Patent Description:
Intramedullary rods, also referred to as intramedullary nails or bone nails, are implantable medical devices that are commonly used for fracture stabilization and fixation. These devices can be made from a variety of materials and can include structural adaptations that facilitate their use and/or enhance their performance.

While intramedullary rods are known, the inclusion of multiple materials in the construction of an intramedullary rod typically results in handling and performance drawbacks.

A need remains, therefore, for improved hybrid intramedullary rods. <CIT> discloses a modular intramedullary nail which, selectively, includes two or three connectable sections that are connectable end to end. In the two section nail the second section is an elongated curved nail component having an elongated, open-ended longitudinal bore, and terminating in a distal end. The three section nail includes an upper proximal nail component having an open-ended bore. The second section is a central nail section that is an elongated curved nail component having an open ended longitudinal bore. The third section is a lower distal nail component having an elongated open ended longitudinal bore. The nail components are connected at the end using corresponding conical socket and conical projecting end portions of adjoining end nail components that can be fitted together and secured upon impact. Upon assembly, the connections are self orienting, providing corresponding tooled "flat" portions adjacent the respective conical socket and conical projecting end portions of the nail components. This interlocking tooled flats align and abut upon assembly so that the adjoining nail components only align in one relative rotational position. The assembled nail thus provides an elongated continuous open ended bore that receives a cannulated fastener. In the three section nail, the fastener extends the full length of the longitudinal bore of the assembled three nail sections. In the two section nail, the fastener extends into the distal end. An upper enlarged head portion of the cannulated fastener grips the proximal nail component. The distal end portion of the cannulated fastener has external threads which engage corresponding internal threads within the bore of the distal nail component.

The invention relates to an intramedullary rod as defined in claim <NUM>. Various example medical devices are described.

An example intramedullary rod comprises a head member, a shaft member partially disposed within the distal recess of the head member, and an outer body member disposed circumferentially around the shaft member and a portion of the head member.

Another example intramedullary rod comprises a head member having a proximal head member end, a distal head member end, a head member distal extension defining a head member cavity, a head member lumen extending between the proximal head member end and the distal head member end, and a head member outer surface, a first opening on a first axial side of the head member, a second opening on a second axial side of the head member, and a passageway extending between the first opening and the second opening; a shaft member having a shaft member proximal end disposed within the head member cavity, the shaft member having a proximal shaft member opening, a distal shaft member opening, and defining a shaft member lumen extending between the proximal shaft member opening and the distal shaft member opening, the shaft member lumen positioned in line with the head member lumen; and an outer body member disposed circumferentially around the shaft member and a portion of the head member.

Another example intramedullary rod comprises a head member defining a recess, a first opening having a first inner diameter, a second opening, and a passageway extending between the first and second openings; a shaft member partially disposed within the recess of the head member; and an outer body member disposed circumferentially around the shaft member and a portion of the head member, the outer body member defining a third opening disposed adjacent the first opening of the head member and providing access to the passageway, the third opening having a second inner diameter that is less than the first inner diameter.

Another example intramedullary rod comprises a head member defining a recess, a first opening having a first inner diameter, a second opening, and a passageway extending between the first and second openings; a shaft member partially disposed within the recess of the head member; and an outer body member disposed circumferentially around the shaft member and a portion of the head member, the outer body member defining a third opening disposed adjacent the first opening of the head member and providing access to the passageway, the third opening having a second inner diameter that is the same as the first inner diameter.

Various example medical device systems are described.

An example medical device system comprises a plurality of a head members and a plurality of shaft members. The head members are identical to each other. Each of the shaft members has a different axial length than the axial length of the other shaft members.

Various example methods of manufacturing medical devices are described.

An example method of manufacturing an intramedullary rod comprises forming a shaft member from a precursor; securing the shaft member to a selected head member; and overmolding the shaft member with a suitable material to form an intramedullary rod having an outer body member disposed circumferentially about the shaft member and a portion of the head member.

Another example method of manufacturing an intramedullary rod comprises forming a shaft member from a precursor; securing the shaft member to a head member defining a recess, a first opening having a first inner diameter, a second opening, and a passageway extending between the first and second openings; and overmolding the shaft member with a suitable material to form an intramedullary rod having an outer body member disposed circumferentially about the shaft member and around the first opening of the head member.

Another example method of manufacturing an intramedullary rod comprises selecting one head member from a medical device system comprising a two or more identical head members and two or more shaft members having different axial lengths; selecting one shaft member from the two or more shaft members of the medical device system; securing the selected shaft member to the selected head member; overmolding the shaft member with a suitable material to form an intramedullary rod having an outer body member disposed circumferentially about the shaft member and a portion of the head member.

Additional understanding of the inventive medical devices, medical device systems, and methods of manufacturing medical devices can be obtained by reviewing the detailed description of selected examples, below, with reference to the appended drawings.

The following detailed description and the appended drawings describe and illustrate various example medical devices and methods. The description and illustration of these examples enable one skilled in the art to make and use examples of the inventive medical devices and to perform examples of the inventive methods. They do not limit the scope of the claims in any manner.

As used herein, the term "lumen," and grammatically related terms, refers to the inside space of a tubular structure. The term does not require any specific dimensions, relative dimensions, configuration, or regularity.

As used herein, the term "circumferential," and grammatically related terms, refers to a structural arrangement of one structure relative to another structure, feature, or property of another structure. The term does not require any specific dimensions, relative dimensions, configuration, or regularity of either structure.

<FIG>, <FIG> illustrate a first example intramedullary rod <NUM> or a portion of the first example intramedullary rod <NUM>. The intramedullary rod <NUM> has a proximal end <NUM>, a distal end <NUM>, and a body <NUM> extending between the proximal end <NUM> and the distal end <NUM>. A first portion <NUM> of the intramedullary rod <NUM> extends along a first longitudinal axis <NUM>, and a second portion <NUM> of the intramedullary rod <NUM> extends along a second longitudinal axis <NUM>. In the illustrated example, the first <NUM> and second <NUM> longitudinal axes intersect at a non-linear angle <NUM>. The intramedullary rod <NUM> includes a head portion <NUM> located at the proximal end <NUM>, a tip portion <NUM> located at the distal end <NUM>, and a shaft portion <NUM> extending between the head portion <NUM> and the tip portion <NUM> and comprising the body <NUM>. Also, the intramedullary rod <NUM> includes a head member <NUM>, a shaft member <NUM> partially disposed within the head member <NUM>, and an outer body member <NUM> disposed circumferentially around the shaft member <NUM> and a portion of the head member <NUM>. A device lumen <NUM> extends through the entire axial length of the intramedullary rod <NUM> from a proximal opening <NUM> of the head member <NUM> to a distal opening <NUM> of the shaft member <NUM>, placing the entire device lumen <NUM> in communication with the environment external to the intramedullary rod <NUM>. As such, the intramedullary rod <NUM> is a cannulated rod, allowing it to be passed over a separate member, such as a wire, to facilitate placement and/or positioning during implantation.

The head portion <NUM> provides structure for receiving a bone screw, such as a locking or lag screw commonly used in the stabilization and fixation of bone fractures, such as hip fractures. The tip portion <NUM> provides structure for interfacing with the medullary canal of a bone, such as a femur, during placement, as well as structure for receiving distal locking screws commonly used in the stabilization and fixation of bone fractures, such as hip fractures.

The head member <NUM> has a proximal end <NUM>, a distal end <NUM>, and a body <NUM> extending between the proximal end <NUM> and the distal end <NUM>. The proximal end <NUM> defines a proximal opening <NUM> and the distal end <NUM> defines a distal opening <NUM>. As best illustrated in <FIG>, the head member <NUM> defines a head member lumen <NUM> extending between the proximal opening <NUM> and the distal opening <NUM>. In the assembled intramedullary rod <NUM>, the proximal opening <NUM> provides access to the head member lumen <NUM> from the environment external to the intramedullary rod <NUM> and the distal opening <NUM> receives a portion of the shaft member <NUM> in a manner that positions the head member lumen <NUM> in line with the shaft member lumen <NUM> defined by the shaft member <NUM> to form device lumen <NUM>. In use, the intramedullary rod <NUM> can be passed over a previously-placed wire such that the wire extends through the head member lumen <NUM> and, ultimately, through device lumen <NUM> if desired or necessary. The intramedullary rod <NUM> can then be advanced over the wire to a desired degree to achieve a desired placement and/or positioning before securing the intramedullary rod <NUM> within the medullary cavity.

The distal end <NUM> of the head member <NUM> defines a circumferential shoulder <NUM> that forms a distal extension <NUM> having a smaller outer diameter than the outer diameter of the portion of the body <NUM> that is on the proximal side of the circumferential shoulder <NUM>. The distal extension <NUM> defines a cavity <NUM> that is bounded by a circumferential wall <NUM> and a transverse wall <NUM>. The circumferential wall <NUM> surrounds the second longitudinal axis <NUM> of the intramedullary rod <NUM>. As best illustrated in <FIG>, the transverse wall <NUM> defines inner opening <NUM> that transitions the inner diameter of the head member lumen <NUM> from the larger inner diameter <NUM> of the portion of the body <NUM> of the head member <NUM> that is proximal to the circumferential shoulder <NUM> to the smaller inner diameter <NUM> of the portion of the body <NUM> of the head member <NUM> that is distal to the circumferential shoulder <NUM>.

The circumferential wall <NUM> defines structure that facilitates formation of an interface <NUM> between the head member <NUM> and the shaft member <NUM>. The transverse wall <NUM> may also define structure that facilitates such interaction. As such, the circumferential wall <NUM>, the transverse wall <NUM>, and, as a result, the cavity <NUM> may have any suitable configuration and a skilled artisan will be able to select an appropriate configuration for each of these structures in an intramedullary rod according to a particular embodiment based on various considerations, including the configuration and nature of the shaft member included in the intramedullary rod. Examples of suitable configurations include circular, splined, and other configurations. In this example, as best illustrated in <FIG>, the circumferential wall <NUM> is circular and smooth, such that cavity <NUM> has a cylindrical form.

The body <NUM> of the head member <NUM> has an outer surface <NUM> that defines a first opening <NUM> on a first axial side of the body <NUM> and a second opening <NUM> positioned a second, opposite axial side of the body <NUM>. A passageway <NUM> extends from the first opening <NUM> to the second opening <NUM>. As best illustrated in <FIG> and <FIG>, the passageway <NUM> extends along an axis <NUM> that is disposed at a transverse angle to the first longitudinal axis <NUM> of the intramedullary rod <NUM>. The passageway is sized and configured to receive a lag screw used for securing the intramedullary rod <NUM> to a bone.

The shaft member <NUM> has a proximal end <NUM>, a distal end <NUM>, and a body <NUM> extending between the proximal end <NUM> and the distal end <NUM>. The proximal end <NUM> defines a proximal opening <NUM> and the distal end <NUM> defines a distal opening <NUM>. As best illustrated in <FIG>, the shaft member <NUM> defines a shaft member lumen <NUM> extending between the proximal opening <NUM> and the distal opening <NUM>. Thus, the shaft member <NUM> is a tubular member. The proximal end <NUM> of the outer body member <NUM> has a proximal engaging surface <NUM> that is in contact interface with the transverse wall <NUM> within the cavity <NUM> of the head member <NUM>. In the assembled intramedullary rod <NUM>, the distal opening <NUM> provides access to the shaft member lumen <NUM> from the environment external to the intramedullary rod <NUM> and the proximal end <NUM> is disposed within the cavity <NUM> of the head member <NUM> in a manner that positions the shaft member lumen <NUM> in line with the head member lumen <NUM> defined by the head member <NUM> to form device lumen <NUM>.

The shaft member <NUM> has an outer surface <NUM>. As described in detail below, the outer body member <NUM> circumferentially surrounds the shaft member <NUM> and is in contact with the outer surface <NUM>. The outer surface <NUM> can be treated in a manner that prepares the shaft member <NUM> for bonding, contact, or other interface with the outer body member <NUM>. If a surface treatment is included, any suitable surface treatment can be used and a skilled artisan will be able to select a suitable surface treatment for an intramedullary rod according to a particular embodiment based on various considerations, such as the materials of the head member and shaft member of the intramedullary rod. Examples of suitable surface treatments include roughening, etching, and other surface treatments. Also, the portion of the outer surface on the proximal end of the shaft member can be left untreated or treated in a different manner than the remainder of the shaft member in an intramedullary rod according to a particular embodiment if desirable or necessary, such as to facilitate formation of a head-shaft assembly.

The outer body member <NUM> has a proximal end <NUM>, a distal end <NUM>, and a body <NUM> extending between the proximal end <NUM> and the distal end <NUM>. The outer body member <NUM> is a tubular member disposed circumferentially around the shaft member <NUM> and the distal extension <NUM> of the head member <NUM>. Thus, the proximal end <NUM> defines a proximal opening <NUM> and the distal end <NUM> defines a distal opening <NUM>. The outer body member <NUM> defines a lumen <NUM> extending between the proximal opening <NUM> and the distal opening <NUM>. The outer body member <NUM> has an outer surface <NUM> and an inner surface <NUM>. As best illustrated in <FIG>, the body <NUM> of the shaft member <NUM> is disposed within the lumen <NUM> of the outer body member <NUM> such that the inner surface <NUM> of the outer body member <NUM> is in contact interface with the outer surface <NUM> of the shaft member <NUM>.

As best illustrated in <FIG>, the distal end <NUM> of the outer body member <NUM> defines first <NUM> and second <NUM> locking screw passageways that extend through the outer body member <NUM> from one side to the other. The locking screw passageways <NUM>, <NUM> are sized and configured for receiving distal locking screws commonly used in the stabilization and fixation of bone fractures, such as hip fractures. While optional, inclusion of locking screw passageways is considered advantageous to facilitate securement of the intramedullary rod <NUM> to bone during placement. Also, any suitable number of locking screw passageways can be included in an intramedullary rod according to a particular embodiment and a skilled artisan will be able to select an appropriate number of locking screw passageways for a particular embodiment based on various considerations, including any number of locking screws considered desirable or potentially necessary for use of the intramedullary rod in stabilization and/or fixation of a particular bone fractures.

As illustrated in <FIG>, a head-shaft assembly <NUM> is formed when the proximal end <NUM> of the shaft member <NUM> is disposed within the cavity <NUM> of the head member <NUM>. This can be accomplished by any suitable technique or process for placing the proximal end <NUM> of the shaft member <NUM> within the cavity <NUM> of the head member <NUM> and securing the shaft member <NUM> to the head member <NUM>, such as press fitting the components together, shrinking the head member cavity <NUM> around the proximal end <NUM> of the shaft member <NUM>, welding, or other suitable technique or process.

It is noted that angle <NUM> can comprise any suitable angle, and the illustrated non-linear angle is merely an example. A linear or substantially linear angle can be used, as can other suitable angles.

Each of the shaft member and outer body member in an intramedullary rod according to an embodiment can have any suitable configuration and a skilled artisan will be able to select an appropriate configuration for each of these elements for a particular embodiment based on various considerations, including the nature of the medullary canal of the bone or bone type with which the intramedullary rod is intended to be used. As best illustrated in <FIG>, each of the shaft member <NUM> and the outer body member <NUM> in intramedullary rod <NUM> has a circular cross-sectional shape. Also, outer body member <NUM> is disposed circumferentially and coaxially around the shaft member <NUM>.

Each of <FIG> illustrates an alternative intramedullary rod having a shaft member and outer body member with an example configuration.

In <FIG>, intramedullary rod 1000b has shaft member 1200b and outer body member 1300b. In this example, each of the shaft member 1200b and the outer body member 1300b in intramedullary rod 1000b has a circular cross-sectional shape. Also, outer body member 1300b is disposed circumferentially and coaxially around shaft member 1200b, similar to the intramedullary rod <NUM>. In this example, however, the outer surface 1340b of outer body member 1300b defines a series of facets 1375b.

In <FIG>, intramedullary rod 1000c has shaft member 1200c and outer body member 1300c. In this example, shaft member 1200c has a circular cross-sectional shape. Outer body member 1300c, however, has a rounded, star-shaped cross-sectional shape such that the outer surface 1340c of outer body member 1300c defines a series of undulations 1375c. Outer body member 1300c is disposed circumferentially and coaxially around shaft member 1200c, similar to the intramedullary rod <NUM>.

In <FIG>, intramedullary rod 1000d has shaft member 1200d and outer body member 1300d. In this example, shaft member 1200d has a circular cross-sectional shape. Outer body member 1300d, however, has an ovoid cross-sectional shape. Outer body member 1300d is disposed circumferentially and coaxially around shaft member 1200d, similar to the intramedullary rod <NUM>.

In <FIG>, intramedullary rod 1000e has shaft member 1200e and outer body member 1300e. In this example, each of shaft member 1200e and outer body member 1300e has an ovoid cross-sectional shape. Outer body member 1300e has a greater thickness on lateral portions that intersect the common minor axis 1375e of the ovoid cross-sectional shapes of the shaft member 1200e and outer body member 1300e, and a lesser thickness on lateral portions that intersect the common major axis 1377e of the ovoid cross-sectional shapes of the shaft member 1200e and outer body member 1300e. Outer body member 1300e is disposed circumferentially and coaxially around shaft member 1200e, similar to the intramedullary rod <NUM>. Also, intramedullary rod 1000e has a locking screw passageway 1350e that extends through the entire thickness of each of the shaft member 1200e and the outer body member 1300e and along the common major axis 1377e of the ovoid cross-sectional shapes of the shaft member 1200e and outer body member 1300e.

In <FIG>, intramedullary rod 1000f has shaft member 1200f and outer body member 1300f. In this example, each of shaft member 1200f and outer body member 1300f has an ovoid cross-sectional shape. Outer body member 1300f has a greater thickness on lateral portions that intersect the common minor axis 1375f of the ovoid cross-sectional shapes of the shaft member 1200f and outer body member 1300f, and a lesser thickness on lateral portions that intersect the common major axis 1377f of the ovoid cross-sectional shapes of the shaft member 1200f and outer body member 1300f. Outer body member 1300f is disposed circumferentially and coaxially around shaft member 1200f, similar to the intramedullary rod <NUM>. Also, intramedullary rod 1000f has a locking screw passageway 1350f that extends through the entire thickness of each of the shaft member 1200f and the outer body member 1300f and along the common minor axis 1375f of the ovoid cross-sectional shapes of the shaft member 1200f and outer body member 1300f.

It may be desirable to position the shaft member off-axis relative to the outer body member. <FIG> illustrates an intramedullary rod <NUM> configured in this manner. In this example, each of the shaft member <NUM> and the outer body member <NUM> in intramedullary rod <NUM> has a circular cross-sectional shape. Also, outer body member <NUM> is disposed circumferentially and non-coaxially around the shaft member <NUM>. Thus, shaft member <NUM> has longitudinal axis <NUM> and outer body member <NUM> has longitudinal axis <NUM> that is not aligned with longitudinal axis <NUM> of shaft member <NUM>. Also, intramedullary rod <NUM> has a locking screw passageway <NUM> that extends through the entire thickness of each of the shaft member <NUM> and the outer body member <NUM>. In this example, locking screw passageway <NUM> extends along a transverse axis <NUM> of shaft member and defines a passageway lumen <NUM> that includes both the longitudinal axis <NUM> of the shaft member <NUM> and the longitudinal axis <NUM> of the outer body member <NUM>.

Each of the shaft member and outer body member in an intramedullary rod according to an embodiment can have a configuration that is substantially consistent along the axial length of the intramedullary rod. For example, as best illustrated in <FIG>, shaft member <NUM> of intramedullary rod <NUM> has a constant outer diameter along its axial length. Also, as best illustrated in <FIG>, intramedullary rod <NUM> includes outer body member <NUM> that has a constant outer diameter along its body <NUM>, and an outwardly flared portion at its proximal end <NUM> and an inwardly tapered portion at its distal end <NUM>.

Each of <FIG> illustrates an alternative intramedullary rod <NUM> having a shaft member <NUM> and outer body member <NUM> with an example configuration. In this example, as best illustrated in <FIG>, the outer body member <NUM> has a thickness that varies along the axial length of the intramedullary rod <NUM>. Also in this example, as best illustrated in <FIG>, the shaft member <NUM> has a configuration that varies along the axial length of the intramedullary rod <NUM>. In the figure, the shaft member <NUM> has a substantially circular cross-sectional shape at the portion on the left side of the figure and a substantially ovoid cross-sectional shape at the portion on the right side of the figure.

Each of the shaft member and outer body member in an intramedullary rod according to an embodiment can have any suitable axial length. Furthermore, the shaft member and outer body member in an intramedullary rod according to an embodiment can have any suitable relative lengths. A skilled artisan will be able to select suitable axial lengths, and relative axial lengths, for the shaft member and outer body member in an intramedullary rod according to a particular embodiment based on various considerations, including the nature of the bone with which the intramedullary rod is intended to be used, the nature of the materials used for the shaft member and the outer body member, and other considerations. The axial lengths, and relative axial lengths, illustrated herein provide examples of axial lengths and relative axial lengths considered suitable for intramedullary rods. For example, <FIG> illustrates the first example intramedullary rod <NUM>. In this example, the shaft member <NUM> has an axial length that is less than the axial length of the outer body member <NUM>. Indeed, the shaft member <NUM> has an axial length that is greater than about <NUM>% of the axial length of the outer body member <NUM> but less than about <NUM>% of the axial length of the outer body member <NUM>. <FIG> illustrates an alternative intramedullary rod 1000i having a shaft member 1200i and outer body member 1300i with an example configuration. In this example, the shaft member 1200i has an axial length that is greater than about <NUM>% of the axial length of the outer body member 1300i but less than about <NUM>% of the axial length of the outer body member 1300i. <FIG> illustrates an alternative intramedullary rod 1000j having a shaft member 1200j and outer body member 1300j with an example configuration. In this example, the shaft member 1200j has an axial length that is greater than about <NUM>% of the axial length of the outer body member 1300j but less than about <NUM>% of the axial length of the outer body member 1300j.

Each of the shaft member and outer body member in an intramedullary rod according to an embodiment can have any outer diameter. Furthermore, the shaft member and outer body member in an intramedullary rod according to an embodiment can have any suitable relative outer diameters. A skilled artisan will be able to select suitable outer diameters, and relative outer diameters, for the shaft member and outer body member in an intramedullary rod according to a particular embodiment based on various considerations, including the nature of the bone with which the intramedullary rod is intended to be used, the nature of the materials used for the shaft member and the outer body member, and other considerations. The outer diameters, and relative outer diameters, illustrated herein provide examples of outer diameters and relative outer diameters considered suitable for intramedullary rods. For example, <FIG> illustrates the first example intramedullary rod <NUM>. Each of <FIG> illustrates an alternative intramedullary rod.

<FIG> illustrate another example intramedullary rod <NUM>. In this example, the shaft member <NUM> extends axially to a distal end <NUM> that is disposed adjacent, but inwardly of, the distal end <NUM> of the outer body member <NUM>. Also, as best illustrated in <FIG>, the shaft member <NUM> defines first <NUM> and second <NUM> locking screw passageways that align with the first <NUM> and second <NUM> locking screw passageways defined by the outer body member <NUM>.

In embodiments in which the shaft member defines one or more locking screw passageways that are aligned with locking screw passageways of the outer body member, various structural arrangements are possible and contemplated. For example, <FIG> illustrates the distal end <NUM> of the intramedullary rod <NUM> illustrated in <FIG>. In this example, second locking screw passageway <NUM> defined by the shaft member <NUM> has the same inner diameter of the second locking screw passageway <NUM> defined by the outer body member <NUM>. As a result, both the openings defined in the walls of the shaft member 2200n have the same diameter as those of the openings defined by the walls of the outer body member <NUM>. <FIG> illustrates another example intramedullary rod 2000b. In this example, second locking screw passageway 2252b defined by the shaft member 2200b has a larger inner diameter than the inner diameter of the second locking screw passageway 2352b defined by the outer body member 2300b. As a result, both of the openings defined in the walls of the shaft member 2200b have larger diameters than those of the openings defined by the walls of the outer body member 2300b. <FIG> illustrates another example intramedullary rod 2000c. In this example, second locking screw passageway 2252c defined by the shaft member 2200c has a larger inner diameter than the inner diameter of the second locking screw passageway 2352c defined by the outer body member 2300c on one side of the intramedullary rod 2000c; on the opposite side, second locking screw passageway 2252c defined by the shaft member 2200c has the same inner diameter than the inner diameter of the second locking screw passageway 2352c defined by the outer body member 2300c. As a result, one of the openings defined in the wall of the shaft member 2200c has a larger diameter than the adjacent opening defined by the wall of the outer body member 2300c while the other of the openings defined in the wall of the shaft member 2200c has the same diameter as the adjacent opening defined by the wall of the outer body member 2300c.

<FIG> illustrate a third example intramedullary rod <NUM> or a portion of the first example intramedullary rod <NUM>. The intramedullary rod <NUM> is similar to the intramedullary rod <NUM> described above, except as detailed below. Thus, intramedullary rod <NUM> has a proximal end <NUM>, a distal end <NUM>, and a body <NUM> extending between the proximal end <NUM> and the distal end <NUM>. The intramedullary rod <NUM> includes a head member <NUM>, a shaft member <NUM> partially disposed within the head member <NUM>, and an outer body member <NUM> disposed circumferentially around the shaft member <NUM> and a portion of the head member <NUM>. A device lumen <NUM> extends through the entire axial length of the intramedullary rod <NUM> from a proximal opening <NUM> of the head member <NUM> to a distal opening <NUM> of the shaft member <NUM>, placing the entire device lumen <NUM> in communication with the environment external to the intramedullary rod <NUM>. As such, the intramedullary rod <NUM> is a cannulated rod, allowing it to be passed over a separate member, such as a wire, to facilitate placement and/or positioning during implantation.

In this example, head member <NUM> defines has an outer surface <NUM> that defines a first opening <NUM> on a first axial side of the body <NUM> and a second opening <NUM> positioned a second, opposite axial side of the body <NUM>. A passageway <NUM> extends from the first opening <NUM> to the second opening <NUM>. As best illustrated in <FIG>, the passageway <NUM> extends along an axis <NUM> that is disposed at a transverse angle to the first longitudinal axis <NUM> of the intramedullary rod <NUM>. The passageway <NUM> is sized and configured to receive a lag screw used for securing the intramedullary rod <NUM> to a bone.

As best illustrated in <FIG>, outer body member <NUM> extends axially beyond the proximal end <NUM> of shaft member <NUM>. Furthermore, outer body member <NUM> defines an opening <NUM> that provides access to passageway <NUM> defined by head member <NUM>. As best illustrated in <FIG>, opening <NUM> has a slightly smaller inner diameter than the inner diameter of first opening <NUM> defined by head member <NUM>. This structural arrangement is considered advantageous at least because it provides a portion of the outer body member <NUM> as sacrificial material at the openings <NUM>, <NUM> to the passageway <NUM> that provides protection against interaction between a lag screw and the head member <NUM>, which may prevent damage and/or notching of the head member that can result when a lag screw or reaming tool is used to place a lag screw in a passageway defined by a head member of an intramedullary rod. In embodiments that include this structural arrangement, the material of the outer body member <NUM> interacts with a lag screw or reamer, and can incur the damage and/or notching that can occur as a result, protecting the head member <NUM> from such damage and/or notching. This, in turn, provides a more stable connection between the intramedullary rod <NUM>, the lag screw, and any bones to which the intramedullary rod <NUM> and lag screw are secured.

<FIG> illustrates another example intramedullary rod <NUM>; <FIG> illustrates a head-shaft assembly <NUM> formed when the proximal end <NUM> of the shaft member <NUM> is disposed within the cavity <NUM> of the head member <NUM>. In this example, the head member <NUM> defines a proximal flange <NUM> that extends radially outward to define a surface <NUM> that, in the assembled intramedullary rod <NUM>, is in contact with the outer body member <NUM>. Inclusion of the proximal flange <NUM> is considered advantageous at least because it provides a surface <NUM> against which the material used to form the outer body member <NUM> during manufacturing can bond, attach, seal, or otherwise interface with. Also in this example, the body <NUM> of the head member <NUM> has an outer surface <NUM> that defines a first opening <NUM> on a first axial side of the body <NUM> and a second opening <NUM> positioned a second, opposite axial side of the body <NUM>. As best illustrated in <FIG>, the outer body member <NUM> extends completely around the first opening <NUM> on the first axial side of the body <NUM>. While not illustrated in the Figure, it is noted that the outer body member <NUM> can optionally also extend completely around the second opening <NUM> on the second axial side of the body <NUM>. It is noted, though, that the outer body member <NUM> can also partially extend around the second opening <NUM>. Also alternatively, the outer body member <NUM> can be formed such that it does not extend, either partially or completely, around the second opening <NUM>.

Also in this example, the outer surface <NUM> of the head member <NUM> defines a circumferential channel <NUM> adjacent the proximal flange <NUM>. The circumferential channel <NUM> has an outer diameter that is less than the outer diameter of the body <NUM> of the head member <NUM>. Also, the body <NUM> of the head member <NUM> defines a longitudinal groove <NUM> that extends from the first opening <NUM> on the first axial side of the body <NUM> to the circumferential channel <NUM>. While not visible in the Figures, it is noted that the body <NUM> of the head member <NUM> can define a second longitudinal groove extending from the second opening <NUM> to the circumferential channel <NUM>, such as a longitudinal groove that is disposed on the body <NUM> of the head member <NUM> diametrically opposite of longitudinal groove <NUM>. As best illustrated in <FIG>, inclusion of the circumferential channel <NUM> and longitudinal groove is considered advantageous at least because both of these features provide structural definition within which portions of the outer body member <NUM> can be disposed, which can contribute structural benefits to the intramedullary rod <NUM>.

<FIG> illustrates another example intramedullary rod <NUM>; <FIG> illustrates a head-shaft assembly <NUM> formed when the proximal end <NUM> of the shaft member <NUM> is disposed within the cavity <NUM> of the head member <NUM>. The example intramedullary rod <NUM> is similar to the example intramedullary rod <NUM> illustrated in <FIG> and described above, except as detailed below. Thus, in this example, the head member <NUM> defines a proximal flange <NUM> that extends radially outward to define a surface <NUM> that, in the assembled intramedullary rod <NUM>, is in contact with the outer body member <NUM>. The body <NUM> of the head member <NUM> has an outer surface <NUM> that defines a first opening <NUM> on a first axial side of the body <NUM> and a second opening <NUM> positioned a second, opposite axial side of the body <NUM>. As best illustrated in <FIG>, the outer body member <NUM> extends completely around the first opening <NUM> on the first axial side of the body <NUM>. The outer surface <NUM> of the head member <NUM> defines a circumferential channel <NUM> adjacent the proximal flange <NUM>. The circumferential channel <NUM> has an outer diameter that is less than the outer diameter of the body <NUM> of the head member <NUM>. Also, the body <NUM> of the head member <NUM> defines a longitudinal groove <NUM> that extends from the first opening <NUM> on the first axial side of the body <NUM> to the circumferential channel <NUM>.

In this embodiment, as best illustrated in <FIG>, the shaft member <NUM> defines a circumferential channel <NUM> near the proximal end <NUM> of the shaft member <NUM>. The circumferential channel <NUM> has an outer diameter that is less than the outer diameter of the portion of the body <NUM> of the shaft member <NUM> that extends between the circumferential channel <NUM> and the distal end <NUM> of the shaft member <NUM>. In the illustrated example intramedullary rod <NUM>, a portion of the body <NUM> of the shaft member <NUM> having a greater outer diameter than that of the circumferential channel <NUM> is disposed between the circumferential channel <NUM> and the proximal end <NUM> of the shaft member <NUM>. It is noted, though, that as an alternative to the circumferential channel <NUM>, a circumferential recess that extends to the proximal end <NUM> of the shaft member <NUM> can be included.

Also in this embodiment, the outer body member <NUM> extends along the shaft member <NUM> only to the distal end of the circumferential channel <NUM>, as best illustrated in <FIG>. This structural arrangement is considered advantageous at least because the circumferential channel <NUM> on the shaft member <NUM> and the circumferential channel <NUM> on the head member <NUM> cooperatively define axial limiting surfaces for the outer body member <NUM>, which can be beneficial in the manufacturing of intramedullary rods, and particularly for relatively long intramedullary rods.

In all embodiments, the shaft member can be made of any material suitable for use in medical devices intended for orthopedic use, including use as a long-term implant. Examples of suitable materials include metals, metal alloys, and polymeric materials. Examples of suitable metals include, but are not limited to, Titanium, Magnesium, and other metals. Examples of suitable metal alloys include, but are not limited to, Ti6A14V, <NUM> LVM, <NUM>. 4441Ti-13Nb-13Zr, Ti-12Mo-6Zr-2Fe, Ti-15Mo-5Zr-3Al, Ti-15Mo, Ti-35Nb-7Zr-5Ta and Ti-29Nb-13Ta-<NUM>. 6Zr Ti-6Al-7Nb and Ti-15Sn-4Nb-2Ta-<NUM>. 2Pd Co-Cr-Mo alloys. Examples of suitable polymeric materials include, but are not limited to, polyaryletherketone (PAEK), polyether ether ketone (PEEK), PEEK (<NUM>, <NUM>, I2, I4), Polyamid, PA66, carbon fiber reinforced polyaryletherketone (CFR PAEK), polyether ketone ketone (PEKK), carbon fiber reinforced polyether ketone ketone (CFR PEKK), carbon fiber reinforced polyether ether ketone (CFR PEEK), CFR PEEK (<NUM> CA30, <NUM> CA20, <NUM> CA30, <NUM> CA20 , I2 CF20, I2 CF30, I4 CF30, I4 CF20), Polyamid CFR, and PA66 CFR.

In all embodiments, the outer body member can be made of any material suitable for use in medical devices intended for orthopedic use, including use as a long-term implant. Examples of suitable types of materials include, but are not limited to, polymeric materials, composite materials, and other materials. Examples of suitable polymeric materials include, but are not limited to, PAEK, CFR PAEK, PEKK, CFR PEKK, PEEK, CFR-PEEK, PEEK (<NUM>, <NUM>, I2, I4), Polyamid, and PA66.

Examples of suitable composite materials include, but are not limited to, polyether ether ketone (PEEK)-Carbon composite materials. The use of PEEK-Carbon composite materials is considered particularly advantageous as they provide desirable manufacturing properties, including the ability to form the outer body member in an intramedullary rod according to a particular embodiment around the shaft member using injection molding techniques and processes. In these embodiments, any suitable PEEK-Carbon composite material can be used, and a skilled artisan will be able to select a suitable PEEK-Carbon material for an outer body member in an intramedullary rod according to a particular embodiment based on various considerations, including the configuration of the shaft member, any desired physical properties, such as flexibility and bendability of the intramedullary rod, and other considerations. The inventors have determined that use of a PEEK-Carbon composite material having between about <NUM>% and about <NUM>% carbon fibers by weight provides an outer body member and intramedullary rod having desirable physical properties and manufacturability.

Examples of suitable blended materials include, but are not limited to, PEEK-Carbon materials, CFR PAEK, CFR PEKK, CFR PEEK (<NUM> CA30, <NUM> CA20, <NUM> CA30, <NUM> CA20, I2 CF20, I2 CF30, I4 CF30, I4 CF20), Polyamid CFR, PA66 CFR.

It is noted that the materials used in a component of an intramedullary rod according to a particular embodiment can include additives, coatings, fillers, and/or other elements if desired. For example, antibiotics, bioactive glass, silver, copper, or another material that can reduce bacterial colonization of the intramedullary rod following implantation can be included in the material of the shaft member, the outer body member, or both. Furthermore, one or more components of an intramedullary rod according to an embodiment can be treated in a manner that facilitates making of the intramedullary rod, provides structural benefit to the intramedullary rod, or that provides other advantages. For example, in embodiments in which the shaft member comprises a metal, the inventors have determined that anodizing the shaft member in an intramedullary rod according to an embodiment prior to overmolding the shaft member with a suitable material to form the outer body member can be advantageous at least because anodization provides additional surface area on the shaft member to which the material of the outer body member can attach or bond during the overmolding process. Accordingly, an intramedullary rod according to any example described herein, or any other embodiment, can include a metal shaft member that comprises an anodized shaft member. In these embodiments, conventional anodization processes can be used to prepare the metal shaft member prior to overmolding the outer body member to form the intramedullary rod.

The inventors have determined that an intramedullary rod having a shaft member formed of a Titanium alloy, such as Ti6Al4V, and an outer body member formed of CFR PEEK provides desirable characteristics and a favorable balance between manufacturability and strength considerations.

<FIG> is a schematic representation of a medical device system <NUM>. The medical device system <NUM> comprises a plurality of a head members 4100a, 4100b, 4100c, and a plurality of shaft members 4200a, 4200b, and 4200c. The medical device system <NUM> provides a modular system that enables efficient manufacturing of intramedullary rods. As such, the medical device system <NUM> can be used in the manufacturing of medical devices, such as in one or more of the methods described herein.

In the example medical device system <NUM>, the head members 4100a, 4100b, 4100c are identical to each other. Accordingly, each of the plurality of head members 4100a, 4100b, 4100c has a proximal end 4102a, 4102b, 4102c, a distal end 4104a, 4104b, 4104c, and a body 4106a, 4106b, 4106c extending between the respective proximal end 4102a, 4102b, 4102c and the respective distal end 4104a, 4104b, 4104c. The proximal end 4102a, 4102b, 4102c of each head member 4100a, 4100b, 4100c defines a proximal opening 4108a, 4108b, 4108c. The distal end 4104a, 4104b, 4104c of each head member 4100a, 4100b, 4100c defines a distal opening 4110a, 4110b, 4110c. Also, each head member 4100a, 4100b, 4100c defines a head member lumen 4112a, 4112b, 4112c extending between the respective proximal opening 4108a, 4108b, 4108c and the respective distal opening 4110a, 4110b, 4110c.

In the illustrated medical device system <NUM>, each of the shaft members 4200a, 4200b, 4200c has a different axial length than the other shaft members 4200a, 4200b, 4200c while having the same diameter as the other shaft members 4200a, 4200b, 4200c. Thus, the first shaft member 4200a has an axial length that is greater than the axial length of the second shaft member 4200b and the axial length of the third shaft member 4200c. The second shaft member 4200b has an axial length that is less than the axial length of the first shaft member 4200a and greater than the axial length of the third shaft member 4200c. The third shaft member 4200c has an axial length that is less than the axial length of the first shaft member 4200a and the axial length of the second shaft member 4200b. In some embodiments, first and second sets of shaft members are included in the medical device system. In these embodiments, each of the shaft members in the first set of shaft members share a common dimension that defines the set and that distinguishes the set from the second set of shaft members. For example, the common dimension can be an axial length of the shaft members. In these embodiments, each of the shaft members in the first set of shaft members is identical to all other shaft members in the first set of shaft members. Similarly, each of the shaft members in the second set of shaft members is identical to all other shaft members in the second set of shaft members. In these embodiments, any number of additional sets of shaft members can be included in the medical device system. For example, a third set of shaft members can be included. In this example, each of the shaft members in the third set of shaft members is identical to all other shaft members in the third set of shaft members but is different from all shaft members in the first set of shaft members and the second set of shaft members on at least one dimension, such as the axial length of the shaft members. In these examples, any suitable number of sets of shaft members can be included.

Any suitable number of head members can be included in a medical device system according to a particular embodiment. Examples of suitable numbers of head members for inclusion in a medical device system according to a particular embodiment include, but are not limited to, one, one or more, two, two or more, a plurality, three, four, five, six, seven, eight, nine, ten, ten or more, eleven, twelve, a dozen, dozens, one hundred, one thousand, and multiples thereof.

Any suitable number of shaft members can be included in a medical device system according to a particular embodiment. Examples of suitable numbers of shaft members for inclusion in a medical device system according to a particular embodiment include, but are not limited to, one, one or more, two, two or more, a plurality, three, four, five, six, seven, eight, nine, ten, ten or more, eleven, twelve, a dozen, dozens, one hundred, one thousand, and multiples thereof.

Also, in embodiments in which the medical device system includes a first set of shaft members and a second set of shaft members, the first set of shaft members can include any suitable number of shaft members and the second set of shaft members can include any suitable number of shaft members. Examples of suitable numbers for each of the first set of shaft members and the second set of shaft members include one, one or more, two, two or more, plurality, three, four, five, six, seven, eight, nine, ten, ten or more, eleven, twelve, a dozen, dozens, one hundred, one thousand, and multiples thereof. Furthermore, in these embodiments, the first and second sets of shaft members can have the same or different numbers of shaft members. For example, a medical device system according to an embodiment can include a first set of shaft members and a second set of shaft members having the same number of shaft members as the first set of shaft members. Also as an example, a medical device system according to an embodiment can include a first set of shaft members and a second set of shaft members having fewer shaft members than the first set of shaft members. Also as an example, a medical device system according to an embodiment can include a first set of shaft members and a second set of shaft members having more shaft members than the first set of shaft members.

The medical device system <NUM> enables a user to select a head member 4100a, 4100b, 4100c without regard for dimension or other considerations since all head members 4100a, 4100b, 4100c are identical. Then, the user can select a shaft member 4200a, 4200b, 4200c with regard to a desired dimension. Using the selected components, the user can proceed to manufacture a medical device, such as an intramedullary rod, such as performing one or more of the methods described herein.

<FIG> is a schematic representation of a method <NUM> of manufacturing an intramedullary rod. An initial step <NUM> comprises forming a shaft member from a suitable precursor, such as a solid rod or cannula. This step can be performed to form a suitable shaft member, such as any of the shaft members described and/or illustrated herein. A next step <NUM> comprises securing the shaft member to a selected head member. The selected head member can be any suitable head member, such as any of the head members described and/or illustrated herein. A next step <NUM> comprises overmolding the shaft member with a suitable material to form the outer body member circumferentially about the shaft member and a portion of the head member.

At this point, a medical device, such as an intramedullary rod, is available. It may be desirable, however, to include additional steps, such as step <NUM>, which comprises finishing the medical device using suitable techniques or processes. Another additional optional step <NUM> comprises performing one or more surface treatments on the medical device, such as roughening, coating, and the like. An optional step, not illustrated in <FIG>, includes anodizing the shaft member prior to the step <NUM> of overmolding the shaft member with a suitable material to form the outer body member circumferentially about the shaft member and a portion of the head member. Inclusion of this step can be advantageous in methods of making an intramedullary rod in which it is desirable to increase the surface area on the shaft member to which the material of the outer body member can attach or bond during the step <NUM> of overmolding the shaft member with a suitable material to form the outer body member.

<FIG> is a schematic representation of a method <NUM> of manufacturing an intramedullary rod. An initial step <NUM> comprises selecting one head member from a medical device system comprising a two or more identical head members and two or more shaft members having different axial lengths. Another step <NUM> comprises selecting one shaft member from the two or more shaft members of the medical device system. Another step <NUM> comprises securing the selected shaft member to the selected head member. Another step <NUM> comprises overmolding the shaft member with a suitable material to form an outer body member circumferentially about the shaft member and a portion of the head member.

Claim 1:
An intramedullary rod (<NUM>, <NUM>, <NUM>), comprising:
a head member (<NUM>, <NUM>, <NUM>) having a proximal head member end, a distal head member end, a head member distal extension defining a head member cavity, a head member lumen extending between the proximal head member end and the distal head member end, and a head member outer surface, a first opening (<NUM>, <NUM>, <NUM>) on a first axial side of the head member, a second opening (<NUM>, <NUM>, <NUM>) on a second axial side of the head member, and a passageway (<NUM>) extending between the first opening and the second opening;
a shaft member (<NUM>, <NUM>, <NUM>) having a shaft member proximal end disposed within the head member cavity, the shaft member having a proximal shaft member opening, a distal shaft member opening, and defining a shaft member lumen extending between the proximal shaft member opening and the distal shaft member opening, the shaft member lumen positioned in line with the head member lumen; and
an outer body member (<NUM>, <NUM>, <NUM>) disposed circumferentially around the shaft member (<NUM>, <NUM>, <NUM>); characterized in that: the outer body member (<NUM>, <NUM>, <NUM>) is further disposed circumferentially around a portion of the head member (<NUM>, <NUM>, <NUM>), and in that the outer body member defines an outer body member opening (<NUM>) disposed over the first opening (<NUM>, <NUM>, <NUM>) of the head member.