hip guide 252. As shown in FIG.
18C, the three silo legs 350A-C extending from the silo barrel 351
are anchored to the bone of the patient's hip region 250 via pins
370A-C, thereby securing the silo barrel guide hole 372 in the
alignment of the guide rod 253 [BLOCK 295]. The barrel 351 includes
a keyed side portion 374 that can be slidingly removed from the
rest of the barrel 351 to reveal a side access slot 376 [BLOCK
300]. As indicated in FIG. 18D, the keyed side portion 374 has been
removed from the rest of the barrel 351 to reveal the side access
slot 376, and the shape-match hip guide 252 has been removed from
engagement with the barrel 351 and removed from the patient's
acetabular cup 251, thereby leaving the silo 350 in a fixed
position properly aligned to guide an impactor. The silo device 350
may then be used to guide the reamer during the reaming of the
acetabular cup 251 [BLOCK 305].
[0101] FIGS. 18E and 18F are views of the patient's actual hip
region 250 further illustrating the process of employing a silo
device 350 with the impactor 262. As shown in FIG. 18E, with the
three silo legs 350A-C extending from the silo barrel 351 and
anchored to the bone of the patient's hip region 250 via pins
370A-C, the prosthetic acetabular cup 260 is inserted into the
patient's acetabular cup 251, which has already been reamed [BLOCK
315]. As illustrated in FIG. 18F, the impactor 262 enters the guide
hole 372 of the silo barrel 351 via the side access slot 376 and is
held in place against the prosthetic cup 260 by reinstallation of
the keyed side portion 374 into the slot 376 [BLOCK 320]. As a
result, the impactor 262 is held against the prosthetic cup 260 in
proper alignment as established by the rod 253 of the hip guide 252
in reference to FIG. 18C. The impactor 262, which is slidingly
retained in the guide hole 372, may then be impacted against the
prosthetic cup 260 to seat the cup 260 in the patient's acetabular
cup 251 [BLOCK 325]. As indicated in FIG. 18G, the silo 350 and
impactor 262 can then be removed, leaving behind the implanted
prosthetic acetabular cup [BLOCK 330].
[0102] As can be understood from a review of the three embodiments
discussed with respect to FIGS. 16A-16B, 17A-17G, and 18A-18F, the
embodiment of FIGS. 16A-16B may be considered a directional guide
only, the embodiment of FIGS. 17A-17G may be considered a
directional guide plus an outrigger device, and the embodiment of
FIGS. 18A-18F may be considered a direction guide plus a silo
device.
[0103] IV. Shape-Match Guide Head.
[0104] FIG. 19 illustrates three different embodiments of the
custom fit mating head of the prosthetic hip guide 252 described
herein. The different embodiments have the following benefits. A
50% and 33% rim overflow models make less fitment with
indecisiveness. Non-overflow models make stronger and unique
positioning because of the exclusion of the inaccurate anterior and
posterior regions for the mating surface at the segmentation
process illustrated in FIG. 8.
[0105] FIG. 20 depicts four different potential mating surface
regions that may or may not be integrated into the mating surface
of the head of the hip guide 252 described herein. Area A is
irregular and somewhat unreliable as a mating surface. Area B is a
suitable mating surface. Area C is illustrative of the fovea. Area
D is considered an extra opportunity for a mating surface of the
head of the hip guide.
[0106] Various modifications and additions can be made to the
exemplary embodiments discussed without departing from the spirit
and scope of the presently disclosed technology. For example, while
the embodiments described above refer to particular features, the
scope of this disclosure also includes embodiments having different
combinations of features and embodiments that do not include all of
the described features. Accordingly, the scope of the presently
disclosed technology is intended to embrace all such alternatives,
modifications, and variations together with all equivalents
thereof.
* * * * *
References