US20110178520A1 - Rotary-rigid orthopaedic rod - Google Patents

Abstract

Apparatus and method for repairing a fractured bone. The apparatus and methods may involve an intramedullary rod. The rod may include a first elongated member and a second elongated member. Each of the first and second elongated members may be configured to bend in a first direction and to resist bending in a second direction. The first and second elongated members may be arranged such that: (1) the rod is bendable when the first direction of the first elongated member is aligned with the first direction of the second elongated member; and (2) the rod is rigid when the first direction of the first elongated member is aligned with the second direction of the second elongated member. Some embodiments may include rods that have sections that may be configured to be curved and rigid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a nonprovisional of U.S. Provisional Applications No. 61/295,244, filed on Jan. 15, 2010, which is hereby incorporated by reference in its entirety.
FIELD OF TECHNOLOGY
• Aspects of the disclosure relate to providing apparatus and methods for repairing bone fractures. In particular, the disclosure relates to apparatus and methods for repairing and/or stabilizing bone fractures utilizing a device that is inserted into a bone.
BACKGROUND OF THE INVENTION
• Currently, there are many known ways to treat long bone fractures. Common fracture treatments include: (1) nonsurgical immobilization; (2) osteosuture and tension band technologies; (3) percutaneous fixation (e.g., using pins, wires, screws etc.); (4) rigid intramedullary nailing (e.g., using a large rod and external screws); (5) flexible plate osteosynthesis (e.g., a “load sharing” suture); (6) arthroplasty (e.g., using a prosthesis); (7) plating and other indication specific techniques. Severe fractures that meet certain clinical criteria may require surgical repair rather than non-surgical immobilization.
• The midshaft of an elongated or long bone is typically classified as the diaphysis.
• In general, fracture fixation may provide longitudinal (along the long axis of the bone), transverse (across the long axis of the bone), and rotational (about the long axis of the bone) stability. Fracture fixation may also preserve normal biologic and healing function.
• There are two primary categories for surgical fixation: a device that is within the skin (internal fixation); and a device that extends out of the skin (external fixation). There are two common types of internal fixation approaches for long bone surgery (a) a plate that is screwed to the outside of the bone; or (b) a rod that goes down the center of the bone.
• Plates are characterized by relatively invasive surgery, support of fractured bone segments from one side outside of bone, and screws that anchor into the plate and through the entire bone. Successful repair is dependent on fracture pattern, bone quality, and patient tolerance of a foreign body, among other factors. Plates may not properly address the alignment and stability requirements for periarticular and intrarticular fractures.
• Intramedullary rods or nails, such as those used in mid shaft treatments, are often used instead of plates and screws to reduce soft-tissue trauma and complications. Typically, an intramedullary rod or nail is fixed in diameter and is introduced into the medullary canal through an incision in the articular surface.
• Flexible intramedullary rod-like solutions utilize structures that can be flexed for insertion into the medullary cavity through a diaphyseal or metaphyseal access site. The structures may then be made rigid inside the intramedullary cavity. The structures are often reinforced with polymers or cements. Making the structures rigid is important for surgical fixation.
• It would be desirable, therefore, to provide apparatus and methods for bone fracture alignment and stabilization.
BRIEF DESCRIPTION OF THE DRAWINGS
• The objects and advantages of the invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
• FIG. 1 shows illustrative apparatus in accordance with principles of the invention;
• FIG. 2 shows a partial cross-section taken along lines2-2 (shown inFIG. 1)
• FIG. 3 shows a perspective view, taken approximately along lines3-3, of a portion of the apparatus shown inFIG. 1, when the apparatus is in a first configuration;
• FIG. 4 shows a partial cross-section taken along the lines4-4 (shown inFIG. 3).
• FIG. 5 shows a partial cross-section taken along the lines5-5 (shown inFIG. 3).
• FIG. 6 shows the view ofFIG. 3 when the apparatus is in a second configuration.
• FIG. 7 shows a perspective view of a portion of the apparatus shown inFIG. 1.
• FIG. 8 shows the apparatus ofFIG. 1, along with other apparatus and a bone;
• FIG. 9 shows a partial cross-sectional view of a portion of the apparatus shown inFIG. 1 taken along lines9-9 (shown inFIG. 1).
• FIG. 10 shows a partial cross-sectional view of a portion of the apparatus shown inFIG. 1 taken along lines10-10 (shown inFIG. 1).
• FIG. 11 shows a partial cross-sectional view taken along lines11-11 (shown inFIG. 1) when the apparatus is in a configuration that is different from that shown inFIG. 1.
• FIG. 12 shows the apparatus ofFIG. 1, along with other apparatus and a different bone.
• FIG. 13 shows a flat model representation of features of apparatus such as that shown inFIG. 1.
• FIG. 14 shows schematic apparatus in accordance with the principles of the invention.
• FIG. 15 shows other schematic apparatus in accordance with the principles of the invention.
• FIG. 16 shows other apparatus in accordance with the principles of the invention.
• FIG. 17 shows yet other apparatus in accordance with the principles of the invention.
• FIG. 18 shows still other apparatus in accordance with the principles of the invention.
• FIG. 19 shows a portion of the apparatus shown inFIG. 18.
• FIG. 20 shows a partial cross-sectional view, taken along lines20-20 (shown inFIG. 19), of the apparatus shown inFIG. 19.
• FIG. 21 shows a pattern that may be used to manufacture apparatus in accordance with the principles of the invention.
• FIG. 22 shows illustrative steps of a process in accordance with the principles of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• Apparatus and method for repairing a fractured bone are provided. The apparatus and methods may involve an intramedullary rod. The rod may include a first elongated member and a second elongated member. An elongated member may be referred to herein as a sleeve. Each of the first and second elongated members may be configured to bend in a first direction and to resist bending in a second direction. The first and second elongated members may be arranged such that: (1) the rod is bendable when the first direction of the first elongated member is aligned with the first direction of the second elongated member; and (2) the rod is rigid when the first direction of the first elongated member is aligned with the second direction of the second elongated member.
• An elongated member may be an elongated tubular member. The first elongated member may be disposed coaxially within the second elongated member. The inner member may have a length that is longer, shorter or substantially the same as the length of outer member. The inner elongated member may include a central longitudinal void or may be solid, essentially solid or porous. The inner elongated member may rotate freely within an outer elongated member.
• The elongated member may include implantable materials such as metals, polymers, composites and any other suitable materials.
• The first direction may correspond to an arrangement of stress-relief features. The stress-relief features may include slots that are longitudinally spaced from each other. The slots may be stress-relief slots. The slots may be configured to provide tension relief. The slots may be configured to provide compression relief. Slots may be longitudinally separated by ribs. The ribs and/or slots may be circumferentially separated by one or more longitudinal members.
• Slots may be formed by different cut patterns/arrangements in an elongated member. The different patterns/arrangements may provide different bending properties. Slots, holes or other void features may be provided by laser cutting or any other suitable method.
• Different materials may be used to construct an elongated member, and different materials may provide different bending properties. Properties of features of an elongated member such as angular separation, thickness, height, separation, ratio of height to separation, composition or material, structure or microstructure or other suitable properties may provide different bending properties. The properties of an elongated member may vary along the longitudinal axis of the elongated member.
• The stress-relief features may include any suitable microstructure, such as one or more of the following: sinters, kerfs, cuts, cells, perforations, holes, patterns, helical paths, cells, slots, tapers, angled cuts and any other suitable structure or microstructure.
• The first direction of an elongated member may correspond to: (a) a first arrangement of slots that are longitudinally spaced from each other for tension relief; and (b) a second arrangement of slots that are longitudinally spaced from each other to provide compression relief. The first and second arrangements of slots may be spaced circumferentially apart from each other on one of the elongated members.
• The apparatus may include a delivery cannula. The delivery cannula may provide a curved entry path into an intramedullary channel through an access hole in a bone.
• The apparatus may include a control shaft. The control shaft may extend through the delivery cannula. The control shaft may manipulate one or more elongated members. The control shaft may be removed after elongated members are rotationally locked or rod is locked to bone. Anchors may lock an elongated member and attach rod to bone.
• The intramedullary rod may include adjustment flanges. The adjustments flanges may be used to adjust the first and second elongated members relative to each other in a circumferential direction.
• An elongated member may include an anchor-receiving feature. The anchor-receiving feature may include holes or voids in the elongated member. The anchor-receiving feature may be tapered, may include mesh-like cells that are configured to engage an anchoring device or may have different sizes, parameters or features. The spacing between the anchor-receiving features and the size and shape of the anchor-receiving features may be configured to cooperate with one or more types of different anchors. The anchor-receiving features may be may be sized as to interact/cooperate with each other. The anchor-receiving features may be sized or shaped differently to reduce or relieve angular stress between an inner and outer elongated member.
• The first and second elongated members may include, respectively, a first anchor-receiving feature and a second anchor-receiving feature. The first and second elongated members may be configured to be positioned relative to each other such that the first anchor-receiving feature and the second anchor-receiving feature are positioned to receive the same anchor. The first and second anchor-receiving features may be distal the first and second arrangements of slots.
• The first and second elongated members may include, respectively, a third anchor-receiving feature and a fourth anchor-receiving feature. The first and second elongated members may be configured to be positioned relative to each other such that the third anchor-receiving feature and the fourth anchor-receiving feature are positioned to receive the same anchor. The third and fourth anchor receiving features may be proximal the first and second arrangements of slots.
• Anchors may penetrate one or more of the anchor-receiving features and secure one elongated member relative to another elongated member. Anchors may prevent the elongated members from rotating out of alignment. Anchors may penetrate bone and may used to apply tension across a bone fracture.
• An elongated member may include one or more elastic sections. An elastic section may apply a compressive or a tensile force between proximal and distal anchors of the elongated member. The tensile force may be applied across the bone fracture by anchoring the elongated member such that the elastic section is in compression. The compressive force may be applied across the bone fracture by anchoring the elongated member such that the elastic section in tension.
• The rod may include a locking mechanism. The locking mechanism may include: (a) a first attachment to the first elongated member; (b) a second attachment to the second elongated member; and (c) a bridging member that is configured to prevent relative rotation about the longitudinal axis of the first elongated member with respect to the second elongated member. One or both of the first and second attachments may be threaded.
• The locking mechanism may include one or more of a threaded nut, a sect screw, a cotter pin, a crimp, a swage, a morse taper and any other suitable mechanical interface or mechanism.
• In some embodiments, the first elongated member may include a fixed-curve portion. The fixed-curve portion may have a fixed curve. The fixed curve may define a fixed-curve plane. The fixed curve plane may include the second direction of the first elongated member.
• In some embodiments, the first elongated member may include a first fixed-curve portion and the second elongated member may include a second fixed-curve portion. The second fixed-curve portion may have a second fixed curve. The second fixed curve may define a second fixed-curve plane. The second fixed curve plane may include the second direction of the second elongated member.
• In some embodiments, the intermedullary rod may be fixed in a rigid state that includes one or more straight sections and one or more curved sections. In some embodiments, rotation of a first elongated member relative to a second elongated member may cause rod to become rigid in a curved or bent configuration to provide mechanical support to different portions of a bone.
• A fixed-curve portion may include a first segment and a second segment. A segment may be a compound segment. The second segment may be directly attached to the first segment. The first segment may include a first rigid bend. The second segment may include a second rigid bend. When the first and second bends lie in the fixed-curve plane: (a) the fixed-curve portion may be resistant to bending in the fixed-curve plane; and (b) the fixed curve portion may be non-resistant to bending in a plane that is different from the fixed-curve plane.
• The first segment may be linked to the second segment by an articulating linkage. The articulating linkage may include a female linkage member and/or a male linkage member. The first and second segments may be formed from a unitary body. The unitary body may be a tube.
• The first elongated member may include a segment that has a first end that includes a first linkage that has a first pivot axis. The first linkage may provide a connection to a first neighboring segment. The segment may have a second end that is spaced a distance apart from the first end. The second end may include a second linkage. The second linkage may include a second pivot axis. The second linkage may provide a connection to a second neighboring segment. The distance may define a longitudinal axis. The distance may define a direction that may be referred to as a longitudinal axis. The second pivot axis may be angularly offset, about the longitudinal axis, from the first pivot axis.
• The first pivot axis may define the first direction of the first elongated member.
• The second pivot axis may define the second direction of the first elongated member.
• The segment may include a first end that includes a first linkage. The first linkage may have a first pivot axis. The first linkage may provide a connection to a first neighboring segment. The segment may include a second end. The second end may be spaced a distance apart from the first end. The second end may include a second linkage. The second linkage may have a second pivot axis. The second pivot axis may provide a connection to a second neighboring segment.
• The distance may define a longitudinal axis. The distance may define a direction that may be referred to a longitudinal axis. The first and second pivot axes may define intersecting lines when the segment is viewed along a direction that is substantially normal to the longitudinal axis.
• The first pivot axis may define the first direction of the first elongated member.
• The second pivot axis may define the second direction of the first elongated member.
• The second pivot axis may be angularly offset, about the longitudinal axis, from the first pivot axis.
• A segment may include a segment body. The segment body may include one or more implantable material such as metal, polymer, composite and any other suitable material. The segment body may include one or more forms such as a cylinder, a prism, a curve and any other suitable shape.
• The segment may be one of a chain of segments. The chain of segments may form all or a portion of the elongated member of the intermedullary rod. The segment chain may be placed inside an outer elongated member. The outer member may be provided with stress relief features that are distributed along the length and circumference of the member. A relative orientation of the chain and the outer elongated member may allow the rod to be oriented in a bendable or rigid orientation.
• The rod may include a bone support extending from an end of the first and/or second elongated members. The end may be a proximal or a distal end. The rod may include two bone supports. One of the bone supports may extend from the first elongated member. The other may extend from the second elongated member.
• The bone support may be fixed to one or more bone fragments. Fixation to bone may include using any suitable anchoring device.
• In some embodiments, the rod may include an outer tubular member that is configured to bend about a first axis and an inner member disposed inside the outer tubular member. The inner member may include a segment that is configured to move: (a) relative to a first attached neighboring segment, about a second axis; and (b) relative to a second attached neighboring segment opposite the first attached neighboring segment, about a third axis.
• The second axis may be substantially parallel to the first axis. The third axis may be substantially perpendicular to the first axis.
• The inner member may be configured to rotate, relative to the outer tubular member, from a first position in which the second axis is parallel to the first axis, and the rod is bendable, to a second position in which the third axis is substantially perpendicular to the first axis, and the rod is resistant to bending.
• The segment may be configured to move relative to the first and second neighboring segments by respective operation of first and second articulating linkages.
• The segment, the first neighboring segment and the second neighboring segment may be formed from a unitary body. The unitary body may be a tube.
• The methods may include a method for delivering an intramedullary rod to a bone. The method may include inserting a flexible intramedullary rod through an angled access hole into an intramedullary channel; and configuring the intramedullary rod in a rigid configuration by aligning a bending feature of a first sleeve with a non-bending feature of a second sleeve.
• The method may include drilling the angled access hole at an angle to a longitudinal axis of the bone. The method may include preparing an intramedullary space to receive the rod. The method may include aligning the first and second sleeves to make the rod flexible. The method may include inserting the rod into the intramedullary space. The method may include rotating the first sleeve relative to the second sleeve to make the rod inflexible. The method may include fixing a rotational offset between the first sleeve and the second sleeve.
• The method may include anchoring a distal end of the rod to the bone. The method may include applying a tension to the rod. The method may include anchoring a proximal end of the rod to the bone.
• The method may include expanding a bone support at one end of the rod.
• The apparatus and methods of the invention will be described in connection with embodiments and features of an illustrative bone repair device and associated hardware and instrumentation. The device and associated hardware and instruments will be described now with reference to the FIGS. It is to be understood that other embodiments may be utilized and structural, functional and procedural modifications may be made without departing from the scope and spirit of the present invention. It will be understood that features shown in connection with one or more of the embodiments may be practiced in accordance with the principles of the invention along with features shown in connection with other embodiments.
• FIG. 1 shows illustrative rotary-rigid rod100.Rod100 may includeouter sleeve140 andinner sleeve150.Inner sleeve150 may have a length that is longer, shorter or substantially the same as the length ofouter sleeve140. The sleeves may be constructed of metal, polymer, composite or other suitable material. In some embodiments, the sleeves may be constructed from Nitinol tube. Void features, such as holes and slots, some of which are shown and described herein, may be provided by laser cutting or any other suitable method.
• Outer sleeve140 may includeproximal end142 anddistal end144.Inner sleeve150 may includeproximal end152 anddistal end154.Outer sleeve140 may includecenter section146.Inner sleeve150 may have corresponding center section156 (shown inFIG. 2). Rotary-rigid rod100, in the configuration shown inFIG. 1, may have longitudinal axis L₁. In some embodiments, rotary-rigid rod100 may have an essentially annular cross section that is substantially perpendicular to axis L₁. Proximal end142 andproximal end152 may include, respectively,adjustment flanges160 and170.Adjustment flanges160 and170 may be used to adjustsleeves140 and150 relative to each other in circumferential direction C or −C about axis L₁.
• FIG. 2 shows a proximal portion of rotary-rigid rod100.Inner sleeve150 is shown substantially flush and coaxially aligned withouter sleeve140.Inner sleeve150 may include a central longitudinal void or may be solid, essentially solid or porous.Inner sleeve150 may rotate freely withinouter sleeve140.
• Outer sleeve140 may includeouter holes241a,241band241c, collectively referred to henceforth as outer holes241.Inner sleeve150 may includeinner holes251a,251band251c, collectively referred to henceforth as inner holes251.Outer holes240 and inner holes250 may be aligned or partially aligned wheninner sleeve150 is in one or more rotational positions with respect toouter sleeve140.
• While only a few of holes shown inFIG. 2 are labeled, it should be apparent that numerous holes of this type may be a part ofrod100. The holes may include mesh-like cells that are configured to engage an anchoring device.
• In some embodiments,rod100 may include corresponding holes in distal ends ofsleeves140 and150.
• Outersleeve center section146 may includeouter ribs242a,242band242c, collectively referred to henceforth asouter ribs242. Innersleeve center section156 may includeinner ribs252a,252band252c, collectively referred to henceforth asinner ribs252.
• FIG. 3 showsouter sleeve140 andinner sleeve150 in an aligned configuration. In the aligned configuration,outer ribs242 are aligned in circumferential direction C withinner ribs252.Inner ribs254, oppositeinner ribs252, are aligned withouter ribs244, oppositeouter ribs242.Outer ribs242 and244 may be circumferentially separated from each other bylongitudinal members246 and248.Inner ribs252 and254 may be circumferentially separated from each other bylongitudinal members256 and258.
• Angle α defines the circumferential extent ofmember256. Angle α may have any suitable magnitude. For example, angle α may range from a fraction of a degree to almost 180 degrees. In some embodiments, angle α may be about 90 degrees. Corresponding angles define the circumferential extent ofmembers246,248 and258. In some embodiments, one or more of the angles corresponding to angle α may have a magnitude that is different from that of angle α.
• Angle β defines the circumferential separation betweenmembers256 and258. Angle β may have any suitable magnitude. For example, angle β may range from a fraction of a degree to almost 180 degrees. In some embodiments, angle β may be about 90 degrees. A corresponding angle defines the circumferential separation betweenmembers246 and248. In some embodiments, one or more of the angles corresponding to angle β may have a magnitude that is different from that of angle β.
• Different magnitudes of angles α and β, and the corresponding angles, may produce in each ofsleeves140 and150 different bending properties along axis L₁. When the sleeves are rotated about axis L₁relative to each other,rod100 may exhibit different bending properties based on the different angular magnitudes.
• For example,outer ribs242 and244 permitouter sleeve140 to bend along axis L₁(about axis L₂) in the direction of either outer rib portion.Inner ribs252 and254 permitinner sleeve150 to bend along axis L₁(about axis L₂) in the direction of either inner rib portion.
• To the extent that inner ribs and outer ribs are non-aligned with each other,rod100 may exhibit resistance to bending along axis L₁.
• Increased thickness t₀oflongitudinal members246 and248 may increase the bending resistance ofouter member140 along axis L₁about axis L₂. Increased thickness t_ioflongitudinal members256 and258 may increase the bending resistance ofinner member150 along axis L₁about axis L₂.
• FIGS. 4 and 5 show heights h₀and h_iofribs242 and252, respectively.Ribs242 and252 may be spaced apart by spacings s_oand s_i, respectively. Relatively greater or lesser ratios h_o:S_oand h_i:s_imay decrease or increase, respectively, the bending resistances ofsleeves140 and150.
• One or more oflongitudinal members246,248,256 and258 may include a composition or material that provides a relatively greater or lesser degree of bending resistance along axis L₁about axis L₂. Suitable compositions or materials may include implantable materials such as metals, polymers, composites and any other suitable materials.
• One or more oflongitudinal members246,248,256 and258 may include a structure or microstructure that provides a relatively greater or lesser degree of bending resistance along axis L₁about axis L₂. Suitable structure or microstructure may include: sinter, kerfs, cuts, cells, perforations, holes, patterns, helical paths, cells, slots, tapers, angled cuts and any other suitable structure or microstructure.
• Properties such as angle α, angle β, thickness t_o, thickness t_i, height h_o, height h_i, separation s_o, separation s_i, ratio h_o:s_o, ratio h_i:s_i, composition or material, structure or microstructure and other suitable properties may vary along axis L₁.
• FIG. 6 showsinner sleeve150 rotated by angle γ relative toouter sleeve140.Inner ribs252 are now aligned withlongitudinal member246.Outer member246 may thus provide resistance to a bending moment about axis L₃.Longitudinal member248 may provide corresponding resistance on the opposite side ofrod100.Longitudinal members256 and258 may similarly provide resistance to bending about axis L₂. When γ is at or near 0°, bending resistance ofrod100 along L₁about L₂will be relatively greater. When γ is at or near 90°, bending resistance ofrod100 will be relatively lesser.
• FIG. 7 shows portions ofouter sleeve140 andinner sleeve150 in perspective view when γ is slightly greater than 0°.
• FIG. 8 showsrod100 when γ is at or near 0°, bending upon delivery to intramedullary space IS in bone B. Bone B includes mid-shaft fracture F.Angled delivery tube800 is present in angled access hole H in boneB. Outer sleeve150 andinner sleeve140 are aligned so thatrod100 can bend about axis L₂. (It will be appreciated that axes L₂and L₃are not fixed longitudinally along axis L₁.)
• After placement in intramedullary space IS,outer sleeve140 andinner sleeve150 may be rotated such that γ is at or near 90° to providerod100 with bending resistance. In some embodiments, the rotation may providerod100 with rigidity.
• In some embodiments,rod100 may be anchored after setting γ at a desired value.Rod100 may anchor distal fracture F by fastening anchors inholes802 atdistal ends144 and154 ofrods140 and150, respectively.Rod100 may anchor proximal fracture F by fastening anchors in holes such as240 and250 (shown inFIG. 2) in proximal ends142 and152 of outer andinner sleeves140 and150, respectively.
• Anchors such as screws that penetrate an outer and an inner hole secureouter sleeve140 relative toinner sleeve150 and prevent the sleeves from rotating out of alignment. Any suitable type of anchor may be used.
• Compression or tension may be applied across fracture F between the distal and proximal fastenings. The tension may be applied by a practitioner after the distal anchors are placed.Rod100 may include one or more elastic sections. An elastic section may apply a compressive or a tensile force between proximal and distal anchors ofrod100. The tensile force may be applied across fracture F by anchoringrod100 such that the elastic section is in compression. The compressive force may be applied across fracture F by anchoringrod100 such that the elastic section in tension.
• In some embodiments,adjustment flanges160 and170 may be set relative to each other to preventsleeves140 and150 from rotating out of alignment. The setting may be based on inter-threading, cooperating keyed members, a keyed or mating outer sleeve, a pin or any other suitable mechanism.
• Setting elements may be integrated intorod100 at proximal or distal ends ofrod100 or anywhere along the length ofrod100. The setting elements may be separate fromrod100. The setting elements may include one or more of a threaded nut, a sect screw, a cotter pin, a crimp, a swage, a morse taper and any other suitable mechanical interface or mechanism.
• FIG. 8 showsholes802 indistal end144 ofouter sleeve140.
• FIG. 9 shows that holes802 may pass through wall thickness w_oofdistal end144. One or more ofholes802 may be tapered at angle δ_orelative to normal direction N_o. One or more ofholes802 may have a radius r_o. Two ormore holes802 may be longitudinally spaced apart by distance d_o. Two or more ofholes802 may be circumferentially spaced apart by arc length c_o. Two or more ofholes802 may be offset fromlongitudinal member246 centerline CL_oby arc length η_o. One or more of parameters w_o, δ_o, r_o, d_o, c_o, η_o, and any other suitable parameters, may be configured to cooperate with one or more types of anchors. One or more of parameters w_o, δ_o, r_o, d_o, c_o, η_o, and any other suitable parameters, may be configured to cooperate with one or more types of anchors and one or more of corresponding parameters w_i, δ_o, r_i, d_i, c_i, η_i(shown inFIG. 10).
• FIG. 10shows holes1002 in wall thickness w_iofdistal end154. One or more ofholes1002 may be tapered at angle δ_irelative to normal direction N_i. One or more ofholes1002 may have a radius r_i. Two ormore holes802 may be longitudinally spaced apart by distance d_i. Two or more ofholes1002 may be circumferentially spaced apart by arc length c_i. Two or more ofholes1002 may be offset fromlongitudinal member256 centerline CL_iby arc length η_i. One or more of parameters w_i, δ_i, r_i, d_i, c_i, η_i, and any other suitable parameters, may be configured to cooperate with one or more types of anchors. One or more of parameters w_i, δ_i, r_i, d_i, c_i, η_i, and any other suitable parameters, may be configured to cooperate with one or more types of anchors and one or more of corresponding parameters w_o, δ_o, r_o, d_o, c_o, η_o(shown inFIG. 9).
• One or more ofholes240 and250 (shown inFIG. 2) may have one or more parameter or feature that is similar to one or more of the parameters and features discussed in connection withholes802 and1002.
• FIG. 11 showsouter sleeve140 andinner sleeve150 with angle γ (shown inFIG. 6) at approximately 0°.Outer holes802 are offset from longitudinal member246 (shown inFIG. 3) centerline CL_oby arc length η_o.Inner holes1002 are offset from longitudinal member256 (shown inFIG. 3) centerline CL_iby arc length η_i.
• One or more ofholes240,340,802 and1002 may have any suitable shape. Each of proximal and distal ends ofouter sleeve140 andinner sleeve150 may include holes of different sizes, parameters and features.
• Inner and outer holes may be sized or shaped differently to reduce or relieve angular stress betweensleeve140 andsleeve150 whensleeves140 and150 are angularly locked relative to each other.
• FIG. 12 showsrod100 in intramedullary cavity IS′ within bone B′, which may be a femur or other long bone. Bone B′ is fractured at fracture F′.Delivery cannula1200 may provide a curved entry path into cavity IS′ through hole H′ in bone B′.
• Delivery cannula1200 may be used to rotateouter sleeve140 relative toinner sleeve150 to makerod100 rigid or partially rigid. For example,cannula1200 may engage the proximal end ofouter sleeve140. A control shaft (not shown) may extend throughcannula1200 and engageinner sleeve150. The control shaft may rotateinner sleeve150 relative toouter sleeve140. The control shaft andcannula1200 may then be disengaged fromrod100.
• Anchors1202 lockouter sleeve140 andinner sleeve150 rotationally with respect to each other.Anchors1202 alsosecure rod100 to bone B′.
• In some embodiments,cannula1200 may be disengaged after the inner and outer sleeves are rotationally locked. In some embodiments,cannula1200 may be disengaged after the inner and outer sleeves are anchored to bone B′.
• In some embodiments, the rod inner or outer sleeves may include more than one pair of longitudinal members. For example, an inner or outer sleeve may include two pairs of longitudinal members.
• FIG. 13 shows illustrative cut-pattern1300 for a sleeve such as outer sleeve140 (shown inFIG. 1).Pattern1300 may be a laser-cut pattern.Pattern1300, which is shown flat for illustration, may be cut in a cylindrical tube to provide compression relief on one side of the tube and relief on the other side of the tube.Pattern1300 may include cutarrangement1302 having length L₁. Pattern1300 may include cutarrangement1304 having length L₂. Lengths L₁and L₂may be any suitable length and may be the same as each other or different from each other.Regions1306 and1308 may correspond to longitudinal members such as246 and248 (shown inFIG. 3), respectively.
• FIGS. 14 and 15 illustrate principles of an intramedullary rod that includes an inner elongated member and an outer tubular member. The rod may be fixed in a rigid state that includes one or more straight sections and one or more curved sections.
• FIG. 14 shows schematicallyillustrative segment1400 that may be one of a chain of segments (not shown) in an inner elongated member of an intramedullary rod.Segment1400 may haveproximal end1402 that is spaced apart fromdistal end1404. Longitudinal axis Ls may extend at least fromproximal end1402 throughdistal end1404.Pivot axis1406 atproximal end1402 andpivot axis1408 atdistal end1404 are axes about whichsegment1400 may move relative to a proximal neighboring segment and a distal neighboring segment, respectively.
• Projection P_dpis the projection ofdistal pivot axis1408 ontoproximal end1402.Distal pivot axis1408 is offset, about axis Ls, fromproximal pivot axis1406, by angle φ. φ may be any suitable angle from about 0° to about 90°.
• An intramedullary rod may include the segment chain and an outer sleeve. The segment chain may be placed inside the outer sleeve. The outer sleeve may be provided with stress relief features that are distributed along the length and circumference of the sleeve. In a first relative orientation of the chain and the outer sleeve, the stress relief features may align with one or both of the pivot axes and the rod may be bendable about the aligned axes.
• In a second relative orientation of the chain and the outer sleeve, the stress relief features may be nonaligned with respect to one or both of the pivot axes and the rod may be rigid about the nonaligned axes and curved based on curvature (not shown) withinsegment1402 along axis Ls. The curvature may be any suitable curvature.
• FIG. 15 shows schematicallyillustrative segment1500 that may be one of a chain of segments (not shown) in an inner elongated member of an intramedullary rod.Segment1500 may haveproximal end1502 that is spaced apart fromdistal end1504. Longitudinal axis L_tmay extend at least fromproximal end1502 throughdistal end1504.Pivot axis1506 atproximal end1502 andpivot axis1508 atdistal end1504 are axes about whichsegment1500 may move relative to a proximal neighboring segment and a distal neighboring segment, respectively.
• Distal pivot axis1508 is offset, about transverse axis L_tt, fromproximal pivot axis1506, by angle ρ. ρ may be any suitable angle from about 0° to about 90°. A chain of segments such as1500, along with an outer sleeve with suitable stress relief, may be used to provide an intramedullary rod that is flexible in a first configuration, but rigid—and curved—in a second configuration. The rod may be rigid and curved by angle ρ in conjunction with any curvature that may be present insegment1500 along axis L_t.
• Compound segments may have proximal and distal pivot axes that are offset contemporaneously by an angle such as φ (shown inFIG. 14) and an angle such as ρ.
• An inner elongated member of an intramedullary rod may include segments such as1400,1500, compound segments, and any suitable combination that are embodied as separate articulating chain links. An inner elongated member of an intramedullary rod may include segments such as1502,1504 and compound segments that are embodied as adjacent portions of a unitary member, such as one formed from a laser-cut tube. The segments may be distributed along the rod to provide flexibility for insertion into a bone and straight or curved rigid sections to distribute stiffness in conformance with bone anatomy. One or more of the segments that provide curved rigid support may be used in conjunction with apparatus for providing straight rigid support.
• FIGS. 16-21 show illustrative features of embodiments that may include rod sections that may have flexible and rigid curved or bent states.
• FIG. 16 showsillustrative rod1600 in collarbone B_c. Rod1600 may have one or features in common withrod100.Rod1600 may include one or more straight sections, such assection1602.Rod1600 may include one or more curved sections, such assections1604,1606 and1608.Bone support1610 may extend fromdistal end1612 ofrod1600.Bone support1610 may be fixed to one or more bone fragments (not shown) in metaphysieal region M or epiphyseal region E of bone Bc using any suitable anchors (not shown).
• Rod1600 may includeouter tubular member1614.Rod1600 may include an inner elongated member (not shown) that is disposed insideouter tubular member1614. The inner elongated member may include segments that are configured to bend relative to neighboring segments along one or more pivot axes.
• Outer tubular member1614 may have stress relief features (not shown) that are distributed to cooperate with one or more of the pivot axes to allowrod1600 to flex during insertion through a bone access hole (not shown) in bone B_c. The bone access hole may be at an angle with respect to axis LBC of bone B_c.Outer tubular member1614 may have rigid features (not shown) that are distributed to interfere with one or more of the pivot axes. Rotation ofouter tubular member1614 relative to the inner elongated member may causerod1600 to become rigid in a curved or bent configuration to provide mechanical support to different portions of bone B_c.
• FIG. 17 showsillustrative rod1700, which may have one or more features in common withrod1600.Rod1700 may includebone support1710 for supporting one or more bone fragments at a distal end of bone B_c. Rod1700 may includebone support1710 for supporting one or more bone fragments at a proximal end of bone B_c. One or more of bone supports1710 and1720 may have one or more features in common with bone support1610 (shown inFIG. 16).
• Rod1700 may includeouter tubular member1714.Rod1700 may include an inner elongated member (not shown) that is disposed insideouter tubular member1714. The inner elongated member may include segments that are configured to bend relative to neighboring segments along one or more pivot axes.
• Rod1700 may include one or more straight sections such assection1702.Rod1700 may include one or more curved or bent sections such assections1704,1706 and1708.
• FIG. 18 shows illustrative innerelongated member1800. Innerelongated member1800 may includesegments1802.Segments1802 may be connected bylinkages1804.Exemplary segment1806 will be discussed in connection withFIG. 19.
• FIG. 19 showsexemplary segment1806.Segment1806 may includebody1808.Segment1806 may includemale linkage member1808 andfemale linkage member1810 for linkage to neighboring segments1802 (shown inFIG. 18).Body1808 may include clearances, such asclearances1814,1816 and1818, to reduce interference betweensegment1806 and neighboringsegments1802.
• Male linkage member1808 may define pivot axis L_mfor articulation with neighboring segment1801 (shown inFIG. 18). Female linkage member1812 may define pivot axis L_ffor articulation with neighboringsegment1803. Pivot axes L_mand L_fare oblique and define two different bending axes for innerelongated member1800. The corresponding outer tubular sleeve may be configured, at a first angular position relative to innerelongated member1800, to permit bending about one or both of pivot axes L_mand L_f. The outer tubular sleeve may be configured, at a second angular position relative to innerelongated member1800, to prevent bending about one or both of pivot axes L_mand L_f.
• FIG. 20 shows angle ρ′, which corresponds to angle ρ (shown inFIG. 15). Angle ρ′, along with any curvature in the body ofsegment1806, may be the basis for rigid curvature when the rod is in its rigid state.
• FIG. 21 shows illustrative cut-pattern2100 for an outer tubular member such as1614 (shown inFIG. 16).Pattern2100 may be a laser-cut pattern.Pattern2100, which is shown flat for illustration, may be cut in a cylindrical tube to provide stress relief in different directions that is distributed along axis L_MD(shown projected onto cut-pattern2100) of the outer tubular member.
• Patterns2102 and2104, which may be similar topatterns1302 and1304 (shown inFIG. 13), may allow bending about a first axis that is normal to axis L_MD(as shown, prior to deformation).Patterns2102 and2104 may be separated byrigid section2106.Patterns2108 and2110 may allow helical bending about axis L_MD(as shown, prior to deformation). The helix allowed bypattern2108 may have an opposite sense of rotation from that ofpattern2110.
• Pattern2112 may allow a high degree of bending about a second axis that is normal to axis L_MD(as shown, prior to deformation).Pattern2114 may allow a high degree of bending about a third axis that is normal to axis L_MD(as shown, prior to deformation).
• Patterns2116 and2118, which may be similar to cutpatterns2102 and2104, may allow bending about a fourth axis that is normal to axis LMD (as shown, prior to deformation). The fourth axis may be angularly offset, about axis LMD, with respect to the first axis (defined bycut patterns2102 and2104).
• Processes in accordance with the principles of the invention may include one or more features of the processes illustrated inFIG. 22. The processes may involve the use of one or more of the apparatus shown and described herein. Some steps of the processes may be performed in an inpatient setting. Some steps of the processes may be performed in an outpatient setting.
• The steps of the processes may be performed in an order other than the order shown and described herein. Some embodiments of the invention may omit steps shown and described in connection with the illustrative methods. Some embodiments of the invention may include steps that are not shown and described in connection with the illustrative methods.
• FIG. 22 shows illustrative steps ofprocess2200 for repairing a fracture. Atstep2202, a practitioner may drill an access hole at angle to a bone axis. Atstep2204, the practitioner may prepare an intramedullary space in the bone to receive a rod. Atstep2206, the practitioner may align inner and outer sleeves of rod to make the rod flexible. Atstep2208, the practitioner may insert rod into the intramedullary space. Atstep2210, the practitioner may rotate the inner sleeve relative to the outer sleeve or rotate the outer sleeve relative to the inner sleeve to reduce or eliminate flexibility of the rod. Atstep2212, the practitioner may fix a rotational offset between sleeves. The practitioner may fix the rotational offset by actuating a mechanism that locks the sleeves with respect to each other, but does not necessarily lock the rod to the bone. Atstep2214, the practitioner may anchor the rod distal end to the bone. Atstep2216, the practitioner may apply tension to the rod. Atstep2218, the practitioner may anchor the rod proximal end to the bone.
• Thus, apparatus and methods for fracture repair have been provided. Persons skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration rather than of limitation. The present invention is limited only by the claims that follow.

Claims (46)

1. An intramedullary rod comprising:

a first elongated member and a second elongated member, each of the first and second elongated members having a first direction and a second direction and being configured to bend in the first direction and to resist bending in the second direction;

wherein the elongated members are arranged such that:

the rod is bendable when the first direction of the first elongated member is aligned with the first direction of the second elongated member; and

the rod is rigid when the first direction of the first elongated member is aligned with the second direction of the second elongated member.

2. The intramedullary rod ofclaim 1 wherein the first elongated member is disposed coaxially within the second elongated member.

3. The intramedullary rod ofclaim 1 wherein each of the first directions corresponds to an arrangement of slots that are longitudinally spaced from each other.

4. The intramedullary rod ofclaim 3 wherein the slots are configured to provide tension relief.

5. The intramedullary rod ofclaim 3 wherein the slots are configured to provide compression relief.

6. The intramedullary rod ofclaim 2 wherein:

the first directions correspond to:

a first arrangement of slots that are longitudinally spaced from each other for tension relief; and

a second arrangement of slots that are longitudinally spaced from each other to provide compression relief; and

the first and second arrangements of slots are spaced circumferentially apart from each other on one of the elongated members.

7. The intramedullary rod ofclaim 1 wherein the first and second elongated members include, respectively, a first and second anchor receiving feature.

8. The intramedullary rod ofclaim 7 wherein the first and second elongated members are configured to be positioned relative to each other such that the first and second anchor receiving features are positioned to receive the same anchor.

9. The intramedullary rod ofclaim 8 wherein the first and second anchor receiving features are distal a first and a second arrangement of slots.

10. The intramedullary rod ofclaim 9 wherein the first and second elongated members include, respectively, a third and fourth anchor receiving feature.

11. The intramedullary rod ofclaim 10 wherein the third and fourth anchor receiving features are proximal the first and second arrangements of slots.

12. The intramedullary rod ofclaim 1 further comprising, when the rod includes a longitudinal axis, a locking mechanism that includes:

a first attachment to the first elongated member;

a second attachment to the second elongated member; and

a bridging member that is configured to prevent relative rotation about the longitudinal axis of the first elongated member with respect to the second elongated member.

13. The intramedullary rod ofclaim 12 wherein one of the first and second attachments is threaded.

14. The intramedullary rod ofclaim 1 wherein the first elongated member comprises a fixed-curve portion that includes a fixed curve, the fixed curve defining a fixed-curve plane, the fixed-curve plane including the second direction of the first elongated member.

15. The intramedullary rod ofclaim 14 wherein, when the fixed-curve portion is a first fixed-curve portion, the second elongated member comprises a second fixed-curve portion that includes a second fixed curve, the second fixed curve defining a second fixed-curve plane, the second fixed curve plane including the second direction of the second elongated member.

16. The intramedullary rod ofclaim 14 wherein:

the fixed-curve portion includes a first segment and a second segment, the second segment being attached to the first segment;

the first segment includes a first rigid bend;

the second segment includes a second rigid bend; and,

when the first and second bends lie in the fixed-curve plane, the fixed-curve portion is resistant to bending in the fixed-curve plane and the fixed curve portion is not resistant to bending in a plane that is different from the fixed-curve plane.

17. The intramedullary rod ofclaim 14 wherein the first segment is linked to the second segment by an articulating linkage.

18. The intramedullary rod ofclaim 14 wherein the first and second segments are formed from a unitary body.

19. The intramedullary rod ofclaim 18 wherein the unitary body is a tube.

20. The intramedullary rod ofclaim 1 wherein the first elongated member comprises a segment that includes:

a first end that includes a first linkage that has a first pivot axis, the first linkage providing a connection to a first neighboring segment; and

a second end that is spaced a distance apart from the first end and includes a second linkage that has a second pivot axis, the second linkage providing a connection to a second neighboring segment;

wherein:

the distance defines a longitudinal axis; and

the second pivot axis is angularly offset, about the longitudinal axis, from the first pivot axis.

21. The intramedullary rod ofclaim 20 wherein the second pivot axis defines the second direction of the first elongated member.

22. The intramedullary rod ofclaim 20 wherein the first pivot axis defines the first direction of the first elongated member.

23. The intramedullary rod ofclaim 1 wherein the first elongated member comprises a segment that includes:

a first end that includes a first linkage that has a first pivot axis, the first linkage providing a connection to a first neighboring segment; and

a second end that is spaced a distance apart from the first end and includes a second linkage that has a second pivot axis, the second linkage providing a connection to a second neighboring segment;

wherein:

the distance defines a longitudinal axis; and

the first and second pivot axes define intersecting lines when the segment is viewed along a direction that is substantially normal to the longitudinal axis.

24. The intramedullary rod ofclaim 23 wherein the second pivot axis defines the second direction of the first elongated member.

25. The intramedullary rod ofclaim 23 wherein the first pivot axis defines the first direction of the first elongated member.

26. The intramedullary rod ofclaim 23 wherein the second pivot axis is angularly offset, about the longitudinal axis, from the first pivot axis.

27. The intramedullary rod ofclaim 26 wherein the first and second elongated members include, respectively, a first and second anchor receiving feature.

28. The intramedullary rod ofclaim 27 wherein the first and second elongated members are configured to be positioned relative to each other such that the first and second anchor receiving features are positioned to receive the same anchor.

29. The intramedullary rod ofclaim 1 further comprising a bone support extending from an end of one of the first and second elongated members.

30. The intramedullary rod ofclaim 29 further comprising, when the bone support is a first bone support and the end is a first end, a second bone support extending from a second end of one of the first and second elongated members.

31. An intramedullary rod comprising:

an outer tubular member that is configured to bend about a first axis; and

an inner member disposed inside the outer tubular member, the inner member including a segment that is configured to move:

relative to a first attached neighboring segment, about a second axis; and

relative to a second attached neighboring segment opposite the first attached neighboring segment, about a third axis;

wherein:

the second axis is substantially parallel to the first axis; and

the third axis is substantially perpendicular to the first axis.

32. The intramedullary rod ofclaim 31 wherein the inner member is configured to rotate, relative to the outer tubular member, from a first position in which the second axis is parallel to the first axis, and the rod is bendable, to a second position in which the third axis is substantially perpendicular to the first axis, and the rod is resistant to bending.

33. The intramedullary rod ofclaim 31 wherein the segment is configured to move relative to the first and second neighboring segments by respective operation of first and second articulating linkages.

34. The intramedullary rod ofclaim 33 wherein the segment, the first neighboring segment and the second neighboring segment are formed from a unitary body.

35. The intramedullary rod ofclaim 34 wherein the unitary body is a tube.

36. A method for delivering an intramedullary rod to a bone, the method comprising:

inserting a flexible intramedullary rod through an angled access hole into an intramedullary channel; and

configuring the intramedullary rod in a rigid configuration by aligning a bending feature of a first sleeve with a non-bending feature of a second sleeve.

37. The method ofclaim 36 further comprising, when the bone has a longitudinal axis, drilling the angled access hole at angle to the bone axis.

38. The method ofclaim 36 further comprising, when the bone includes an intramedullary space, preparing the intramedullary space to receive the rod.

39. The method ofclaim 36 further comprising aligning the first and second sleeves.

40. The method ofclaim 36 further comprising inserting the rod into the intramedullary space.

41. The method ofclaim 36 further comprising rotating the first sleeve relative to the second sleeve.

42. The method ofclaim 36 further comprising fixing a rotational offset between the first sleeve and the second sleeve.

43. The method ofclaim 36 further comprising anchoring a distal end of the rod to the bone.

44. The method ofclaim 36 further comprising applying a tension to the rod.

45. The method ofclaim 36 further comprising anchoring a proximal end of the rod to the bone.

46. The method ofclaim 36 further comprising expanding a bone support at one end of the rod.

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