U.S. patent application number 12/888027 was filed with the patent office on 2011-01-20 for guide pin placement for hip resurfacing.
This patent application is currently assigned to WRIGHT MEDICAL TECHNOLOGY, INC.. Invention is credited to Brad L. Penenberg.
Application Number | 20110015642 12/888027 |
Document ID | / |
Family ID | 38972406 |
Filed Date | 2011-01-20 |
United States Patent
Application |
20110015642 |
Kind Code |
A1 |
Penenberg; Brad L. |
January 20, 2011 |
GUIDE PIN PLACEMENT FOR HIP RESURFACING
Abstract
An instrument for guide pin placement in a femoral head and neck
of a patient, the instrument having a reference pin guide member
and a retrograde pin guide member adjustably attached to the
reference pin guide member. The reference guide pin member has a
bore configured for use in positioning and guiding an external
reference pin. The retrograde pin guide member has a plurality of
retrograde pin bores for use in positioning and guiding a
retrograde reference pin into the femoral neck and head of the
patient using a retrograde approach. If an initial retrograde
reference pin is not positioned properly, one of the plurality of
retrograde pin bores is used to insert another retrograde reference
pin in a more desirable position using a retrograde approach.
Inventors: |
Penenberg; Brad L.; (Beverly
Hills, CA) |
Correspondence
Address: |
DUANE MORRIS LLP - Philadelphia;IP DEPARTMENT
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103-4196
US
|
Assignee: |
WRIGHT MEDICAL TECHNOLOGY,
INC.
Arlington
TN
|
Family ID: |
38972406 |
Appl. No.: |
12/888027 |
Filed: |
September 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11738183 |
Apr 20, 2007 |
7819879 |
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12888027 |
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60793795 |
Apr 21, 2006 |
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Current U.S.
Class: |
606/96 |
Current CPC
Class: |
A61B 17/175 20130101;
A61B 17/1721 20130101 |
Class at
Publication: |
606/96 |
International
Class: |
A61B 17/56 20060101
A61B017/56 |
Claims
1. An instrument for guide pin placement in a femoral head and a
femoral neck of a patient comprising: a reference pin guide member
having a bore configured for use in positioning and guiding an
external reference pin, a retrograde pin guide member for use in
positioning and guiding a retrograde reference pin, said retrograde
pin guide member having a plurality of retrograde pin bores
positioned and configured for use in positioning and guiding a
retrograde reference pin into the femoral neck and the femoral head
of the patient using a retrograde approach, and said retrograde pin
guide member adjustably attached to said reference pin guide
member, said adjustable attachment configured to provide selective
adjustment and setting of a position of said external reference pin
and said retrograde reference pin relative to one another.
2. The instrument of claim 1, wherein said plurality of pin bores
are distributed on said retrograde pin guide member such that said
pin bores are spaced apart by a substantially uniform distance from
adjacent ones of said pin bores.
3. The instrument of claim 1, wherein said pin bores are fixed in
parallel to one another.
4. The instrument of claim 1, wherein said adjustable attachment
further comprises an up-down adjustment means.
5. The instrument of claim 1, wherein said adjustable attachment
further comprises a rotational adjustment means.
6. The instrument of claim 4, wherein said adjustable attachment
further comprises a rotational adjustment means, and wherein said
up-down and rotational adjustment means are provided by a rod
member slidingly engaged in a sleeve member, and a selective
locking means for selectively locking said rod member in a set
relative to said sleeve member.
7. The instrument of claim 6, wherein said sleeve member depends
downward from said reference guide pin member and said rod member
extends upward from said retrograde guide pin member.
8. The instrument of claim 4, wherein said adjustable attachment
further comprises a flexion-extension adjustment means, said
flexion-extension adjustment means positioned between said
retrograde guide pin member and said rod member to thereby allow
selection of a flexion-extension orientation of said retrograde pin
guide member.
9. The instrument of claim 8, wherein said flexion-extension means
is a universal joint.
10. The instrument of claim 8, further comprising a
flexion-extension locking means for selectively locking said
retrograde pin guide member in a selected position relative to said
instrument.
11-20. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority to
Application Ser. No. 60/793,795, filed Apr. 21, 2006, which is
pending.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable
FIELD OF THE INVENTION
[0003] The present invention relates to hip surgery, and more
particularly to placement of pin guides for use in hip
resurfacing.
BACKGROUND OF THE INVENTION
[0004] In conventional total hip arthroplasty, the head and neck of
the natural femur are removed and replaced with an artificial
femoral head and neck. The artificial head and neck are attached to
a stem that is secured in the intramedullary canal of the femur.
Over the years, total hip arthroplasty has had excellent clinical
success. However, various conditions can arise in which it becomes
necessary to perform revision surgery on the hip joint. The
presence of the implant in the femur can sometimes result in stress
shielding, osteolysis or other conditions that lead to the gradual
loss of bone stock and loosening of the implant. An infection may
require removal of the implant. Additionally, the useful life of an
artificial hip joint is about 15 to 25 years, and a young hip
patient will therefore typically require a revision surgery at some
point in his or her lifetime.
[0005] When performing a revision hip procedure, it is desirable to
have as much bone stock available as possible. Accordingly, efforts
have been made to develop surface replacement arthroplasty
procedures that preserve bone stock in hip procedures. In surface
replacement arthroplasty of the hip, the natural femoral head and
neck are preserved, but are resurfaced to receive an artificial
femoral head. An example of such a femoral head for use in surface
replacement arthroplasty procedures is shown in FIGS. 1, 2, 7 and 8
of U.S. Pat. No. 6,156,069 Amstutz), which is incorporated herein
by reference. As shown in FIG. 1 of Amstutz, the femoral head
includes a central tapered stem and a spherical surface replacement
portion. An inner surface of the prosthesis covers the reamed bone
of the femoral head, while the central tapered stem is centered in
the femoral head and neck. Femoral heads of the type shown in
Amstutz are available from Wright Medical Technology, Inc., 5677
Airline Road, Arlington, Tenn. 38002.
[0006] In one technique of surface replacement arthroplasty, the
surfacing of the femoral head and the resulting positioning of the
femoral component are based on the placement of a guide pin in the
femoral neck and head. The surgeon opens the hip, dislocates the
femur, and then centers the guide pin in the femoral head and neck
using an antegrade approach. The guide pin protrudes from the
femoral head, and is used to orient surfacing instruments. Amstutz
provides views of a guide pin centered in the head and neck of a
femur (FIGS. 9 and 10 of U.S. Pat. No. 6,156,069), Amstutz further
describes instruments and techniques for accurate placement of the
guide pin, along with use of the guide pin to surface the femoral
head for receipt of the femoral implant.
[0007] Because surfacing of the femoral head is based on the
position of the guide pin, accurate placement of the guide pin in
the femoral head and neck is critical in surface replacement
arthroplasty techniques such as those described in Amstutz.
However, assessing the femoral head, neck relationship
intra-operatively after dislocation and then placing the guide pin
in an antegrade fashion can be somewhat complicated and unreliable.
A relatively large exposure is required, particularly for
inexperienced surgeons. A large exposure increases bleeding, pain
and the risk of infection.
[0008] The present invention improves on prior art surface
replacement arthroplasty by incorporating a retrograde approach for
centering the guide pin. Retrograde approaches are used in hip
fracture fixation using plates and a cannulated lag screw. A guide
pin is placed retrograde into the desired position within the
femoral neck and head. The procedure takes about ten minutes and is
accomplished with the patient in a supine position using image
guidance (i.e. C-arm). The guide pin is then used to place the
cannulated lag screw. An example of one such femoral fracture
fixation technique is discussed in U.S. Pat. No. 4,522,201
(Tongue).
[0009] Retrograde approaches have also been used to drive
resurfacing instruments located in the hip via a driveshaft located
in the femoral head and neck. The resurfacing instruments are
introduced through a main incision, and are connected to the end of
a driver that is inserted retrograde through a channel formed in
the femoral head and neck. U.S. Patent Application Publication
2003/0028196 (Bonutti) teaches a technique for reaming, the
acetabulum using a drive shaft disposed in the femoral head and
neck (see particularly FIGS. 68-73). U.K. Patent 2,372,702 (McMinn)
teaches a similar technique for resurfacing the femoral head (see
particularly FIGS. 4-6). As shown in FIG. 2 of McMinn, a guide-wire
is inserted through the lateral aspect of the femur and up into the
femoral head and neck, with the desired position obtained using
either an external alignment jig, a navigation system, or x-ray
control. Following insertion of the guide-wire, the femoral head is
dislocated from the acetabulum. The guide-wire is then
over-drilled, producing a canal, typically of 8.5 mm in diameter,
up the femur, femoral neck, and exiting through the zenith of the
femoral head. Once the canal has been completed, the drill is
removed and preparation of the femoral head is then commenced. The
first step in femoral head preparation, shown in FIG. 4 of McMinn,
is the insertion of a drive rod up the canal in the femur. An
appropriately sized sleeve cutter of generally hollow cup shape is
inserted through the main incision and releasably secured to the
end of the drive rod, which extends out of the top of the femoral
head. The rod is driven by any suitable power means and the cutter
advanced down onto the femoral head so that the periphery thereof
is thus resected.
[0010] The cutter is then unscrewed and removed via the main
incision, with the drive rod being removed via the femoral neck
incision. The next method step, shown in FIG. 5, involves the
application of a sleeve resection guide to the periphery of the
femoral head, with the guide being inserted through the main
incision. An appropriate amount of zenith of the femoral head, as
determined by the positioning of the guide, is then resected using
a powered cutting blade, thereby maintaining the patient's correct
leg length. After completion, the guide is removed through the main
incision. The drive rod is then again inserted through the femoral
neck incision and up along the canal so that the threaded end of
the drive rod extends from the top of the resected femoral head. As
indicated in FIG. 6 of McMinn, an appropriately sized chamfer
cutter is then inserted through the main incision and attached to
the end of the drive rod. The drive rod is moved down the canal so
that the cutter is brought down onto the femoral head so that when
the drive rod is powered to rotate, the cutter similarly rotates
and cuts the femoral head to provide a chamfer thereon. Once the
chamfering of the femoral head shown in FIG. 6 has been carried
out, the femoral head preparation is complete.
[0011] Prior art techniques such as Roman and McMinn form a large
hole in the lateral cortex and into the head and neck for direct
retrograde access of cutting instruments. Such large holes may lead
to fracture in the sub-trochanteric region. Additionally, the
procedures are not done preoperatively, and do not provide
teachings concerning the placement of guide pins for use in surface
replacement arthroscopy of the type described in Amstutz.
[0012] As for as the inventor is aware, retrograde approaches have
not been used to center guide pins for use in surface replacement
arthroplasty. There is thus a need for the novel approach for pin
guide placement presented herein.
OBJECTS AND SUMMARY OF THE INVENTION
[0013] It is an object of the invention to provide a less invasive
approach for establishing the position of a guide pin for use in a
femoral resurfacing procedure.
[0014] It is an object of the invention to provide a retrograde
approach for establishing the position of a guide pin for use in a
femoral resurfacing procedure.
[0015] It is an object of the invention to provide guide pin
placement instruments and procedures that reduce exposure, risk of
mal-alignment, soft tissue trauma, bleeding, pain, time of recovery
and other factors associated with total or partial hip
resurfacing.
[0016] The objects and advantages of the invention are achieved by
providing an instrument for guide pin placement in a femoral head
and a femoral neck of a patient, the instrument comprising
generally a reference pin guide member and a retrograde pin guide
member adjustably attached to the reference pin guide member. The
reference guide pin member has a bore configured for use in
positioning and guiding an external reference pin. The retrograde
pin guide member is used to position and guide a retrograde
reference pin. The retrograde pin guide member has a plurality of
retrograde pin bores positioned and configured for use in
positioning and guiding a retrograde reference pin into the femoral
neck and the femoral head of the patient using a retrograde
approach. The adjustable attachment is configured to provide
selective adjustment and setting of a position of the external
reference pin and the retrograde reference pin relative to one
another.
[0017] The plurality of pin bores are preferably distributed on the
retrograde pin guide member such that the pin bores are spaced
apart by a substantially uniform distance from adjacent ones of the
pin bores. In one embodiment, the pin bores are fixed in parallel
to one another.
[0018] The adjustable attachment preferably includes an up-down
adjustment means and/or a rotational adjustment means. The up-down
and rotational adjustment means can be provided by a rod member
slidingly engaged in a sleeve member, and a selective looking means
for selectively locking the rod member in a set position relative
to the sleeve member. In one embodiment, the sleeve member depends
downward from the reference guide pin member and the rod member
extends upward from the retrograde guide pin member. The adjustable
attachment can include a flexion-extension adjustment means, the
flexion-extension adjustment means being positioned between the
retrograde guide pin member and the rod member to allow selection
of a flexion-extension orientation of the retrograde pin guide
member. The flexion-extension means is can be a universal joint. A
flexion-extension locking means can be provided for use in
selectively locking the retrograde pin guide member in a selected,
position relative to the instrument.
[0019] Methods of setting a guide pin in a femoral neck of a
patient for use in resurfacing a femoral head in a hip procedure
are also provided. In one embodiment, a retrograde reference pin is
inserted into the femoral neck from a retrograde approach until a
distal end of the retrograde reference pin pierces a femoral cortex
of the femur, thus firming a guide pin track in the femoral neck
and a guide pin opening through the femoral cortex. The retrograde
reference pin is removed from the femur to thereby expose the guide
pin track and the guide pin opening. The guide pin opening is
located, and a definitive guide pin is inserted antegrade through
the guide pin opening and into the guide pin track. The definitive
guide pin is used to resurface the femoral head.
[0020] Before inserting, the retrograde reference pin, an external
reference pin can be laid along an exterior of the patient in
general alignment with the femoral neck for use as a varus-valgus
reference guide during formation of the guide pin track. The
external reference pin, femoral neck and femoral head are viewed
under external imaging, in order to determine a desired location of
the guide pin track. The external reference pin as a varus-valgus
reference guide during formation of the guide pin track.
[0021] After forming the guide pin track, the position of the
retrograde reference pin in the femoral neck is studied under
external imaging in order to verify whether the guide pin track is
properly oriented. If the guide pin track is not properly oriented,
a second retrograde reference pin is inserted into the femoral neck
from a retrograde approach until a distal end of the second
retrograde reference pin pierces a femoral cortex of the femur to
thereby form a second guide pin track in the femoral neck and a
second guide pin opening through the femoral cortex.
[0022] The retrograde reference pin can be inserted before opening
the hip of the patient, while the step of inserting the definitive
guide pin into the guide pin track occurs after opening and
dislocating the hip of the patient. The opening, of the hip is
preferably accomplished through a minimal incision of about 8 cm or
less.
[0023] In total or partial hip resurfacing, it is desirable to use
a retrograde approach to centering the guide pin because once the
center of the neck has been established, the operation is much
easier. By using the techniques described herein to shoot a pin
through the lateral femoral cortex of the femur under flouro, a
surgeon is able to find the neck easily in two planes.
[0024] The foregoing and other objects, features, aspects and
advantages of the invention will become more apparent from the
following detailed description of the invention when considered in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a front-side perspective view of one preferred
embodiment of a method of centering a guide pin according to the
invention.
[0026] FIG. 2 is a fluoroscopy view of a method of centering a
guide pin according to the invention.
[0027] FIG. 3 is a representative view of use of a guide pin
opening and track to establish a definitive guide pin in the head
and neck of the femur.
[0028] FIG. 4 is a preferred embodiment of one guide pin placement
instrument of the invention.
PREFERRED EMBODIMENTS OF THE INVENTION
[0029] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings which
form a part hereof, and in which are shown by way of illustration
specific embodiments in which the invention may be practiced. It is
to be understood that other embodiments may be utilized and
structural changes may be made without departing from the scope of
the present invention.
[0030] As shown in FIGS. 1-4, the invention provides methods and
instruments for precise positioning of a guide pin for use in
resurfacing a femoral head and neck. As will be described in
further detail below, internal imaging (currently, CRM or
fluoroscopy images) and a retrograde approach are used to select
and establish the position of a guide pin track 112 in the femoral
head 102 and neck 101 prior to opening the hip. As indicated in
FIG. 3, the hip is then opened (preferably using a minimally
invasive approach, such as an incision of 8 cm or less), a
definitive guide pin 192 is inserted antegrade into the guide pin
track 112, and the definitive guide pin 192 is used to carry out
the resurfacing procedure.
[0031] FIGS. 1 and 4 show one embodiment of a preferred guide pin
placement instrument 1 for use in carrying out the procedures
described herein. The instrument 1 features a reference pin guide
member 10 having a retrograde pin bore 52 for use in positioning
and guiding an external reference pin 91 and a retrograde pin guide
member 50 for positioning and guiding a retrograde reference pin
92. The guide pin placement instrument 1 is preferably provided
with adjustment mechanisms that allow for selective adjustment and
setting of the position of the external reference pin 91 and the
retrograde reference pin 92 relative to one another. The adjustment
mechanisms allow the instrument 1 to accommodate patients of
various sizes, and also provide for fine-tuning the position of the
external reference pin 91 and retrograde reference pin 92.
Adjustments preferably include up/down, rotation (varus/valgus),
and flexion/extension. In the embodiment shown in FIG. 4, up/down
and rotational adjustments are provided by a rod member 30
slidingly engaged in a sleeve member 20. A selective locking means
60, such as a set screw 60, is provided for selectively locking the
rod member 30 in a set position relative to the sleeve member 20.
The position of the retrograde reference pin 92 is adjusted upward
(anteriorly) relative to the external reference pin 91 by sliding
the rod member 30 further into the sleeve member 20, and is
likewise adjusted downward (posteriorly) by sliding the rod member
30 in the opposite direction. Rotating the rod member 30 within the
sleeve 20 allows for rotational varus/valgus adjustment of the
retrograde reference pin 92. As discussed in further detail below,
the varus/valgus adjustment of the retrograde reference pin 92 is
preferably made with reference to the external reference pin 91
while working under external imaging. When a desired position is
attained, the set screw 60 is threaded down to lock the rod member
30 in position in the sleeve member 20. In the embodiment shown in
FIG. 4, the sleeve member 20 depends downward from the reference
guide pin member 10 while the rod member 30 extends upward from the
retrograde guide pin member 50. However, the orientation of the rod
30 and sleeve 29 members could be reversed.
[0032] In the instrument 1 embodiment shown in FIG. 4,
flexion/extension adjustment is provided by a flexion-extension
adjustment means 40 that is positioned between the retrograde guide
pin member 50 and the rod member 30. The flexion-extension
adjustment means 40 allows the surgeon to select the
flexion-extension orientation of the retrograde pin guide member
50, and thereby fine-tune the orientation of the retrograde
reference pin 92. In a preferred embodiment, the flexion-extension
adjustment means 40 is a universal, joint, such that adjustments
can be made in all dimensions. The simplest form of universal joint
would be a ball-and-socket joint. Alternatively, the
flexion-extension means 40 can be a hinge joint, such that
adjustments cart be made only in one plane. A flexion-extension
locking means 70, such as a set screw 79, is preferably provided
tot selectively locking the retrograde pin guide member 50 in a
selected, position relative to the instrument 1.
[0033] As shown in FIG. 4, a preferred embodiment of a guide pin
placement instrument 1 features a retrograde pin guide member 50
that has a plurality of pin bores 52. The various pin bores 52 are
sized to closely but slidingly receive retrograde reference pins
92. As will be described in further detail below, the plurality of
pin bores 52 are provided for use in guiding placement of a second
retrograde reference pin 92, and are used in situations where the
surgeon is not satisfied with the orientation of the first
retrograde reference pin 92. Using the first retrograde reference
pin 92 as a reference, a correction, i.e. a change in orientation
of the guide pin track 112 (preferably in only one plane), can be
effected by choosing a second retrograde pin bore 52 in the
retrograde pin guide member 50 and, if necessary, readjusting the
instrument 1 to obtain the necessary correction. The various pin
bores 52 are preferably spaced a uniform distance from adjacent pin
bores 52, such as 2 mm, 3 mm or 4 mm apart. The pin bores 52 are
also preferably set at the same angle relative to one another, i.e.
with axes in parallel. By referencing the retrograde pin bore 52 of
the first retrograde reference pin 92, the surgeon can readily
select an alternate retrograde pin bore 52 that is likely to
provide a more desirable (typically, more centered) orientation.
Alternatively, the retrograde pin guide member 50 can be provided
with a single bore in the manner of the retrograde pin guide member
10, in which case it would be necessary to readjust the instrument
1 in order to position a second retrograde reference pin 92. Thus,
one advantage of the instrument 1 shown in FIGS. 1 and 4 is that it
eliminates or minimizes the need to readjust the position of the
retrograde pin guide member 10.
[0034] FIG. 1 shows an external view of the surgical technique of
the invention. In general, the surgeon uses the anterior external
reference pin 91 and external imaging (e.g. fluoroscopy) in order
to center the retrograde reference pin 92 as closely as possible to
the plane of the center of the femoral neck 101. The surgeon
initiates the procedure by palpitating the greater trochanter in
order to establish the location of the stab wound or opening 100.
As indicated in FIGS. 1 and 2, the location of the stab wound 100
is distal to the greater tochanter so as to provide access to the
lateral cortex 104 of the femur. Once the location of the stab
wound is determined, a stab wound 100 is made at the selected
location.
[0035] After making the stab wound 100, the surgeon orients the
instrument 1 in the manner shown in FIG. 1, with the external,
reference pin 91 resting anteriorly on the skin of the patient. As
indicated in FIG. 1, the stab wound 100 defines the entry point of
the retrograde reference pin 92, and therefore also sets the
general position of the external reference pin 91. The distal end
of the external reference pin 91 will typically rest in the frontal
groin area of the patient. As shown in the imaging/fluoroscopy view
of FIG. 2, positioning, the external reference pin 91 at this
location and in general alignment with the retrograde reference pin
92 allows the external reference pin 91 to serve as a varus-valgus
reference guide during formation of the guide pin track 112 under
fluoroscopy.
[0036] As indicated in FIG. 2, the target for entry of the
retrograde reference pin 92 is on the lateral cortex 104 distal to
the greater trochanter. Accurate placement of the guide pin is
critical in hip resurfacing procedures. In prior art resurfacing
procedures, surgeons (particularly inexperienced surgeons) require
a large exposure of the femoral head and neck. With the technique
of the present invention, it is easy even for inexperienced
surgeons to identify the target location based on external
palpitation of the greater trochanter external anatomy. Thus, the
invention improves accuracy of guide pin placement while also
allowing for reduction of exposure, which in turn reduces bleeding,
pain, and risk of infection.
[0037] With the instrument positioned as shown in FIG. 1, the
surgeon views the femoral head 102 and neck 101 under fluoroscopy
for such alternative imaging systems as may be available or
developed in the future) in order to determine the desired location
of the guide pin track 112. As shown in FIG. 2, the ex mall
reference pin 91 is used as a guide to identify the proper
varus/valgus angle for the guide pin track 112. As indicated, in
FIGS. 2 and 3, the preferred position of the guide pin track 112 is
in the center or axis A of the femoral neck 101. However, any
desired position, e.g. additional valgus, can be selected during
percutaneous pin placement. A preferred angle is about 140
degrees.
[0038] Working under fluoroscopy, the surgeon then drills the
retrograde reference pin 92 through the lateral femoral cortex and
through the neck 101 along the selected path of the guide pin track
112 until the distal end of the retrograde reference pin 92
penetrates the surface of the femoral head 102, leaving a guide pin
opening 110 on the femoral head 102. The retrograde reference pin
92 preferably has a diameter of 2 to 3 mm, a size that is
sufficient to leave a visible hole 110 on the surface of the
femoral head 102. The location of the guide pin hole 110 is
preferably about 12 mm above the fovea.
[0039] The position of the retrograde reference pin 92 is then
studied under fluoroscopy to verify whether the guide pin track 112
is properly oriented. If properly oriented, the retrograde
reference pin 92 is then removed from the femur via the stab wound
100.
[0040] If fluoroscopy shows that the retrograde reference pin 92 is
not sufficiently centered, a second guide pin track 112 can be
formed. The guide pin placement instrument 1 shown in FIG. 4
assists in selecting a better orientation for the second guide pin
track 112. Preferably prior to fully removing the first retrograde
reference pin 92, an adjacent retrograde pin bore 52 is selected,
i.e. a hole that is likely to provide a better centering. A second
retrograde reference pin 92 is passed through the selected second
retrograde pin bore 52. The relative position of the first and
second retrograde pin bores 52 in the retrograde pin guide member
50 maintains an offset between the second retrograde reference pin
92 and the first retrograde reference pin 92, and thus directs the
pin 92 into the femoral neck 101 along the desired path of the
guide pin track 112.
[0041] Once the guide pin track 112 is properly oriented, the
retrograde reference pin 92 is removed. The hip is then opened and
dislocated in a standard manner. As indicated in FIG. 3, upon
exposing the hip, the guide pin hole 110 can be readily identified
as a small hole on the surface 110 of the femoral head 102. In
prior art resurfacing procedures, surgeons (particularly
inexperienced surgeons) required a large exposure of the femoral
head and neck. With the technique of the present invention, it is
easy even for inexperienced surgeons to identify the target
location based on external palpitation of the greater trochamer
external anatomy. Thus, the invention improves accuracy of guide
pin placement while also allowing for reduction of exposure, which
in turn reduces bleeding, pain, and risk of infection.
[0042] As shown in FIG. 3, once the guide pin hole 110 has been
identified, a standard guide pin 192 (e.g. 3/8 inch Steinmann pin)
can be readily inserted through the hole/guide pin opening 110 and
installed in the guide pin track 112 through blunt insertion, Once
the guide pin 192 is lodged in the guide pin track 112, the guide
pin 192 can be used for any femoral head arthroplasty procedure
that uses a guide pin, such as, for example, the procedure
disclosed in U.S. Pat. No. 6,156,069 (Amstutz). The stab wound 100
can be used for a drain at the end of the surgical procedure.
Unlike prior art procedures, there is no need to expose the area
around the femoral neck 101. The guide pin track 112 assures that
the guide pin 192 is properly centered in the femoral neck 101. If
desired, the procedure for insetting the retrograde guide pin 92
and establishing the guide pin track 112 can be performed the day
before the operation, since it is not necessary to open the hip in
order to perform this portion of the procedure.
[0043] Advantages of the procedure include precise pin placement
without the difficulties associated with prior art procedures. Less
exposure is required than with procedures that use prior art neck
gauges. Less exposure is of course desirable in MIS techniques. The
technique assures ideal positioning of the femoral prosthesis with
minimal soft tissue trauma, such as might occur using the
traditional approach of directly visualizing the cortical surfaces
of the femoral neck. This reduces the likelihood of compromising
blood supply, reduces bleeding, and reduces post-operative pain.
The procedure cart significantly shorten the duration of the
procedure. Because radiologic confirmation is obtained in each
case, the risk of mal-alignment is significantly reduced. The
foregoing factors can accelerate recovery by the patient.
[0044] Although the present invention has been described in terms
of specific embodiments, it is anticipated that alterations and
modifications thereof will no doubt become apparent to those
skilled in the art. It is therefore intended that the following
claims be interpreted as covering all alterations and modifications
that fall within the true spirit and scope of the invention.
* * * * *