Methods and apparatuses for vertebral body distraction and fusion employing a coaxial screw gear sleeve mechanism

A distractible intervertebral body fusion device adapted for implantation into an intervertebral disc space of a patient, comprising:

• a first bearing surface configured to interface with an end plate of a superior vertebra of the intervertebral disc space;
• a second bearing surface configured to interface with an end plate of an inferior vertebra of the intervertebral disc space;
• and
• a pair of coaxial screw gear sleeve mechanisms disposed between the first bearing surface and the second bearing surface, each coaxial screw gear sleeve mechanism including:
• a post having a threaded exterior surface on a portion of the post projecting inwardly from one of the first bearing surface and the second bearing surface;
• and
• a corresponding sleeve configured to surround the post and having:
• a threaded interior surface on a portion of the sleeve projecting inwardly from the other of the first bearing surface and the second bearing surface and configured to interface with the threaded exterior surface of the post;
• and
• a geared exterior surface on a portion of the sleeve;
• and
• a drive mechanism having a surface configured to interface with and drive the geared exterior surface of each sleeve such that selective operation of the drive mechanism causes a distraction of the first bearing surface and the second bearing surface with respect to the superior vertebra and the inferior vertebra of the intervertebral disc space, and
• wherein the threaded interior surface and geared exterior surface of the sleeve of one of the coaxial screw gear sleeve mechanisms have a screw pitch orientation generally opposite of a screw pitch orientation of the threaded interior surface and geared exterior surface of the other coaxial screw gear sleeve mechanism.

A distraction device, comprising:

• a first bearing surface;
• a second bearing surface;
• and
• at least one coaxial screw gear sleeve mechanism disposed between the first bearing surface and the second bearing surface, the coaxial screw gear sleeve mechanism including:
• a threaded post;
• a corresponding sleeve having an interior thread mating with the threaded post and an exterior gear defined along a helical thread extending along a height of the sleeve;
• and
• a drive mechanism mating with the exterior gear of the sleeve to cause the threaded post and the corresponding sleeve to distract the first and second bearing surfaces, the threaded post and corresponding sleeve distracting the first and second bearing surfaces telescopically due to the sleeve distracting relative to one of the first bearing surface and the second bearing surface and the threaded post distracting relative to the corresponding sleeve.

A distractible device, comprising:

• a first bearing surface;
• a second bearing surface;
• and
• a pair of coaxial screw gear sleeve mechanisms disposed between the first bearing surface and the second bearing surface, each coaxial screw gear sleeve mechanism including:
• a threaded post;
• a corresponding sleeve having an interior thread mating with the threaded post and an exterior gear;
• and
• a drive mechanism mating with the exterior gear of each sleeve to cause the threaded post and the corresponding sleeve to distract the first and second bearing surfaces, and
• wherein the interior thread and exterior gear of the sleeve of one of the coaxial screw gear sleeve mechanisms have a screw pitch orientation generally opposite of a screw pitch orientation of the interior thread and exterior gear of the other coaxial screw gear sleeve mechanism.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• and
• a size-adjustable support engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising commonly-actuated, coaxial first and second axially rotatable joints to provide the adjustable separation distance, wherein the support comprises a sleeve member with one of:
• a helical external thread including a plurality of superimposed teeth and an internal thread;
• or
• a helical internal thread including a plurality of superimposed teeth and an external thread.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• and
• a size-adjustable support engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising commonly-actuated, coaxial first and second axially rotatable joints to provide the adjustable separation distance, wherein the support comprises a sleeve member with one of:
• an external thread including a plurality of superimposed teeth and an internal thread;
• or
• an internal thread including a plurality of superimposed teeth and an external thread, and
• wherein the teeth are formed by removing a portion of the thread on which they are superimposed to a depth less than a root depth of the thread.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• and
• a size-adjustable support engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising commonly-actuated, coaxial first and second axially rotatable joints to provide the adjustable separation distance, wherein the support comprises a sleeve member with one of:
• an external thread including a plurality of superimposed teeth and an internal thread;
• or
• an internal thread including a plurality of superimposed teeth and an external thread, and
• wherein a pitch of the external thread is different than a pitch of the internal thread.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• and
• a size-adjustable support engaging the first and second members to provide an adjustable separation distance between the first and second members via a telescoping expansion of the size-adjustable support, the support comprising commonly-actuated, coaxial first and second axially rotatable joints to provide the adjustable separation distance, wherein the support comprises a first and a second sleeve member each having an associated post, the first sleeve member rotationally mounted in a first threaded lumen within the first member and the second sleeve member rotationally mounted in a second, substantially parallel threaded lumen within the first member, the size-adjustable support telescopically expandable due to an expansion of the first sleeve member and the second sleeve member expanding relative to the first member and each associated post expanding relative to the first sleeve member and the second sleeve member.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• and
• a size-adjustable support engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising commonly-actuated, coaxial first and second axially rotatable joints to provide the adjustable separation distance, wherein the support comprises a first and a second sleeve member, the first sleeve member rotationally mounted in a first threaded lumen within the first member and the second sleeve member rotationally mounted in a second, substantially parallel threaded lumen within the first member, and
• wherein the first sleeve member includes an external thread of a first hand and including a plurality of superimposed teeth, and an internal thread of a second opposite hand;
• and
• wherein the second sleeve member includes an external thread of the second opposite hand and including a plurality of superimposed teeth, and an internal thread of the first hand.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• a size-adjustable support, engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising a first sleeve and associated post member and a second sleeve and associated post member, each of the sleeves having one of an external helical thread including a plurality of superimposed teeth or an internal helical thread including a plurality of superimposed teeth;
• and
• a drive member configured to engage the teeth of the first and second sleeve to telescopically expand each sleeve relative to one of the first and second members and each threaded post member relative to the corresponding sleeve.

A size-adjustable implant positionable between adjacent first and second vertebral bodies, the implant comprising:

• a first member, sized and shaped to contact the first vertebral body;
• a second member, sized and shaped to contact the second vertebral body;
• a size-adjustable support, engaging the first and second members to provide an adjustable separation distance between the first and second members, the support comprising a first sleeve or post member and a second sleeve or post member, each of the sleeves or post members having one of an external helical thread including a plurality of superimposed teeth or an internal helical thread including a plurality of superimposed teeth;
• and
• a drive member configured to engage the teeth of the first and second sleeve or post members, and
• wherein the drive member includes a first and a second threaded section, the first threaded section including a helical thread of a first hand and engageable with the teeth of the first sleeve or post member, and the second threaded section including a helical thread of a second opposite hand and engageable with the teeth of the second sleeve or post member.