WO2018009725A1

WO2018009725A1 - Bone defect bridging devices and related methods

Info

Publication number: WO2018009725A1
Application number: PCT/US2017/040990
Authority: WO
Inventors: Michael MULLANEY
Original assignee: Amdt Holdings Inc
Current assignee: Amdt Holdings Inc
Priority date: 2016-07-06
Filing date: 2017-07-06
Publication date: 2018-01-11
Anticipated expiration: 2019-01-06

Abstract

The present disclosure provides junction bridging devices and related methods that apply loads across a junction between first and second biological segments. The devices include a first housing including internal threads and a first engagement surface, and a second housing including a second engagement surface. The first and second housings are axially translatable and rotationally fixed. The devices further include an externally threaded barrel axially fixed and rotational coupled to the second housing, the external threads being engaged with the internal threads of the first housing. The devices also include an inner sleeve rotationally fixed within the second housing, and a power spring coupled to the barrel and the inner sleeve. The power spring exerts a preloaded torque to the barrel to effectuate axial rotation of the barrel with respect to the first housing that axially translates the first housing away from the second housing.

Description

BONE DEFECT BRIDGING DEVICES AND RELATED METHODS

FIELD OF THE INVENTION

[0101] The present application relates generally to orthopedic devices and related methods for bridging bone defects. More specifically, but not exclusively, the present application is directed to defect bridging devices and related methods that promote bone growth and prevent bone resorption.

BACKGROUND OF THE INVENTION

[0102] First and second bone segments with defects, voids or other junctions therebetween may be fixed or joined to each other to promote fusion to each other. Bone segments are commonly fixed to each other via a nail, pin, rod or the like. For example, an intramedullary nail is commonly inserted within, and fixed to, first and second bone segments, such as via screws, k-wire, etc., such that it spans the junction therebetween. Such a nail construct may take up forces between the bone segments and limit the relative movement of bone segments (e.g., translation away from each other and/or toward each other along the axis of the nail). The nail construct may initially be configured such that the junction is in compression to promote bone healing and, ultimately, achieve fusion of the first and second bone segments.

[0103] To further promote fusion of the first and second bone segments, a cage and/or biologies are typically implanted within the junction between the two bone segments and at least partially about the nail. The nail construct and cage and/or biologies may be configured such that the cage and/or biologies are in compression between the first and/or second bone segments to promote bone growth and, ultimately, achieve fusion.

[0104] In some scenarios, the nail construct may take up loads (e.g., compressive load) across the junction of the first and second bone segments such that the bone segments do not experience anatomical loading that promote bone growth (e.g., stress shielding). Further, relative movement of the first and second bone segments may occur (such as via bending, twisting, translation, etc. of the nail) and act to compress and reduce the thickness of the cage and/or biologies. Such thinning of the cage and/or biologies may prevent, reduce or eliminate the forces against the first and second bone segments. Bone resorption of the first and/or second bone segment at the junction may take place during integration of the nail and healing of the first and second bone segments because normal anatomical loads are not realized across the junction of the bone segments because of the nails or other device.

[0105] The prevention, reduction or elimination of the compressive forces across a junction of first and second bone segments may prevent the promotion of bone growth and promote bone resorption.

[0106] Accordingly, bone and/or tissue junction bridging devices and related methods that consistently or constantly apply appropriate loads across the junction, and thereby promote bone growth and prevent bone resorption, are desirable.

SUMMARY OF THE INVENTION

[0107] The present application discloses embodiments related to internal defect restorative devices and related methods for the junctions of first and second bone and/or tissue segments. The devices may be cannulated for use with an intramedullary nail, pin or other elongated substantially stiff member extending between the first and second segments and across the junction/defect site. The devices may "float" along the axis of the nail, pin or like member within the junction/defect, and act to engage the first and second bone and/or tissue segments to fill the junction/defect.

[0108] This devices may be configured to provide an expanding force that acts to apply a compressive pressure to the interfaces of the first and second bone and/or segments and the engagement surfaces of the implanted device. The devices may be configured such that the compressive forces acting on the devices does not result in collapse of the devices. Further, the devices may be configured such that when subjected to a lack of expansion constraint below a certain force threshold (e.g., below a predefined compressive force threshold, such as no compressive force within a void between the bone and/or tissue segments that is larger than the device) the devices expand until the threshold is met (e.g., expand to fill the void). However, the devices may also be configured such that when subjected to external forces acting to collapse the devices (and a void between the bone and/or tissue segments) the devices oppose such forces. The devices may thereby be configured to apply a constant oneway expanding force acting between the devices and the bone and/or tissue segments to accommodate and/or prevent any bone resorption and preclude movement between the segments.

[0109] In one aspect, the present disclosure provides a device for bridging a void between first and second biological segments. The device comprises a first housing including internal threads and a first engagement surface for engaging the first biological segment. The device also comprises a second housing including a second engagement surface for engaging the second biological segment, the first and second housings being axially translatable and rotationally fixed to each other. The device further comprises an externally threaded barrel rotationally coupled to the second housing, the external threads being engaged with the internal threads of the first housing. The device also comprises an inner sleeve rotationally fixed within the first housing, and an elastic member coupled to the barrel and a second end coupled to the inner sleeve. The elastic member is preloaded such that it exerts a preloaded torque to the barrel that, when released, effectuates axial rotation of the barrel with respect to the first housing to axially translate the first housing away from the second housing such that the first engagement surface engages the first biological segment and the second engagement surface engages the second biological segment. [0110] In some embodiments, when the preloaded torque is released, the first engagement surface exerts a compressive force to the first biological segment and the second engagement surface exerts a compressive force to the second biological segment. In some embodiments, when the preloaded torque is released, the device spans the void.

[0111] In some embodiments, the elastic member is a spiral torsion spring. In some such embodiments, a first portion of the spiral torsion spring is coupled to the barrel and a second portion of the spiral torsion spring is coupled to the inner sleeve. In some other such embodiments, the first portion of the spiral torsion spring is coupled to an inner portion surface of the barrel and the second portion of the spiral torsion spring is coupled to an outer surface portion of the inner sleeve. In some embodiments, the barrel rotates about the inner sleeve, and the elastic member extends about inner sleeve and is positioned between the barrel and the inner sleeve. In some embodiments, the barrel is axially fixed to the second housing. In some embodiments, the inner sleeve is axially to the first housing.

[0112] In some embodiments, the first housing includes a first housing segment that engages the second housing, and a first adapter that forms the first engagement surface. In some such embodiments, the first adapter engages an axial end of the first housing segment. In some other such embodiments, the second housing includes a second housing portion that engages the first housing portion, and a second adapter that forms the second engagement surface. In some such embodiments, the second adapter engages an axial end of the second housing segment. In some other such embodiments, the first and second adapters define the axial ends of the device. In some other such embodiments, the device further comprises at least one spacer positioned at least one of axially between the first adapter and the first housing segment and axially between the second adapter and the second housing segment.

[0113] In some embodiments, the device defines a cylindrical shape. In some

embodiments, axial rotation of the barrel with respect to the first housing is selectively prevented via a locking mechanism to selectively configure the device in a preloaded state. In some such embodiments, movement of the locking mechanism releases the preloaded state such that the preloaded torque effectuates axial rotation of the barrel with respect to the second housing. In some embodiments, axial translation between the first and second housings is selectively prevented via a locking mechanism to selectively configure the device in a preloaded state. In some such embodiments, the movement of the locking mechanism releases the preloaded state such that the preloaded torque effectuates axial rotation of the barrel with respect to the second housing.

[0114] In some embodiments, the device is cannulated. In some such embodiments, the first housing, the second housing and the inner sleeve define an inner aperture. In some other such embodiments, the device further comprises an elongate member extending through the inner aperture. In some such embodiments, the device is axially slidable along the elongate member. In some other such embodiments, the elongate member is coupled to the first and second biological segments.

[0115] In another aspect, the present disclosure provides a method of bridging a void between first and second biological segments. The method includes implanting a device in a preloaded state within the void that extends only partially between the first and second biological segments. The method also include releasing a preloaded force of the device such that the device axially expands and engages the first and second biological segments.

[0116] In some embodiments, the device is a device described above, and wherein releasing the preloaded force comprises releases a preloaded torque to a barrel of the device. In some embodiments, implanting the device includes coupling an elongate member to the first and second biological segments such that the elongate gate member extends through the void, and wherein the device is axially slidably coupled to the elongate member. [0117] In another aspect, the present disclosure provides a method of preventing resorption of a first bone segment and a second bone segment that include a void therebetween. The method includes implanting a device described above in a preloaded state within the void such that the device extends only partially between the first and second bone segments. The method further includes releasing a preloaded torque of a barrel of the device to effectuate axial rotation of the barrel with respect to a first housing of the device to axially translate the first housing away from a second housing of the device such that a first engagement surface of the device engages the first bone segment and a second engagement surface of the device engages the second bone segment.

[0118] In some embodiments, releasing the preloaded torque to the barrel effectuates a compressive force between the first engagement surface and the first bone segment and a compressive force between the second engagement surface and the second bone segment.

[0119] These, and other objects, features and advantages of this disclosure will become apparent from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0120] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and together with the detailed description herein, serve to explain the principles of the present disclosure. The drawings are only for purposes of illustrating some embodiments and are not to be construed as limiting the present disclosure. It is emphasized that, in accordance with the standard practice in the industry, various features may not be drawn to scale. The foregoing and other objects, features and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: [0121] FIG. 1 illustrates a rear perspective view of an implanted exemplary bone and/or tissue junction/defect bridging device according to the present disclosure that prevents bone resorption;

0122] FIG. 2 illustrates a side perspective view of the implanted device of FIG. 1 ;

0123] FIG. 3 illustrates an enlarged side perspective view of the implanted device of FIG.

0124] FIG. 4 illustrates a perspective view of the device of FIG. 1 ;

0125] FIG. 5 illustrates a front view of the device of FIG. 1 ;

0126] FIG. 6 illustrates a back view of the device of FIG. 1 ;

Γ0127] FIG. 7 illustrates a left side view of the device of FIG. 1 ;

0128] FIG. 8 illustrates a right side view of the device of FIG. 1 ;

0129] FIG. 9 illustrates a top view of the device of FIG. 1 ;

0130] FIG. 10 illustrates a front view of the device of FIG. 1 ;

0131] FIG. 1 1 illustrates a side cross-sectional view of the device of FIG. 10;

[0132] FIG. 12 illustrates a top cross-sectional view of the device of FIG. 10;

0133] FIG. 13 illustrates an enlarged side cross-sectional view of a portion of the device of FIG. 10 as indicated in FIG. 1 1 ;

0134] FIG. 14 illustrates a front cross-sectional view of the device of FIG. 1 ;

0135] FIG. 15 illustrates a side cross-sectional view of the device of FIG. 1 ;

[0136] FIG. 16 illustrates an exploded perspective view of the device of FIG. 1 ;

0137] FIG. 17 illustrates another exploded perspective view of the device of FIG. 1 ;

0138] FIG. 18 illustrates as exploded perspective view of a portion of the device of FIG.

[0139] FIG. 19 illustrates as exploded perspective view of another portion of the device of FIG. 1 ; [0140] FIG. 20 illustrates a perspective view of a sub-assembly of device of FIG. 1;

[0141] FIG. 21 illustrates a perspective exploded view of an exemplary threaded barrel and exemplary spring of the sub-assembly of FIG. 21;

[0142] FIG. 22 illustrates a perspective cross-sectional view of the sub-assembly of FIG. 21;

[0143] FIG. 23 illustrates a top cross-sectional view of the sub-assembly of FIG. 21;

[0144] FIG. 24 illustrates a front cross-sectional view of the device of FIG. 1 in a collapsed state; and

[0145] FIG. 25 illustrates a front cross-sectional view of the device of FIG. 1 in an expanded state.

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

[0146] In this detailed description and the following claims, the words proximal, distal, anterior, posterior, medial, lateral, superior and inferior are defined by their standard usage for indicating a particular part of a bone or implant according to the relative disposition of the natural bone or directional terms of reference. For example, "proximal" means the portion of an implant nearest the torso, while "distal" indicates the portion of the implant farthest from the torso. As for directional terms, "anterior" is a direction towards the front side of the body, "posterior" means a direction towards the back side of the body, "medial" means towards the midline of the body, "lateral" is a direction towards the sides or away from the midline of the body, "superior" means a direction above and "inferior" means a direction below another object or structure. In addition, for the purposes of this disclosure when referencing the device, the term "proximal" will mean the portion of the device closest or nearest the insertion instrument. The term "distal" shall mean the portion of the device farthest away from the insertion instrument. The terms osteosynthesis, osteotomy and the like are used herein to refer to the promotion of bone formation/growth and bone in-growth, as explained further below.

[0147] When introducing elements of various embodiments of the present invention, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of parameters are not exclusive of other parameters of the disclosed embodiments.

Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular embodiment may similarly be applied to any other embodiment disclosed herein.

[0148] Referring to the drawings, wherein like reference numerals are used to indicate like or analogous components throughout the several views, and with particular reference to FIGS. 1-25 there is illustrated a bone junction/defect bridging device 110 that prevents bone resorption and, potentially, promotes bone growth. The device 110 may be configured to be positioned within a void, defect or any other junction between a first biological segment (e.g., a first bone and/or tissue segment) and a second biological segment (e.g., a second bone and/or tissue segment). The first and second segments may be or include any bones or portions of bones, and the junction therebetween may be a joint, fracture, defect, void or any other type of interface or junction between the first and second segments. In this way, the device 110 is configured to be implanted within and fill various bone and/or tissue junctions/voids having a multitude of differing interface configurations and/or a variety of bone/tissue conditions. For example, the device 110 may be an internal segment defect restorative device for periarticular defects in one non-limiting example. As another non- limiting example, the device 110 may be an internal segment defect restorative device, such as for diaphyseal segmental defects. In one non-limiting example shown in FIGS. 1-3, the device 110 may is configured as internal segment defect restorative device, such as for a failed total ankle arthroplasty. However, as noted above, however, the device 110 may be configured for, and utilized with, any defect site with any number of biological segments. As shown in FIGS. 1-25, in some embodiments the device 110 may take on a generally cylindrical shape.

[0149] As shown in FIGS. 1-25, the device 110 may be a modular expandable assembly utilized in conjunction with an elongate fixation member 120 (see FIGS. 1-3), such as but not limited to a nail, pin, k-wire or rod (e.g., an intramedullary nail). The device 110 may include an internal aperture 60 configured to allow the fixation member 120 to slidably extend therethrough (i.e., the device 100 may be cannulated). The internal aperture 60 may thereby include any configuration, size, orientation or arrangement to suit a particular elongate fixation member 120 for a particular patient or surgery (i.e., to slidably couple therewith). In this way, the device 110 may be able to be used in conjunction with virtually any elongate fixation member 120.

[0150] The internal aperture 60 and the device 110 may be configured such that the device 110 is positioned concentric with the fixation member 120 within the implantation site (e.g., junction, defect and/or void) between the first and second segments. While the fixation member 120 may be fixed to each segment on opposing sides of the implantation site and may function to set the overall arrangement, size (e.g., length), orientation or other configuration of the implantation site and the first and second segments, the cannulated device 110 may float within the defect along (and potentially concentric to) the fixation member 120 to fill the site. In some embodiments, the fixation member 120 may be fixed to each segment by being implanted within the first and second segments. In some

embodiments, the fixation member 120 may be fixed to each segment via one or more screws, pins, k-wire or other surgical fixation mechanism. [0151] While the fixation member 120 may bridge the implantation site and control overall configuration of the first and second segments, the device 110 may be configured to provide a suitable interface between the opposing surfaces of the first and second segments on either side of the site. For example, as shown in FIGS. 4-11, 14-19 and 24-29, the device 110 may include first and second adapters 9A, 9B affixed at either end of the device 110. The first and second adapters 9A, 9B may include outer engagement surfaces 25A, 25B that are configured to engage and accommodate the particular configuration bone/tissue segments at the device- to-segment interfaces. For example, in the case of a removed failed arthroplasty, one of the engagement surfaces 25A, 25B of the first and second adapters 9A, 9B may be configured with the interface geometry of the failed and removed device. In another embodiment, the engagement surfaces 25A, 25B of the first and/or second adapters 9A, 9B may be configured to accept geometry of diaphyseal bone having a variety of rough diameters. However, the engagement surfaces 25A, 25B of the first and second adapters 9A, 9B may include and surface configuration (shaped, sized, oriented, etc.) to suit the free ends of any first and second bone and/tissue segments at the implantation site. In some embodiments, the engagement surfaces 25A, 25B and/or other portions of the first and second adapters 9A, 9B may be constructed of materials and geometries that promote bone ingrowth. For example, the engagement surfaces 25A, 25B of the first and second adapters 9A, 9B may include porous engagement surfaces.

[0152] The first and second adapters 9 A, 9B may also interface with first and second housings 1, 2, respectively, such as on interface surfaces or sides 36A, 36B substantially opposing the engagement surfaces 25 A, 25B thereof. In some configurations, such as based on a particular implantation site or first and/or second segments, at least one of the first and second adapters 9A, 9B may interface (e.g., engage) directly with the first and second housings 1, 2, respectively. In some configurations, as shown in FIGS. 4-11, 14-19 and 24- 29, the first and/or second adapters 9A, 9B may interface (e.g., engage) indirectly with the first and second housings 1, 2, respectively, via one or more corresponding spacer 8. The spacers 8 may thereby be positioned between the first and second adapters 9A, 9B and the first and second housings 1, 2, respectively, if included. The spacer(s) 8 may be utilized to adjust the axial length of the device 110 to match the size of the implantation site (e.g., the length of a defect and/or void between the first and second segments). In this way, any number of number of spacers 8, and any number of spacer 8 sizes, may or may not be used to suit a particular anatomical arrangement. The spacer(s) 8 may thereby provide for adjustment of the axial length of the device 110 to match the axial length of the impastation site, and may be used/configured for a particular anatomical arrangement, or may not be used at all. For example, as shown in FIGS. 4-11, 14-19 and 24-29, the second adapter 9B may be coupled to a spacer 8, but the first adapter 9A may be coupled directly to the first housing 1.

[0153] The interface surfaces or sides 36A, 36B of the first and second adapters 9A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 may be mating or interlocking surfaces configured to removable couple the components. For example, as shown in FIGS. 11, 14-19 and 24-29, the interface surfaces or sides 36A, 36B of the first and second adapters 9 A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 male be configured as mating male and female surfaces. In some embodiments, the interface surfaces or sides 36 A, 36B of the first and second adapters 9 A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 may be formed as a self-locking taper. In some embodiments, the interface surfaces or sides 36 A, 36B of the first and second adapters 9 A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 may be straight or tapered helical threads. In some embodiments, the interface surfaces or sides 36 A, 36B of the first and second adapters 9 A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 may include an anti-rotation mechanism, such as a key or pin. The interface surfaces or sides 36 A, 36B of the first and second adapters 9 A, 9B and the corresponding interface surfaces or sides 38 A, 38B of the spacers 8 and/or the interface surfaces or sides 35 of the first and second housings 1, 2 may be configured to align, and maintain such alignment, of the first and second adapters 9A, 9B, the spacers 8 and/or the first and second housings 1, 2 along the axis of the internal aperture 60 (and thereby the elongate member 120).

[0154] As shown in FIGS. 4-8, 10, 11, 14-19, 24 and 25, the first and second housings 1, 2 may be axially slidably engaged (e.g., along the axis of the aperture 60 and/or fixation member 120) with each other through an arrangement of tangs 26 and slots 25. The tangs 26 and slots 25 may be provided or formed on an opposing side of the first and second housings 1, 2 as the interface surfaces or sides 35. The tangs 26 and slots 25 may be provided or spaced about the circumference of the aperture 60 and/or fixation member 120. The tangs 26 and slots 25 may be configured to mate with each other such that they control concentricity and prevent relative rotation about the axis of the aperture 60 and/or the fixation member 120 between the first and second housings 1 and 2, while allowing for relative translation along the axis (i.e., axial translation of the first and second housings 1 and 2 away from and toward each other). However, other mechanisms or configurations for maintaining concentricity, preventing relative rotation, and allowing axial translation between the first and second housings 1, 2 may be utilized, and may be chosen based on envelope requirements of the device 110 and/or according to a particular application or implantation site. For example, as opposed to the tangs 26 and slots 25, keyed cylindrical fits between the first and second housings 1 and 2 may be utilized.

[0155] The device 110 may also include an externally-threaded hollow barrel 3 positioned within the aperture 60 of the second housing 2, as shown in FIGS. 5-8, 11, 13-18, 20-22, 24 and 25. The threaded barrel 3 and the second housing 2 may be held concentric, and the threaded barrel 3 may be axial fixed to the second housing 2. For example, a snap ring 4 may engage with a groove 44 within the barrel 3 and a shoulder 46 on the second housing 2 to axial fix the threaded barrel 3 within the second housing 2 and keep the threaded barrel 3 and the second housing 2 concentric. The device 110 may be configured such that the barrel 3 is able to rotate about the axis of the aperture 60 within housing 2.

[0156] As shown in FIGS. 11, 14-18, 24 and 25, the first housing 1 may include internal threads within the aperture 60 thereof. For example, at least the interior surfaces of the tangs 26 of the first housing 1 may include internal threads. Other portions of the interior of the first housing 1 may include internal threads. The internal threads of the first housing 1 and the external threads of the barrel 3 may mate or engage when the first and second housings 1, 2 mate (e.g., via the tangs 26 and slots 25). Rotation of the barrel 3 about its axis relative to the second housing 2 (i.e., within the second housing 2), and by extension the first housing 1, thereby drives an axial translation or motion of first housing 1 relative to second housing 2 (because the first and second housings 1, 2 are rotationally fixed to each other). In this way, rotation of the barrel 3 in a first direction about its axis may force the first housing 1 to move axially toward the second housing, and rotation of the barrel 3 in a second direction about its axis that opposes the first direction may force the first housing 1 to move axially away the second housing.

[0157] To effectuate rotation of barrel 3 relative to the first and second housings 1 and 2, the device 110 may include an elastic member 7 that is elastically deformable. In one exemplary embodiment, the elastic member 7 may be a power, coil (e.g., flat coil), spiral torsion, constant force or clock spring, as shown in FIGS. 11-19 and 21-25. The elastic member 7 may extend, be wound, or spiral about the axis of the aperture 60 and the barrel 3 and an inner sleeve 6 of the device 110. The elastic member may be rotationally engaged with the inner sleeve 6 of the device 100 through an inner tang 28 of the spring 7 being keyed, inserted, seated or positioned into a groove 29 within the inner sleeve 6, as shown in FIGS. 17-23. As also shown in FIGS. 17-23, the inner sleeve 6 may be held concentric and fixed within the first housing 1. For example, the device 110 may include a snap ring 5 that is engaged within a groove 55 formed within the first housing 1 to fix the inner sleeve 6 within the aperture 60 of the first housing 1. As explained further below, after coupling the spring 7 to the inner sleeve 6 and winding or preloading the spring 7, the inner sleeve 6 may be rotationally locked or fixed to the first housing. The spring 7 may couple to the barrel 3 via any mechanism. For example, as shown in FIGS. 17-23 the spring 7 may include an outer tang 27 that is keyed, inserted, seated or positioned into a groove or slot 45 that extends at least into the inner surface of the barrel 3. The spring 7 may thereby extend about the inner sleeve 6, and the barrel 3 may be positioned over the inner sleeve such that the spring 7 is positioned between the inner sleeve 6 and the barrel 3. The inner sleeve 6, barrel 3 and/or spring 7 may thereby be substantially concentric, with the spring nested between the inner sleeve 6 and the barrel 3.

[0158] Rotation of the inner sleeve 6 relative to barrel 3 with spring 7 coupled to the inner sleeve 6 relative to barrel 3 may thereby wind the elastic member 7 into a preloaded state. The inner sleeve 6 may be rotationally locked or fixed to the first housing 1 in such a preloaded state such that the elastic member 7 exerts the preloaded torque to the barrel 3 relative to the housing 1 in a first rotational direction. The inner sleeve 6 may be rotational locked or fixed to the first housing 1 via any mechanism, such as a pin, flat, set screw, or any other configuration. Once the preloaded energy of the wound spring 7 is released and the first and second housings 1, 2 are engaged with each other, the torque generated by the preloaded elastic member 7 will act to rotate the threaded barrel 3 (because the sleeve 6 is rotationally fixed to the first housing 1) (that is axially fixed to the second housing 2) with respect to the internal threads of the first barrel 1 to axially drive or translate the first housing 1 away from second housing 2 to expand of the overall axial length of the device 110 (i.e., the length of the device 110 extending between he engagement surfaces 25 A, 25B of the first and second adapters 9 A, 9B).

[0159] The device 110 may be axially fixed in a preloaded state or axial length via any mechanism. For example, the barrel 3 may be selectively or releasably rotationally and/or axially fixed to the first and/or second housing 1, 2 via any mechanism. As another example, the first and/or second housing 1, 2 may be selectively or releasably axially fixed to each other via any mechanism. The device 110 may be implanted (over the elongate fixation member 120 (e.g., the elongate fixation member 120 may extend through the aperture 60 of the device 110) within the implantation site between the first and second biological segments (e.g., a defect and/or void between first and second bone segments) in the fixed and preloaded state, and subsequently activated (by removal of a mechanism, such as a pin, for example) such that the preloaded energy of the spring 7 is released and the barrel 3 is free to axially rotate and axially translate with respect to the first housing 1, and the first and second housings 1, 2 are free to axially translate with respect to each other. Once the preloaded energy of the spring 7 is released and the barrel 3 is free to axially rotate and axially translate with respect to the first housing 1, and the first and second housings 1, 2 are free to axially translate with respect to each other, the torque of the elastic member 7 will effectuate axial translation of the first and second housings 1, 2 away from each other (e.g., the first housing 1 translated away from the first housing 1) and thereby, expand to the size of the implantation site and provide an expanding force against the first and second segments. The expanding force may apply a substantially constant compressive pressure to the first and second bone and/or tissue segments and engagement surfaces 25 A, 25B of the device 110 over some axial distance. In such an implanted and activated state, the device 110 thereby may apply a constant expanding force acting between the device 110 and the first and/or second biological segments, such as to bone resorption if the first and/or second biological segments, include bone.

[0160] Although the torque generated by the elastic member 7 may be relatively low, which could generate a relatively low axial expansion force of the device 1 10, the nature of the threaded barrel 3 and the first housing 1 may be such that an appreciably larger force applied in opposition to this axial expansion force may serve to only stop or prevent further the expansion, and may not result in a reversal of the axial expansion (i.e., axial contraction) of the device 110, even when subjected to a compressive load in excess of the expanding force the device 110 provides. Stated differently, relatively high axial compressive forces acting on the engagement surfaces 25 A, 25B of the device 110 will not result in axial collapse of the device 110. In this way, the device 110 may provide for a one-way axial expansion and force applied to the first and second biological segments. This one-way expansion is ideally suited to accommodate bone and/or tissue healing process when, in many cases, some degree of resorbsion takes place. Such resorbsion, absent the axial force exerted against the first and second biological segments via the device 110, may result in a relaxation of the loading on a segmental filler portion for example, thereby leaving the elongate fixation member 120 to pick up the load and preventing a union of the segmental region (i.e., the implantation site). For example, the one-way axial expansion and force applied to the first and second biological segments by the device 110 is ideally suited to promote bone healing by preventing bone resorbsion. [0161] It is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein."

Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term "operably connected" is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112, sixth paragraph, unless and until such claim limitations expressly use the phrase "means for" followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0162] While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention.

Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the disclosure may include only some of the described

embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

[0163] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

CLAIMS I claim:

1. A device for bridging a void between first and second biological segments, comprising:

a first housing including internal threads and a first engagement surface for engaging the first biological segment;

a second housing including a second engagement surface for engaging the second biological segment, the first and second housings being axially translatable and rotationally fixed to each other;

an externally threaded barrel rotationally coupled to the second housing, the external threads being engaged with the internal threads of the first housing;

an inner sleeve rotationally fixed within the first housing; and

an elastic member coupled to the barrel and a second end coupled to the inner sleeve, wherein the elastic member is preloaded such that it exerts a preloaded torque to the barrel that, when released, effectuates axial rotation of the barrel with respect to the first housing to axially translate the first housing away from the second housing such that the first engagement surface engages the first biological segment and the second engagement surface engages the second biological segment.

2. The device of claim 1, wherein, when the preloaded torque is released, the first engagement surface exerts a compressive force to the first biological segment and the second engagement surface exerts a compressive force to the second biological segment.

3. The device of claim 1, wherein, when the preloaded torque is released, the device spans the void.

4. The device of claim 1, wherein the elastic member is a spiral torsion spring.

5. The device of claim 4, wherein a first portion of the spiral torsion spring is coupled to the barrel and a second portion of the spiral torsion spring is coupled to the inner sleeve.

6. The device of claim 4, wherein the first portion of the spiral torsion spring is coupled to an inner portion surface of the barrel and the second portion of the spiral torsion spring is coupled to an outer surface portion of the inner sleeve.

7. The device of claim 1, wherein the barrel rotates about the inner sleeve, and wherein the elastic member extends about inner sleeve and is positioned between the barrel and the inner sleeve.

8. The device of claim 1, wherein the barrel is axially fixed to the second housing.

9. The device of claim 1, wherein the inner sleeve is axially to the first housing.

10. The device of claim 1, wherein the first housing includes a first housing segment that engages the second housing, and a first adapter that forms the first engagement surface.

11. The device of claim 10, wherein the first adapter engages an axial end of the first housing segment.

12. The device of claim 10, wherein the second housing includes a second housing portion that engages the first housing portion, and a second adapter that forms the second engagement surface.

13. The device of claim 12, wherein the second adapter engages an axial end of the second housing segment.

14. The device of claim 12, wherein the first and second adapters define the axial ends of the device.

15. The device of claim 12, further comprising at least one spacer positioned at least one of axially between the first adapter and the first housing segment and axially between the second adapter and the second housing segment.

16. The device of claim 1, wherein the device defines a cylindrical shape.

17. The device of claim 1, wherein axial rotation of the barrel with respect to the first housing is selectively prevented via a locking mechanism to selectively configure the device in a preloaded state.

18. The device of claim 17, wherein movement of the locking mechanism releases the preloaded state such that the preloaded torque effectuates axial rotation of the barrel with respect to the second housing.

19. The device of claim 1, wherein axial translation between the first and second housings is selectively prevented via a locking mechanism to selectively configure the device in a preloaded state.

20. The device of claim 19, wherein movement of the locking mechanism releases the preloaded state such that the preloaded torque effectuates axial rotation of the barrel with respect to the second housing.

21. The device of claim 1, wherein the device is cannulated.

22. The device of claim 21, wherein the first housing, the second housing and the inner sleeve define an inner aperture.

23. The device of claim 21, further comprising an elongate member extending through the inner aperture.

24. The device of claim 23, wherein the device is axially slidable along the elongate member.

25. The device of claim 23, wherein the elongate member is coupled to the first and second biological segments.

26. A method of bridging a void between first and second biological segments, comprising:

implanting a device in a preloaded state within the void that extends only partially between the first and second biological segments; and releasing a preloaded force of the device such that the device axially expands and engages the first and second biological segments.

27. The method of claim 26, wherein the device is the device of claim 1, and wherein releasing the preloaded force comprises releasing the preloaded torque to the barrel.

28. The method of claim 26, wherein implanting the device includes coupling an elongate member to the first and second biological segments such that the elongate gate member extends through the void, and wherein the device is axially slidably coupled to the elongate member.

29. A method of preventing resorption of a first bone segment and a second bone segment that include a void therebetween, comprising:

implanting a the device of claim 1 in a preloaded state within the void such that the device extends only partially between the first and second bone segments; and

releasing the preloaded torque to the barrel to effectuate axial rotation of the barrel with respect to the first housing to axially translate the first housing away from the second housing such that the first engagement surface engages the first bone segment and the second engagement surface engages the second bone segment.

30. The method of claim 29, wherein releasing the preloaded torque to the barrel effectuates a compressive force between the first engagement surface and the first bone segment and a compressive force between the second engagement surface and the second bone segment.