U.S. patent application number 11/090102 was filed with the patent office on 2005-10-20 for methods for treating fractures of the femur and femoral fracture devices.
Invention is credited to Ferrante, Joseph M., James, Anthony, McReynolds, Keith, Watanabe, Kohsuke.
Application Number | 20050234457 11/090102 |
Document ID | / |
Family ID | 34968041 |
Filed Date | 2005-10-20 |
United States Patent
Application |
20050234457 |
Kind Code |
A1 |
James, Anthony ; et
al. |
October 20, 2005 |
Methods for treating fractures of the femur and femoral fracture
devices
Abstract
The present invention relates to methods and devices for
treating femoral fractures, wherein a polyaxial cross member is
employed to accommodate a wide range of angles and
anteversions/retroversions in the femur, and different securing
mechanisms can also be employed to hold and retain such polyaxial
cross member in place at the desired orientation.
Inventors: |
James, Anthony; (Memphis,
TN) ; McReynolds, Keith; (Olive Branch, MS) ;
Ferrante, Joseph M.; (Bartlett, TN) ; Watanabe,
Kohsuke; (Memphis, TN) |
Correspondence
Address: |
CHIEF PATENT COUNSEL
SMITH & NEPHEW, INC.
1450 BROOKS ROAD
MEMPHIS
TN
38116
US
|
Family ID: |
34968041 |
Appl. No.: |
11/090102 |
Filed: |
March 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60557027 |
Mar 26, 2004 |
|
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|
Current U.S.
Class: |
606/62 ; 606/281;
606/287; 606/289; 606/293; 606/294; 606/66; 606/71 |
Current CPC
Class: |
A61B 17/746 20130101;
A61B 17/72 20130101; A61B 17/748 20130101; A61B 17/7241
20130101 |
Class at
Publication: |
606/069 |
International
Class: |
A61B 017/58 |
Claims
1. An apparatus for treating fractures of the femur comprising: a
first plate configured to secure to an exterior of a femur, the
first plate providing a first opening; an extended portion having a
polyaxial joint affixed at one end, the extended portion configured
to extend through the first opening. a cross member configured for
insertion into the extended portion to permit sliding compression
of a fracture of the femur and rotation about a plurality of axes
as provided by the polyaxial joint; and a securing mechanism
configured to hold the polyaxial joint at a predetermined
orientation in the first opening.
2. The apparatus of claim 1, wherein the first plate includes the
first opening; and the securing mechanism comprises: a second plate
arranged to secure the polyaxial joint in the first opening; and at
least one fastening element configured to fasten the second plate
to the first plate to hold the polyaxial joint at the predetermined
orientation.
3. The apparatus of claim 2, wherein an area of the first plate
surrounding the first opening is depressed in a shape of the second
plate to urge the second plate to an outer surface of the first
plate when the second plate is fastened to the first.
4. The apparatus of claim 1, wherein the first plate and the second
plate are arranged on different planes when the second plate is
fastened to the first plate.
5. The apparatus of claim 1, wherein the securing mechanism
comprises: a securing element arranged to form the first opening
with the first plate and secure the polyaxial joint in the first
opening; and at least one fastening element configured to fasten
the securing element to the first plate to hold the polyaxial joint
at the predetermined orientation in the first opening.
6. The apparatus of claim 5, wherein the securing element has a
first shape that complements a second shape at one end of the first
plate to form a curved shape for the opening.
7. The apparatus of claim 1, wherein the first plate includes the
first opening; and the securing mechanism comprises: a second plate
configured to be threaded to the first plate to secure the
polyaxial joint in the first opening and holds the polyaxial joint
at the predetermined orientation.
8. The apparatus of claim 1, wherein: the securing mechanism
comprises an expandable collet arranged inside the first opening;
and the extended portion is tapered along its long axis and
insertable into the expandable collet to lock the polyaxial joint
at the predetermined orientation in the first opening.
9. The apparatus of claim 8, wherein the polyaxial joint comprises
a member having at least a curved surface and one or more expansion
slots.
10. The apparatus of claim 9, wherein the tapered extended portion
is threaded at one end, and the member is threaded for affixing to
the threaded end of the tapered extended portion.
11. The apparatus of claim 8, wherein the expandable collet
comprises a plurality of separate sections.
12. The apparatus of claim 1, wherein the polyaxial joint comprises
a member having at least one spherical surface.
13. The apparatus of claim 1, wherein the member comprises a
surface having one or more surface features, and the opening
includes an inner surface having one or more surface features which
physically cooperate with the member surface features.
14. The apparatus of claim 12 wherein the opening includes a curved
inner surface.
15. The apparatus of claim 12, wherein the opening includes a
tapered inner surface.
16. The apparatus of claim 5, wherein the securing element is
configured to have one end integral with the first plate and
another end separated from first plate by a gap; and the at least
one fastening element is configured to fasten the securing element
to the first plate at the gap.
17. The apparatus of claim 16, wherein the at least one fastening
element is configured to fasten the securing element to the first
plate at an outside perimeter of the first plate.
18. The apparatus of claim 12, wherein the spherical member
comprises a plurality of separate sections.
19. The apparatus of claim 7, wherein the second plate includes one
or more ball bearings that make contact with the polyaxial joint as
the second plate is threaded to the first plate to further hold the
polyaxial joint at the predetermined orientation.
20. The apparatus of claim 1, wherein the securing mechanism
includes: an interference element arranged for insertion between an
inner surface of the first opening and the polyaxial joint to
prevent movement of the polyaxial joint and lock the polyaxial
joint at a predetermined orientation in the first opening.
21. The apparatus of claim 1, wherein the securing mechanism
includes: an interference element arranged to protrude from a
position at a perimeter of the opening to exert pressure on the
polyaxial joint to prevent movement of the polyaxial joint and lock
the polyaxial joint at the predetermined orientation in the first
opening.
22. The apparatus of claim 1, wherein the securing mechanism
includes: a spring-loaded member and a fastening element; the
fastening element is configured to exert pressure on the
spring-loaded member to extend a length of the spring-loaded
member; and the spring-loaded member is configured to protrude from
a position at a perimeter of the first opening in response to the
exerted pressure to lock the polyaxial joint at the predetermined
orientation in the first opening.
23. The apparatus of claim 1, wherein the securing mechanism
includes: a cam lock having a rotating member and a pressure
member, wherein the pressure member is configured to protrude from
a position at a perimeter of the opening to exert pressure on the
polyaxial joint, based on a rotation of the rotating member, to
prevent movement of the polyaxial joint.
24. An apparatus for treating fractures of the femur comprising: a
first plate configured to secure to an exterior of a femur, the
first plate providing a first opening; an extended portion having a
polyaxial joint affixed at one end, the extended portion is
configured to extend through the first opening; and a cross member
configured for insertion into the extended portion to permit
sliding compression of a fracture of the femur and rotation about a
plurality of axes as provided by the polyaxial joint; wherein the
polyaxial joint comprises two sections arranged on each side of the
first opening to compress the first plate therebetween and lock the
extended portion in place at a predetermined orientation.
25. An apparatus for treating fractures of the femur comprising: a
first plate configured to secure to an exterior of a femur, the
first plate providing a first opening; an extended portion having a
cylindrical-shape joint affixed at one end, the extended portion is
configured to extend through the first opening; a cross member
configured for insertion into the extended portion to permit
sliding compression of a fracture of the femur and rotation about
an axis as provided by the cylindrical-shape joint; and a securing
mechanism configured to lock the polyaxial joint at a predetermined
orientation in the first opening.
26. An apparatus for treating fractures of the femur comprising: An
intramedullary rod having a proximal end and a distal end and
configured for insertion into the marrow canal of the femur, the
intramedullary rod includes a proximal pair of openings closer to
the proximal end than to the distal end; a spherical joint inserted
internal to the intramedullary rod near the proximal pair of
openings in the intramedullary rod; a cross member configured for
insertion through the proximal pair of openings and the spherical
joint to permit sliding compression of a fracture of the femur and
rotation about a plurality of axes as provided by the spherical
joint; and a securing mechanism internal to the intramedullary rod
and configured to lock the polyaxial joint at a predetermined
orientation in the first opening.
27. The apparatus of claim 26, wherein the securing mechanism
comprises: a setting element configured to exert pressure on the
spherical joint to lock the spherical joint at the predetermined
orientation.
28. The apparatus of claim 27, wherein the setting element
comprises a screw.
29. The apparatus of claim 6, wherein the securing mechanism
comprises: a cam lock having a rotating member and a pressure
member, wherein the pressure member is configured to exert pressure
on the spherical joint, based on a rotation of the rotating member,
to prevent movement of the polyaxial joint.
30. The apparatus of claim 26, wherein the spherical joint includes
a first through bore configured to receive the cross member
therethrough.
31. The apparatus of claim 26, wherein the spherical joint includes
at least two through bores, one of which is configured to receive
the cross member therethrough.
32. The apparatus of claim 31, wherein the other through bore in
the spherical joint is configured to receive another cross
member.
33. The apparatus of claim 31, wherein the other through bore in
the spherical joint is configured to receive a guiding mechanism
that is used to guide the cross member.
34. The apparatus of claim 26, further comprising: an extended
portion that engages the spherical joint and extends out of the
intramedullary rod through at least one of the proximal pair of
openings.
35. The apparatus of claim 26, further comprising: another
spherical joint inserted internal to the intramedullary rod near
the proximal pair of openings in the intramedullary rod;
36. A method for treating fractures of the femur, comprising:
inserting a cross member into a head of a femur at a desired angle;
placing an extended portion through a first opening in a first
plate to enclose a part of the cross member; permitting a sliding
compression of a fracture of the femur through the cross member
enclosing in the extended portion; and arranging the first plate to
touch a lateral side of the femur, while maintaining the extended
portion through the first opening and the enclosure of the cross
member at the desired angle, by rotating a polyaxial joint that is
affixed at one end of the extended portion; and once the first
plate is arranged at a desired position at the lateral side of the
femur, engaging a securing mechanism to lock the polyaxial joint at
an orientation that corresponds to the desired angle of the cross
member.
37. A method for treating fractures of the femur comprising:
inserting an intramedullary rod having a proximal end and a distal
end into a femur, the intramedullary rod further having a proximal
pair of openings closer to the proximal end than to the distal end
and a spherical joint internal to the intramedullary rod and near
the proximal pair of openings; determining a proper angle for
insertion of a cross member to engage a head of the femur; rotating
the spherical joint to an orientation that corresponds with the
proper angle for the cross member to engage the femoral head;
engaging a secure mechanism to lock the spherical joint at the
corresponding orientation; and inserting the cross member through
the pair of proximal openings and the spherical joint to engage the
femoral head, the cross member permitting a sliding compression of
a fracture of the femur.
Description
PRIORITY INFORMATION
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/577,027, filed Mar. 26, 2004, entitled,
"Compression Hip Screw and Intramedullary Nail with Polyaxial
Adjustable Neck Screw," which is incorporated herein by reference
in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to methods and
devices for treating femoral fractures. More specifically, the
present invention relates to the use of novel compression hip screw
and intramedullary nail assemblies with a polyaxial cross member
for treating fractures to the femur.
[0004] 2. Background of the Invention
[0005] There are a variety of devices used to treat femoral
fractures. Fractures of the neck, head or intertrochanter of the
femur have been successfully treated with a variety of compression
hip screw and intramedullary nail assemblies. A common compression
hip screw (CHS) assembly generally includes a side plate having a
barrel member, a lag screw, and a compression screw. The side plate
is secured to the exterior of the femur, and the barrel member is
inserted into a predrilled hole at a proper angle in the direction
of the femoral head. The lag screw, which has a threaded end and a
smooth portion, is inserted through the barrel member so that it
extends across the break or fracture line and into the femoral
head. The threaded portion engages the femoral head. The
compression screw connects the lag screw to the plate. By adjusting
the tension of the compression screw, the active compression or
reduction of the fracture can be adjusted. The smooth portion of
the lag screw is free to slide through the barrel member to permit
the adjustment of the compression screw for active compression.
Furthermore, under load of a patient's body weight, while proper
angulation of the femoral head is maintained, the lag screw can
slide inside the barrel member to allow the fractured sides of the
break to bear on each other for passive compression and optimal
healing of the fracture. Some examples of CHS assemblies are the
Ambi Classic compression hip screw assembly manufactured by Smith
& Nephew Inc. of Memphis, Tenn., and those shown in Fixel, U.S.
Pat. No. 4,432,358; Callender, Jr., U.S. Pat. No. 3,374,786; Pugh
et al., U.S. Pat. No. 2,702,543; Griggs, U.S. Pat. No. 4,530,355;
Blosser, U.S. Pat. No. 3,094,120; and Wagner, U.S. Pat. No.
3,842,825.
[0006] A typical intramedullary nail assembly generally includes an
intramedullary rod and a cross member directed toward the femoral
head. The intramedullary rod is inserted into the marrow canal of
the femur. The angled cross-member is inserted through the femur
and a proximal end of the intramedullary rod. Some examples of the
intramedullary nail assemblies are the Russell-Taylor (RT)
reconstruction nail assembly and IMHS (intramedullary hip screw)
assembly manufactured by Smith & Nephew Inc. of Memphis, Tenn.
A description of the IMHS assembly is in U.S. Pat. No. 5,032,125,
issued on Jul. 16, 1991 to Durham et al., which is herein
incorporated by reference in its entirety. As with the common CHS
assembly mentioned earlier, both the RT reconstruction nail and the
IMHS assemblies allow: a) active sliding compression that surgeons
can apply during surgery to reduce the fracture; and b) passive
sliding compression under load of a patient's body weight. While
the IMHS assembly employs a barrel member similar in some ways to
the barrel member in the common CHS assembly, the RT reconstruction
nail relies on its own structure without any barrel to provide the
active/passive sliding compression.
SUMMARY OF THE INVENTION
[0007] Summary of the Problems
[0008] The aforementioned conventional devices have a fixed-angle
opening oriented toward the femoral head, through which the sliding
lag screw or cross-member is inserted. As a result, the lag screw
or cross member can only be oriented at a single fixed angle
relative to the side plate or intramedullary rod. Thus, when
treating proximal femur fractures with such devices, surgeons are
limited to using implants with a fixed anteversion/retroversion,
regardless of the patient anatomy, which can vary significantly
from one patient to the next. Such a limitation frequently leads to
suboptimal cross member placement, which can lead to screw cut-out
through the femoral head and further damage the proximal femur.
Constrained by the fixed anteversion/retroversion in conventional
femur fracture devices, surgeons could resort to making adjustments
to accommodate a patient's anatomy by contouring the side plate, if
a compression hip screw assembly is used; or aligning the
intramedullary rod, if an intramedullary nail assembly is used, to
properly situate the fixed-angle lag screw across the fracture in
the femur. However, such adjustments often require additional
surgical operations to the muscles and tissues surrounding the
proximal femur that would pose further health risks to the patient.
There exists a compression hip screw assembly with a variable neck
angle named VHS.TM. (variable hip screw) from Biomet of Warsaw,
Ind. However, such device uses a high-profile worm gear mechanism
for angle adjustment and does not allow for continuously variable
retroversion/anteversion.
[0009] Summary of the Solutions
[0010] The present invention advantageously addresses at least the
above needs and other needs by providing methods for treating
fractures of the femur and femoral fracture devices that can
accommodate variances in a patient's anatomy through the use of a
polyaxial adjustable cross member.
[0011] Accordingly, in one embodiment of the present invention,
there is provided an apparatus for treating fractures of the femur
comprising: a first plate configured to secure to an exterior of a
femur, the first plate providing a first opening; an extended
portion having a polyaxial joint affixed at one end, the extended
portion configured to extend through the first opening; a cross
member configured for insertion into the extended portion to permit
sliding compression of a fracture of the femur and rotation about a
plurality of axes as provided by the polyaxial joint; and a
securing mechanism configured to lock the polyaxial joint at a
predetermined orientation in the first opening.
[0012] In another embodiment of the present invention, there is
provided an apparatus for treating fractures of the femur
comprising: an intramedullary rod having a proximal end and a
distal end and configured for insertion into the marrow canal of
the femur, the intramedullary rod including a proximal pair of
openings closer to the proximal end than to the distal end; a
spherical joint inserted internal to the intramedullary rod near
the proximal pair of openings in the intramedullary rod; a cross
member configured for insertion through the proximal pair of
openings and the spherical joint to permit sliding compression of a
fracture of the femur and rotation about a plurality of axes as
provided by the spherical joint; and a securing mechanism internal
to the intramedullary rod and configured to lock the polyaxial
joint at a predetermined orientation in the first opening.
[0013] Alternative embodiments include the use of different
securing mechanisms to lock the polyaxial joint in place and
methods for using the same.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The preferred embodiments are illustrated by way of example
and not limited in the following figure(s), in which:
[0015] FIG. 1 depicts aspects of a polyaxial compression hip screw
(CHS) assembly, in accordance with one embodiment of the present
invention;
[0016] FIG. 2 depicts the polyaxial CHS assembly shown in FIG. 1,
broken down into its various components, in accordance with an
embodiment of the present invention;
[0017] FIG. 3 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0018] FIG. 4 depicts the polyaxial CHS assembly shown in FIG. 2,
broken down into its various components, in accordance with an
embodiment of the present invention;
[0019] FIG. 5 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0020] FIG. 6 depicts the polyaxial CHS assembly shown in FIG. 5,
broken down into its various components, in accordance with an
embodiment of the present invention;
[0021] FIG. 7 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0022] FIG. 8 depicts the polyaxial CHS assembly shown in FIG. 7,
broken down into its various components, in accordance with an
embodiment of the present invention;
[0023] FIGS. 9A-D depict aspects of a polyaxial CHS assembly, in
accordance with various embodiments of the present invention;
[0024] FIGS. 10A-B depict various configurations for the side wall
or inner surface of an opening in the side plate of a polyaxial CHS
assembly, in accordance with one embodiment of the present
invention;
[0025] FIG. 11 depicts an embodiment of a polyaxial joint for use
in a compression hip screw (CHS) assembly, in accordance with
another embodiment of the present invention;
[0026] FIG. 12 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0027] FIG. 13 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0028] FIGS. 14A-B depict aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0029] FIG. 15 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiments of the present invention;
[0030] FIG. 16 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0031] FIGS. 17A-B depict aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0032] FIGS. 18A-B depict aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0033] FIG. 19 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0034] FIG. 20 depicts aspects of a polyaxial CHS assembly, in
accordance with another embodiment of the present invention;
[0035] FIG. 21 depicts aspects of a polyaxial intramedullary (IM)
nail assembly, in accordance with another embodiment of the present
invention;
[0036] FIG. 22 depicts aspects of a polyaxial intramedullary (IM)
nail assembly, in accordance with another embodiment of the present
invention; and
[0037] FIG. 23 depicts an exemplary shape for an opening in the
side plate of a compression hip screw assembly, in accordance with
an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Reference is now made in detail to embodiments of the
present invention, aspects of certain illustrative embodiments of
which are illustrated in the accompanying drawings, in which like
numerals indicate like elements, showing femoral fracture devices
with a polyaxial adjustable cross member that can: a) rotate about
a wide range of angles and anteversion/retroversions during
treatments for optimal angular placement of such cross member
across the fracture site; and b) withstand high weight-bearing
loads once its optimal angular placement is set to prevent
undesirable axial and bending moments. Among other advantages in
certain cases, but not necessary to the operation or structure of
any particular embodiments or devices according to the invention,
cut-out of such cross member through the femoral head can be
reduced. In other cases, although once again this aspect is not
necessary to operation or structure of any particular embodiments
or devices according to the invention, inventory of parts for
femoral fracture devices of the present invention can also be
substantially reduced because a one-size device can be used for
different angles and anteversions/retroversions.
[0039] FIG. 1 depicts aspects of a polyaxial compression hip screw
(CHS) assembly 100 having a polyaxial cross member in accordance
with one embodiment of the present invention. This particular
polyaxial CHS assembly 100 includes a side plate 110, a barrel
member 120, a cross member 130, a compression screw 150, and a
securing mechanism 140. FIG. 2 depicts the compression hip screw
assembly 100 of FIG. 1, broken down into its various components.
The side plate 110 is a support plate and, preferably, it can be
contoured for contacting and securing to the exterior of the
fractured proximal femur of a patient via, e.g., screws into the
holes 112. In one embodiment, the side plate 110 can also be a
compression plate. Holes 112 can be threaded, or unthreaded, or a
combination of both, to allow screws to operate as fixation screws
or compression screws. As one example, some holes can be threaded
for fixation screws, to form a rigid screw/plate construct, and
some holes can be unthreaded to receive compression screws, for
active compression during surgery. As another example, some or all
holes can include a threaded portion and a non-threaded portion to
receive either compression or fixation screws.
[0040] The barrel member 120 is an extended portion that
incorporates a spherical or ball joint 122 on one end and extends
through an opening 114 in the side plate 110. The ball joint 122 is
allowed to pivot, preferably but not necessarily continuously, in a
polyaxial manner in the opening 114 through a predetermined range
of motion in preferably multiple degrees of rotational freedom.
Accordingly, the ball joint 122 can have a potentially infinite
number of positions across its range of motion relative to the
opening 114; alternatively, structure such as detents or other
desired features can be included to cause the ball joint 122 to
cooperate with the opening 114 in a manner that only allows certain
settings, such as certain degrees of angulation relative to the
side plate 110. The cross member 130 is a component that is able to
engage the proximal portion of the femur, such as the femoral head.
In one embodiment, the cross member 130 can be a lag screw and is
described and illustrated as such throughout the present disclosure
for simplicity. However, alternative embodiments are contemplated
wherein the cross member 130 can be any fastening element, with or
without threads, that can engage and anchor to the proximal portion
of the femur, such as the femoral head. The lag screw 130 includes
a threaded end 132 and a smooth portion 134. It is inserted through
the barrel member 120 and extends across the fracture line and into
the femoral head. In the particular embodiment shown, the
compression screw 150 secures the lag screw 130, via the threaded
bore 136, within the barrel member 120 and/or ball joint 122. By
adjusting the tension of the compression screw 150, the compression
(reduction) of the fracture can be adjusted. The smooth portion 134
of the lag screw 130 is free to slide through the barrel member 120
to permit the adjustment of the compression screw 150 during active
compression. The smooth portion 134 also provides for sliding
compression of the fracture site due to the patient's
weight-bearing and muscle forces.
[0041] The securing mechanism 140 includes a securing element 144,
such as a top plate, and one or more fastening elements 146, such
as screws, that secure the barrel member 120 to an end of the side
plate 110, which can have a depression around the opening 114 to
accommodate and if desired, help urge the top plate 144 toward the
outer surface of the side plate 110. In operation, the lag screw
130 is inserted at a proper angle relative to the femur to engage,
for example, the femoral head. Once the proper angle is achieved,
the barrel member 120 with its ball joint 122 is inserted through
the opening 114 in the side plate 110 and over the lag screw 130
until the side plate 110 is in contact with the lateral side of the
femur. At this juncture, the side plate 110 can be adjusted in
multiple planes until it fits, preferably flush, to the side of the
femur. The securing mechanism 140 is then engaged; in this case,
the screws 146 are tightened to press the top plate 144 against the
side plate 110 and bias the ball joint 122 against the side wall of
the four-sided opening 114 so that the ball joint 122 make contact
with such side wall at one or more areas to hold or retain the ball
joint 122 in place at the desired orientation. The surgery is
continued and completed in a standard manner.
[0042] As a body implant, the polyaxial CHS assembly 100 can be
subjected to high weight-bearing loads with combined axial
(rotational) and bending (downward and off-axis) components. For
example, according to some accounts, the lag screw 130 can be
subjected to three times the patient's body weight every time the
patient takes a step, with a typical cyclical loading of
approximately one million times (i.e., steps) a year over the life
cycle of the implant (some are never removed); and to even higher
loads for more strenuous activities such as stair climbing and
running. Such high weight-bearing loads can cause undesirable
rotation of the lag screw 130 about its long axis, overwhelm the
securing mechanism 140, and shift the ball joint 122 away from the
desired orientation. Hence, an anti-rotation aspect can be
incorporated into the polyaxial CHS assembly to prevent the
rotation of its cross member. In the particular polyaxial CHS
assembly 100, the lag screw 130 is keyed with a depression 138,
that is preferably flat with two side walls, along its long axis,
as shown in FIG. 2. Correspondingly, internal to barrel member 120
is a protrusion (not shown) that extends out from the inner wall of
the barrel member 120 and into the depression 138 when the lag
screw 130 is inserted through the barrel member 120. Thus, such
protrusion is bounded by the side walls of the depression 138, and
the lag screw 130 is prevented from rotating once its threaded end
132 is engaged in the femoral head to keep the femoral head from
rotating and/or the threads end 132 from rotating out of the bone.
However, the rotational stress that urges a rotation of the lag
screw 130 is now further imparted on the ball joint 122.
[0043] To withstand the expected high weight-bearing loads and the
resulting rotational stress to the lag screw 130 as discussed
above, the polyaxial CHS assembly 100 can be designed with proper
geometric configurations as already described above and further
described later. Additionally, suitable types of material having
proper tensile strength and kinds of surface texture for the
various components of such a polyaxial CHS assembly can be chosen
in light of the expected loads. Additional embodiments of a
polyaxial CHS assembly are further described below.
[0044] FIG. 3 depicts aspects of a polyaxial CHS assembly 200 with
a polyaxial cross member in accordance with another embodiment of
the present invention. The polyaxial CHS assembly 200 functions
similarly to the assembly 100 depicted in FIG. 1, with like
numerals indicating like elements, except for the securing
mechanism 240. FIG. 4 depicts the polyaxial CHS assembly 200,
broken down into its various components to further illustrate the
securing mechanism 240. In this particular polyaxial CHS assembly
200, the securing mechanism 240 includes a securing element 244,
such as a generally concave-shaped clamp, and one or more fastening
elements 246, such as screws, that clamp down to the side plate 110
and secure the ball joint 122 to the side plate 110. The clamp 244
cooperates with one end of the side plate 110 to form an opening
114, for example a circular opening, in which the ball joint 122
can pivot in a polyaxial manner. Once the lag screw 130 is situated
at a proper angle relative to the femur, and the side plate 110 is
adjusted as described earlier, the one or more screws 246 are
tightened in the opposing screw slots in the clamp 244 and side
plate 110 to bias the ball joint 122 against the side wall of the
opening 114 so that the ball joint 122 can make contact with such
side wall at one or more areas to hold and retain the ball joint
122 in place at the desired orientation.
[0045] Although FIGS. 3 and 4 depict a clamp 244 that cooperates
with the side plate 110 to form the circular opening 114,
alternative embodiments are contemplated wherein the opening 114
can have different shapes, with clamp 244 and one end of the side
plate 110 having different shapes to form the shape of the opening
114. The different shapes for the opening 114 can be devised as
desired such that the opening 114 can provide a proper seat for the
ball joint 122 and contact the ball joint 122 at one or more areas
to assist in maintaining the ball joint 122 at the desired
orientation under high-weight bearing loads as discussed earlier.
For example, the clamp 244 and one end of the side plate 110 can
both have half-rectangular shapes that cooperate with each other to
form a rectangular-shaped opening 114 similar to the same one shown
in FIG. 2. In another example, the clamp 244 and the end of the
side plate 110 can have shapes that cooperate with each other to
form an opening 114 in the shape shown in FIG. 23. Additionally,
the clamp 244 and the end of the side plate 110 can have shapes
different from each other.
[0046] FIG. 5 depicts aspects of a CHS assembly 300 with a
polyaxial cross member in accordance with still another embodiment
of the present invention. The polyaxial CHS assembly 300 functions
similarly to the assemblies 100 and 200 shown in FIGS. 1 and 3,
with like numerals indicating like elements, except for the
securing mechanism 340. FIG. 6 depicts the polyaxial CHS assembly
300, broken down into its various components to further illustrate
the securing mechanism 340. As shown, the securing mechanism 340
includes a securing element 344, such as a top plate, that can be
threaded to one end of the side plate 110 to secure the ball joint
122 to the side plate 110. Also as shown, the top plate 344
includes holes on its surface to which a tool can be applied to
turn the top plate 344. However, alternative embodiments are
contemplated in which the top plate 344 can be adapted for any tool
to be used to turn the top plate 344. Once the lag screw 130 is
inserted at the proper angle as mentioned earlier, the top plate
344 is threaded tightly to the one end of the side plate 110 to
bias the ball joint 122 against the side wall of the opening 114 so
that the ball joint 122 can make contact with such side wall at one
or more areas to hold and retain the ball joint 122 in place at the
desired orientation.
[0047] In addition to the top plate 344 being threaded, it can have
an internal design that includes one or more ball bearings 1610
placed in one or more angled slots 1620 as shown in FIG. 16. In
this embodiment, as the top plate 344 is turned in one direction,
e.g., clockwise, to engage the side plate 110 and the ball joint
122, each bearing 1610 rolls along its respective angled slot 1620
in the other direction, e.g., counterclockwise, until it reaches a
stopping position, whereby it is compressed between the ball joint
122 and the wall of its respective angled slot 1620. Thus, such
compression further holds or maintains the ball joint 122 in place
at the desired orientation.
[0048] FIG. 7 depicts aspects of a CHS assembly 400 with a
polyaxial cross member in accordance with still another embodiment
of the present invention. The polyaxial CHS assembly 400 functions
similarly to the assemblies 100, 200, and 300 shown in FIGS. 1, 3,
and 5, with like numerals indicating like elements, except for the
securing mechanism 440. FIG. 8 depicts the polyaxial CHS assembly
400, broken down into its various components to further illustrate
the securing mechanism 440. In this particular polyaxial CHS
assembly 400, the securing mechanism 440 includes a securing
element 444, such as a top plate, and one or more fastening
elements 446, such as screws, that secure the barrel member 120 to
an end of the side plate 110. This embodiment is different from the
one shown in FIG. 2 in that the side plate 110 is not depressed
around the opening 114 in order to accommodate the top plate 444.
Instead, the top plate 444 is set abutted against the one end of
the side plate 110 as shown in FIG. 7. Once the lag screw 130 is
inserted at the proper angle, the screws 446 are tightened to press
the top plate 444 against the side plate 110 and bias the ball
joint 122 against the side wall of the opening 114 so that the ball
joint 122 can make contact with such side wall at one or more areas
to hold and retain the ball joint 122 in place at the desired
orientation.
[0049] To avoid further repetition in the present disclosure,
additional embodiments of a CHS assembly with a polyaxial cross
member are described next without any further reference to those
common components that are already described earlier.
[0050] FIG. 9A depicts aspects of a polyaxial CHS assembly 900, as
viewed directly into the side plate 110, having additional
"press-fit sleeve" securing mechanism 940 in accordance with one
embodiment of the present invention. Similar to the polyaxial CHS
assembly 300 depicted in FIGS. 5-6, the side plate 110 in the
polyaxial CHS assembly 900 includes an opening 114 at one end. The
securing mechanism 940 includes an expandable collet 944 that can
secured to the side wall of the opening 114 by another securing
mechanism, such as the securing mechanism 240 shown in FIGS. 3-4
and described earlier. The expandable collet 944 can be a
single-piece design, as shown in FIG. 9A, or a multiple-piece
design, for example, a two-piece design as shown in FIG. 9B. The
multiple-piece design of the collet 944 allows it to be used with
other securing mechanisms as described later.
[0051] In the particular embodiments shown in FIGS. 9A-B, the
barrel member 120 is tapered along its long axis. FIG. 9C depicts a
cross section of the barrel member 120, as cut along its long axis
towards the opening 114, showing the tapered sides. As shown in
FIGS. 9A-B, as the tapered barrel member 120 is inserted,
preferably with its tapered end first, into an opening in the
center of the expandable collet 944 and at the desired angle to
cover the lag screw 130, it causes the collet 944 to compress
against the side wall of the opening 114. The pressure that the
collet 944 exerts back to the tapered barrel member 120, due to
contact with the larger diameter of the tapered barrel member 120
as it is further inserted into the collet 944, serves to hold and
retain the barrel member 120, and thus the lag screw 130, in place
at the proper angulation. Thus, the collet 944 can be used as a
polyaxial joint in place of the ball joint 122 shown in FIGS.
1-8.
[0052] According to another embodiment for the additional "press
fit sleeve" securing mechanism, the tapered barrel member 120 shown
in FIG. 9C can further be threaded on its surface at one end. FIG.
9D depicts a cross section of the barrel member 120T, as cut along
its long axis towards the opening 114, showing the tapered sides
and threaded surface. Accordingly, the collet 944 is also threaded
in the opening at its center in order to receive the threaded
barrel member 120T. In this embodiment, as the barrel member 120T
is inserted, preferably with its tapered end first, into the
threaded center opening of the expandable collet 944 and at the
desired angle to cover the lag screw 130, the threadings on the
barrel member 120T eventually engages with the threadings in the
expandable collet 944 and as the barrel member 120T is turned along
its threadings, it causes the collet 944 to expand into the side
wall of the opening 114 and secures the collet 944 to the opening
114 in the side plate 110. Also, the pressure that collet 944
exerts back to the tapered barrel member 120, due to the threaded
contact with the barrel member 120T serves to hold and retain the
barrel member 120, and thus the lag screw 130, in place at the
proper angle.
[0053] FIG. 12 depicts a polyaxial CHS assembly 1200, as viewed
directly into the side plate 110, with another embodiment for a
securing mechanism. Similar to some of the previously-described
polyaxial CHS assemblies, the side plate 110 in the polyaxial CHS
assembly 1200 includes an opening 114 at one end. It also has a gap
1220 at one portion in the side wall of the opening 110. The
securing mechanism then includes a slot or hole 1240 and a
fastening element 1260, such as a screw, that can be inserted into
the slot 1240 to bring the separated portions of the side plate 110
together and close the gap 1220. Thus, once the lag screw 130 is at
a proper angle, the barrel member 120 is inserted through the
opening 114 to cover the lag screw 130 at the desired orientation,
the screw 1260 is tightened or compressed in the slot 1240 to bias
the ball joint 122 against the side wall of the opening 114 so that
the ball joint 122 can make contact with such side wall at one or
more areas to hold and retain the ball joint 122 in place at the
desired orientation. Furthermore, as with the securing mechanism
240 shown in FIGS. 3-4, the securing mechanism shown in FIG. 12 can
also be used to secure the expandable collet 944, shown in FIG. 9A,
to the side wall of the opening 114.
[0054] FIG. 13 depicts a polyaxial CHS assembly 1300, as viewed
directly into the side plate 110, with still another embodiment for
a securing mechanism. Similar to some of the previously-described
polyaxial CHS assemblies, the side plate 110 in the polyaxial CHS
assembly 900 includes an opening 114 at one end. As with the
embodiment shown in FIG. 12, the side plate 110 also has a gap 1220
at one portion in the side wall of the opening 110. However, in
place of the internal slot 1240, external slots 1340 are provided
to the separated portions of the side plate 110, through which a
fastening element 1360, such as a screw, can be inserted and
tightened to bring the separated portions together and close the
gap 1220 to hold and retain the ball joint 122 in place at the
desired location, as explained earlier. In other embodiments
similar to the one shown in FIG. 13, in place of the external slots
1340 and screw 1360, a cam lock, a latch, or any known locking
mechanism can be arranged along the gap 1220 to bring the separated
portions of the side plate 110 together and close such gap.
Furthermore, as with the securing mechanism 240 shown in FIGS. 3-4,
the securing mechanism shown in FIG. 13 and the above alternate
embodiments can also be used to secure the expandable collet 944,
shown in FIG. 9A, to the side wall of the opening 114.
[0055] FIGS. 14A-B depict side views of a CHS assembly 1400 with a
polyaxial cross member in accordance with still another embodiment
of the present invention. Similar to some of the
previously-described polyaxial CHS assemblies, the side plate 110
in the polyaxial CHS assembly 1400 includes an opening 114 at one
end. However, FIG. 14A shows a cross-sectional view of the ball
joint 122 that is constructed from two half sections 1430 and 1450.
In this embodiment, the barrel member 120 can be press-fitted,
welded, made integral with (i.e., as a single structure), or
secured in any desired manner with either one of the half sections
1430, 1450 of the ball joint 122; e.g., the first half section
1430. The remaining half section, e.g., the half section 1450, of
the ball joint 122 can be internally threaded and separate from the
first half section 1430. The barrel member 120 is further threaded
at one end to receive the threads of the second half section 1450
so that the first half section 1430 can be held in place as the
second half section 1450 is turned to create a distance between the
two half sections 1430 and 1450, as shown by the arrows in FIG.
14A. Thus, the ball joint 122, formed from two half sections, is
pre-fitted into the opening 114 of the side plate 110. In
operation, the lag screw 130 is first inserted at a proper angle
relative to the femur to engage, for example, the femoral head.
Once the proper angle is achieved, the side plate 110, with the
pre-fitted barrel member 120 and ball joint 122, is introduced to
the lateral side of the femur so that the barrel member 120 can be
placed over the lag screw 130. Again, at this junction, the side
plate 110 can be adjusted in multiple planes until it fits,
preferably flush, to the side of the femur. The barrel member 120
is then turned to separate the two half sections 1430,1450 of the
ball joint 122 and compress them against the edges of the opening
114, as shown in FIG. 14B, to hold and retain the ball joint 122 in
place at the desired orientation. The surgery is continued and
completed in a standard manner.
[0056] FIG. 15 depicts another embodiment for a CHS assembly 1500
with a polyaxial cross member. In this embodiment, in place of a
ball joint 122 is a polyaxial joint that is formed from two half
sections 1530 and 1550. The side plate 110 is contoured at the
opening 114 (hidden from view) to accommodate the contours of the
two half sections 1530 and 1550. For example, in the particular CHS
assembly 1500, the side plate 110 at the opening 114 and the two
half sections 1530 and 1550 are curved. The barrel member 120 can
be press-fitted, welded, made integral with (i.e., as a single
structure), or secured in any desired manner with the first half
section 1530. The second half section 1550 can be internally
threaded and separated from the first half section 1550 by the side
plate 110. The barrel member 120 is further threaded at one end to
allow the threaded second half section 1550 to engage the barrel
member 120. Once the lag screw 130 is set at a proper angle, the
barrel member 120 with the attached half section 1530 can be placed
over the lag screw 130. Next, the side plate 110 is attached to the
femur so that the barrel member 120 protrudes through the opening
114 in the side plate 110. In this embodiment, the opening 114 is
larger than the barrel member 120 to enable the latter to be set at
a desired orientation. Thus, while the first half section 1530 is
held in place by the barrel member 120, the second half section
1550 is threaded onto the barrel member 120 to compress the side
plate 110 in between the two half sections 1530 and 1550 of the
polyaxial joint. The resulting compression locks the barrel member
120 in place at the desired orientation. In an alternative
embodiment, the barrel member 120 can be press-fitted, welded, made
integral with (i.e., as a single structure), or secured in any
desired manner with the second half section 1550, and the first
half section 1530 is internally threaded. The barrel member 120 is
also threaded on its surface to engage the threaded first half
section 1530 so that when the barrel member 120 is turned, the
second half section 1550 is compressed against the side plate 110,
and the first half section 1530 is drawn also compress against side
plate (110) and hold the barrel member 120 in place at the desired
orientation.
[0057] Alternative embodiments are further contemplated wherein the
polyaxial joint is neither a ball joint or those shown in FIG. 15,
but a cylinder that can achieve uni-axial motion based on its long
axis, and the lag screw 130 can be set at any angle along that
singular axis of motion.
[0058] FIGS. 17A-B depict aspects of a polyaxial CHS assembly 1700,
as viewed directly into the side plate 110, with another embodiment
for a securing mechanism. In this embodiment, the securing
mechanism includes an interference element 1710, such as a screw,
that can be inserted in the opening 114 between the ball joint 122
and the side plate 110 anywhere along the side wall of the opening
114 such that it interferes with the movement of the ball joint
122. FIG. 17B depicts a cross section taken along the line A-A' of
FIG. 17A with the screw 1710. The pressure resulting from the
interference caused by the screw 1710 prevents the ball joint 122
from moving. Alternatively, the ball joint 122 and/or the screw
1710 can deform as the latter is tightened or compressed in the
opening 114 so that such deformation prevents the ball joint 122
from moving and holds and retains the ball joint 122 in place at
the desired orientation. Although only one interference element
1710 is shown in FIGS. 17A-B, alternative embodiments are
contemplated wherein there are more than one interference elements
1710 that can be inserted along the side wall of the opening 114 to
provide additional holds on the ball joint 122 and withstand the
high weight-bearing loads on the lag screw 130 as discussed
earlier. Furthermore, the securing mechanism shown in FIGS. 17A-B
and the above alternate embodiments can also be used to secure the
multi-section expandable collet 944, shown in FIG. 9B, to the side
wall of the opening 114.
[0059] FIGS. 18A-B depict aspects of a polyaxial CHS assembly 1800,
as viewed directly into the side plate 110, with another embodiment
for a securing mechanism, which employs an interference concept
similar to the above embodiment in FIGS. 17A-B to lock the ball
joint 122 in place. In this embodiment, the securing mechanism also
includes an interference element 1810, such as a screw, that
originates from the side plate 110 and engages the ball joint 122
in the opening 114 of the side plate 110. The screw 1810 can be
situated anywhere along the perimeter of the opening 114 in order
to engage the ball joint 122. It can protrude through the side wall
of the opening 114 or from an area next to such side wall. As shown
in the FIGS. 18A-B, the screw 1810 is applied against the ball
joint 122, and the resulting pressure prevents the later from
moving. Alternatively, due to the forced contact between the screw
1810 and the ball joint 122, the contacting areas of both elements
can be deformed and prevent the ball joint 122 from moving. As
further shown in FIGS. 18A-B, the screw 1810 can be located
anywhere along the side wall 114 so long as it can make contact
with the ball joint 122. Although only one interference element
1810 is shown in FIGS. 18A-B, alternative embodiments are
contemplated wherein there are more than one interference elements
1810 that can be inserted along the side wall of the opening 114 to
provide additional holds on the ball joint 122 and withstand the
high weight-bearing loads on the lag screw 130 as discussed
earlier. Furthermore, the securing mechanism shown in FIGS. 18A-B
and the above alternate embodiments can also be used to secure the
multi-section expandable collet 944, shown in FIG. 9B, to the side
wall of the opening 114.
[0060] FIG. 19 depicts aspects of a polyaxial CHS assembly 1900, as
viewed directly into the side plate 110, with another embodiment
for a securing mechanism. In this embodiment, the securing
mechanism is situated in a similar position to that of the screw
1810 shown in FIGS. 18A, B, i.e., anywhere along the side wall of
the opening 114. It includes a fastening element 1910, such as a
screw, and a spring-loaded member 1930. The screw 1910 is inserted
through an opening in the spring-loaded member 1930 to exert
pressure and straighten out the later. As the spring-loaded member
1930 is straightened, it compresses the ball joint 122 between the
side wall of the opening 114 in the side plate 110 and the
spring-loaded member and holds and retains the ball joint in place
at the desired orientation for the barrel member 120. Furthermore,
the securing mechanism shown in FIG. 19 can also be used to secure
the multi-section expandable collet 944, shown in FIG. 9B, to the
side wall of the opening 114.
[0061] FIG. 20 depicts aspects of a polyaxial CHS assembly 2000, as
viewed directly into the side plate 110, with another embodiment
for a securing mechanism. In this embodiment, the securing
mechanism 2000 is a cam lock having a rotating member 2010 and a
pressure member 2030. The rotating member 2010 can be rotated to
apply force to the pressure member 2030, which then engages and
compresses the ball joint 122 between the pressure member 2030 and
a side wall of the opening 114 to hold and retain the ball joint
122 in place at the desired orientation. The rotating member 2010
can include an overcenter feature so that it retains itself in
place against the pressure member 2030 once rotated beyond a
certain position.
[0062] In the various embodiments of a polyaxial CHS assembly
described above, the inner surface or side wall of the opening 114
can have various geometrical configurations. For example, FIG. 10A
depicts a cross section of the opening 114 as taken from line A-A'
in FIG. 9, wherein the opening 114 is enclosed by a curved or
spherical side wall 1015. The side wall 1015 can have the same
curvature as the ball joint 122 so that when the latter is inserted
into the opening 114 and set at a desired orientation, the ball
joint 122 can contact the side wall 1015 at one or more areas to
assist one of the aforementioned securing mechanisms in retaining
the ball joint 122 in place at the desired orientation. In another
example, as also shown in FIG. 10A, the opening 114 is enclosed by
a tapered side wall 1025, which have protrusions 1027 at the edges
of the side wall to help grip, compress, or make contact with the
ball joint 122 at at least two points to assist one of the
aforementioned securing mechanisms in retaining the ball joint 122
in place at the desired location. The protrusions 1027 can be
configured, positioned, and oriented as desired. In still another
example, the side wall of the opening 114 in the side plate 110
shown in FIGS. 2, 4, 6, 8, 12, 13, 16, 19, and 20 can be tapered
in, as the side wall runs from the side plate's front surface
(facing out of the femur and shown in the figures) to its back
surface (facing into the femur and hidden in the figures) to
provide a secure seating for the ball joint 122. Furthermore, the
top plates 144, 344, and 444 shown in FIGS. 2, 6, and 8 can have
their openings tapered in the opposite direction, i.e., the side
wall of such an opening is tapered in as the side wall runs from
the top plate's back surface (facing into the femur and hidden in
the figures) to the top plate's front surface. In combination, the
tapered opening 114 and the tapered opening of the top plate in
FIG. 2, 6, or 8 provide additional hold on the ball joint 122
therebetween.
[0063] According to an embodiment of the present invention, the
side wall of the opening 114, which can have various geometrical
configurations, can further include one or more protrusions 1030,
e.g., raised bumps, as shown in FIG. 10B, and the ball joint 122
correspondingly includes one or more indentations 1040, e.g.,
dimples, on its surface (e.g., similar to a golf ball). FIG. 10B
shows only some of the protrusions 1030 and indentations 1040 for
illustration purposes. It should be noted that the protrusions 1030
can be distributed uniformly throughout the side wall of the
opening 114; likewise, the indentations 1040 can be distributed
uniformly throughout the surface of the ball joint 122.
Alternatively, the protrusions 1030 can be distributed uniformly
throughout the surface of the ball joint 122, and the indentations
1040 can be distributed uniformly through the side wall of the
opening 114. The cooperation of the protrusions 1030 and
indentation 1040, wherever they may be distributed, can limit the
ball joint 122 to preset angulations. However, such cooperation can
provide an additional hold on the ball joint 122 at the preset
angulations and assist the lag screw 130 in withstanding the high
weight-bearing loads mentioned earlier. Thus, the densities of the
protrusions 1030 and the indentations 1040 and their locations on
the side wall of the opening 114 and the surface of the ball joint
122 can be strategically chosen to provide desired angulations of
the ball joint 122 about desired axes, wherein such angulations and
desired axes are found useful in accommodating the human anatomy
for fracture treatments, such as sliding compression. The ball
joint 122 is then rotated to a desired location for the barrel 120,
and one or more of the protrusions 1030 are aligned and latched
with the one or more indentations 1040 on the surface of the ball
joint 122 to further hold the ball joint 122 at the desired
orientation.
[0064] In some or all of the various embodiments of a polyaxial CHS
assembly described above, wherein the ball joint 122 is employed,
the ball joint 122 further can be a collet-type ball joint with one
or more slots or slits for expansion. FIG. 11 depicts a cross
section of the ball joint 122 having expansions slots 1221 that are
preferably arranged in a general direction along the axis of
insertion of the ball joint 122 into the opening 114. As the ball
joint 122 is biased against the opening 114 to hold it in place at
a desired orientation, the ball joint 122 compresses against the
expansions slots 1221, which will counter with an expansion force
(due to their spring-like actions) to further press the ball joint
122 against the opening 114 and assist with the holding of the ball
joint 122 at the desired orientation.
[0065] Although some or all of the above-described embodiments of a
polyaxial CHS assembly depict a rectangular, square, or circular
opening 114 in the side plate 110 to accommodate the ball joint
122, other embodiments are contemplated wherein the opening 114 can
be circular, elliptical, polygonal, or any other shape, or any
combination thereof so as to create a proper seat for the ball
joint 122.
[0066] Furthermore, although some or all of the above-described
embodiments of a polyaxial assembly depict the ball joint 122 as a
part of or integral to the barrel member 120, alternative
embodiments are contemplated wherein the ball joint 122 is a
separate component from the barrel member 120 but attached,
affixed, or secured to one end of the barrel member 120 in any
desired manner.
[0067] Still furthermore, although some or all of the
aforementioned embodiments of a polyaxial CHS assembly have been
described wherein screws are used as fastening elements,
alternative embodiments are contemplated wherein each of the
mentioned fastening element can be a straight screw, a tapered
screw, a tapered pin, a nail, a rivet, a bolt (and nut), or any
element that can be used for fastening purposes and/or contacting
the ball joint 122 to exert pressure or compression and/or hinder
movement of the ball joint 122.
[0068] FIG. 21 depicts another femoral fracture device, namely, an
intramedullary nail (IM) assembly 2100, with a polyaxial cross
member in accordance with an embodiment of the present invention.
The IM nail assembly 2100 includes an IM rod 2110 that has a
proximal end and a stem distal thereto (not shown). Closer to the
proximal end are the openings 2114 and 2115 opposite to one
another. The IM nail assembly 2100 further includes a ball joint
2122, a securing mechanism 2116, a cross member (not shown) which
can maintain sliding contact with the ball joint 2212 to allow
sliding compression of the fracture being treated, and a
compression member (not shown) on the opposite side of the IM rod
2110 that extends through the opening 2115 and the ball joint 2122
to engage the cross member.
[0069] The securing mechanism 2116, such as a set screw, is
configured to secure the ball joint 2122 in place. It can be a
straight screw, a tapered screw, a straight pin, a tapered pin, a
nail, or any element that can exert pressure on the ball joint 2122
and hinder movement of such ball joint. The cross member in the IM
nail assembly 2100 also extends through the femoral neck, across
the fracture line, and into the femoral head; thus, it functions
similarly to the cross member 130 shown in the various polyaxial
compression hip screw assemblies described earlier. The compression
member can be adjusted in order to adjust the compression
(reduction) of the fracture and thus functions similarly to the
compression member 150 shown in the various polyaxial compression
hip screw assemblies described earlier.
[0070] According to one embodiment of the present invention, the IM
nail assembly 2100 is structurally similar in some ways to a
conventional IMHS assembly as described in, for example, U.S. Pat.
No. 5,032,125 issued on Jul. 16, 1991, to Durham et al., which is
herein incorporated by reference in its entirety, except that the
conventional barrel in the IMHS assembly that is used to receive
the cross member is now replaced with the ball joint 2122 with a
through bore. Alternatively, the IM nail assembly 2100 can further
include a barrel extension that is structurally and functionally
similar to a barrel member 120 in one of the aforementioned
polyaxial CHS assembly, whereby such barrel extension protrudes out
of IM rod 2110 through the opening 2114. Also, the internal design
of the IM rod 2110 is configured to receive the ball joint 2122,
which articulates within the IM rod 2110 and is locked in place
with the setting member 2116. The through bore in the ball joint
2122 is configured to receive the cross member via the opening 2114
in the IM rod 2110. In operation, the IM rod 2110 is first inserted
into the marrow canal of the femur. Next, the cross member is
inserted through the femur, the opening 2115, and the ball joint
2122 in the IM rod 2110, and out through the opening 2114 to the
femoral head at a proper angle. Once the proper angle is achieved,
the setting member 2116 exerts pressure (e.g., is tightened or
compressed) on the ball joint 2122 to lock the ball joint 2122, and
consequently the cross member, in place at the desired
orientation.
[0071] Accordingly, the polyaxial IM nail assembly 2100 functions
similarly to the above-described polyaxial compression hip screw
assemblies in that it allows angulation and
anteversion/retroversion of the cross member.
[0072] FIG. 22 depicts a polyaxial IM nail assembly 2200 in
accordance with another embodiment of the represent invention. The
IM nail assembly 2200 is structurally and functionally similar to
the IM nail assembly 2100 depicted in FIG. 2, except that a cam
lock 2250 is used in place of the setting member 2116 to lock the
ball joint 2122 at the desired orientation. The cam lock 2250 is
similar to one depicted in FIG. 20 in that it also includes a
rotating member 2253 and a pressure member 2255. Again, the
rotating member 2053 can be rotated to push up the pressure member
2255, which then engages and compresses the ball joint 122 to
prevent movement on the desired orientation. The rotating member
2253 can include an overcenter feature so that it retains itself in
place against the pressure member 2030 once rotated beyond a
certain position.
[0073] As with the side wall in the opening 114 of the
above-described embodiments for a polyaxial CHS assembly, the
seating (e.g., inner wall of the IM rod 2110) for the ball joint
2122 inside the IM rod 2110 for the above-described various
embodiments of an IM nail assembly can have various geometrical
configurations, such as spherical or tapered. For instance, the
seating can be a conical tapered section that can wedge the ball
joint 2122 in place to lock it as the setting member 2116 or cam
lock 2250 exerts pressure on the ball joint 2122. To enhance the
locking of the ball joint 2122, such seating can further include
one or more protrusions, e.g., raised bumps, and the ball joint 122
correspondingly includes one or more indentations 1040, e.g.,
dimples, on its surface (e.g., similar to a golf ball), as
described earlier with reference to FIG. 10B. Additionally, the
ball joint 2122 can be a collet-type ball with one or more
expansion slots as previously shown in FIG. 9D to further enhance
the locking of the such ball joint.
[0074] According to additional embodiments of the present
invention, the above polyaxial designs for the cross member in an
IM nail assembly can be applied to other fastening and/or anchoring
elements in the nail assembly as well. For example, ball joints
similar to ball joints 2122 (in above embodiments for a polyaxial
IM nail assembly) or ball joints 122 (in above embodiments for a
polyaxial CHS assembly) can be used with anchoring elements to
optimize their orientation in securing the distal end of the IM rod
2116 within the marrow canal of the femur. U.S. Pat. No. 4,827,917
issued on May 9, 1989 to David L. Brumfield, which is herein
incorporated by reference in its entirety, discloses such anchoring
elements with which ball joints can be used. Furthermore, the IM
nail assembly as disclosed in the same patent includes two cross
members; one is a lag screw and the other is an additional
anchoring element; thus, alternative embodiments are contemplated
wherein the ball joint 2122 can include more than one through bore
(and thus more than one pair of openings 2114, 2115) to accommodate
multiple cross members, or the IM rod 2116 can be configured to
accommodate more than one ball joint for the multiple cross
members. Furthermore, the ball joint 2122 can include more than one
through bore, one to accommodate a cross member and another one to
accommodate the guide wire for the cross member.
[0075] Although the invention has been described with reference to
these preferred embodiments, other embodiments could be made by
those in the art to achieve the same or similar results. Variations
and modifications of the present invention will be apparent to one
skilled in the art based on this disclosure, and the present
invention encompasses all such modifications and equivalents.
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