WO2011067668A1

WO2011067668A1 - Steerable femoral fracture reduction device

Info

Publication number: WO2011067668A1
Application number: PCT/IB2010/003217
Authority: WO
Inventors: David Wilson; Michael Dunbar; Allan Hennigar; Andrew Allan
Original assignee: Dalhousie University
Priority date: 2009-12-01
Filing date: 2010-12-01
Publication date: 2011-06-09

Abstract

A steerable intramedullary fracture reduction device allows for improved and non¬ invasive femoral fracture reduction. In some aspects, the steerable intramedullary fracture reduction device comprises a rod having a flexible section along at least a portion of the rod, a steering mechanism operatively coupled to the flexible portion for adjusting a curvature of the flexible section of the rod responsive to an operator input, and a tension assembly operatively coupled to the flexible portion for forcing the flexible portion in a substantially linear arrangement responsive to an actuation of the tension assembly. In some aspects, the steerable intramedullary fracture reduction device further comprises a thumbwheel connected to a gearbox and output shaft attachment and a joystick. In some aspects, the steerable intramedullary fracture reduction device comprises a first plurality of rod segments capable of moving with one degree of freedom and a second plurality of rod segments capable of moving with two degrees of freedom.

Description

STEERABLE FEMORAL FRACTURE REDUCTION DEVICE

FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to the field of orthopedic tools, and in particular, to a steerable intramedullary fracture reduction device and methods of use thereof.

BACKGROUND

[0002] Fracture of the femur is an extremely traumatic injury. The femur is the largest and strongest bone in the body. Femoral fractures are most frequently associated with either extreme bone fragility or high energy injuries. Repair of femur fractures is generally successful, but complications can occur. Potential complications include infection (Prasarn et al., Injury, 40: 1220-5 (2009)), non-union (Canadian Orthopaedic Trauma Society, J Bone Joint Surg Am., 85-A:2093-6 (2003)), and severe deformity (Court-Brown et al, Trauma, Lippincott Williams & Wilkins; (2005); Oostenbroek et al, Acta Orthop, 1 : 1-5 (2009)). There are many causes of infection, but surgical time and invasiveness are significant risk factors. Reducing surgical time diminishes the bacterial load in a surgical wound and decreases the likelihood of bacterial colonization. Furthermore, reducing the invasiveness of the procedure decreases patient bacterial exposure. Blood loss and patient morbidity are also reduced with shorter operating times. Bone fragment non-union is generally a result of the energy imparted during the fracture and the amount of soft tissue injury. Failure to reduce the fracture during the operation also has a negative impact on fracture healing and biomechanical strength of the construct. Subsequently, it is sometimes necessary to open the fracture site through the skin in order to reduce the fracture, despite the fact that this further damages the soft tissue envelope and can paradoxically reduce the union rates.

[0003] Mid-shaft femoral fractures are extremely serious injuries that are ideally treated with minimally invasively surgical techniques. The fracture is generally repaired using a locked intra-medullary rod that is implanted through a small portal and placed across the fracture gap to rigidly hold the bone in place while healing occurs. Clinically, it is difficult to achieve and maintain the reduction (i.e., realignment of the bones in the correct orientation) of the fracture while the definitive fracture fixation device is put in place without open surgery. The muscles that cross the mid-shaft of the femur are among the strongest in the body, and tend to resist a surgeon's attempt to correctly reduce the fracture. It is important that the bones are properly aligned before the definitive fracture fixation device is implanted because poor alignment can lead to one or more of non-union of the fracture (i.e., failure to heal), deformity, and loss of function.

[0004] Currently, surgeons are able to achieve fracture reduction only through manual manipulation of a patient's leg while determining bone fragment alignment from single plane fluoroscopic images (video x-ray). Where there is lateral or rotational displacement of the bone sections, however, it is particularly difficult to align and rotationally move the bone sections. Even after reduction is achieved, a surgeon must maintain the reduction manually while the definitive fixation device is implanted. Manual manipulation of the reduction is extremely difficult and proper alignment and implantation of the definitive fracture fixation device is generally only achieved after multiple repetitions. Repetition of the manual manipulation process results in increased tissue damage, blood loss, and increased surgical time, which has been conclusively shown to increase the complication rate (Christou et al., Arch Surg, 122: 165-9 (1987)). Moreover, failure to achieve adequate reduction using a minimally invasive technique leads to open surgery, which is highly invasive and has associated morbidity (Court-Brown et al, Trauma, Lippincott Williams & Wilkins; (2005)).

[0005] To address these problems, a number of potential solutions have been

investigated. However, no known device is capable of being steered through the medullary canal and across a fracture without first manually aligning the fracture ends.

[0006] Accordingly, there is a need in the art for a minimally invasive device that will aid surgeons in the process of femoral fracture reduction without the need for significant manual manipulation.

SUMMARY

[0007] The present disclosure addresses long-felt needs in the field of orthopedic tools by providing a minimally invasive steerable femoral fracture reduction device that is easy to use, cost effective, practical, time efficient, and does not require significant manual manipulation of femoral fractures.

[0008] The present disclosure relates generally to a steerable intramedullary fracture reduction device comprising a rod having a flexible section along at least a portion of the rod, a steering mechanism operatively coupled to the flexible portion for adjusting a curvature of the flexible section of the rod in response to an operator input, and a tension assembly operatively coupled to the flexible portion for forcing the flexible portion into a substantially linear arrangement in response to an actuation of the tension assembly. In certain aspects, the device further comprises a bone interface device, wherein the bone interface device is capable of securing the steerable intramedullary into the intramedullary canal of the bone.

[0009] In certain aspects, the steerable intramedullary fracture reduction device comprises a flexible rod comprising a plurality of rod segments, wherein the rod segments include a plurality of longitudinal holes that are pivotally coupled in series so that the holes are aligned, and wherein a central lumen is further formed through the rod and rod segments; a plurality of wires passing through the plurality of holes in the rod segments and attached to the distal end of the flexible rod; and a control assembly coupled to the plurality of wires and configured to apply tension selectively to one or more of the wires, thereby causing a torque on a distal end of the flexible rod. In certain aspects, the device further comprises a bone interface device, wherein the bone interface device is capable of securing the steerable intramedullary into the intramedullary canal of the bone.

[0010] In further aspects, the present disclosure relates to a rod comprising a rigid portion, a primary segmented portion, and a secondary segmented portion, wherein the segmented portions are flexible and can be steered across and through a fracture using a steering mechanism. In certain aspects, the device further comprises a terminal primary segment and a steerable terminal secondary segment, wherein the terminal primary segment serves as a connector between the primary segmented portion and the secondary segmented portion and the steerable terminal secondary segment is used as a steering tip and is positioned at the distal tip of the steerable intramedullary fracture reduction device.

[0011] In further aspects, the present disclosure relates to methods of reducing a bone fracture comprising the steps of inserting a steerable intramedullary fracture reduction device into the medullary canal of the proximal end of a bone fragment, guiding the device through the proximal bone fragment, steering the device across the fracture gap and into the distal bone fragment using the steering mechanism, guiding the device through the distal bone fragment, and reducing the fracture using the tension assembly.

[0012] In some aspects, a steerable terminal secondary segment can be steered into the fracture gap after which the rod can be flexed to align the steerable terminal secondary segment with the axis of the distal bone fragment to facilitate entry of the steerable terminal secondary segment into the medullary canal of the distal bone fragment. Once the secondary portion of the device is navigated into the distal medullary canal, the device can be navigated through the medullary canal until the primary segmented portion is positioned across the fracture gap. The primary segmented portion is then forced into a straight alignment, which generates a torque on the proximal and distal bone fragments, thereby correcting the misalignment of the two bone fragments. In certain aspects, a small diameter rod can then be advanced down the central lumen of the device, after which the steerable intramedullary fracture reduction device can be removed. Once the device is removed, the definitive nail is passed over of the small diameter rod. The small diameter rod can then be removed leaving the definitive nail in place.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 (A) shows the intramedullary fracture reduction device in situ prior to fracture reduction, in accordance with one aspect of the present disclosure. (B) Shows the intramedullary fracture reduction device in situ following fracture reduction.

[0014] FIG. 2 shows rod segments with holes for the male (A) and female (B) articulations as one aspect of the present disclosure.

[0015] FIG. 3 shows an expandable washer as one aspect of the bone interface device in its untensioned (A) and tensioned (B) conformations.

[0016] FIG. 4 shows one aspect of the control assembly in which the control assembly comprises a ratchet assembly and a control arm.

[0017] FIG. 5 shows one aspect of the present disclosure in which the device is steered across the fracture gap and through the distal and proximal fracture fragments.

[0018] FIG. 6 shows one aspect of the present disclosure in which a threaded flexible tube is inserted into the medullary canal and reduction is achieved by inserting a screw into it.

[0019] FIG. 7 shows straight rod and segmented rod elements in accordance with one aspect of the present disclosure. (A) Shows the assembled rod, and (B) and (C) show the ball joint segments. [0020] FIG. 8 shows rod segments with holes in accordance with one aspect of the present disclosure.

[0021] FIG. 9 shows one aspect of the present disclosure, including a straight rod portion (A) and ball joint assemblies (B) and (C) for a rod with exposed holes.

[0022] FIG. 10 shows one aspect of the present disclosure, including (A) a control assembly, a rod having a straight rod portion, a primary segmented portion, and a secondary segmented portion. (B) Shows the rod in greater detail.

[0023] FIG. 11 shows one aspect of the present disclosure, including a straight rod portion (A) having a threaded collar (B) at the proximal end of the straight rod portion and a disk joint assembly (C) at the distal end of the straight rod portion.

[0024] FIG. 12(A) and (B) show a disk jointed primary segment in accordance with one aspect of the present disclosure.

[0025] FIG. 13 shows connection joints between the primary and secondary rod portions (i.e., the terminal primary segment) in accordance with one aspect of the present disclosure. According to one aspect (A) and (B), the wires for controlling the primary segments are attached using set screws. According to a second aspect (C) and (D), the wires for controlling the primary segments are attached using a derailleur cable.

[0026] FIG. 14(A) and (B) show a ball jointed secondary segment in accordance with one aspect of the present disclosure.

[0027] FIG. 15 shows a ball-jointed steerable terminal secondary segment of the steerable intramedullary fracture reduction device in accordance with one aspect of the present disclosure, including a central lumen and holes through which wires can pass. According to one aspect (A) and (B), tapped holes are provided in which secondary wires can be affixed to the steerable terminal secondary segment. According to a second aspect (B) and (C), grooves are provided in which the studded end of a derailleur cable can be seated.

[0028] FIG. 16 shows a joystick for controlling the steerable terminal secondary segments in accordance with one aspect of the present disclosure. According to one aspect (A) and (B), the wires can be affixed using set screws. According to a second aspect (B) and (C), derailleur cables can be used. [0029] FIG. 17(A), (B), and (C) show a control assembly housing in accordance with one aspect of the present disclosure. The control assembly housing can have two halves that enclose the control assembly components and can be combined to form a single control assembly unit housing.

[0030] FIG. 18(A), (B), (C), and (D) show a control assembly housing in accordance with one aspect of the present disclosure. The control assembly housing can have two halves that enclose the control assembly components and can be combined to form a single control assembly unit housing.

[0031] FIG. 19 shows a control assembly in accordance with one aspect of the present disclosure including a thumbwheel and joystick, wherein the control assembly is connected to a straight rod.

[0032] FIG. 20 shows a control assembly in accordance with one aspect of the present disclosure including a worm gear gearbox, thumbwheel, and joystick, wherein the control assembly is connected to a straight rod.

[0033] FIG. 21 shows an output shaft attachment according to one aspect of the present disclosure.

[0034] FIG. 22 shows femoral fracture reduction according to one aspect of the present disclosure including the steering of the secondary segmented portion, primary segmented portion, and rigid rod portion into the medullary canal (A) and subsequent fracture reduction (B).

[0035] The figures depict various aspects of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

DETAILED DESCRIPTION

[0036] The present disclosure relates generally to a steerable intramedullary fracture reduction device. Further aspects of the present disclosure provide for methods of reducing fractures using a steerable intramedullary fracture reduction device. [0037] Various aspects of a steerable intramedullary fracture reduction device 100 in accordance with an embodiment of the present disclosure are shown in FIGS. 1-22. In FIG. 1A there is shown the device 100 in one aspect of the present disclosure as used, for example, in steering the device 100 through proximal and distal bone fragments, 310 and 320 in a fractured femur 300. The steerable intramedullary fracture reduction device 100 includes a rod 110 having a flexible section 111 along at least a portion of the rod 110, a steering mechanism 130 operative ly coupled to the flexible portion 111 for adjusting the curvature of the flexible section 111 of the rod in response to operator input, and a tension assembly 140 operatively coupled to the flexible portion 111 for forcing the flexible portion 111 into a substantially linear arrangement in response to an actuation of the tension assembly 140. In certain aspects, the device further comprises a bone interface device 120 attached to the distal end 150 of the rod.

[0038] The device is preferably made of a non-toxic, non-reactive material such as stainless steel. The device is preferably manufactured under sterile conditions or is sterilizable, for example, by autoclaving, gamma irradiation, or other suitable sterilization method. The device can be reusable or it can be disposable.

[0039] In FIG. IB there is shown the device 100 in another aspect of the present disclosure as used, for example, in aligning proximal 310 and distal bone fragments 320 in a fractured femur 300 by forcing the flexible rod 110 into a substantially linear arrangement by applying pressure at the proximal end 160 of the flexible rod 110.

[0040] When a tubular bone 300 is fractured at a fracture site 330, the steerable intramedullary fracture reduction device 100 can be inserted into the medullary canal 340 of the bone. As can be seen in FIG. 1 A, the device is inserted into the intramedullary channel of the bone through a previously drilled hole 350 for ultimate insertion of the intramedullary nail. A small hole 350 is made in the outer cortex of the bone portion 300 with an

introducing bone drill and drill bit or bone awl to access the medullary canal of the bone. Once the hole 350 is created in the bone, the device 100 is inserted into the medullar cavity of the bone. The steerable device 100 allows the operator to steer device 100 into and through broken sections of bone such as 310 and 320, and, by manipulation of device 100, these sections can be aligned longitudinally. Even relatively severe transverse displacement of bone sections can thus be aligned, due to the ability to steer the flexible portion of the rod 111 , as will be discussed below. [0041] In FIG. 1A there is shown the device 100 in one aspect of the present disclosure. In this aspect, the device 100 comprises of a segmented rod 110 having an outer diameter less than about 12 mm and preferably about 10 mm. The rod 110 is segmented into a plurality of rod segments 112. As seen in FIG. 2, the rod segments include a plurality of longitudinal holes, 170 and 172, and the rod segments 112 are pivotally coupled in series so that the holes 170 and 172 are aligned. A central lumen 174 is further formed through the rod 110 and the rod segments 112. The rod 110 has articulations between each segment 112 and wires running in holes 170 and 172 along the periphery. As seen in FIG. 1(A) and 3, a plurality of wires 210 pass through the plurality of holes 170 and 172 in the rod segments 112 and attach to the distal end of the flexible rod 150.

[0042] A control assembly 180 is coupled to the plurality of wires and configured to apply tension selectively to one or more of the wires, thereby causing a torque on the distal end 150 of the flexible rod 110. A plurality of straightening wires originate at a tension assembly 140 at the proximal end 160 of the device 100 that the surgeon holds. These wires terminate at the distal end 150 of the device 100 engaging with a bone interface device 120. In some aspects, the bone interface device 120 is a collapsible rubber washer 200 that expands when the straightening wires are under tension. FIG. 3(A) shows the untensioned expandable washer 200 and (B) shows the tensioned expandable washer 200. The device 100 attaches to the intramedullary canal 340 at the distal end of the bone 310 (i.e., distal to the fracture) when the expandable washer 200 is locked in a tensioned position.

[0043] A plurality of additional wires pass through a plurality of additional holes 172 down the segmented rod 110 and attach to the distal rod segment 113 at one end and to a control arm 184 at the other end. Using the control arm 184, the surgeon can tension each wire independently, which enables steering of the device 100. In combination with manual rotation of the device 100, the control arm 184 gives the surgeon the ability to control the motion of the distal end of the rod 150 through three degrees of freedom, thereby allowing the surgeon to steer the device 100 across the fracture gap 330 under fluoroscopic guidance.

[0044] As shown in FIG. 4, the control assembly 180 is positioned at the proximal end

160 of the device 100 and enables the surgeon to steer the device 100 through the

intramedullary canals 340 of the proximal and distal bone fragments, 320 and 310, and across one or more fractures 330. Using the control arm 184, the surgeon can control the curvature of the flexible rod 110, which enables steering of the device 100. [0045] As shown in FIG. 4, the control assembly 180 can in some aspects be made up of a control arm 184 and a tension assembly 182. The tension assembly 182 can be coupled to a plurality of straightening wires passing through a plurality of holes 170 through the rod segments. The control arm 182 can be coupled to a plurality of wires to facilitate steering of the device 100 and is configured to apply tension selectively to one or more of the wires, thereby causing a torque on the distal end 150 of the fiexible rod 110.

[0046] As shown in FIG. 1(A), the tension assembly 140 can be coupled to a plurality of wires passing through a plurality of holes 172 through the rod segments. The tension assembly may be a ratchet or any other suitable means for applying a longitudinal moment of about 74 Nm between the distal 150 and proximal ends 160 of the rod 110, or about 500 N for a 15 cm rod. The tension assembly 140 is operatively coupled to the flexible portion 111 of the rod 110 for forcing the flexible portion 111 into a substantially linear arrangement responsive to an actuation of the tension assembly 140. The device 100 is configured such that the tension assembly 140 can be controlled by a surgeon.

[0047] Once the device 100 has been steered across the fracture gap 330, the surgeon can optionally engage the bone interface device 120. As shown in FIG. 1(A) and 3, the bone interface device 120 is coupled to the distal end 150 of the fiexible rod 110. The bone interface device 120 is configured to expand radially from the fiexible rod 110 in response to an actuation of the bone interface device 120. The bone interface device 120 can be any mechanism capable of resisting movement of the rod within the interior wall of the bone 300 and along the longitudinal axis of the flexible rod 110. In certain aspects, the attached bone interface device is capable of remaining interfaced with the bone while subject to a longitudinal moment of about 74 Nm between the distal 150 and proximal ends 160 of the rod 110, or about 500 N for a 15 cm rod. In various aspects, the bone interface device 120 increases the friction between the flexible rod 110 and the intramedullary canal. In further aspects, the bone interface device causes the flexible rod 110 to become attached to the bone. The bone interface can be a flexible tip or a bone anchor device at the distal end of the flexible rod 110. The bone interface device may be, for instance, a flexing tip segment (e.g., a steerable terminal secondary segment 124), an expandable washer, a camming assembly, deployable spikes, or a series of balloon catheters.

[0048] A bone interface device 120 can optionally be used according to the present disclosure. As shown in FIG. 3, a bone interface device 120 can in one aspect be an expandable washer 200. As the surgeon ratchets the straightening wires down tightly, the expandable washer 200 is expanded and locks the device 100 into the distal end of the bone 310 (i.e., distal relative to the fracture 330). FIG. 3(A) shows the untensioned expandable washer 200 and FIG. 3(B) shows the tensioned expandable washer 200. The device 100 attaches to the intramedullary canal 340 at the distal end of the bone 310 when the expandable washer 200 is locked in a tensioned position. By further tightening these wires the surgeon also forces the segmented rod 110 into a straight alignment, thereby correctly aligning the fracture 330. With the distal end 150 of the flexible rod locked in place and the alignment of the fracture 330 corrected, the fracture 330 can be rotationally controlled and reduced to the correct length.

[0049] In further aspects, the bone interface device is a plurality of spikes. The spikes expand radially from the flexible rod 110 when tension is applied along the longitudinal axis of the rod 110. In further aspects, the bone interface device is one or more balloon catheters expandable under pressure. The balloon catheters can be pressurized at the proximal end of the device 160 using a gas, water, saline, or other similarly suitable fluid. The balloon catheters may be spaced apart around the circumference of the rod 110, or a single balloon catheter may be segmented into compartments around the circumference of the rod 110, to prevent flow of the fluid within the balloon catheter so that the rod 110 stays fixed relative to the bone when the balloon catheters are expanded.

[0050] Once the device 100 is properly positioned within the medullary canals of both bone fragments, 310 and 320, the tension assembly 140 can be further actuated by a surgeon to create a longitudinal force across the device 100. Actuation of the tension assembly 140 thus compresses the fracture site 330 and reduces the fracture distance.

[0051] In FIG. 5 there is shown the device 100 in another aspect of the present disclosure in which the device is steered across the fracture gap 330 and through the distal 310 and proximal 320 fracture fragments.

[0052] In FIG. 6 there is shown the device 100 in another aspect of the present disclosure in which the rod 110 is a flexible tube 114. The flexible tube 114 can be threaded. In this aspect, the tension assembly 140 is a threaded screw 142 capable of screwing into the flexible tube 114. Once the threaded flexible tubing 114 has been inserted into the medullary canal 340 of the femur, a threaded screw 142 is screwed into the threaded flexible tube 114. As the screw 142 is threaded down past the fracture gap 330, it forces the bones fragments 310 and 320 to align, thus reducing the fracture 330. The threaded tube 114 may be made of any material that is sufficiently flexible to steer it across a fracture 330 and sufficiently durable to withstand significant forces experienced during threading.

[0053] In FIGS. 7-9 there is shown the device 100 in another aspect of the present disclosure in which the rod 110 consists of a straight rod portion 115 as well as a series of ball jointed segments 112 having both female and male articulation. The holes 172 and 170 can either be unexposed, as depicted in FIGS. 7-8, or as exposed channels, as depicted in FIG. 9. In this aspect, the diameter of the device is about 12 mm, and the cross section consists of a plurality of holes 172 and 170, which contain wires for steering and tightening. Each ball jointed segment 112 is about 25 mm in length. The device 100 is steered using a plurality of wires. The wires can be about 1 mm diameter or any other suitable diameter. The wires are run through the device 110 and attached to the distal segment 113. These wires allow the operator to steer from side to side. As the rod 110 is rotated and moved inward into the femoral canal, two additional degrees of freedom are obtained. Therefore, the surgeon can move the device 100 through three degrees of freedom when steering the device 100 across the fracture gap 330 under fluoroscopic guidance. Once the device 100 has been steered across the fracture gap 330, the fracture must be reduced. To do so, a plurality of straightening wires passing through the device 100 are ratcheted such that the device 100 assumes a substantially linear alignment. The straightening wires can be about 1.5 mm in diameter or any other suitable diameter. As the device 100 is ratcheted into a straight position, the bone fracture is reduced as shown in FIG. IB.

[0054] When the facture 330 has been adequately reduced, the surgeon has two options: first, the fracture 330 can be definitively plated using a fracture fixation plate, or second, a thin intermediate intramedullary rod compatible with most commercial nailing systems can be inserted down the hollow lumen 174 of the reduction device 100. This rod would maintain the corrected fracture while the reduction device 100 is removed and the definitive intramedullary rod fixation is placed down the medullary canal.

[0055] The device 100 of the present disclosure is suitable for reduction of transverse bone displacements, lateral bone displacements, and rotationally displaced bone fragments. In the case of rotational displacements, the device 100 within bone fragment 310 can be rotated by rotation of the device 100 until proper rotational positioning is achieved. The device 100 can optionally be affixed to the bone fragment using a bone interface device 120.

[0056] The device 100 can be used to reduce multiple bone fractures 330 occurring together in a given bone 300. In the case of multiple fractures, the device is steered across each fracture gap 330, and each bone fragment is sequentially aligned as described above.

[0057] Although as described herein, the fracture reducing device 100 of the present disclosure is preferred for use in reducing fractures of the femur, it is contemplated that such device 100 can also be used with other fractured bones with proper sizing of the rod so as to permit its entry and passage within the medullary canal of the respective fractured bone. For instance, the device 100 can also be used with the tibia and humerus bones. Moreover, although the rod as shown in the preferred embodiments herein in the Figures is generally of a linear configuration, the rod can also be curved if desired in order to accommodate or correspond to the general curvature of the respective medullary canal involved.

[0058] In FIG. 10 there is shown the device 100 in another aspect of the present disclosure in which the device 100 comprises a segmented rod 110 having a rigid rod portion 115, a primary segment portion 117 comprising primary segments 1 16 and 119, and a secondary segment portion 118 comprising secondary segments 123 and 124. As seen in FIG. 10, the primary and secondary segment portions are distal to the control assembly 180 and the rigid rod 115 is proximal to the control assembly 180. As seen in FIG. 7, the segmented rod 110 has a plurality of longitudinal holes, 170 and 172, and the rod segments 112 are pivotally coupled in series so that the holes 170 and 172 are aligned. A central lumen 174 is further formed through the rod 110. The rod 110 has articulations between each segment and wires running through holes 170 and 172 along the periphery. As seen in FIG. 1(A) and 3, a plurality of wires 210 passes through the plurality of holes 170 and 172 in the rod segments 112 and attach at the distal end of the flexible rod 150 or within the control assembly 180.

[0059] As seen in FIG. 10, the control assembly 180 comprises a joystick 134, thumbwheel 132, and access point 125 for positioning a wire or additional rod into the lumen of the segmented rod 110. Once the device 100 has been steered through the intramedullary canals 340 of the fractured bone 300, the segmented rod 110 is forced into a linear alignment, thereby reducing the fracture. [0060] The primary segment portion 117 is operably linked to the thumbwheel 132 with a plurality of wires 210. The primary segment portion 117 is steerable. In some aspects, the primary segment portion 117 is biaxially steerable and is configured to generate a large corrective torque to the distal segment of bone. The angle maintained by the primary segment portion 117 is controlled by turning the thumbwheel 132. When the thumbwheel 132 is rotated, it causes a subset of the connected plurality of wires 210 to become tightened and a second subset of the connected plurality of wires 210 to become loosened. The tightening and loosing of the plurality of wires 210 causes deflection of the primary segment portion 117 to which the wires are attached.

[0061] The secondary segment portion 118 is operably linked to the joystick 134 by a plurality of wires 210. The secondary segment portion 118 is also steerable. In some aspects, the secondary segment portion 118 is polyaxially steerable and is configured to allow precise manipulation of the steerable terminal secondary segment across the fracture gap. The angle maintained by the secondary segment portion 118 is controlled by movement of the joystick 134. When the joystick 134 is moved, it causes a ball assembly 135 to pivot within the control assembly 180. The pivoting of the ball assembly 135 causes a subset of the connected plurality of wires 210 to become tightened and a second subset of the connected plurality of wires 210 to become loosened. The tightening and loosing of the plurality of wires 210 causes deflection of the secondary segment portion 118 to which the wires are attached. In certain aspects, the steerable terminal secondary segment 124 is capable of acting as a bone interface device 120. In further aspects an additional bone interface device 120 is incorporated into the device 100.

[0062] In certain aspects, the steerable intramedullary fracture reduction device 100 is advanced down the medullary canal of the proximal bone fragment 320. Once into the fracture gap, the secondary segment portion 118 of the flexible rod 110 is curved by actuation of the control assembly 180 and manually positioned by rotating the device 100. Manual rotation is employed since the movement of the secondary segmented portion 118 is biaxial. As part of the process, the steerable terminal secondary segment 124 is positioned near the end of the distal bone fragment 310. The secondary segment portion 118 is then flexed to align the steerable terminal secondary segment 124 with the long axis of the distal bone fragment 310 in order to facilitate entry of the tip into the medullary canal of the distal bone fragment 310. With the steerable terminal secondary segment 124 aligned with the long axis of the distal bone fragment 310, the flexible rod 110 is advanced into the medullary canal of the distal bone fragment 310. Once successfully navigated into the medullary canal of the distal bone fragment 310, control of the steerable terminal secondary segment 124 is relaxed and the flexible rod 110 is advanced such that the primary segment portion 117 is positioned across the fracture gap. With the device 110 in position across the gap, the primary segmented portion 1 17 is straightened generating a torque correcting the misalignment of the two segments of bone 310 and 320. With the primary segmented portion 117 straightened, the two bone fragments 310 and 320 are aligned and a small diameter rod can be advanced down a canal in the center of the device. The small diameter rod can be any rod that is traditionally used to maintain fracture reduction. With the small rod advanced completely, the device 110 can be withdrawn from the medullary canal. The small rod will hold the reduction and facilitate intramedullary reaming so that the procedure can continue routinely.

[0063] In FIG. 11(A) there is shown a rigid rod 115 in another aspect of the present disclosure in which the rigid rod 115 comprises a threaded collar 126 at the proximal end 121 of the rigid rod 115 and a disk joint 151 at the distal end 122 of the rigid rod 115. The rigid rod 115 is capable of being connected in series to other rod components to form a segmented rod 110. The threaded collar 126 is connected to the proximal end of the rigid rod 115 through the use of set screws 127 as shown in FIG. 11(B). The rigid rod 115 (and thus the segmented rod 110) can be connected to the control assembly 180 by threading the threaded collar 126 into the control assembly 180. As seen in FIG. 11(B), the segmented rod 110 has a plurality of longitudinal holes, 170 and 172, through which a plurality of wires 210 pass. A central lumen 174 is further formed through the rigid rod 115. As see in FIG. 11(C), the distal end 122 of the rod 1 15 can comprise a disk joint 151.

[0064] In FIG. 12 there is shown a primary segment 116 as found in the primary segment portion 117 in another aspect of the present disclosure. As seen in FIG. 12, the segmented rod 110 has a plurality of longitudinal holes, 170 and 172, and the primary segments 116 are pivotally coupled in series so that the holes 170 and 172 are aligned. A central lumen 174 is further formed through the primary segments 116. The primary segments 116 are connected in series. Any suitable number of primary segments 116 can be used. For example, there can be 5, 6, 7, 8, 9, 10, or 11 jointed primary segments 116 connected in series. In some aspects, there are 9 primary segments 116 connected in series. The primary segments are connected using a disk joint 151 and a disk socket 152. The primary segments 116 are operably linked to the control assembly 180. The disk joint configuration of the primary segments 116 allows one degree of freedom of motion within the primary segment portion 117 as controlled by the thumbwheel component 132 of the control assembly 180.

[0065] FIG. 13 shows another aspect of the present disclosure in which there is a terminal primary segment 119 that is positioned between the primary segments 1 16 in the primary segment portion 117 and the secondary segment portion 118. The terminal primary segment 119 comprises both a ball joint component 153 and a disk socket component 152, making it compatible with both the primary segments 116 and the secondary segments 123. In some aspects such as shown in FIG. 13(A), the terminal primary segment 119 has tapped holes 128 for the attachment of a plurality of wires 210, which control the position of the primary segment portion 117. The plurality of wires 210 can be affixed using set screws. In further aspects such as sown in FIG. 13(C), the connection joint 119 comprises grooves 129 wherein the studded end of a derailleur cable can be seated.

[0066] In FIG. 14 there is shown the secondary segments 123 as found in the secondary segment portion 118. As seen in FIG. 14, the segmented rod 1 10 comprises a plurality of longitudinal holes, 170 and 172, and the secondary segments 123 are pivotally coupled in series so that the holes 170 and 172 are aligned. A central lumen 174 is further formed through the secondary segments 123. The secondary segments 123 are connected in series. Any suitable number of secondary segments 123 can be used. The secondary segment portion 118 is operably linked to the control assembly 180. The ball joint configuration 154 of the secondary segments 123 allows two degrees of freedom of motion within the secondary segment portion 118 as controlled by the joystick component 134 of the control assembly 180.

[0067] In FIG. 15 there is shown a steerable terminal secondary segment 124 in accordance with one aspect of the present disclosure, including a central lumen 174 and holes 172 through which wires a plurality of wires 210 can pass. The steerable terminal secondary segment 124 is positioned at the distal end 150 of the secondary segment portion 118. In some aspects such as shown in FIG. 15(A), the steerable terminal secondary segment 124 has tapped holes 131 for the attachment of the plurality of wires 210, which control the position of the secondary segment portion 118. The plurality of wires 210 can be affixed using set screws. In further aspects such as shown in FIG. 15(C), the steerable terminal secondary segment 124 comprises grooves 133 wherein the studded end of a derailleur cable can be seated.

[0068] In FIG. 16 there are shown various aspects of a joystick steering mechanism 134 in accordance with one aspect of the present disclosure. The joystick 134 comprises a ball assembly 135 that fits into a complementarily shaped cavity within the control assembly housing 137. The ball assembly 135 can have a tapped hole through its center. The joystick 134 can also have a thumb stick 138 that is that is threaded into the hole in the ball assembly 135. The secondary segment portion 118 is operably linked to the joystick 134 with a wire or plurality of wires 210. The angle maintained by the secondary segment portion 118 is controlled by the movement of the joystick 134. As the ball assembly 135 is rotated within the control assembly housing 137, the attached wires are loosened or tightened, depending on the particular direction of movement of the ball assembly 135.

[0069] In some aspects, the wires are held in place at both ends using set screws. In this aspect, and as shown in FIG. 16(A), the wire attachment device 139 of the joystick 134 has tapped holes 143 for the attachment of the plurality of wires 210 that control the movement and orientation of the secondary segment portion 118 using set screws. The wire attachment device 139 is threaded into the side of the ball assembly 135 that is opposite the thumb stick 145. In some aspects, four wires 210 are attached to the wire attachment device 139 at one end and at the steerable terminal secondary segment 124 at the other end. The wires can be attached at the wire attachment device 139 within a series of tapped holes 143 which are positioned radially along the wire attachment device 139. The wire attachment device can have a tapped hole along its longitudinal axis, into which a screw can be inserted, thereby fastening the wires to the wire attachment device 139.

[0070] In further aspects, derailleur cables can be used to control the position of the position of the secondary segment portion 118. In this aspect, it can be beneficial to tighten the attached wires near the joystick 134. This aspect is shown in FIG. 16(C). In this aspect, an inner lumen tube 146 can be passed through the center of the ball assembly 135, for example, by threading the inner lumen tube 146 into the ball assembly 135. A wire attachment device 139 is provided and can be attached to the inner lumen tube 146 opposite the ball assembly 135. The wire attachment assembly can have a tapped hole 143, which accommodates a set screw. The wires are passed through the inner lumen tube 146 and fixed in place by the set screw of the wire attachment device 139. [0071] In FIG. 17 there is shown a control assembly housing 137 in another aspect of the present disclosure. The control assembly housing 137 encloses the control assembly elements, for example the thumbwheel 134, worm gear gearbox 147, and joystick 134, and is configured such that it can fit within the hand of the user. The control assembly housing 137 can be produced in two distinct subparts, which can be combined by any suitable means to obtain a single control assembly housing unit 137. By providing two combinable subunits, the thumbwheel 132, worm gear gearbox 147, and joystick 134 can more easily be incorporated into the control assembly 180.

[0072] In FIGS. 18-19 there is shown a control assembly housing 137 in another aspect of the present disclosure. The control assembly as configured in FIGS. 18-19 advantageously fits within the user's hand for improved ease of operation. The control assembly 180 can comprise a thumbwheel 134, worm gear gearbox 147, and joystick 134 and is connected to a rod 110.

[0073] In FIG. 20 there is shown the control assembly 180 in another aspect of the present disclosure in which the control assembly 180 comprises a joystick 134, thumbwheel 132, and worm gear gearbox 147. A U-channel 148 can optionally be mounted between the worm gear gearbox 147 and the control assembly housing 137, which advantageously provides greater strength to the control assembly housing 137. The wires 210 are attached to the control assembly 180 by any suitable means, such as by a set screw. The primary segments are operably linked to the thumbwheel 132 with a wire or series of wires 210. The angle maintained by the primary segment portion 117 is controlled by turning the

thumbwheel 132. The thumbwheel 132 can be operably linked to the worm gear gearbox 147. In some aspects, two wires are attached to the primary segment portion 117 at one end and pass through the worm gear gearbox 147 at the other end. In some aspects, those wires can be counter wrapped around the output shaft 149 of the worm gear gearbox 147. When using counter wrapping, the action of the worm gear gearbox 147 causes one of the wires to tighten while the other loosens, resulting in the bending of the primary segment portion 117 toward the side that is tightened. The secondary segment portion 118 is operably linked to the joystick 134 by one or a series of wires 210. The angle maintained by the secondary segment portion 118 is controlled by movement of the joystick 134. The joystick 134 can be positioned on the upper portion of the control assembly housing 137 as shown in FIG. 20. [0074] In FIG. 21 there is shown the output shaft attachment 149, which can optionally be included with the control assembly 180. In some aspects, two wires are attached to the primary segment portion 117 at one end and pass through the worm gear gearbox 147 at the other end. In some aspects, those wires can be counter wrapped around the output shaft of the worm gear gearbox 147. By using the output shaft attachment 149, it is possible to achieve the full range of motion of the primary segment portion 117 within a single rotation of the thumbwheel 132. The output shaft attachment 149 thus eliminates the risk of over- rotating the thumbwheel 132, which would result in tightening of both counter- wrapped wires.

[0075] In FIG. 22 there is shown femoral fracture reduction according to one aspect of the present disclosure including (A) the steering of the secondary segmented portion 118, primary segmented portion 117, and rigid rod portion 115 into the medullary canal, wherein the device is controlled by the control assembly 180; and (B) the reduction of the femoral fracture using the device 100 by forcing the segmented portions of the rod, 117 and 118, into a linear alignment after steering it through the medullary canal of both bone fragments 310 and 320.

[0076] In the preceding detailed description, reference has been made to the

accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the present invention may be practiced. These embodiments, and certain variants thereof, have been described in sufficient detail to enable those skilled in the art to practice embodiments of the present invention. It is to be understood that other suitable embodiments may be utilized and that logical, mechanical, chemical and electrical changes may be made without departing from the spirit or scope of such inventive disclosures. To avoid unnecessary detail, the description omits certain information known to those skilled in the art. The preceding detailed description is, therefore, not intended to be limited to the specific forms set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be reasonably included within the spirit and scope of corresponding claims.

[0077] It should be noted that the language used herein has been principally selected for readability and instructional purposes, and it can not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure is intended to be illustrative, but not limiting, of the scope of claimed methods. [0078] As used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to "a bone fragment" includes a combination of two or more bone fragments, and the like.

[0079] Any terms not directly defined herein shall be understood to have the meanings commonly associated with them as understood within the art of the present disclosure.

Certain terms are discussed herein to provide additional guidance to the practitioner in describing the compositions, devices, methods and the like of aspects of the present disclosure, and how to make or use them. It will be appreciated that the same thing can be said in more than one way. Consequently, alternative language and synonyms can be used for any one or more of the terms discussed herein. No significance is to be placed upon whether or not a term is elaborated or discussed herein. Some synonyms or substitutable methods, materials and the like are provided. Recital of one or a few synonyms or equivalents does not exclude use of other synonyms or equivalents, unless it is explicitly stated. Use of examples, including examples of terms, is for illustrative purposes only and does not limit the scope and meaning of the aspects of the present disclosure herein.

[0080] "About" as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20% or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

Claims

What is claimed is:

1. A steerable intramedullary fracture reduction device comprising: a rod having a flexible section along at least a portion of the rod; a steering mechanism operatively coupled to the flexible portion for adjusting a curvature of the flexible section of the rod responsive to an operator input; and a tension assembly operatively coupled to the flexible portion for forcing the flexible portion in a substantially linear arrangement responsive to an actuation of the tension assembly.

2. The device of claim 1, wherein the rod comprises a flexible tube.

3. The device of claim 2, wherein the flexible tube comprises a threaded flexible tube and the tension assembly comprises a threaded screw capable of screwing into the flexible tube.

4. The device of claim 1, wherein the steering mechanism comprises a plurality of wires attached to the distal end of the rod, wherein operator input to one or more of the wires causes tension along the flexible portion of the rod and adjusts the curvature of the flexible section of the rod.

5. The device of claim 1, wherein the rod comprises a plurality of rod segments, wherein the rod segments comprise a plurality of longitudinal holes and are pivotally coupled in series so that the holes are aligned.

6. The device of claim 5, further comprising a plurality of wires passing through the plurality of holes in the rod segments and attached to the distal end of the flexible rod.

7. The device of claim 1, wherein the steering mechanism comprises a joystick, thumbwheel, or combination thereof.

8. The device of claim 5, wherein the device further comprises a thumbwheel, a gearbox, and an output shaft attachment connected to the thumbwheel, wherein the output shaft attachment enables a full range of motion in the attached plurality of rod segments to be achieved through one rotation of the thumbwheel.

9. The device of claim 1, wherein the steering mechanism further comprises a control arm and a ratchet assembly.

10. The device of claim 1, further comprising a bone interface device attached to the distal end of the rod.

11. The device of claim 10, wherein the bone interface device comprises a flexible tip.

12. The device of claim 10, wherein the bone interface device comprises a bone anchor device.

13. The device of claim 10, wherein the bone interface device comprises an expandable rod segment.

14. The device of claim 10, wherein the bone attachment assembly is configured to expand radially from the flexible rod responsive to an actuation of the bone interface device.

15. The device of claim 14, wherein the bone interface device is an expandable washer responsive to actuation by the tension assembly.

16. The device of claim 10, wherein the bone interface device is one or more balloon catheter expandable under pressure.

17. The device of claim 16, wherein the balloon catheter is pressurized using a gas, water, saline, or the like.

18. The device of claim 7, wherein the rod segments comprise a plurality of longitudinal holes and are pivotally coupled in series so that the holes are aligned and wherein the tension assembly comprises a plurality of wires passing through the plurality of holes in the rod segments and are attached to the distal end of the flexible rod.

19. The device of claim 7, wherein the rod comprises a rigid portion, a first plurality of rod segments capable of moving with one degree of freedom, a second plurality of rod segments capable of moving with two degrees of freedom, or a combination thereof.

20. The device of claim 19, wherein the second plurality of rod segments is operably connected to a joystick and the first plurality of rod segments is operably connected to a thumbwheel.

21. A steerable intramedullary fracture reduction device comprising: a flexible rod comprising a rigid portion, a first flexible portion, and a second flexible portion, wherein the first and second flexible portions comprise a plurality of rod segments, wherein the rod segments include a plurality of longitudinal holes and are pivotally coupled in series so that the holes are aligned, and wherein a central lumen is further formed through the rod and rod segments; a plurality of wires passing through the plurality of holes in the rod segments and attached to the distal end of the flexible rod; and a control assembly coupled to the plurality of wires and configured to apply

tension selectively to one or more of the wires, thereby causing a torque on a distal end of the flexible rod.

22. The device of claim 21, wherein the second flexible portion further comprises a steerable terminal rod segment.

23. The device of claim 22, wherein the device further comprises a thumbwheel, a gearbox, and an output shaft attachment connected to the thumbwheel, wherein the output shaft attachment enables a full range of motion in the attached plurality of rod segments to be achieved through one rotation of the thumbwheel.

24. The device of claim 23, wherein the second flexible portion is operably connected to the joystick and the first flexible portion is operably connected to the thumbwheel.

25. The device of claim 21, further comprising a bone interface device attached to the distal end of the rod.

26. A method of reducing a bone fracture, wherein the bone has distal and proximal ends and distal and proximal bone fragments, comprising the steps of: inserting the device of claim 1 into the medullary canal of the proximal end of a bone; guiding the device through the proximal bone fragment; steering the device across a fracture using the steering mechanism; guiding the device through the distal bone fragment; reducing the fracture using the tension assembly.

27. The method of claim 26, further comprising the step of interfacing the device with the bone.

28. The method of claim 27, wherein the interfacing comprises anchoring the device to the bone.

29. The method of claim 27, wherein the interfacing comprises flexing a segment of the device.

30. The method of claim 26, wherein the bone is a femur.

31. The method of claim 27, further comprising the step of rotating the bone after attaching the device to achieve proper bone fragment alignment.

32. The method of claim 26, further comprising the step of rotating the bone after fracture reduction to achieve proper bone alignment.

33. A method of reducing a bone fracture, wherein the bone has distal and proximal ends and distal and proximal fragments, comprising the steps of: inserting the device of claim 19 into the medullary canal of the bone at the

proximal end; guiding the device through the proximal bone fragment;

steering the device across the fracture using the control assembly;

guiding the device through the distal bone fragment;

reducing the fracture using the control assembly.

34. The method of claim 33, further comprising the steps of:

inserting a rod through the lumen of the device following fracture reduction; removing the device from the medullary canal; and

pinning the rod to the bone fragment.

35. The method of claim 34, wherein the bone is a femur.