Intramedullary fixation system for management of pelvic and acetabular fractures

BACKGROUND

0001<figref idref="f0001">FIG. 1A</figref> depicts a frontal view of the skeletal structure forming the pelvic ring, and <figref idref="f0002">FIGS. 1B and 1C</figref> depict cross-sectional side views of the skeletal structure forming the pelvic ring. As shown in <figref idref="f0001">FIGS. 1A</figref>, <figref idref="f0002">1B and 1C</figref>, the pelvic ring includes right and left ilium bones <b>105, 110,</b> the sacrum <b>115</b> and their associated ligamentous connections. The main connections are through and around the right and left sacrociliac joints <b>120, 125</b> at the posterior of the pelvis and the pubic symphysis <b>130</b> at the anterior of the pelvis. The pelvic ring is a key structural element of the skeletal system because it is a weight-bearing structure interposed between the upper body and the legs. As such, if a fracture occurs and it is untreated, the pelvic ring may not heal (nonunion) or may heal in a poor position (malunion). Nonunion can lead to chronic pain and an inability to walk. Malunion can result in a short leg or one which points in the wrong direction. Because of these problems, it is necessary to reposition to normal the fragments which have become displaced during the fracturing (reduction). Once the fragments are repositioned, it is necessary to hold them in place (fixation) until the healing of the fracture is complete. This process may take approximately 6 to 8 weeks.

0002Because the pelvic ring forms a ring structure, it cannot be disrupted in one place when a fracture occurs. Typically, a disruption, or "break," occurs in both the posterior and anterior portions of the pelvic ring. The disruptions in the pelvic ring can be through one or more of the bones <b>105, 110, 115,</b> through the posterior sacrociliac joints <b>120, 125,</b> through the pubic symphysis <b>130</b> at the front, or any number of combinations of the above. If the acetabulum (a portion of each ilium bone <b>105, 110</b> forming the hip socket) is fractured, the smooth bearing surface of the acetabulum must be restored to as close to its original shape as possible in order to allow for proper movement at the hip. Once restored, the acetabulum must be held in the restored position until healing occurs.

0003Conventional treatment of a pelvic fracture includes reduction of the fracture fragments and fixation with plates and screws along the surface of the bone. However, placing a plate on the bone requires a significant operation with resulting high blood loss. In some cases, a straight intramedullary screw may be placed along a curved path. While the screw is less invasive, the fixation may be inadequate because the straight screw cannot be implanted very far into a curved bone. This may result in inadequate fixation. Moreover, the screw must be relatively small in diameter to avoid extending through the bone. Surgically speaking, implanting a screw such that it extends from the bone can result in significant hazard to the patient because it may puncture or otherwise impinge upon important vascular and nervous structures.

0004<patcit id="pcit0001" dnum="WO2008116175A2"><text>WO 2008/116 175 A2</text></patcit> discloses an intramedullary structure that is not lockable in a curved shape.

SUMMARY

0005It is an object of the present invention to provide an intermedullary bone-fixation system for configuring and locking a flexible device comprised in the system, which may solve one or more problems in the art. The object is achieved by the features of the respective independent claim. Further embodiments are defined in the respective dependent claims.

0006As used in this document, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term "comprising" means "including, but not limited to."

BRIEF DESCRIPTION OF THE FIGURES

0007<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1A</figref> depicts a frontal view of the skeletal structure forming the pelvic ring.</li><li><figref idref="f0002">FIGS. 1B and 1C</figref> depict cross-sectional side views of the skeletal structure forming the pelvic ring.</li><li><figref idref="f0003">FIG. 2A</figref> depicts an exemplary device for treating a bone</li><li><figref idref="f0003">FIG. 2B</figref> depicts interior portions of the exemplary device of <figref idref="f0003">FIG. 2A</figref></li><li><figref idref="f0004">FIG. 3</figref> depicts an exemplary expansion sleeve</li><li><figref idref="f0004">FIG. 4</figref> depicts an alternate exemplary expansion sleeve</li><li><figref idref="f0005">FIG. 5</figref> depicts an alternate exemplary expansion sleeve</li><li><figref idref="f0006">FIG. 6</figref> depicts an exemplary bead segment and flexible device incorporating a plurality of bead segments</li><li><figref idref="f0007">FIG. 7</figref> depicts a flow diagram for an exemplary method of treating a bone</li><li><figref idref="f0008">FIG. 8</figref> depicts a device for treating a bone according to the invention as claimed</li><li><figref idref="f0009">FIGS. 9A and 9B</figref> depict an external view and a cut-away view, respectively, of exemplary bead segments</li><li><figref idref="f0010">FIGS. 10A-D</figref> depict points of contact between the exemplary bead segments of <figref idref="f0009">FIGS. 9A and 9B</figref>.</li><li><figref idref="f0011">FIG. 11</figref> depicts a flexible device incorporating a plurality of bead segments</li><li><figref idref="f0012">FIGS.12A</figref> and <figref idref="f0013">12B</figref> depict an exploded view and a cut-away view of an exemplary tensioning assembly.</li></ul>

DETAILED DESCRIPTION

0008The following term shall have, for the purposes of this application, the meaning set forth below.

0009The terms "fixing" or "to fix" refer to holding or setting something in place. In particular, a bone fracture may be fixed by causing a device placed across the point of fracture to become rigid, thereby stabilizing the bone on either side of the fracture. Additionally, the device itself may become fixed by making the device become rigid as a result of actuation of an actuator.

0010<figref idref="f0003">FIG. 2A</figref> depicts an exemplary device for treating a bone according to an embodiment. <figref idref="f0003">FIG. 2B</figref> depicts interior portions of the exemplary device according to an embodiment. As shown in <figref idref="f0003">FIGS. 2A and 2B</figref>, the device <b>200</b> may include a flexible tube <b>205,</b> a stiffening mechanism <b>210</b> and an actuator <b>215.</b> The flexible tube <b>205</b> may have a distal end <b>205a</b> and a proximal end <b>205b.</b> The flexible tube <b>205</b> may include a plurality of slits, such as <b>206,</b> in an outer housing configured to allow the flexible tube to flex. In an embodiment, the flexible tube <b>205</b> may comprise stainless steel and/or nitinol.

0011The stiffening mechanism <b>210</b> may be located within the flexible tube <b>205</b> and may be configured to cause the flexible tube to become rigid. In an embodiment, the stiffening mechanism <b>210</b> may include a plurality of expansion sleeves. Exemplary expansion sleeves are disclosed in <figref idref="f0004 f0005">FIGS. 3-5</figref> and are discussed in further detail below.

0012<figref idref="f0004">FIG. 3</figref> depicts an exemplary expansion sleeve according to an embodiment. As shown in <figref idref="f0004">FIG. 3</figref>, the expansion sleeve may include a jam nut <b>305</b> having expansion beads <b>310a</b> and <b>310b,</b> cladding <b>315</b> covering at least a portion of the expansion beads, a plurality of expanding segments, such as <b>320,</b> and a bore <b>325.</b> The jam nut <b>305</b> may include an expansion bead <b>310a</b> having a convex end and an expansion bead <b>310b</b> having a concave end. Each of the expansion beads <b>310a</b> and <b>310b</b> may taper down in diameter from the convex/concave end to the other end of the bead. The convex expansion bead <b>310a</b> of a first expansion sleeve and the concave expansion bead <b>310b</b> of a second adjacent expansion sleeve are configured to enable the adjacent expansion sleeves to abut each other when the actuator <b>215</b> is actuated. The cladding <b>315</b> may be made of, for example and without limitation, silicone and may provide some compliance when the expansion sleeve <b>305</b> contacts the interior surface of the flexible tube <b>205.</b> The jam nut <b>305</b> may be actuated by causing the expansion beads <b>310a</b> and <b>310b</b> to be moved towards each other causing the cladding <b>315</b> to expand. As such, the expanding segments <b>320</b> may be configured to be in a non-actuated state against the cladding <b>315</b> when the jam nut <b>305</b> is not actuated. In contrast, when the jam nut <b>305</b> is actuated, the cladding <b>315</b> may force the expanding segments <b>320</b> to abut an interior surface of the flexible tube <b>205.</b> As such, the expanding segments <b>320</b> may cause the flexible tube <b>205</b> to become rigid when the jam nut <b>305</b> is in an actuated state. The bore <b>325</b> may be configured to receive a cannula, as discussed below.

0013<figref idref="f0004">FIG. 4</figref> depicts an alternate exemplary expansion sleeve according to an embodiment. As shown in <figref idref="f0004">FIG. 4</figref>, expansion sleeve <b>405</b> may include expansion beads <b>410a</b> and <b>410b,</b> a retaining spring <b>415,</b> a plurality of expanding segments, such as <b>420,</b> and a bore <b>425.</b> The expansion sleeves may include an expansion bead <b>410a</b> having a convex end and an expansion bead <b>410b</b> having a concave end. Each of the expansion beads <b>410a</b> and <b>410b</b> may taper down in diameter from the convex/concave end to the other end of the bead. The convex expansion bead <b>410a</b> of a first expansion sleeve and the concave expansion bead <b>410b</b> of a second adjacent expansion sleeve are configured to enable the adjacent expansion sleeves to abut each other when the actuator <b>215</b> is actuated. The retaining spring <b>415</b> may provide some compliance when the expansion sleeve <b>405</b> contacts the interior surface of the flexible tube <b>205.</b> The expansion sleeve <b>405</b> may be actuated by causing the expansion beads <b>410a</b> and <b>410b</b> to be moved towards each other causing the expanding segments <b>420</b> to be pushed towards an inner surface of the flexible tube <b>205.</b> As such, the retaining spring <b>415</b> may be configured to restrain the expanding segments <b>420</b> when in a non-actuated state. In contrast, when the actuator <b>215</b> is actuated, the expanding segments <b>420</b> may be configured to abut an interior surface of the flexible tube <b>205.</b> In this way, the expanding segments <b>420</b> may cause the flexible tube <b>205</b> to become rigid when in an actuated state. The bore <b>425</b> may be configured to receive a cannula, as discussed below.

0014<figref idref="f0005">FIG. 5</figref> depicts an alternate exemplary expansion sleeve according to an embodiment. As shown in <figref idref="f0005">FIG. 5</figref>, expansion sleeve <b>505</b> may include expansion beads <b>510a</b> and <b>510b,</b> one or more O-rings <b>515,</b> a plurality of expanding segments, such as <b>520,</b> and a bore <b>525.</b> The expansion sleeves may include an expansion bead <b>510a</b> having a convex end and an expansion bead <b>510b</b> having a concave end. Each of the expansion beads <b>510a</b> and <b>510b</b> may taper down in diameter from the convex/concave end to the other end of the bead. The convex expansion bead <b>510a</b> of a first expansion sleeve and the concave expansion bead <b>510b</b> of a second adjacent expansion sleeve are configured to enable the adjacent expansion sleeves to abut each other when the actuator <b>215</b> is actuated. The one or more O-rings <b>515</b> may provide some compliance when the expansion sleeve <b>505</b> contacts the interior surface of the flexible tube <b>205.</b> The expansion sleeve <b>505</b> may be actuated by causing the expansion beads <b>510a</b> and <b>510b</b> to be moved towards each other causing the expanding segments <b>520</b> to be pushed towards an inner surface of the flexible tube <b>205.</b> As such, the one or more O-rings <b>515</b> may be configured to restrain the expanding segments <b>520</b> when in a non-actuated state. In contrast, when the actuator <b>215</b> is actuated, the expanding segments <b>520</b> may be configured to abut an interior surface of the flexible tube <b>205.</b> As such, the expanding segments <b>520</b> may cause the flexible tube <b>205</b> to become rigid when in an actuated state. The bore <b>525</b> may be configured to receive a cannula, as discussed below.

0015The expansion sleeves discussed in <figref idref="f0004 f0005">FIGS. 3-5</figref> are exemplary and are not meant to be limiting. Additional and/or alternate devices for forming expansion sleeves may be used within the scope of this disclosure.

0016Referring back to <figref idref="f0003">FIG. 2</figref>, the actuator <b>215</b> may be configured to cause the stiffening mechanism <b>210</b> to cause the flexible tube <b>205</b> to become rigid in response to the actuator being actuated. In an embodiment, the actuator <b>215</b> may include, for example and without limitation, a cap <b>220</b> connected to the proximal end of the flexible tube <b>205.</b> In an embodiment, the cap <b>220</b> may be configured to permit the flexible tube <b>205</b> to be rotated, thereby allowing the flexible tube to be inserted into a bone. The cap <b>220</b> may also be configured to cause the stiffening mechanism <b>210</b> to become rigid. For example, if the stiffening mechanism <b>210</b> comprises a plurality of expansion sleeves, the cap <b>220,</b> when rotated, may be configured to cause each of the plurality of expansion sleeves to abut an interior surface of the flexible tube <b>205.</b>

0017In an alternate embodiment, the actuator <b>215</b> may include a cannula <b>225</b> with a locking assembly <b>230.</b> The cannula <b>225</b> may extend through a bore in each of a plurality of expansion sleeves, such as <b>305, 405</b> or <b>505.</b> The cannula <b>225</b> may include a distal end connected to a distal expansion sleeve located at the distal end of the flexible tube <b>205</b> and a proximal end extending from the proximal end of the flexible tube. In an embodiment, the cannula <b>225,</b> when actuated, may cause the plurality of expansion sleeves <b>305, 405</b> or <b>505</b> to actuate, which may cause the flexible tube <b>205</b> to become rigid, as described above. The locking assembly <b>230</b> may be used to actuate the cannula <b>225.</b> For example, the locking assembly <b>230</b> may cause the cannula <b>225</b> to become tensioned. The locking assembly <b>230</b> may then be used to lock the cannula <b>225</b> in the actuated state.

0018In an alternate embodiment, the cannula <b>225</b> may extend through a bore in each of a plurality of bead segments, such as <b>605</b> in <figref idref="f0006">FIG. 6</figref>. Each of the bead segments <b>605</b> may further include a distal end and a proximal end. In an embodiment, the distal end of a bead segment <b>605</b> may be sized and shaped to be received by, receive or otherwise engage a proximal end of an adjacent bead segment in response to the cannula <b>225</b> being actuated. For example, the distal end of each bead segment <b>605</b> may be convex, and the proximal end of each bead segment may be concave. Conversely, the distal end and proximal end of each bead segment <b>605</b> may be concave and convex, respectively. Additional or alternate shapes for the distal and proximal ends of bead segments <b>605</b> may be used within the scope of this disclosure.

0019In an embodiment, each of the bead segments <b>605</b> may be about 8 mm in diameter and about 12 mm in length. In an embodiment, each of the bead segments <b>605</b> may be about 2 mm to about 15 mm in diameter. In an embodiment, each of the bead segments <b>605</b> may be about 5 mm to about 25 mm in length. Alternately sized bead segments <b>605</b> may also be used within the scope of this disclosure.

0020The cannula <b>225</b> may include a distal end connected to a distal bead segment located at the distal end of the flexible tube <b>205</b> and a proximal end extending from the proximal end of the flexible tube. In an embodiment, the cannula <b>225,</b> when actuated, may cause the plurality of bead segments <b>605</b> to actuate, which may cause the flexible tube <b>205</b> to become rigid. The locking assembly <b>230</b> may be used to actuate the cannula <b>225.</b> For example, the locking assembly <b>230</b> may cause the cannula <b>225</b> to become tensioned. The locking assembly <b>230</b> may then be used to lock the cannula <b>225</b> in the actuated state.

0021In an embodiment, a screw <b>235</b> may additionally be positioned at the distal end of the flexible tube <b>205.</b> The screw <b>235</b> may be used to enable the flexible tube <b>205</b> to be inserted into a bone. In an embodiment, the screw <b>235</b> may be a high helix angle screw. In an embodiment, the screw <b>235</b> may move a distance into a medium, such as a bone, that is approximately equal to its diameter when rotated one revolution. In other words, a screw <b>235</b> having a diameter of 12 mm may move forward approximately 12 mm when rotated once.

0022<figref idref="f0007">FIG. 7</figref> depicts a flow diagram for an exemplary method of treating a bone according to an embodiment. As shown in <figref idref="f0007">FIG. 7</figref>, a guide wire may be inserted <b>705</b> into an intramedullary space of a bone. The guide wire may include a bent section having a sharpened tip at a distal portion of the guide wire. The guide wire may be inserted <b>705</b> by rotating the guide wire to orient the bent section of the guide wire and selectively hammering the guide wire to cause the bent section to form a curved path in bone based on the orientation of the bent section. In an embodiment, inserting <b>705</b> the guide wire may include using a fluoroscope to determine the orientation of the bent section of the guide wire. In an embodiment, the guide wire may be attached to a hammer drill during insertion <b>705.</b> During insertion of the guide wire, a user may orient the bent tip so that it is positioned in the direction that the guide wire is to be inserted <b>705.</b> The hammer drill may then be activated to cause the guide wire to be inserted into the bone in such direction. In particular, the sharpened tip may be used to cause the hole to be formed in the bone. If the user determines that the direction of insertion <b>705</b> for the guide wire is to be changed, the guide wire may be re-oriented prior to further insertion of the guide wire. In an embodiment, a straight path may be approximated by inserting the guide wire in a succession of short curved paths that are substantially 180 degrees opposed to each other. As such, although the present method may be used to insert a guide wire into curved bone, such as at least a portion of a pelvic ring, a posterior column of an acetabulum or an anterior column of an acetabulum of a patient, the method may also be used to insert a guide wire into a substantially straight bone as well.

0023In an embodiment, the guide wire may include one or more of stainless steel and nitinol. In an embodiment, the guide wire may be about 1 mm to about 1.5 mm in diameter. It will be apparent to those of ordinary skill in the art that the guide wire may be of a different size depending upon the particular bone into which the guide wire is to be inserted and that the disclosed size range is merely exemplary.

0024A tunnel may be formed <b>710</b> surrounding the guide wire in the bone. In an embodiment, the tunnel may be formed <b>710</b> using a cannulated reamer with a flexible drive shaft that fits over and around the guide wire. The cannulated reamer may include a bore configured to receive the guide wire. As such, the guide wire may guide the direction of the cannulated reamer in forming <b>710</b> the space in the bone.

0025The cannulated reamer may be configured to have a diameter sufficient to allow a flexible device, such as at least one of the flexible tubes described in reference to <figref idref="f0003">FIGS. 2</figref>, <figref idref="f0006">6</figref> and <figref idref="f0008">8</figref>, to be inserted <b>715</b> into the tunnel. In an embodiment, the cannulated reamer may be short enough to enable the reamer to form and follow a curved hole defined by the guide wire.

0026The flexible device may be caused <b>720</b> to become rigid when in the tunnel. In particular, the rigid flexible device may be used to treat a bone fracture. In an embodiment, the flexible device may be caused <b>720</b> to become rigid by operating an actuator and, in response to operating the actuator, rigidizing the flexible device from a flexible state to a more rigid state. For example, expansion sleeves, jam nuts and/or bead segments described above in reference to <figref idref="f0004 f0005 f0006">FIGS. 3-6</figref> may be used to abut against an interior surface of the flexible device causing the flexible device to hold its shape when actuated. In an embodiment, the expansion sleeves may include one or more of a spring, one or more jam nuts and one or more O-rings. In an embodiment, a flexible device may be caused <b>720</b> to become rigid by actuating a cannula extending through each of a plurality of expansion sleeves. In an alternate embodiment, a flexible device may be caused <b>720</b> to become rigid by rotating a cap located at a proximal end of the flexible device.

0027<figref idref="f0008">FIG. 8</figref> depicts an alternate exemplary device for treating a bone according to an embodiment. As shown in <figref idref="f0008">FIG. 8</figref>, the device <b>800</b> may include a flexible tube <b>805,</b> a plurality of rods <b>810</b> contained within the flexible tube, and an actuator (not shown). The flexible tube <b>805</b> may include a distal end and a proximal end. In an embodiment, the flexible tube <b>805</b> may include a series of slits configured to allow the tube to flex. In an embodiment, the flexible tube <b>805</b> may include stainless steel and/or nitinol.

0028In an embodiment, the plurality of rods <b>810</b> may be affixed to each other at the distal end of the flexible tube <b>805</b> and/or affixed to the distal end of the flexible tube. The plurality of rods <b>810</b> may substantially or completely fill the flexible tube <b>805</b> such that the rods cannot substantially move with respect to each other inside the flexible tube. In particular, the rods <b>810</b> remain parallel to each other and are constrained from deflecting in a radial direction. In an embodiment, the plurality of rods <b>810</b> move axially as the flexible tube <b>805</b> is flexed. As such, a rod <b>810</b> positioned along the inside of a curve traverses a shorter distance that a rod positioned along the outside of the curve, where the relative lengths of the rods change as the curve is modified.

0029The actuator may be configured to cause the plurality of rods to be fixed in place when actuated. In an embodiment, the actuator may be configured to cause the plurality of rods <b>810</b> to be fixed in place by causing the plurality of rods to lock in place at the proximal end of the flexible tube <b>805.</b> If the plurality of rods <b>810</b> are locked together at the proximal end of the flexible tube <b>805,</b> any curve(s) in the tube may be fixed in place.

0030In an embodiment, the device <b>800</b> may further include a screw <b>815</b> positioned at the distal end of the flexible tube <b>805.</b> The screw <b>815</b> may be used to enable the flexible tube <b>805</b> to be inserted into a bone. In an embodiment, the screw <b>815</b> may be a high helix angle screw. In an embodiment, the screw <b>815</b> may move a distance into a medium, such as a bone, that is approximately equal to its diameter when rotated one revolution. In other words, a screw <b>815</b> having a diameter of 12 mm may move forward approximately 12 mm when rotated once.

0031In an embodiment, the device <b>800</b> may further include a sleeve (not shown) located within the flexible tube <b>805.</b> The sleeve may be configured to contain the plurality of rods <b>810.</b> In an embodiment, the actuator may be configured to cause the plurality of rods <b>810</b> to be fixed by causing the sleeve to apply a normal force towards a center of the sleeve in response to the actuator being actuated. As such, the sleeve may compress the plurality of rods <b>810</b> causing the rods to be incapable of movement, thereby causing the flexible tube <b>805</b> to become rigid.

0032In an embodiment, a device for treating a bone may include a flexible tube similar to one of the flexible tubes described above, a spring contained within the flexible tube and an actuator configured to cause the spring to exert a normal force against an inner surface of the flexible tube in response to the actuator being actuated. The normal force exerted by the spring may cause the flexible tube to become rigid. The flexible tube may include a series of slits configured to allow the tube to flex. The flexible tube may include stainless steel and/or nitinol. In an embodiment, a screw may be positioned at the distal end of the flexible tube.

0033In an embodiment, a bone-treating device may be manufactured in the following manner or by performing similar operations. A flexible tube may be formed of a flexible material, such as super-elastic nitinol or spring-tempered stainless steel. The flexible tube may include a plurality of slits to allow the tube to be axially flexible, but stiff in torsion. Alternately, a gooseneck wound spring may be used. In an embodiment, a screw may be attached to a distal end of the flexible tube, and a cap may be attached to a proximal end of the flexible tube. The cap may include a structure that permits the cap to be turned by a wrench.

0034A stiffening system is inserted into the flexible tube such that a distal end of the stiffening system is attached to a distal end of the flexible tube. The stiffening system includes a cannula connected at a distal end to the distal end of the flexible tube and a plurality of bead segments or expansion sleeves threaded along the cannula. Each of the bead segments or expansion sleeves includes a bore permitting the cannula to pass therethrough. The bead segments and expansion sleeves are described in greater detail in reference to <figref idref="f0004 f0005 f0006">FIGS. 3-6</figref>.

0035Alternately, the stiffening system includes a plurality of thin rods attached at a distal end of the flexible tube. In an embodiment, the thin rods may be inserted inside of a sleeve surrounding the thin rods that is configured to prevent the rods from moving when actuated. Alternately, the stiffening system may include a lock at the proximal end of the flexible tube that is used to lock the thin rods in place.

0036In an embodiment, a bone containing a device for treating the bone may include the bone, and a device comprising a tube having a distal end and a proximal end, a stiffening mechanism configured to cause the tube to remain in a rigid state. In an embodiment, the device may include a screw positioned at the distal end of the tube.

0037In an embodiment, the stiffening mechanism may include a plurality of bead segments including a distal bead segment. Each of the plurality of bead segments may include a distal end and a proximal end. The distal end of each bead segment of the plurality of bead segments, other than the distal bead segment, may receive the proximal end of an adjacent bead segment of the plurality of bead segments. In an embodiment, each of the bead segments may be about 8 mm in diameter and about 12 mm in length. In an embodiment, each of the bead segments may be about 2 mm to about 15 mm in diameter. In an embodiment, each of the bead segments may be about 5 mm to about 25 mm in length. Alternately sized bead segments may also be used within the scope of this disclosure.

0038In an alternate embodiment, the stiffening mechanism may include a plurality of expansion sleeves. An expansion sleeve may include, for example and without limitation, a spring, one or more jam nuts, and/or one or more O-rings.

0039The above-described devices and methods may be used to treat a bone fracture. For example, bone fragments at the point of a fracture may be repositioned into a proper alignment, and a device, such as one described above, may be inserted in order to fix the bone fracture to allow healing to complete.

0040Alternately, the above-described devices and methods may be used to prophylactically treat a bone in order to provide support. For example, a metastatic tumor may cause a weak spot in a bone. A device may be inserted to provide support for such a weak spot. As another example, a device may be inserted to support the posterior and anterior columns of the acetabulum for the management of a complex total hip replacement procedure or a revision of a previous total hip replacement. Additional uses of the devices and methods described herein may also be performed within the scope of this disclosure.

0041In an alternate embodiment, a device without a flexible tube may be manufactured for use as described above. <figref idref="f0009">FIGS. 9A and 9B</figref> depict an external view and a cut-away view, respectively, of exemplary bead segments according to an embodiment. As shown in <figref idref="f0009">FIGS. 9A and 9B</figref>, the bead segments, such as <b>900,</b> may include a male surface <b>905</b> and a female (hollow) surface <b>910</b> and a bore. The bore of each bead segment may be configured to receive a stiffening cable or cannula as described above in reference to <figref idref="f0004 f0005 f0006">FIGS. 3-6</figref>.

0042The male surface <b>905</b> and the female surface <b>910</b> may have a shape that permits torque transfer from one bead segment to the next. For example, the male surface <b>905,</b> and the female surface <b>910</b> may have a spherical and at a proximal end and a conical cross-section at a distal end, as described further below in reference to <figref idref="f0010">FIGS. 10A-D</figref>. Alternate cross-sectional shapes may also be used for the male surface <b>905</b> and the female surface <b>910</b> within the scope of this disclosure. For example, other multisided shapes, such as square cross-sections, pentagonal cross-sections, hexagonal cross-sections, heptagonal cross-sections, octagonal cross-sections, spherical cross-sections, conical cross-sections or the like, may be used within the scope of this disclosure.

0043The shapes of the male surface <b>905</b> and the female surface <b>910</b> of adjacent bead segments may permit torque to be transmitted from one bead to the next to drive a distal screw (such as <b>1110</b> in <figref idref="f0011">FIG. 11</figref>). In addition, the shapes of the male surface <b>905</b> and the female surface <b>910</b> of adjacent bead segments may enable the bead segments to pivot with respect to each other allowing the chain to form curved shapes.

0044The male surface <b>905</b> of each bead segment may include a narrowed neck <b>915</b> proximal to the ball to increase the bead-to-bead rotational angle. The narrowed neck <b>915</b> may further enable the open ends of the female surface <b>910</b> of an adjacent bead to be modified such that the male surface <b>905</b> of the bead cannot disengage. In an embodiment, the female surface <b>915</b> may be modified post-assembly in order to secure the connection. For example, a circlip may be added to a groove on the inside of the cavity of the female surface <b>915.</b> Alternately, the edge of the female surface <b>915</b> may be crimped or rolled such that the inner diameter of the female surface is reduced at the edge. In this manner, a string of bead segments may be kept in an interlocked arrangement even if a central stiffening cable (not shown) is broken.

0045<figref idref="f0010">FIGS. 10A-D</figref> depict points of contact between the exemplary bead segments of <figref idref="f0009">FIGS. 9A and 9B</figref>. The male surface <b>905</b> and the female surface <b>910</b> of adjacent bead segments <b>900</b> have shapes that are capable of transmitting torque, such as hexagons. <figref idref="f0010">FIGS. 10A-D</figref> identify details of how the male surface <b>905</b> and the female surface <b>910</b> of the adjacent bead segments <b>900</b> interact. The female surface <b>910</b> may be substantially straight-sided with a cross-section that is similar in nature to the male surface <b>905</b> of the adjacent bead segment <b>900.</b> At the distal end of the female surface <b>910,</b> a cone shape having a circular cross-section may be used. The corners of the male surface <b>905</b> of the adjacent bead segment <b>900</b> may make point contact with the cone-shaped portion of the female surface <b>910.</b> This may cause localized points of high stress, which may lead to improved friction over line contact. In particular, the conical-shaped portion of the female surface 910 may permit improved friction as compared to a hexagonal prism because the hexagonal prism may not make even line contact around the male socket <b>905</b> as the adjacent bead segments <b>900</b> pivot with respect to each other. The described design may enable an interference fit, such as is shown in <figref idref="f0010">FIG. 10D</figref>, which may enable even higher friction as the point regions are distorted.

0046<figref idref="f0011">FIG. 11</figref> depicts a flexible device incorporating a plurality of bead segments according to an embodiment. As shown in <figref idref="f0011">FIG. 11</figref>, the flexible device <b>1100</b> includes a plurality of bead segments, such as <b>1105,</b> a distal screw <b>1110,</b> a stiffening cable (not shown) inside the flexible device, and a tensioning assembly <b>1115.</b> Each bead segment <b>1105</b> may be substantially similar to any of the bead segments identified herein or any other bead segment possessing similar characteristics to a bead segment identified within the scope of this disclosure, without limitation.

0047The stiffening cable may be a multi-stranded wire that passes through the bead segments <b>1105.</b> The stiffening cable may be anchored at the distal screw <b>1110</b> at the distal end of the flexible device <b>1100</b> and at the tensioning assembly <b>1115</b> at a proximal end of the flexible device. In an embodiment, the stiffening cable may be anchored at each of the distal and proximal ends by thermal welding, soldering, gluing, welding a tapered collet in place or the like.

0048While the stiffening cable may be soldered to an anchor so that stress is distributed along an entire hole in which the stiffening cable is anchored such that the solder may wick throughout the hole, a mechanically suitable solder may not be biocompatible. In an embodiment, soldering the stiffening cable to a tapered collet may be used to avoid bioincompatibility within a patient. The collet may be fitted over a stiffening cable and then pressed into a conical hole, which distorts the collet into the cable. The collet may be welded in place at its outside edge so that the cable itself does not experience heating. In such an embodiment, the stiffening cable may receive substantially equal stress in each direction around the tapered collet.

0049<figref idref="f0012">FIGS.12A</figref> and <figref idref="f0013">12B</figref> depict an exploded view and a cut-away view of an exemplary tensioning assembly <b>1115</b> according to an embodiment. As shown in <figref idref="f0012">FIG. 12A</figref>, the tensioning assembly <b>1115</b> may include a hex ball tensioner <b>1205,</b> a cable anchor <b>1210,</b> a tensioning sleeve <b>1215,</b> a collet <b>1220</b> and a lock nut <b>1225.</b> A stiffening cable may be located in the center of the tensioning assembly <b>1115,</b> but is not shown in <figref idref="f0012">FIGS. 12A</figref> and <figref idref="f0013">12B</figref> to enable better viewing of the remaining components of the tensioning assembly.

0050In an embodiment, the stiffening cable may be secured with the tapered collet <b>1220</b> resting in the socket of the cable anchor <b>1210.</b> The tensioning sleeve <b>1215</b> may be threaded over the cable anchor <b>1210.</b> The cable anchor <b>1210</b> may have a square rod which slides in the hex ball tensioner <b>1205.</b> In operation, the cable anchor <b>1210</b> may be held in place by a user operated tool while the tensioning sleeve <b>1215</b> is threaded in. Threading in the tensioning sleeve <b>1215</b> may cause the cable anchor <b>1210</b> to be pushed out. A spline of the cable anchor <b>1210,</b> when held by a user such as a surgeon, may prevent the entire assembly from rotating while the tensioning sleeve <b>1215</b> is rotated by a second external tool. The lock nut <b>1225</b> may be applied. In an embodiment, the lock nut <b>1225</b> may have the same thread pitch inside and out. As such, the lock nut <b>1225</b> may be threaded into the bone as it threads onto the cable anchor <b>1210</b> without drawing the cable anchor out of the bone, such as the pelvis, into which it is inserted. Application of the tensioning assembly <b>1115</b> may cause the flexible device to become rigid within the patient in order to assist in fixing the bone.

EXAMPLE 1: KIT FOR MEDICAL USE

0051A kit may be sold to physicians, surgeons or other medical professionals or medical institutions for use in treating a bone fracture. The kit includes a flexible device similar to those discussed above (e.g., device <b>200</b> or device <b>800</b>). The kit may also include a hammer drill (or hammer drill attachment for a surgical drill) and a guide wire configured to be attached to the hammer drill (or hammer drill attachment). The guide wire includes a bent section having a sharpened tip at a distal portion of the guide wire. The kit may also include a cannulated reamer. The cannulated reamer includes a flexible drive shaft and a bore configured to receive the guide wire. The kit may further include instructions for using the flexible device to treat a bone fracture. In particular, the kit may include instructions for using the hammer drill, guide wire and/or cannulated reamer to insert the guide wire into a bone and to use the cannulated reamer to form a tunnel in the bone using the guide wire as a guide. The instructions for inserting the guide wire using the hammer drill may include instructions for rotating the guide wire into a particular orientation based on the direction of the hole to be formed and instructions for using the hammer drill to form the hole.

EXAMPLE 2: MEDICAL DEVICE USING EXPANSION SLEEVES

0052A flexible device for treating a bone includes a nitinol flexible tube having a plurality of slits configured to allow the flexible device to flex, a plurality of expansion sleeves contained within the flexible tube, and a cannula configured to actuate the bead segments. The cannula, when actuated, may cause each expansion sleeve to expand and abut an inner surface of the flexible tube, thereby causing the flexible device to become rigid. An exemplary medical device using expansion sleeves is disclosed in <figref idref="f0003">FIG. 2</figref>.

EXAMPLE 3: EXPANSION SLEEVE WITH SILICONE CLADDING

0053An expansion sleeve includes a jam nut having expansion beads, silicone cladding covering at least a portion of the expansion beads, a plurality of expanding segments and a bore configured to receive a cannula. Adjacent expansion beads are configured to engage each other based on the size and shape of their adjacent surfaces when actuated. For example, adjacent surfaces may be convex and concave. Each of the expansion beads may taper down in diameter from an exposed surface to an internal surface of the bead. The jam nut is actuated by causing the expansion beads to be moved towards each other, which, in turn, causes the cladding to expand. As such, the expanding segments are configured to be in a non-actuated state against the cladding when the jam nut is not actuated. In contrast, when the jam nut is actuated, the cladding forces the expanding segments to abut an interior surface of the flexible tube. As such, the expanding segments cause the flexible tube to become rigid when the jam nut is in an actuated state.

EXAMPLE 4: EXPANSION SLEEVE WITH RETAINING SPRING

0054An expansion sleeve includes expansion beads, a retaining spring, a plurality of expanding segments and a bore configured to receive a cannula. Adjacent expansion beads are configured to engage each other based on the size and shape of their adjacent surfaces when actuated. For example, adjacent surfaces may be convex and concave. The expansion sleeve is actuated by causing the expansion beads to be moved towards each other causing the expanding segments to be pushed towards an inner surface of the flexible tube. As such, the retaining spring is configured to restrain the expanding segments when in a non-actuated state. In contrast, when the actuator is actuated, the expanding segments are configured to abut an interior surface of the flexible tube. In this way, the expanding segments cause the flexible tube to become rigid when in an actuated state.

EXAMPLE 5: EXPANSION SLEEVE WITH O-RINGS

0055An expansion sleeve includes expansion beads, one or more O-rings, a plurality of expanding segments, and a bore configured to receive a cannula. Adjacent expansion beads are configured to engage each other based on the size and shape of their adjacent surfaces when actuated. For example, adjacent surfaces may be convex and concave. The expansion sleeve is actuated by causing the expansion beads to be moved towards each other causing the expanding segments to be pushed towards an inner surface of the flexible tube. As such, the one or more O-rings are configured to restrain the expanding segments when in a non-actuated state. In contrast, when the actuator is actuated, the expanding segments are configured to abut an interior surface of the flexible tube. As such, the expanding segments cause the flexible tube to become rigid when in an actuated state.

EXAMPLE 6: MEDICAL DEVICE USING BEAD SEGMENTS

0056A flexible device for treating a bone includes a stainless steel flexible tube having a plurality of slits configured to allow the flexible device to flex, a plurality of bead segments contained within the flexible tube, and a cannula configured to actuate the bead segments. The cannula, when actuated, may cause each bead segment to engage adjacent bead segments, thereby stiffening the bead segments and causing the flexible device to become rigid. An exemplary medical device using bead segments is disclosed in <figref idref="f0006">FIG. 6</figref>.

EXAMPLE 7: MEDICAL DEVICE USING RODS

0057A flexible device includes a flexible tube, a sleeve within the flexible tube and a plurality of rods contained within the sleeve. The rods are configured to be connected to a distal end of the flexible tube and to bend as the flexible tube is flexed. The sleeve, when actuated, is configured to compress the rods together to restrict their movement in a lateral direction (i.e., in the proximal or distal directions with respect to the flexible tube). An exemplary medical device using rods is disclosed in <figref idref="f0008">FIG. 8</figref>.

0058In the above detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations. The scope of the invention is defined by the appended claims.

0059The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

0060With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

0061It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). While various compositions, methods, and devices are described in terms of "comprising" various components or steps (interpreted as meaning "including, but not limited to"), the compositions, methods, and devices can also "consist essentially of" or "consist of" the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups. It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (<i>e.g.,</i> "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (<i>e.g</i>., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (<i>e.g</i>., " a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (<i>e.g</i>., " a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

0062In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

0063As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.