APPLICATION
of
JILL M. EMBRY
ROBERT J. BOOCK
for
LETTERS PATENT OF THE UNITED STATES
for
IMPLANTABLE VERTEBRAL BODY LIFT
LUEDEKA, NEELY & GRAHAM, P.C. P.O. Box 1871
Knoxville, Tennessee 37901 Telephone: (865) 546-4305 Facsimile: (865) 523-4478
In accordance with one aspect, the invention relates to vertebral lift
device. In a preferred embodiment, the device includes an expandable member made
of a bio-compatible material and having a plurality of interconnected structural
members. The expandable member has a first dimension for insertion thereof into a
damaged vertebral body having a damaged dimension. The interconnected structural
members of the expandable member are expandable to a second dimension
substantially corresponding to dimensions of the vertebral body prior to its damage.
The expandable member defines a void area within a periphery defined by the structural
members when the expandable member is expanded to the second dimension for
receiving a restoration agent. A covering configured to substantially cover the exterior
of the expandable member is provided to inhibit leakage of the restoration agent
received within the void area.
In another aspect, the invention relates to a method for restoring a
vertebral body. In a preferred embodiment, the method includes the steps of
introducing the covered expandable member into the damaged vertebral body with the
expandable member configured in its first dimension; expanding the expandable
member to its second dimension within the damaged vertebral body to substantially
restore the vertebral body to its pre-damage dimensions; maintaining the expandable
member in the vertebral body at its second dimension and introducing a restoration
agent into the void area of the expandable member; maintaining the restoration agent
within the expandable member to support the vertebral body at a restored state; and
maintaining the expandable member in the vertebral body at its second dimension to ,
assist the restoration agent in maintaining the dimensions of the vertebral body in the
restored state.
BRIEF-DESCRIPTION OF THE DRAWINGS
Further features of preferred embodiments of the invention will become
apparent by reference to the detailed description of preferred embodiments when
considered in conjunction with the figures, which are not to scale, wherein like
reference numbers, indicate like elements through the several views, and wherein,
FIG. 1 is a front view of a vertebral lift device in accordance with a
preferred embodiment of the invention.
FIG.2 is a side view of the device of FIG. 1 shown in an expanded state.
FIG. 3 is a side view of the device of FIG. 1 shown in an unexpanded
state.
FIG. 4 is a side view of a vertebral lift device in accordance with an
alternate embodiment of the invention.
FIG. 5 is an end view of the device of FIG. 4.
FIG. 6 is a side view of another embodiment of a vertebral lift device,
shown in an expanded state.
FIG. 7 is an end view of the device of FIG. 6.
FIG. 8 is a side view of still another embodiment of a vertebral lift
device, shown in an expanded state.
FIG. 9 is an end view of the device of FIG. 8.
FIGS. 10 and 11 are side and end views, respectively, of a modified
version of the device of FIGS. 8 and 9.
FIGS. 12 and 13 are side and perspective views, respectively, of an
expandable member of the device of FIGS. 10 and 11.
FIGS. 14 and 15 are side and end views, respectively, of a modified
version of the device of FIGS. 6 and 7.
FIG. 16 is a side view of a lift device having a plurality of ring members
in accordance with yet another embodiment of the invention.
FIG. 17 shows the device of FIG. 16 in an elongated state.
FIG. 18 is a detailed view of a ring member component of the device of
FIGS. 16 and 17.
FIGS. 19 and 20 are perspective and end views, respectively, of another
embodiment of a ring member.
FIGS. 21 and 22 are perspective and end views, respectively, of a lift
device having a plurality of the ring members of FIGS. 19 and 20, and configured in
an expanded and elongated state.
FIG. 23 is a side perspective view of still another embodiment of a lift
device provided by a coiled member.
FIGS. 24 and 25 show variations of the device of FIG. 23 wherein the
range of coil dimensions is illustrated.
FIG. 26 shows the device of FIG.25 elongated and expanded to provide
differing coil diameters along the length of the device as may occur when expanding
the device within a vertebral body.
FIG. 27 is a top plan view of a vertebral lift device in accordance with a
still further embodiment.
FIG. 28 is a side view of the device of FIG. 27.
FIG. 29 is a front view of the device of FIG. 27.
FIGS. 30 and 31 are perspective views of an expandable member
component of the device of FIG. 27.
FIG. 32 is a side view of a vertebral lift device in accordance with yet
another embodiment.
FIG. 33 is a top view of the device of FIG. 32.
FIG.34 is a perspective view of an expandable member component of the
device of FIG. 32.
FIG. 35 is a perspective view of an introduction member and an
associated coupling.
FIG. 36 shows an alternate embodiment of an introduction member and
coupling.
DETAILED DESCRIPTION
The invention relates to vertebral lift devices of various configurations
for insertion into a vertebral body and which are operable to be expanded to
substantially expand a fractured vertebral body to its pre- fracture dimensions during a
surgical procedure wherein a preferably flowable bone treatment agent is introduced
into the vertebral body. In this regard, it will be understood that the bone treatment
agent may be a variety of materials suitable for supporting a vertebral body, such as
bone cement, microspheres, gels, and the like. In addition to conventional bone
cement, a preferred restoration agent is a flowable material having microparticulates
of a pre-set or polymerized hydrogel material dispersed within a carrier, as described
in U.S. Application Serial No. /o/fflf, Hf . entitled HYDROGEL BONE VOID
FILLER and filed concurrently herewith.
The lift devices of the invention may be left within the vertebral body to
help maintain the vertebral body at the desired restored expanded condition. The lift
devices are also desirably configured to include a covering to help retain the bone
cement or other agent in desired locations and to otherwise inhibit undesirable post
introduction migration of the bone cement.
In one preferred embodiment, and with reference to FIGS. 1-3, the
invention relates to a vertebral lift 10 having an introduction member 12 and an
expandable member 14. A covering 16 is provided to cooperate with the expandable
member 14 to inhibit leakage of bone cement or other bone treatment agent introduced
during a surgical procedure corresponding to use of the device 10 to repair a fractured
vertebral body.
The introduction member 12 preferably provided by an elongate mandrel
of metal, plastic, or other polymeric material configured in dimension to be received
through the lumen of a conventional bone needle. The member 12 cooperates with the
expandable member 14 for expansion and/or detachment thereof. For example, the
member 12 may be rotated to introduce rotational forces to the member 14 for
expansion purposes and to detach the introduction member 12 and the expandable
member 14 from engagement with one another. Alternatively, the introduction member
12 may be utilized to push or pull on the expandable member 14 to expand it.
In the case of the expandable member 14 having kinetic expansion forces,
such as being made of a spring material, a retention device may be utilized to retain the
expandable member 14 in a compressed state and the introduction member 12
manipulated to release the retention device to allow the expandable member 14 to
expand. In this regard, it will be understood that "expansion" includes radial expansion
or elongate expansion or both and including other growth in dimension as may be
involved as the expandable body enlarges in a manner to correspond to the desired
restored dimensions of the vertebral body.
The expandable member may also be made of a thermally active material
that undergoes significant expansion or contraction when exposed to body
temperatures. For example, shaped memory alloys, such as nickel and titanium allows
exhibit significant contraction when exposed to body temperatures from an ambient
temperature. This contraction can be used to release the expandable member from a
compacted orientation and allow the components thereof to spring to an expanded
orientation.
A coupling 18 is preferably provided to detachably couple the
introduction member 12 and the expandable member 14. For example, the coupling
member 18 may be configured to be thermally activated, e.g., to expand, contract,
dissolve, or degrade, or example, in the presence of a predetermined thermal condition
to accomplish desired detachment of the introduction member and the expandable
member 14. An example of such a coupling member is described in connection with
FIG. 35. The coupling member 18 may also enable mechanical separation, wherein the
coupling member is mechanically manipulated to detach from the expandable member
14, such as described in connection with FIG. 36.
The introduction member 12 also preferably includes a flow path 20 such
as an internal channel for introducing bone cement into the interior portions of the
expandable member 14 to provide the bone cement to desired locations within a
vertebral body.
The expandable member 14 is configured to have sufficiently small
dimensions in an unexpanded state so as to allow it to be introduced by the introduction
member 12 to a vertebral body through a bone needle. The expandable member 14 is
preferably of substantially rectangular configuration and includes a peripheral
expandable frame 22 and a plurality of interconnected expandable spanning members
24 that connect between the edges of the frame 22.
The expandable member 14 is operable to be expanded once it is
desiraWy positioned in a vertebral body so as to sufficient dimensions and strength to
expand a fractured vertebral body to dimensions corresponding substantially to the pre-
fracture dimensions of the vertebral body. In this regard, the expandable member 14
may be expanded by mechanical forces, such as rotational forces imparted thereto by
the introduction member 12, or as by thermal action, wherein the material from which
the expandable member 14 is formed expands when exposed to a threshold
temperature, such as the internal body temperatures of a patient. Examples of preferred
materials include degradable and non-degradable metals and polymers which are
sufficiently non-toxic so as to enable the expandable member 14 to be left within the
vertebral body following the surgery.
The covering 16 is preferably a bio-compatible polymeric elastomer mesh
or metal mesh material that is configured to substantially cover the exterior of the
expandable member 14 to inhibit bone cement or the like introduced into a void area
26 of the expanded member 14 from leaking out of the void area 26. Preferred
materials include polyester and nickel/titanium alloys (e.g. nitinol) having a silicon or
other elastomeric coating to facilitate elasticity of the mesh and promote self-sealing
properties. The void area 26 is defined by the periphery of the structure provided by
the frame 22 and spanning members 24 and around which the covering 16 is disposed.
The covering 16, for example, may be an interwoven expandable polymer
material which allows for cell infiltration, yet maintains injected material, such as bone
cement, within its confines. Thus, while in the various views herein coverings are only
partially depicted for clarity purposes, it will be understood that the coverings
preferably substantially cover encloses the expandable member with which they are
associated.
Accordingly, in a desired method or use of the device 10 to restore a
fractured vertebral body, the expandable member 14 having the covering 16 and
attached to the introduction member 12 is introduced to a desired location within the
vertebral body by manipulation of the introduction member 12. The expandable
member 14 is then expanded, as by manipulation of the introduction member 12 or by
exposure to desired thermal conditions. Bone cement is then introduced into the void
area 26 of the expanded member 14, preferably via the introduction member 12, and
the cement cures to a hardened state. The introduction member 12 is then detached
from the expandable member 14 and the expandable member 14 is left in the vertebral
body in the expanded state with the injected bone cement maintained within the
expandable member 14 by the covering 16.
With reference to FIGS.4 and 5, there is shown an alternate embodiment
of a vertebral lift 30 having an introduction member 32 and an expandable member 34.
A covering 36 is preferably provided to cooperate with the expandable member 34 to
inhibit leakage of bone cement. The introduction member 32 and the covering 36 are
preferably substantially identical to the introduction member 12 and the covering 16.
The expandable member 34 is preferably operable in the same manners
as described for the expandable member 14. The expandable member 34 is preferably
of substantially egg-shaped or ovaloid configuration and includes a plurality of arched
expandable ribs 38. An elastomeric bumper tip 40 is preferably provided at the
terminal end of the expandable member 34 to minimize trauma during introduction of
the expandable member 34 into a vertebral body. A void area 42 is defined within the
expandable member 34 for receiving bone cement or the like in the manner of the void
area 26.
With reference to FIGS.6 and 7, there is shown an alternate embodiment
of a vertebral lift 50 having an introduction member 52 and an expandable member 54.
A covering 56 is preferably provided to cooperate with the expandable member 54 to
inhibit leakage of bone cement. The introduction member 52 and the covering 56 are
preferably substantially identical to the introduction member 12 and the covering 16.
The expandable member 54 is preferably operable in the same manners
as described for the expandable member 14. The expandable member 54 is preferably
configured as an inverted cone or umbrella shape and includes a plurality of
expandable ribs 58. A void area 59 is defined within the expandable member 54 for
receiving bone cement or the like in the manner of the void area 26.
With reference to FIGS.8 and 9, there is shown an alternate embodiment
of a vertebral lift 60 having an introduction member 62 and an expandable member 64.
A covering 66 is preferably provided to cooperate with the expandable member 54 to
inhibiHeakage of bone cement. The vertebral lift 60 is similar to the vertebral lift 50,
except that it has a half-cone shape instead. The expandable member 64 includes a
plurality of expandable ribs 68 and defines a void area 69.
With reference to FIGS. 10-13, there is shown an alternate embodiment
of a vertebral lift 70 having an introduction member 72, an expandable member 74, and
a covering 76. The vertebral lift 70 includes a plurality of expandable ribs 78 extending
from a ring member 75 and defines a void area 79 and is similar to the vertebral lift 60
except that it further includes lateral ribs 77.
FIGS. 14 and 15 show an alternate embodiment of an expandable
member 74' that is similar to the expandable member 74, except that it includes
expandable ribs 78' and accompanying lateral ribs 77' completely around ring member
75'.
With reference to FIGS. 16 and 17, there is shown an alternate
embodiment of an expandable member 84 having a covering 86 to inhibit leakage of
bone cement. The expandable member 84 preferably cooperates with an introduction
member, such as the introduction member 12 described previously, for desirably
expanding the expandable member 84 to desired dimensions for restoration of the
fractured vertebral body into which it is installed.
The expandable member 84 preferably includes a plurality of rings 88
oriented in an end-to-end fashion to provide the expandable member 84 with a
generally cylindrical configuration which defines an internal annular void area 90 for
receiving bone cement. FIG. 17 shows the expandable member 84 with the rings 88
expanded by elongation, with the rings 88 substantially uniformly spaced apart. It will
be understood, however, that the rings may be non-uniformly spaced apart and/or the
uniformly or non-uniformly enlarged by diametrical expansion.
In this regard, and with additional reference to FIG. 18, there is shown
an enlarged view of one of the rings 88. The ring 88 preferably includes a plurality of
apertures 92 which extend through the thickness of the ring 88 and configured for
receiving wires 94 (FIG. 17) or other elongate members which may be manipulated to
retain the expandable member 84 in a desired state of expansion.
FIGS. 19 and 20 show an alternate embodiment of a ring 88' that is
useful in the same manner as the ring 88 and includes apertures 92' for receiving wires,
such as the wires 94. FIGS. 21 and 22 are perspective and end views, respectively,
showing how the rings 88' may be positioned in an expanded and elongated orientation
in a vertebral body, with the wires 94 which would extend through the apertures 92
omitted for clarity.
With reference to FIGS. 23, 24, 25 and 26, there is shown an alternate
embodiment of an expandable member 104 having a covering 106 to inhibit leakage
of bone cement from an internal annular void area 102. The expandable member 104
preferably cooperates with an introduction member, such as the introduction member
12 described previously, for desirably expanding the expandable member 104 to desired
dimensions for restoration of the fractured vertebral body into which it is installed.
The expandable member 104 is preferably configured as a coiled member
and includes a plurality of interconnected coils 108. FIGS. 24 and 25 show examples
of the coils having different dimensions. For example, coils 108a shown in FIG.24 are
thinner than coils 108b shown in FIG.25. FIG.26 shows the expandable member 104
with the coils 108 non-uniformly expanded, wherein the diameters of various ones of
the expanded coils are different. As will be appreciated, this flexibility is particularly
suitable for use in restoration of non-uniform vertebral dimensions.
With reference to FIGS.27-29, there is shown an alternate embodiment
of a vertebral lift 110 having an introduction member 112 and an expandable member
114. The introduction member 112 may attach to either end of the member 114, or
more preferably, to an aperture 113 defined thereon (FIGS.30 and 31). A covering 116
is preferably provided to cooperate with the expandable member 114 to inhibit leakage
of bone cement. The introduction member 112 and the covering 116 are preferably
substantially identical to the introduction member 12 and the covering 16.
With additional reference to FIGS. 30-31, the expandable member 1 14
is preferably operable in the same manners as described for the expandable member 14.
The expandable member 114 includes a plurality of expandable struts 118 which
projecffrom a lateral member 117 to define a void area 119 for receiving bone cement
5 or the like in the manner of the void area 26. As will be appreciated, the covering 116
substantially encloses the void area 119 to retain the injected bone cement within the
area 119.
The struts 118 preferably are received within a groove 117' of the lateral
member 117 for introduction of the member 114 into a vertebral body, with the struts
118 opening from the groove 117' to the orientation as shown in FIGS. 30-31 when
exposed to the elevated temperature of the patient within the vertebral body. In this
regard, the expandable member 114 is preferably made of a nickel and titanium alloy
(e.g. nitinol) which significantly contracts when exposed to body temperature (coming
from an ambient environment). Thus, the material used to make the expandable
member 114 will contract once placed in the vertebral body, causing the struts 118 to
be released from the groove 117' and thereby spring or expand to the orientation shown
in FIGS. 30 and 31. Thus, while the material from which the expandable member 114
is made actually contracts within the vertebral body, the overall dimension of the
expandable member 114 is increased as the struts 118 are released from the compacted
) state within the groove 117'.
With reference to FIGS. 32 and 33, there is shown an alternate
embodiment of a vertebral lift 120 having an introduction member 122 and an
expandable member 124. A covering 126 is preferably provided to cooperate with the
expandable member 124 to inhibit leakage of bone cement. The introduction member
122 and the covering 126 are preferably substantially identical to the introduction
member 12 and the covering 16.
With additional reference to FIG. 34, the expandable member 124 is
preferably operable in the same manners as described for the expandable member 14.
The expandable member 124 is preferably a jointed extensible framework and includes
a first plurality of interconnected frame members 128 and a second set of
interconnected frame members 128' which cooperate to define a void area 129 for
receiving bone cement or the like in the manner of the void area 26. The sets of frame
members 128 and 128' are spaced apart by spanning members 130. Thus, the expansion
of the expandable member 124 is defined by the expansion of the sets of frame
members 128 and 128' as well as the spanning members 130.
With reference now to FIG. 35, there is shown a preferred embodiment
of a thermal activated coupling member 140 which may be used to provide the coupling
18 described previously. In this embodiment, the coupling member 140 is provided in
a coiled configuration and made of a shaped memory alloy, most oreferably a nickel
and titanium alloy such as nitinol. Nitinol contracts when heated and produces a much
greater thermal movement (expansion, contraction) than standard metals. Thus, in a
preferred embodiment, the coupling member 140 is disposed around the introduction
member 12, with a free end 142 thereof engaged with a portion of the expandable
member 14.
For example, the free end 142 may engage the aperture 1 13 of the
expandable member 114 of FIGS .30 and 31 for introduction of the expandable member
into the vertebral body. Upon exposure to the elevated temperature within the vertebral
body, the coupling member will contract and disengage from the expandable member,
thus enabling the introduction member 12 and the coupling member to be withdrawn
from the patient, with the expandable member left in the vertebral body.
With reference now to FIG. 36, there is shown a preferred embodiment
of a mechanical coupling member 150 which may be used to provide the coupling 18
described previously. In this embodiment, the coupling member 150 has a plurality of
fingers 152 surrounding a projection 154 (such as for mating with the aperture 113 of
the member 114). A sleeve 156 is slidable upon the introduction member 12 to bear
against the fingers 152 to urge them away from the expandable member to
mechanically detach it from the projection 154.
The foregoing embodiments represent various vertebral lift devices
suitably configured for insertion into a vertebral body and which are operable to be
expanded to substantially expand a fractured vertebral body to its pre-fracture
dimensions during a surgical procedure wherein a bone cement or the like is introduced
into the vertebral body. The coverings associated with the devices advantageously
inhibit leakage of bone cement materials and the expandable members are
advantageously maintained within the vertebral body after the surgical procedure to
provide additional structure to maintain the restored vertebral body.
In this regard, it will be realized that the devices may be configured in
various dimensions and of various materials as may be suited for a particular
application, with the selection of such dimensions and materials being readily
ascertainable by one of ordinary skill in the art.
Accordingly, the foregoing description of certain exemplary embodiments of the
present invention has been provided for purposes of illustration only, and it is
understood that numerous modifications or alterations may be made in and to the
illustrated embodiments without departing from the spirit and scope of the invention
as defined in the following claims.