U.S. patent application number 15/202434 was filed with the patent office on 2017-07-13 for surgical impaction centering apparatus and method.
The applicant listed for this patent is Kambiz Behzadi. Invention is credited to Kambiz Behzadi.
Application Number | 20170196707 15/202434 |
Document ID | / |
Family ID | 59274718 |
Filed Date | 2017-07-13 |
United States Patent
Application |
20170196707 |
Kind Code |
A1 |
Behzadi; Kambiz |
July 13, 2017 |
SURGICAL IMPACTION CENTERING APPARATUS AND METHOD
Abstract
A system and method for improving installation of a prosthesis.
Devices include prosthesis installation tools, prosthesis assembly
tools, site preparation systems, and improved power tools used in
implant site preparation.
Inventors: |
Behzadi; Kambiz;
(Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Behzadi; Kambiz |
Pleasanton |
CA |
US |
|
|
Family ID: |
59274718 |
Appl. No.: |
15/202434 |
Filed: |
July 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62277294 |
Jan 11, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/4687 20130101;
A61F 2250/006 20130101; A61F 2002/4681 20130101; A61F 2002/4666
20130101; A61F 2002/30565 20130101; A61F 2/34 20130101; A61F 2/4603
20130101; A61F 2002/30525 20130101; A61F 2002/365 20130101; A61F
2002/469 20130101; A61F 2/4607 20130101; A61F 2/4657 20130101; A61F
2002/3625 20130101; A61F 2002/3627 20130101; A61F 2002/4671
20130101; A61F 2002/4632 20130101; A61F 2/3609 20130101; A61F
2002/4694 20130101; A61F 2002/3611 20130101; A61B 34/20 20160201;
A61F 2/4609 20130101; A61F 2002/30604 20130101; A61F 2002/30718
20130101; A61F 2002/30617 20130101; A61F 2002/4629 20130101; A61F
2002/4688 20130101; A61B 17/142 20161101; A61B 17/1666 20130101;
A61F 2/3662 20130101; A61F 2/4637 20130101; A61F 2002/4627
20130101 |
International
Class: |
A61F 2/46 20060101
A61F002/46; A61F 2/34 20060101 A61F002/34; A61F 2/36 20060101
A61F002/36; A61B 17/92 20060101 A61B017/92 |
Claims
1. An axially-impactful device for imparting a force on a portion
of a prosthesis to be installed in an installation direction with
said prosthesis including an attachment structure, comprising: a
rod having a shaft including a proximal stop and a distal stop
spaced apart from said proximal stop, said rod including a proximal
end, a distal end spaced apart from said distal end, and a
longitudinal axis extending from said proximal end to said distal
end through said rod; a hammer slidingly coupled to said shaft
between said stops; and an attachment system coupled to said distal
end, said attachment system configured to both engage the
attachment structure and align said longitudinal axis with the
installation direction.
2. The device of claim 1 further comprising a force transfer engine
coupled to said rod and to said hammer, said force transfer engine
responding to an actuation control to move said hammer along said
shaft towards said distal stop and subsequently have said hammer
strike said distal stop with an axial installation force, said rod
transferring said axial installation force to said distal end.
3. The device of claim 2 wherein said force transfer engine
produces a predetermined axial installation force in response to
said actuation signal.
4. The device of claim 2 wherein said force transfer engine
includes a cockup mechanical apparatus having a spring coupled to
said hammer.
5. The device of claim 3 wherein said force transfer engine
includes a cockup mechanical apparatus having a spring coupled to
said hammer.
6. The device of claim 2 wherein said force transfer engine
includes a robot control apparatus having a robotic actuator
coupled to said hammer.
7. The device of claim 3 wherein said force transfer engine
includes a robot control apparatus having a robotic actuator
coupled to said hammer.
8. The device of claim 2 wherein said force transfer engine
includes a pneumatic apparatus including a pressurized fluid
coupled to said hammer.
9. The device of claim 3 wherein said force transfer engine
includes a pneumatic apparatus including a pressurized fluid
coupled to said hammer.
10. The device of claim 3 wherein said predetermined axial
installation force is fixed and non-adjustable.
11. The device of claim 3 wherein said predetermined axial
installation force is variable and adjustable.
12. The device of claim 11 wherein said predetermined axial
installation force is selected from a set of different
predetermined values.
13. The device of claim 1 wherein the prosthesis includes an
acetabular cup having a generally semispherical exterior wall with
an apex defining a prosthesis plane tangent to said exterior wall,
wherein the attachment structure is disposed proximate said apex
and parallel to said prosthesis plane, and wherein said rod is
normal to said prosthesis plane.
14. The device of claim 13 wherein said distal stop includes an
impact surface stricken by said hammer, and wherein said impact
surface defines an impact plane generally coplanar with said
prosthesis plane.
15. The device of claim 1 further comprising a pressure sensor
coupled to said rod, said pressure sensor configured to provide
feedback regarding an applied force to the prosthesis responsive to
said hammer striking said distal stop.
16. The device of claim 1 further comprising a sound sensor
acoustically coupled to the prosthesis, said sound sensor
configured to provide feedback regarding a seatedness of the
prosthesis at an installation site responsive to said hammer
striking said distal stop.
17. The device of claim 15 further comprising a sound sensor
acoustically coupled to the prosthesis, said sound sensor
configured to provide feedback regarding a seatedness of the
prosthesis at an installation site responsive to said hammer
striking said distal stop.
18. The device of claim 1 wherein the prosthesis includes a
component prosthesis having a trunion and a head to be installed
onto said trunion, said trunion including an installation axis,
said head including a bore complementary to a taper of said trunion
with said bore including a bore axis with said bore axis aligned
with said installation axis when said head is installed onto said
trunion taper, and wherein said attachment structure aligns said
longitudinal axis with said bore axis and with said installation
axis with the installation direction co-aligning said bore axis
with said installation axis.
19. The device of claim 18 further comprising a force transfer
engine coupled to said rod and to said hammer, said force transfer
engine responding to an actuation signal to move said hammer along
said shaft towards said distal stop and subsequently have said
hammer strike said distal stop with an axial installation force,
said rod transferring said axial installation force to said distal
end.
20. The device of claim 18 further comprising a pressure sensor
coupled to said rod, said pressure sensor configured to provide
feedback regarding an applied force to the prosthesis responsive to
said hammer striking said distal stop.
21. The device of claim 18 further comprising a sound sensor
acoustically coupled to the prosthesis, said sound sensor
configured to provide feedback regarding a seatedness of the
prosthesis at an installation site responsive to said hammer
striking said distal stop.
22. A method for imparting for imparting a force on a portion of a
prosthesis to be installed in an installation direction with said
prosthesis including an attachment structure, comprising: a)
coupling a rod to the attachment structure, said rod having a shaft
including a proximal stop and a distal stop spaced apart from said
proximal stop, said rod including a proximal end, a distal end
spaced apart from said distal end, and a longitudinal axis
extending from said proximal end to said distal end through said
rod wherein said rod further includes a hammer slidingly coupled to
said shaft between said stops; and b) sliding said hammer along a
path defined by said shaft to produce a strike against said distal
stop; c) transferring, responsive to said strike, an
axially-constrained non-torqueing force to the prosthesis.
23. The method of claim 22 further comprising: d) controlling an
impact profile of said strike of said hammer against said distal
stop using a force transfer engine coupled to said rod and to said
hammer, said force transfer engine responding to an actuation
control to move said hammer along said shaft towards said distal
stop and subsequently have said hammer produce said strike against
said distal stop with an axial installation force, said rod
transferring said axial installation force to said distal end.
24. The method of claim 23 wherein said force transfer engine
produces a predetermined axial installation force in response to
said actuation signal.
25. The method of claim 23 wherein said force transfer engine
includes a cockup mechanical apparatus having a spring coupled to
said hammer.
26. The method of claim 24 wherein said force transfer engine
includes a cockup mechanical apparatus having a spring coupled to
said hammer.
27. The method of claim 23 wherein said force transfer engine
includes a robot control apparatus having a robotic actuator
coupled to said hammer.
28. The method of claim 24 wherein said force transfer engine
includes a robot control apparatus having a robotic actuator
coupled to said hammer.
29. The method of claim 23 wherein said force transfer engine
includes a pneumatic apparatus including a pressurized fluid
coupled to said hammer.
30. The method of claim 24 wherein said force transfer engine
includes a pneumatic apparatus including a pressurized fluid
coupled to said hammer.
31. The method of claim 24 wherein said predetermined axial
installation force is fixed and non-adjustable.
32. The method of claim 24 wherein said predetermined axial
installation force is variable and adjustable.
33. The method of claim 32 wherein said predetermined axial
installation force is selected from a set of different
predetermined values.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. patent application
Ser. No. 62/277,294 which is hereby expressly incorporated by
reference in its entirety for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates generally to installation of a
prosthesis, and more specifically, but not exclusively, to
improvements in prosthesis placement and positioning.
BACKGROUND OF THE INVENTION
[0003] The subject matter discussed in the background section
should not be assumed to be prior art merely as a result of its
mention in the background section. Similarly, a problem mentioned
in the background section or associated with the subject matter of
the background section should not be assumed to have been
previously recognized in the prior art. The subject matter in the
background section merely represents different approaches, which in
and of themselves may also be inventions.
[0004] Earlier patents issued to the present applicant have
described problems associated with prosthesis installation, for
example acetabular cup placement in total hip replacement surgery.
See U.S. Pat. Nos. 9,168,154 and 9,220,612, which are hereby
expressly incorporated by reference thereto in their entireties for
all purposes. Even though hip replacement surgery has been one of
the most successful operations, it continues to be plagued with a
problem of inconsistent acetabular cup placement. Cup
mal-positioning is the single greatest cause of hip instability, a
major factor in polyethylene wear, osteolysis, impingement,
component loosening and the need for hip revision surgery.
[0005] These incorporated patents explain that the process of cup
implantation with a mallet is highly unreliable and a significant
cause of this inconsistency. The patents note two specific problems
associated with the use of the mallet. First is the fact that the
surgeon is unable to consistently hit on the center point of the
impaction plate, which causes undesirable torques and moment arms,
leading to mal-alignment of the cup. Second, is the fact that the
amount of force utilized in this process is non-standardized.
[0006] In these patents there is presented a new apparatus and
method of cup insertion which uses an oscillatory motion to insert
the prosthesis. Prototypes have been developed and continue to be
refined, and illustrate that vibratory force may allow insertion of
the prosthesis with less force, as well, in some embodiments, of
allowing simultaneous positioning and alignment of the implant.
[0007] There are other ways of breaking down of the large
undesirable, torque-producing forces associated with the discrete
blows of the mallet into a series of smaller, axially aligned
controlled taps, which may achieve the same result incrementally,
and in a stepwise fashion to those set forth in the incorporated
patents, (with regard to, for example, cup insertion without
unintended divergence).
[0008] There are two problems that may be considered independently,
though some solutions may address both in a single solution. These
problems include i) undesirable and unpredictable torques and
moment arms that are related to the primitive method currently used
by surgeons, which involves manually banging the mallet on an
impaction plate mated to the prosthesis and ii) non-standardized
and essentially uncontrolled and unquantized amounts of force
utilized in these processes.
[0009] What is needed is a system and method for improving
installation of a prosthesis.
BRIEF SUMMARY OF THE INVENTION
[0010] Disclosed is a system and method for improving installation
of a prosthesis. The following summary of the invention is provided
to facilitate an understanding of some of the technical features
related to prosthesis assembly and installation, and is not
intended to be a full description of the present invention. A full
appreciation of the various aspects of the invention can be gained
by taking the entire specification, claims, drawings, and abstract
as a whole. The present invention is applicable to other prosthesis
in addition to acetabular cups, other modular prosthesis in
addition to assembly of modular femoral and humeral prosthesis, and
to other alignment and navigation systems in addition to referenced
light guides.
[0011] An embodiment of the present invention may include axial
alignment of force transference, such as, for example, an axially
sliding hammer moving between stops to impart a non-torqueing
installation force. There are various ways of motivating and
controlling the sliding hammer, including a magnitude of
transferred force. Optional enhancements may include pressure
and/or sound sensors for gauging when a desired depth of
implantation has occurred.
[0012] Other embodiments include adaptation of various devices for
accurate assembly of modular prostheses, such as those that include
a head accurately impacted onto a trunion taper that is part of a
stem or other element of the prosthesis.
[0013] Still other embodiments include an alignment system to
improve site preparation, such as, for example, including a
projected visual reference of a desired orientation of a tool and
then having that reference marked and available for use during
operation of the tool to ensure that the alignment remains proper
throughout its use, such as during a reaming operation.
[0014] Further embodiments include enhancement of various tools,
such as those used for cutting, trimming, drilling, and the like,
with ultrasonic enhancement to make the device a better cutting,
trimming, drilling, etc. device to enable its use with less
strength and with improved accuracy.
[0015] Any of the embodiments described herein may be used alone or
together with one another in any combination. Inventions
encompassed within this specification may also include embodiments
that are only partially mentioned or alluded to or are not
mentioned or alluded to at all in this brief summary or in the
abstract. Although various embodiments of the invention may have
been motivated by various deficiencies with the prior art, which
may be discussed or alluded to in one or more places in the
specification, the embodiments of the invention do not necessarily
address any of these deficiencies. In other words, different
embodiments of the invention may address different deficiencies
that may be discussed in the specification. Some embodiments may
only partially address some deficiencies or just one deficiency
that may be discussed in the specification, and some embodiments
may not address any of these deficiencies.
[0016] Other features, benefits, and advantages of the present
invention will be apparent upon a review of the present disclosure,
including the specification, drawings, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying figures, in which like reference numerals
refer to identical or functionally-similar elements throughout the
separate views and which are incorporated in and form a part of the
specification, further illustrate the present invention and,
together with the detailed description of the invention, serve to
explain the principles of the present invention.
[0018] FIG. 1-FIG. 6 illustrate embodiments including installation
of a prosthesis, including installation into living bone;
[0019] FIG. 1 illustrates an embodiment of the present invention
for a sliding impact device;
[0020] FIG. 2 illustrates a lengthwise cross-section of the
embodiment illustrated in FIG. 1 including an attachment of a
navigation device;
[0021] FIG. 3 illustrates a cockup mechanical gun embodiment, an
alternative embodiment to the sliding impact device illustrated in
FIG. 1 and FIG. 2;
[0022] FIG. 4 illustrates an alternative embodiment to the devices
of FIG. 1-3 including a robotic structure;
[0023] FIG. 5 illustrates an alternative embodiment to the devices
of FIG. 1-4 including a pressure sensor to provide feedback;
[0024] FIG. 6 illustrates an alternative embodiment to the feedback
system of FIG. 5 including a sound sensor to provide feedback for
the embodiments of FIG. 1-5;
[0025] FIG. 7-FIG. 10 illustrate prosthesis assembly embodiments
including use of variations of the prosthesis installation
embodiments of FIG. 1-FIG. 6, such as may be used to reduce a risk
of trunionosis;
[0026] FIG. 7 illustrates a modular prosthesis and assembly
tools;
[0027] FIG. 8 illustrates a femoral head to be assembled onto a
trunion attached to a femoral stem;
[0028] FIG. 9 illustrates alignment of an installation device with
the femoral head for properly aligned impaction onto the trunion,
such as an embodiment of FIG. 1-FIG. 6 adapted for this
application;
[0029] FIG. 10 illustrates use of a modified vibratory system for
assembly of the modular prosthesis;
[0030] FIG. 11-FIG. 12 illustrate an improvement to site
preparation for an installation of a prosthesis;
[0031] FIG. 11 illustrates an environment in which a prosthesis is
installed highlighting problem with site preparation; and
[0032] FIG. 12 illustrates an alignment system for preparation and
installation of a prosthesis;
[0033] FIG. 13 illustrates modified surgical devices incorporating
vibratory energy as at least an aid to mechanical preparation.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Embodiments of the present invention provide a system and
method for improving installation of a prosthesis. The following
description is presented to enable one of ordinary skill in the art
to make and use the invention and is provided in the context of a
patent application and its requirements.
[0035] Various modifications to the preferred embodiment and the
generic principles and features described herein will be readily
apparent to those skilled in the art. Thus, the present invention
is not intended to be limited to the embodiment shown but is to be
accorded the widest scope consistent with the principles and
features described herein.
[0036] Definitions
[0037] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
general inventive concept belongs. It will be further understood
that terms, such as those defined in commonly used dictionaries,
should be interpreted as having a meaning that is consistent with
their meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0038] The following definitions apply to some of the aspects
described with respect to some embodiments of the invention. These
definitions may likewise be expanded upon herein.
[0039] As used herein, the term "or" includes "and/or" and the term
"and/or" includes any and all combinations of one or more of the
associated listed items. Expressions such as "at least one of,"
when preceding a list of elements, modify the entire list of
elements and do not modify the individual elements of the list.
[0040] As used herein, the singular terms "a," "an," and "the"
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to an object can include
multiple objects unless the context clearly dictates otherwise.
[0041] Also, as used in the description herein and throughout the
claims that follow, the meaning of "in" includes "in" and "on"
unless the context clearly dictates otherwise. It will be
understood that when an element is referred to as being "on"
another element, it can be directly on the other element or
intervening elements may be present therebetween. In contrast, when
an element is referred to as being "directly on" another element,
there are no intervening elements present.
[0042] As used herein, the term "set" refers to a collection of one
or more objects. Thus, for example, a set of objects can include a
single object or multiple objects. Objects of a set also can be
referred to as members of the set. Objects of a set can be the same
or different. In some instances, objects of a set can share one or
more common properties.
[0043] As used herein, the term "adjacent" refers to being near or
adjoining. Adjacent objects can be spaced apart from one another or
can be in actual or direct contact with one another. In some
instances, adjacent objects can be coupled to one another or can be
formed integrally with one another.
[0044] As used herein, the terms "connect," "connected," and
"connecting" refer to a direct attachment or link. Connected
objects have no or no substantial intermediary object or set of
objects, as the context indicates.
[0045] As used herein, the terms "couple," "coupled," and
"coupling" refer to an operational connection or linking. Coupled
objects can be directly connected to one another or can be
indirectly connected to one another, such as via an intermediary
set of objects.
[0046] The use of the term "about" applies to all numeric values,
whether or not explicitly indicated. This term generally refers to
a range of numbers that one of ordinary skill in the art would
consider as a reasonable amount of deviation to the recited numeric
values (i.e., having the equivalent function or result). For
example, this term can be construed as including a deviation of
.+-.10 percent of the given numeric value provided such a deviation
does not alter the end function or result of the value. Therefore,
a value of about 1% can be construed to be a range from 0.9% to
1.1%.
[0047] As used herein, the terms "substantially" and "substantial"
refer to a considerable degree or extent. When used in conjunction
with an event or circumstance, the terms can refer to instances in
which the event or circumstance occurs precisely as well as
instances in which the event or circumstance occurs to a close
approximation, such as accounting for typical tolerance levels or
variability of the embodiments described herein.
[0048] As used herein, the terms "optional" and "optionally" mean
that the subsequently described event or circumstance may or may
not occur and that the description includes instances where the
event or circumstance occurs and instances in which it does
not.
[0049] As used herein, the term "size" refers to a characteristic
dimension of an object. Thus, for example, a size of an object that
is spherical can refer to a diameter of the object. In the case of
an object that is non-spherical, a size of the non-spherical object
can refer to a diameter of a corresponding spherical object, where
the corresponding spherical object exhibits or has a particular set
of derivable or measurable properties that are substantially the
same as those of the non-spherical object. Thus, for example, a
size of a non-spherical object can refer to a diameter of a
corresponding spherical object that exhibits light scattering or
other properties that are substantially the same as those of the
non-spherical object. Alternatively, or in conjunction, a size of a
non-spherical object can refer to an average of various orthogonal
dimensions of the object. Thus, for example, a size of an object
that is a spheroidal can refer to an average of a major axis and a
minor axis of the object. When referring to a set of objects as
having a particular size, it is contemplated that the objects can
have a distribution of sizes around the particular size. Thus, as
used herein, a size of a set of objects can refer to a typical size
of a distribution of sizes, such as an average size, a median size,
or a peak size.
[0050] Embodiments of the present invention may include one of more
solutions to the above problems. The incorporated U.S. Pat. No.
9,168,154 includes a description of several embodiments, sometimes
referred to herein as a BMD3 device, some of which illustrate a
principle for breaking down large forces associated with the
discrete blows of a mallet into a series of small taps, which in
turn perform similarly in a stepwise fashion while being more
efficient and safer. The BMD3 device produces the same displacement
of the implant without the need for the large forces from the
repeated impacts from the mallet. The BMD3 device may allow
modulation of force required for cup insertion based on bone
density, cup geometry, and surface roughness. Further, a use of the
BMD3 device may result in the acetabulum experiencing less stress
and deformation and the implant may experience a significantly
smoother sinking pattern into the acetabulum during installation.
Some embodiments of the BMD3 device may provide a superior approach
to these problems, however, described herein are two problems that
can be approached separately and with more basic methods as an
alternative to, or in addition to, a BMD3 device. An issue of
undesirable torques and moment arms is primarily related to the
primitive method currently used by surgeons, which involves
manually banging the mallet on the impaction plate. The amount of
force utilized in this process is also non-standardized and
somewhat out of control.
[0051] With respect to the impaction plate and undesirable torques,
an embodiment of the present invention may include a simple
mechanical solution as an alternative to some BMD3 devices, which
can be utilized by the surgeon's hand or by a robotic machine. A
direction of the impact may be directed or focused by any number of
standard techniques (e.g., A-frame, C-arm or navigation system).
Elsewhere described herein is a refinement of this process by
considering directionality in the reaming process, in contrast to
only considering it just prior to impaction. First, we propose to
eliminate the undesirable torques by delivering the impacts by a
sledgehammer device or a structure (e.g., hollow cylindrical mass)
that travels over a stainless rod.
[0052] FIG. 1 illustrates an embodiment of the present invention
for a sliding impact device 100, and FIG. 2 illustrates a
lengthwise cross-section of sliding impact device 100 including an
attachment of a navigation device 205.
[0053] Device 100 includes a moveable hammer 105 sliding axially
and freely along a rod 110. Rod 110 includes a proximal stop 115
and distal stop 120. These stops that may be integrated into rod
110 to allow transference of force to rod 110 when hammer 105
strikes distal stop 120. At a distal end 210 of rod 110, device 100
includes an attachment system 215 for a prosthesis 220. For
example, when prosthesis 220 includes an acetabular cup having a
threaded cavity 225, attachment system 215 may include a
complementary threaded structure that screws into threaded cavity
225. The illustrated design of device 100 allows only a perfect
axial force to be imparted. The surgeon cannot deliver a blow to
the edge of an impaction plate. Therefore the design of this
instrument is in and of itself protective, eliminating a problem of
"surgeon's mallet hitting on the edge of the impaction plate" or
other mis-aligned force transference, and creating undesirable
torques, and hence unintentional mal-alignment of prosthesis 220
from an intended position/orientation.
[0054] A longitudinal axis 230 extends through the ends of rod 110.
Attachment system 215 aligns prosthesis 220 to axis 230 when rod
110 is coupled to threaded cavity 225. An apex of prosthesis 220
(when it generally defines a hollow semispherical shell) supports a
structure that defines threaded cavity 225 and that structure may
define a plane 235 that may be tangent to the apex, with plane 235
about perpendicular to axis 230 when rod 110 engages prosthesis
220. Operation of device 100 is designed to deliver only axial
(e.g., aligned with axis 230 and thus non-torqueing) forces to
prosthesis 220. Other embodiments illustrated in FIG. 3-FIG. 6 may
be similarly configured.
[0055] FIG. 3 illustrates a cockup mechanical gun 300 embodiment,
an alternative embodiment to the sliding impact device illustrated
in FIG. 1 and FIG. 2. An alternate embodiment includes cockup
mechanical gun 300 that uses the potential energy of a cocked up
spring 305 to create an axially aligned impaction force. Hammer 105
is drawn back and spring 305 is locked until an operator actuates a
trigger 310 to release spring 305 and drive hammer 105 along rod
110 to strike distal stop 120 and transfer an axially aligned
impacting force to prosthesis 220.
[0056] Each pull of trigger 310 creates the same predetermined
fixed unit of force (some alternatives may provide a variably
predetermined force). The surgeon cannot deliver a misaligning
impact to an impaction plate with this design.
[0057] FIG. 4 illustrates an alternative robotic device 400
embodiment to the devices of FIG. 1-3 including a robotic control
structure 405. For example, device 100 and/or device 300 may be
mounted with robot control structure 405 and the co-axial impacts
may be delivered mechanically by a robotic tool using pneumatic or
electric energy.
[0058] FIG. 5 illustrates an alternative embodiment 500 to the
devices of FIG. 1-4 including a pressure sensor 505 to provide
feedback during installation. With respect to management of the
force required for some of these tasks, it is noted that with
current techniques (the use of the mallet) the surgeon has no
indication of how much force is being imparted onto the implant
and/or the implant site (e.g., the pelvis). Laboratory tests may be
done to estimate what range of force should be utilized in certain
age groups (as a rough guide) and then fashioning a device 500, for
example a modified sledgehammer 100 or cockup gun 300 to produce
just the right amount of force. Typically the surgeon may use up to
2000 N to 3000 N of force to impact a cup into the acetabular
cavity. Also, since some embodiments cannot deliver the force in an
incremental fashion as described in association with the BMD3
device, device 500 includes a stopgap mechanism. Some embodiments
of the BMD3 device have already described the application of a
sensor in the body of the impaction rod. Device 500 includes
sensing system/assembly 505 embedded in device 500, for example
proximate rod 110 near distal end 210, and used to provide valuable
feedback information to the surgeon. Pressure sensor 505 can let
the surgeon know when the pressures seems to have maximized,
whether used for the insertion of an acetabular cup, or any other
implant including knee and shoulder implants and rods used to fix
tibia and femur fractures. When pressure sensor 505 is not showing
an advance or increase in pressure readings and has plateaued, the
surgeon may determine it is time to stop operation/impacting. An
indicator, for example an alarm can go off or a red signal can show
when maximal peak forces are repeatedly achieved. As noted above,
the incorporated patents describe a presence of a pressure sensor
in an installation device, the presence of which was designed as
part of a system to characterize an installation pulse pattern
communicated by a pulse transfer assembly. The disclosure here
relates to a pressure sensor provided not to characterize the
installation pulse pattern but to provide an in situ feedback
mechanism to the surgeon as to a status of the installation, such
as to reduce a risk of fracturing the installation site. Some
embodiments may also employ this pressure sensor for multiple
purposes including characterization of an applied pulse pattern
such as, for example, when the device includes automated control of
an impacting engine coupled to the hammer. Other embodiments of
this invention may dispose the sensor or sensor reading system
within a handle or housing of the device rather than in the central
rod or shaft.
[0059] FIG. 6 illustrates an alternative device 600 embodiment to
the feedback system of FIG. 5 including a sound sensor 605 to
provide feedback for the embodiments of FIG. 1-5. Surgeons
frequently use a change in pitch (sound) to gauge whether an
implant (e.g., the cup) has "bottomed out" (an evaluation of a
"seatedness" of the implant) and device 600 includes sound sensor
605 either attached or coupled to rod 110 or otherwise disposed
separately in the operating room. Sound sensor system/assembly 605
may be used in lieu of, or in addition to, pressure sensor
system/assembly 505 illustrated in FIG. 5.
[0060] FIG. 7-FIG. 10 illustrate prosthesis assembly embodiments
including use of variations of the prosthesis installation
embodiments of FIG. 1-FIG. 6, such as may be used to reduce a risk
of trunionosis or for other advantage. FIG. 7 illustrates a modular
prosthesis 700 and assembly tool 705. Prosthesis 700 includes a
head 710 and a trunion taper 715 at an end of a stem 720 (e.g., a
femoral stem for supporting a ball head to fit within an acetabular
cup used in a total hip replacement procedure). During the
procedure, the surgeon assembles prosthesis 700 by using tool 705
which may include an impact rod 725 attached to a head coupler 730.
The surgeon uses tool 705 to drive head 710 onto trunion taper 715
which conventionally includes a free mallet striking tool 705. Such
a procedure may be prone to the similar problems as installation of
a prosthesis into an implant site, namely application of off-axis
torqueing forces and an uncertainty of applied force and completion
of assembly.
[0061] It is believed that even a 0.1 degree mal-alignment on head
710 on trunion taper 715 may lead to progressive wear and
metalosis. Variations of the embodiments of devices illustrated in
FIG. 1-FIG. 6 and its associated content may be developed to help
resolve this problem. In the case of "non-torqueing axiallity" of
forces from an assembly device, a bore of the head may define an
axis, the trunion taper may define an axis, with the assembly
device aligning these axes and then applying its forces in co-axial
alignment with these co-axially aligned axes. Such an embodiment
may reduce or eliminate any force-responsive rotations of the head
with respect to the taper as the head is seated into position by
the assembly device.
[0062] FIG. 8 illustrates a femoral head 805, a variation of head
710 illustrated in FIG. 7, to be assembled onto trunion taper 715
that is coupled to femoral stem 720. A center dot 810 may be placed
on femoral (or humeral) head 805 to be impacted using tool 705.
[0063] FIG. 9 illustrates alignment of an installation device 900,
a variation of any of devices 100-600, with femoral head 805 for
properly aligned impaction onto trunion taper 715, such as an
embodiment of FIG. 1-FIG. 6 adapted for this application. Such
adaptation may include, for example, an axial channel 910 to view
dot 810, and align force transference, prior to operation of hammer
105.
[0064] Dot 810 can be aligned with an impactor/device/gun. Once
axial alignment, such as through the sight channel, has been
confirmed, a sledgehammer, a cockup gun, or other similar device
can bang the impactor onto femoral (humeral) head 805 to impact it
on trunion taper 715. The co-axiality of the head and the device
can be confirmed visually (for example, through a hollow cylinder
that comprises a center shaft of the device) or with a variety of
electronic and laser methods.
[0065] FIG. 10 illustrates use of a modified vibratory system 1000,
a variation of installation device 900 for assembly of the modular
prosthesis illustrated in FIG. 7. Alternatively to device 900, a
variation of the BMD3 device can be used to insert the femoral and
humeral heads 710 onto trunion taper 715. For example, a version of
the BMD3 device where femoral head 710 is grasped by a "vibrating
gun" and introduced methodically and incrementally onto trunion
taper 715. Since there are no large forces being applied to the
head/trunion junction, there is essentially no possibility, or a
reduced possibility, of head 710 seating onto trunion taper 715 in
a misaligned fashion. It would be possible to use the same
technique of marking the center of head 710 and lining it up with
trunion taper 715 and device axially before operating the
device.
[0066] FIG. 11-FIG. 12 illustrate an improvement to site 1100
preparation for an installation of a prosthesis 1105. FIG. 11
illustrates an environment 1100 in which prosthesis 1105 is
installed highlighting a problem with site preparation for a
prosthesis installation procedure having variable density bone
(line thickness/separation distance reflecting variable bone
density) of acetabulum 1110.
[0067] There is a secondary problem with the process of acetabular
preparation and implantation that leads to cup mal-alignment.
Currently, during the process of acetabular reaming, surgeons make
several assumptions. One common assumption is that the reamer is
fully seated in a cavity and surrounded on all sides by bone.
Another common assumption is that the bone that is being reamed is
uniform in density. Imagine a carpenter that is preparing to cut a
piece of wood with a saw. Now imagine that parts of this piece of
wood are embedded with cement and some parts of the piece of wood
are hollow and filled with air. The carpenter's saw will not
produce a precise cut on this object. Some parts are easy to cut
and some parts are harder to cut. The saw blades skives and bends
in undesirable ways. A similar phenomenon happens in acetabular
preparation with a reamer and when performing the cuts for knee
replacement with a saw. With respect to the acetabulum, the side of
the cavity that is incomplete (side of the reamer that is
uncovered) will offer less resistance to the reamer and therefor
the reamer preferentially reams towards the direction of the
uncovering. Second, the reamer cuts the soft bone much more easily
than the dense and sclerotic bone, so the reamer moves away from
the sclerotic bone and moves toward the soft bone. From a machining
perspective, the reaming and preparation of the acetabulum may not
be concentric or precise. This maybe a significant factor in the
surgeon's inability to impact the cup in the desired location
[0068] FIG. 12 illustrates an alignment system 1200 for preparation
and installation of a prosthesis to help address/minimize this
effect. A first step that can be taken is to include directionality
into the process of reaming at the outset, and not just at the last
step during impaction. Current technique allows the surgeon to ream
the cup haphazardly moving the reamer handle in all directions,
being ignorantly unaware that he is actually creating a preference
for the sinking path of the acetabular implant. Ultimately the
direction in which the surgeon reams may in fact be determining the
position/path of the final implant. The surgeon then impacts the
cup using the traditional A-frame or any of the currently used
intra-operative measurement techniques such as navigation or
fluoroscopy. These methods provide information about the position
of the cup either as it is being implanted or after the
implantation has occurred. None of these techniques predetermine
the cup's path or function to guide the cup in the correct
path.
[0069] Proposed is a method and a technique to eliminate/reduce
this problem. Before the surgeon begins to ream the acetabulum, the
reamer handle should be held, with an A-frame attached, in such a
way to contemplate the final position of the reamer and hence the
implant, (e.g., hold the reamer in 40 degree abduction and 20
degree anteversion reaming is started). This step could also be
accomplished with navigation or fluoroscopy. The surgeon could, for
example, immediately mark this position on a screen or the wall in
the operating room as described below and as illustrated in FIG.
12. After the anticipated position of the reamer is marked, the
surgeon can do whatever aspect of reaming that needs to be done.
For example the first reaming usually requires medialization in
which the reamer is directed quite vertically to ream in to the
pulvinar. Typically three or four reamings are done. First, the
acetabular cavity is medialized. The other reamings function to get
to the subchondral bone in the periphery of the acetabulum. One
solution may be that after each reaming, the reamer handle be held
in the final anticipated position of the implant. In some cases it
may be difficult to have an A-frame attached to every reamer and to
estimate the same position of the reamer in the operating space
accurately with the A-frame.
[0070] An alternative to that is also proposed to address this
process. For example, at a proximal end of the reamer shaft handle
will be placed a first reference system 1205, for example a laser
pointer. This laser pointer 1205 will project a spot 1210 either on
a wall or on a screen 1215, a known distance from the operating
room table. That spot 1210 on wall 1215 (or on the screen) is then
marked with another reference system 1220, for example a second
independent laser pointer that sits on a steady stand in the
operating room. Thereafter manipulating the shaft handle so that
the first reference system has the desired relationship, example
co-aligned, with the second reference system, the surgeon knows
that the device attached to the handle has the desired orientation.
So when the first reamer is held in the anticipated and desired
final alignment of the implant (e.g., 40 degree abduction, 20
degree anteversion for many preferred installation angles of an
acetabular cup), the laser pointer at the proximal end of the
reamer handle projects a spot on the wall or screen. That spot is
marked with the second stationary laser, and held for the duration
of the case. All subsequent reamings will therefore not require an
A-frame to get a sense of the proper alignment and direction of the
reamer. The surgeon assures that no matter how he moves the reamer
handle in the process of reaming of the acetabulum, that the
reaming finishes with the reamer handle (laser pointer) pointing to
the spot on the wall/screen. In this manner, directionality is
assured during the reaming process. In this way the sinking path of
the actual implant is somewhat predetermined. And no matter what
final intra -operative monitoring technique is used (A-frame,
C-Arm, Navigation) that the cup will likely seat/sink more closely
to the desired final position.
[0071] FIG. 13 illustrates modified surgical devices 1300
incorporating vibratory energy as at least an aid to mechanical
preparation. Also proposed herein is another concept to address a
problem associated with non-concentric reaming of the acetabulum
caused by variable densities of the bone and the uncovering of the
reamer. Imagine the same carpenter has to cut through a construct
that is made out of wood, air, and cement. The carpenter does not
know anything about the variable densities of this construct. There
are two different saws available: one that cuts effectively through
wood only, and ineffectively through the cement. Also available is
a second saw that cuts just as effectively through cement as wood.
Which of these saws would improve a chance of producing a more
precise cut? Proposed is a mixing of ultrasonic energy with the
standard oscillating saw and the standard reamer. In effect any
oscillating equipment used in orthopedics, including the saw,
reamer, drill, and the like may be made more precise in its ability
to cut and prepare bone with the addition of ultrasonic energy.
This may feel dangerous and counterintuitive to some, however, the
surgeon typically applies a moderate amount of manual pressure to
the saw and reamers, without being aware, which occasionally causes
tremendous skiving, bending and eccentric reaming. An instrument
that does not requires the surgeon's manual force maybe
significantly safer and as well as more precise and effective.
[0072] A further option includes disposition of a sensor in the
shaft of the ultrasonic reamers and saws so that the surgeon can
ascertain when hard versus soft bone is being cut, adding a measure
of safety by providing a visual numerical feedback as to the amount
of pressure being utilized. This improvement (the ability to cut
hard and soft bone with equal efficacy) will have tremendous
implications in orthopedic surgery. When the acetabular cavity is
prepared more precisely, with significantly lower tolerances,
especially when directionality is observed, the acetabular implant
(cup) may more easily follow the intended sinking path.
[0073] Other applications of this concept could be very useful.
Pressfit and ingrowth fixation in total knee replacements in
particular (as well as ankle, shoulder and other joints to a lesser
degree) are fraught with problems, particularly that of
inconsistent bony ingrowth and fixation. The fact that a surgeon is
unable to obtain precise cuts on the bone may be a significant
factor in why the bone ingrowth technology has not gotten off the
ground in joints other than the hip. The problem is typically
blamed on the surgeon and his less than perfect hands. The
experienced surgeon boasts that only he should be doing this
operation (i.e.: non-cemented total knee replacement). This concept
(a more precise saw that cuts hard and soft bone equally allowing
lower tolerances) has huge potential in orthopedics, in that it can
lead to elimination of the use of cement in orthopedic surgery
altogether. This can spark off the growth and use of bone ingrowth
technology in all aspects of joint replacement surgery which can
lead to tremendous time saving in the operating room and better
results for the patients.
[0074] The system and methods above has been described in general
terms as an aid to understanding details of preferred embodiments
of the present invention. In the description herein, numerous
specific details are provided, such as examples of components
and/or methods, to provide a thorough understanding of embodiments
of the present invention. Some features and benefits of the present
invention are realized in such modes and are not required in every
case. One skilled in the relevant art will recognize, however, that
an embodiment of the invention can be practiced without one or more
of the specific details, or with other apparatus, systems,
assemblies, methods, components, materials, parts, and/or the like.
In other instances, well-known structures, materials, or operations
are not specifically shown or described in detail to avoid
obscuring aspects of embodiments of the present invention.
[0075] Reference throughout this specification to "one embodiment",
"an embodiment", or "a specific embodiment" means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
present invention and not necessarily in all embodiments. Thus,
respective appearances of the phrases "in one embodiment", "in an
embodiment", or "in a specific embodiment" in various places
throughout this specification are not necessarily referring to the
same embodiment. Furthermore, the particular features, structures,
or characteristics of any specific embodiment of the present
invention may be combined in any suitable manner with one or more
other embodiments. It is to be understood that other variations and
modifications of the embodiments of the present invention described
and illustrated herein are possible in light of the teachings
herein and are to be considered as part of the spirit and scope of
the present invention.
[0076] It will also be appreciated that one or more of the elements
depicted in the drawings/figures can also be implemented in a more
separated or integrated manner, or even removed or rendered as
inoperable in certain cases, as is useful in accordance with a
particular application.
[0077] Additionally, any signal arrows in the drawings/Figures
should be considered only as exemplary, and not limiting, unless
otherwise specifically noted. Combinations of components or steps
will also be considered as being noted, where terminology is
foreseen as rendering the ability to separate or combine is
unclear.
[0078] The foregoing description of illustrated embodiments of the
present invention, including what is described in the Abstract, is
not intended to be exhaustive or to limit the invention to the
precise forms disclosed herein. While specific embodiments of, and
examples for, the invention are described herein for illustrative
purposes only, various equivalent modifications are possible within
the spirit and scope of the present invention, as those skilled in
the relevant art will recognize and appreciate. As indicated, these
modifications may be made to the present invention in light of the
foregoing description of illustrated embodiments of the present
invention and are to be included within the spirit and scope of the
present invention.
[0079] Thus, while the present invention has been described herein
with reference to particular embodiments thereof, a latitude of
modification, various changes and substitutions are intended in the
foregoing disclosures, and it will be appreciated that in some
instances some features of embodiments of the invention will be
employed without a corresponding use of other features without
departing from the scope and spirit of the invention as set forth.
Therefore, many modifications may be made to adapt a particular
situation or material to the essential scope and spirit of the
present invention. It is intended that the invention not be limited
to the particular terms used in following claims and/or to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
any and all embodiments and equivalents falling within the scope of
the appended claims. Thus, the scope of the invention is to be
determined solely by the appended claims.
* * * * *