Rotary-rigid orthopaedic rod

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

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 lines 2-2 (shown in FIG. 1)

FIG. 2A shows a portion of the apparatus shown in FIG. 2 in a different state from that shown in FIG. 2.

FIG. 3 shows a perspective view, taken approximately along lines 3-3, of a portion of the apparatus shown in FIG. 1, when the apparatus is in a first configuration;

FIG. 4 shows a partial cross-section taken along the lines 4-4 (shown in FIG. 3).

FIG. 5 shows a partial cross-section taken along the lines 5-5 (shown in FIG. 3).

FIG. 6 shows the view of FIG. 3 when the apparatus is in a second configuration.

FIG. 7 shows a perspective view of a portion of the apparatus shown in FIG. 1.

FIG. 8 shows the apparatus of FIG. 1, along with other apparatus and a bone;

FIG. 9 shows a partial cross-sectional view of a portion of the apparatus shown in FIG. 1 taken along lines 9-9 (shown in FIG. 1).

FIG. 10 shows a partial cross-sectional view of a portion of the apparatus shown in FIG. 1 taken along lines 10-10 (shown in FIG. 1).

FIG. 11 shows a partial cross-sectional view taken along lines 11-11 (shown in FIG. 1) when the apparatus is in a configuration that is different from that shown in FIG. 1.

FIG. 12 shows the apparatus of FIG. 1, along with other apparatus and a different bone.

FIG. 13 shows a flat model representation of features of apparatus such as that shown in FIG. 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 in FIG. 18.

FIG. 20 shows a partial cross-sectional view, taken along lines 20-20 (shown in FIG. 19), of the apparatus shown in FIG. 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 set 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 rod 100. Rod 100 may include outer sleeve 140 and inner sleeve 150. Inner sleeve 150 may have a length that is longer, shorter or substantially the same as the length of outer sleeve 140. 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 sleeve 140 may include proximal end 142 and distal end 144. Inner sleeve 150 may include proximal end 152 and distal end 154. Outer sleeve 140 may include center section 146. Inner sleeve 150 may have corresponding center section 156 (shown in FIG. 2). Rotary-rigid rod 100, in the configuration shown in FIG. 1, may have longitudinal axis L₁. In some embodiments, rotary-rigid rod 100 may have an essentially annular cross section that is substantially perpendicular to axis L₁. Proximal end 142 and proximal end 152 may include, respectively, adjustment flanges 160 and 170. Adjustment flanges 160 and 170 may be used to adjust sleeves 140 and 150 relative to each other in circumferential direction C or −C about axis L₁.

FIG. 2 shows a proximal portion of rotary-rigid rod 100. Inner sleeve 150 is shown substantially flush and coaxially aligned with outer sleeve 140. Inner sleeve 150 may include a central longitudinal void or may be solid, essentially solid or porous. Inner sleeve 150 may rotate freely within outer sleeve 140.

Outer sleeve 140 may include outer holes 241a, 241b and 241c, collectively referred to henceforth as outer holes 241. Inner sleeve 150 may include inner holes 251a, 251b and 251c, collectively referred to henceforth as inner holes 251. Outer holes 240 and inner holes 250 may be aligned or partially aligned when inner sleeve 150 is in one or more rotational positions with respect to outer sleeve 140.

While only a few of holes shown in FIG. 2 are labeled, it should be apparent that numerous holes of this type may be a part of rod 100. The holes may include mesh-like cells that are configured to engage an anchoring device.

In some embodiments, rod 100 may include corresponding holes in distal ends of sleeves 140 and 150.

Outer sleeve center section 146 may include outer ribs 242a, 242b and 242c, collectively referred to henceforth as outer ribs 242. Inner sleeve center section 156 may include inner ribs 252a, 252b and 252c, collectively referred to henceforth as inner ribs 252.

FIG. 2A shows illustrative setting element 290 bridging between flanges 160 and 170.

FIG. 3 shows outer sleeve 140 and inner sleeve 150 in an aligned configuration. In the aligned configuration, outer ribs 242 are aligned in circumferential direction C with inner ribs 252. Inner ribs 254, opposite inner ribs 252, are aligned with outer ribs 244, opposite outer ribs 242. Outer ribs 242 and 244 may be circumferentially separated from each other by longitudinal members 246 and 248. Inner ribs 252 and 254 may be circumferentially separated from each other by longitudinal members 256 and 258.

Angle α defines the circumferential extent of member 256. 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 of members 246, 248 and 258. 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 between members 256 and 258. 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 between members 246 and 248. 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 of sleeves 140 and 150 different bending properties along axis L₁. When the sleeves are rotated about axis L₁ relative to each other, rod 100 may exhibit different bending properties based on the different angular magnitudes.

For example, outer ribs 242 and 244 permit outer sleeve 140 to bend along axis L₁ (about axis L₂) in the direction of either outer rib portion. Inner ribs 252 and 254 permit inner sleeve 150 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, rod 100 may exhibit resistance to bending along axis L₁.

Increased thickness t₀ of longitudinal members 246 and 248 may increase the bending resistance of outer member 140 along axis L₁ about axis L₂. Increased thickness t_i of longitudinal members 256 and 258 may increase the bending resistance of inner member 150 along axis L₁ about axis L₂.

FIGS. 4 and 5 show heights h₀ and h_i of ribs 242 and 252, respectively. Ribs 242 and 252 may be spaced apart by spacings s_o and s_i, respectively. Relatively greater or lesser ratios h_o:S_o and h_i:s_i may decrease or increase, respectively, the bending resistances of sleeves 140 and 150.

One or more of longitudinal members 246, 248, 256 and 258 may include a composition or material that provides a relatively greater or lesser degree of bending resistance along axis L₁ about axis L₂. Suitable compositions or materials may include implantable materials such as metals, polymers, composites and any other suitable materials.

One or more of longitudinal members 246, 248, 256 and 258 may include a structure or microstructure that provides a relatively greater or lesser degree of bending resistance along axis L₁ about 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 shows inner sleeve 150 rotated by angle γ relative to outer sleeve 140. Inner ribs 252 are now aligned with longitudinal member 246. Outer member 246 may thus provide resistance to a bending moment about axis L₃. Longitudinal member 248 may provide corresponding resistance on the opposite side of rod 100. Longitudinal members 256 and 258 may similarly provide resistance to bending about axis L₂. When γ is at or near 0°, bending resistance of rod 100 along L₁ about L₂ will be relatively greater. When γ is at or near 90°, bending resistance of rod 100 will be relatively lesser.

FIG. 7 shows portions of outer sleeve 140 and inner sleeve 150 in perspective view when γ is slightly greater than 0°.

FIG. 8 shows rod 100 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 tube 800 is present in angled access hole H in bone B. Outer sleeve 150 and inner sleeve 140 are aligned so that rod 100 can bend about axis L₂. (It will be appreciated that axes L₂ and L₃ are not fixed longitudinally along axis L₁.)

After placement in intramedullary space IS, outer sleeve 140 and inner sleeve 150 may be rotated such that γ is at or near 90° to provide rod 100 with bending resistance. In some embodiments, the rotation may provide rod 100 with rigidity.

In some embodiments, rod 100 may be anchored after setting γ at a desired value. Rod 100 may anchor distal fracture F by fastening anchors in holes 802 at distal ends 144 and 154 of rods 140 and 150, respectively. Rod 100 may anchor proximal fracture F by fastening anchors in holes such as 240 and 250 (shown in FIG. 2) in proximal ends 142 and 152 of outer and inner sleeves 140 and 150, respectively.

Anchors such as screws that penetrate an outer and an inner hole secure outer sleeve 140 relative to inner sleeve 150 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. Rod 100 may include one or more elastic sections. An elastic section may apply a compressive or a tensile force between proximal and distal anchors of rod 100. The tensile force may be applied across fracture F by anchoring rod 100 such that the elastic section is in compression. The compressive force may be applied across fracture F by anchoring rod 100 such that the elastic section in tension.

In some embodiments, adjustment flanges 160 and 170 may be set relative to each other to prevent sleeves 140 and 150 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 into rod 100 at proximal or distal ends of rod 100 or anywhere along the length of rod 100. The setting elements may be separate from rod 100. The setting elements may include one or more of a threaded nut, a set screw, a cotter pin, a crimp, a swage, a morse taper and any other suitable mechanical interface or mechanism.

FIG. 8 shows holes 802 in distal end 144 of outer sleeve 140.

FIG. 9 shows that holes 802 may pass through wall thickness w_o of distal end 144. One or more of holes 802 may be tapered at angle δ_o relative to normal direction N_o. One or more of holes 802 may have a radius r_o. Two or more holes 802 may be longitudinally spaced apart by distance d_o. Two or more of holes 802 may be circumferentially spaced apart by arc length c_o. Two or more of holes 802 may be offset from longitudinal member 246 centerline CL_o by 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_i, r_i, d_i, c_i, η_i (shown in FIG. 10).

FIG. 10 shows holes 1002 in wall thickness w_i of distal end 154. One or more of holes 1002 may be tapered at angle δ_i relative to normal direction N_i. One or more of holes 1002 may have a radius r_i. Two or more holes 802 may be longitudinally spaced apart by distance d_i. Two or more of holes 1002 may be circumferentially spaced apart by arc length c_i. Two or more of holes 1002 may be offset from longitudinal member 256 centerline CL_i by 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 in FIG. 9).

One or more of holes 240 and 250 (shown in FIG. 2) may have one or more parameter or feature that is similar to one or more of the parameters and features discussed in connection with holes 802 and 1002.

FIG. 11 shows outer sleeve 140 and inner sleeve 150 with angle γ (shown in FIG. 6) at approximately 0°. Outer holes 802 are offset from longitudinal member 246 (shown in FIG. 3) centerline CL_o by arc length η_o. Inner holes 1002 are offset from longitudinal member 256 (shown in FIG. 3) centerline CL_i by arc length η_i.

One or more of holes 240, 340, 802 and 1002 may have any suitable shape. Each of proximal and distal ends of outer sleeve 140 and inner sleeve 150 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 between sleeve 140 and sleeve 150 when sleeves 140 and 150 are angularly locked relative to each other.

FIG. 12 shows rod 100 in intramedullary cavity IS′ within bone B′, which may be a femur or other long bone. Bone B′ is fractured at fracture F′. Delivery cannula 1200 may provide a curved entry path into cavity IS′ through hole H′ in bone B′.

Delivery cannula 1200 may be used to rotate outer sleeve 140 relative to inner sleeve 150 to make rod 100 rigid or partially rigid. For example, cannula 1200 may engage the proximal end of outer sleeve 140. A control shaft (not shown) may extend through cannula 1200 and engage inner sleeve 150. The control shaft may rotate inner sleeve 150 relative to outer sleeve 140. The control shaft and cannula 1200 may then be disengaged from rod 100.

Anchors 1202 lock outer sleeve 140 and inner sleeve 150 rotationally with respect to each other. Anchors 1202 also secure rod 100 to bone B′.

In some embodiments, cannula 1200 may be disengaged after the inner and outer sleeves are rotationally locked. In some embodiments, cannula 1200 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-pattern 1300 for a sleeve such as outer sleeve 140 (shown in FIG. 1). Pattern 1300 may be a laser-cut pattern. Pattern 1300, 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. Pattern 1300 may include cut arrangement 1302 having length L₁. Pattern 1300 may include cut arrangement 1304 having length L₂. Lengths L₁ and L₂ may be any suitable length and may be the same as each other or different from each other. Regions 1306 and 1308 may correspond to longitudinal members such as 246 and 248 (shown in FIG. 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 schematically illustrative segment 1400 that may be one of a chain of segments (not shown) in an inner elongated member of an intramedullary rod. Segment 1400 may have proximal end 1402 that is spaced apart from distal end 1404. Longitudinal axis Ls may extend at least from proximal end 1402 through distal end 1404. Pivot axis 1406 at proximal end 1402 and pivot axis 1408 at distal end 1404 are axes about which segment 1400 may move relative to a proximal neighboring segment and a distal neighboring segment, respectively.

Projection P_dp is the projection of distal pivot axis 1408 onto proximal end 1402. Distal pivot axis 1408 is offset, about axis Ls, from proximal pivot axis 1406, 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) within segment 1402 along axis Ls. The curvature may be any suitable curvature.

FIG. 15 shows schematically illustrative segment 1500 that may be one of a chain of segments (not shown) in an inner elongated member of an intramedullary rod. Segment 1500 may have proximal end 1502 that is spaced apart from distal end 1504. Longitudinal axis L_t may extend at least from proximal end 1502 through distal end 1504. Pivot axis 1506 at proximal end 1502 and pivot axis 1508 at distal end 1504 are axes about which segment 1500 may move relative to a proximal neighboring segment and a distal neighboring segment, respectively.

Distal pivot axis 1508 is offset, about transverse axis L_tt, from proximal pivot axis 1506, by angle ρ. ρ may be any suitable angle from about 0° to about 90°. A chain of segments such as 1500, 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 in segment 1500 along axis L_t.

Compound segments may have proximal and distal pivot axes that are offset contemporaneously by an angle such as φ (shown in FIG. 14) and an angle such as ρ.

An inner elongated member of an intramedullary rod may include segments such as 1400, 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 as 1502, 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 shows illustrative rod 1600 in collarbone B_c. Rod 1600 may have one or features in common with rod 100. Rod 1600 may include one or more straight sections, such as section 1602. Rod 1600 may include one or more curved sections, such as sections 1604, 1606 and 1608. Bone support 1610 may extend from distal end 1612 of rod 1600. Bone support 1610 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).

Rod 1600 may include outer tubular member 1614. Rod 1600 may include an inner elongated member (not shown) that is disposed inside outer tubular member 1614. The inner elongated member may include segments that are configured to bend relative to neighboring segments along one or more pivot axes.

Outer tubular member 1614 may have stress relief features (not shown) that are distributed to cooperate with one or more of the pivot axes to allow rod 1600 to flex during insertion through a bone access hole (not shown) in bone B₀. The bone access hole may be at an angle with respect to axis LBC of bone B_c. Outer tubular member 1614 may have rigid features (not shown) that are distributed to interfere with one or more of the pivot axes. Rotation of outer tubular member 1614 relative to the inner elongated member may cause rod 1600 to become rigid in a curved or bent configuration to provide mechanical support to different portions of bone B_c.

FIG. 17 shows illustrative rod 1700, which may have one or more features in common with rod 1600. Rod 1700 may include bone support 1710 for supporting one or more bone fragments at a distal end of bone B_c. Rod 1700 may include bone support 1710 for supporting one or more bone fragments at a proximal end of bone B_c. One or more of bone supports 1710 and 1720 may have one or more features in common with bone support 1610 (shown in FIG. 16).

Rod 1700 may include outer tubular member 1714. Rod 1700 may include an inner elongated member (not shown) that is disposed inside outer tubular member 1714. The inner elongated member may include segments that are configured to bend relative to neighboring segments along one or more pivot axes.

Rod 1700 may include one or more straight sections such as section 1702. Rod 1700 may include one or more curved or bent sections such as sections 1704, 1706 and 1708.

FIG. 18 shows illustrative inner elongated member 1800. Inner elongated member 1800 may include segments 1802. Segments 1802 may be connected by linkages 1804. Exemplary segment 1806 will be discussed in connection with FIG. 19.

FIG. 19 shows exemplary segment 1806. Segment 1806 may include body 1808. Segment 1806 may include male linkage member 1808 and female linkage member 1810 for linkage to neighboring segments 1802 (shown in FIG. 18). Body 1808 may include clearances, such as clearances 1814, 1816 and 1818, to reduce interference between segment 1806 and neighboring segments 1802.

Male linkage member 1808 may define pivot axis L_m for articulation with neighboring segment 1801 (shown in FIG. 18). Female linkage member 1812 may define pivot axis L_f for articulation with neighboring segment 1803. Pivot axes L_m and L_f are oblique and define two different bending axes for inner elongated member 1800. The corresponding outer tubular sleeve may be configured, at a first angular position relative to inner elongated member 1800, to permit bending about one or both of pivot axes L_m and L_f. The outer tubular sleeve may be configured, at a second angular position relative to inner elongated member 1800, to prevent bending about one or both of pivot axes L_m and L_f.

FIG. 20 shows angle ρ′, which corresponds to angle ρ (shown in FIG. 15). Angle ρ′, along with any curvature in the body of segment 1806, may be the basis for rigid curvature when the rod is in its rigid state.

FIG. 21 shows illustrative cut-pattern 2100 for an outer tubular member such as 1614 (shown in FIG. 16). Pattern 2100 may be a laser-cut pattern. Pattern 2100, 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-pattern 2100) of the outer tubular member.

Patterns 2102 and 2104, which may be similar to patterns 1302 and 1304 (shown in FIG. 13), may allow bending about a first axis that is normal to axis L_MD (as shown, prior to deformation). Patterns 2102 and 2104 may be separated by rigid section 2106. Patterns 2108 and 2110 may allow helical bending about axis L_MD (as shown, prior to deformation). The helix allowed by pattern 2108 may have an opposite sense of rotation from that of pattern 2110.

Pattern 2112 may allow a high degree of bending about a second axis that is normal to axis L_MD (as shown, prior to deformation). Pattern 2114 may allow a high degree of bending about a third axis that is normal to axis L_MD (as shown, prior to deformation).

Patterns 2116 and 2118, which may be similar to cut patterns 2102 and 2104, 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 by cut patterns 2102 and 2104).

Processes in accordance with the principles of the invention may include one or more features of the processes illustrated in FIG. 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 of process 2200 for repairing a fracture. At step 2202, a practitioner may drill an access hole at angle to a bone axis. At step 2204, the practitioner may prepare an intramedullary space in the bone to receive a rod. At step 2206, the practitioner may align inner and outer sleeves of rod to make the rod flexible. At step 2208, the practitioner may insert rod into the intramedullary space. At step 2210, 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. At step 2212, 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. At step 2214, the practitioner may anchor the rod distal end to the bone. At step 2216, the practitioner may apply tension to the rod. At step 2218, 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

1. An intramedullary rod defining a longitudinal axis and comprising: a first elongated member disposed coaxially within a second elongated member, the first elongated member having inner stress relief features and an inner longitudinal member and the second elongated member having outer stress relief features and an outer longitudinal member;

2. The intramedullary rod of claim 1 wherein each of the outer stress relief features and the inner stress relief features correspond to an arrangement of slots that are longitudinally spaced from each other.

3. The intramedullary rod of claim 2 wherein the slots are configured to provide tension relief.

4. The intramedullary rod of claim 2 wherein the slots are configured to provide compression relief.

5. The intramedullary rod of claim 1 wherein: the outer stress relief features and the inner stress relief features correspond to: a first arrangement of slots that are longitudinally spaced from each other for tension relief; anda second arrangement of slots that are longitudinally spaced from each other to provide compression relief; andthe first and second arrangements of slots are spaced circumferentially apart from each other on one of the elongated members.

6. The intramedullary rod of claim 1 wherein the first and second elongated members include, respectively, a first and second anchor receiving feature.

7. The intramedullary rod of claim 6 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.

8. The intramedullary rod of claim 7 wherein the first and second anchor receiving features are distal a first and a second arrangement of slots.

9. The intramedullary rod of claim 8 wherein the first and second elongated members include, respectively, a third and fourth anchor receiving feature.

10. The intramedullary rod of claim 9 wherein the third and fourth anchor receiving features are proximal the first and second arrangements of slots.

11. The intramedullary rod of claim 1 further comprising a locking mechanism that includes: a first adjustment flange attached to the first elongated member;a second adjustment flange attached to the second elongated member; anda setting element that is configured to prevent relative rotation about the longitudinal axis of the first elongated member with respect to the second elongated member.

12. The intramedullary rod of claim 11 wherein one of the first and second adjustment flanges is threaded.

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

14. The intramedullary rod of claim 13 further comprising, when the bone support is a first hone 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.

15. An intramedullary rod defining a longitudinal axis and comprising a first elongated member disposed coaxially within and a second elongated member, the first elongated member having inner stress relief features and an inner longitudinal member and the second elongated member having outer stress relief features and an outer longitudinal member; wherein the elongated members are arranged such that the rod is more easily bendable when the first elongated member is circumferentially rotated about the longitudinal axis to align the outer stress relief features with the inner stress relief features than when the first elongated member is circumferentially rotated about the longitudinal axis to align the outer longitudinal member with the inner stress relief features.

16. The intramedullary rod of claim 15 wherein each of the outer stress relief features and the inner stress relief features corresponds to an arrangement of slots that are longitudinally spaced from each other.

17. The intramedullary rod of claim 16 wherein the slots are configured to provide tension relief.

18. The intramedullary rod of claim 16 wherein the slots are configured to provide compression relief.

19. The intramedullary rod of claim 15 wherein: the outer stress relief features and the inner stress relief features correspond to: a first arrangement of slots that are longitudinally spaced from each other for tension relief; anda second arrangement of slots that are longitudinally spaced from each other to provide compression relief; andthe first and second arrangements of slots are spaced circumferentially apart from each other on one of the elongated members.

20. The intramedullary rod of claim 15 wherein the first and second elongated members include, respectively, a first and second anchor receiving feature.

21. The intramedullary rod of claim 20 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.

22. The intramedullary rod of claim 21 wherein the first and second anchor receiving features are distal a first and a second arrangement of slots.

23. The intramedullary rod of claim 22 wherein the first and second elongated members include, respectively, a third and fourth anchor receiving feature.

24. The intramedullary rod of claim 23 wherein the third and fourth anchor receiving features are proximal the first and second arrangements of slots.

25. The intramedullary rod of claim 15 further comprising a locking mechanism that includes: a first adjustment flange attached to the first elongated member;a second adjustment flange attached to the second elongated member; anda setting element that is configured to prevent relative rotation about the longitudinal axis of the first elongated member with respect to the second elongated member.

26. The intramedullary rod of claim 25 wherein one of the first and second adjustment flanges is threaded.

27. The intramedullary rod of claim 15 further comprising a bone support extending from an end of one of the first and second elongated members.

28. The intramedullary rod of claim 27 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.