Expandable cervical interbody and instruments thereof
A system including an implant and a tool for inserting and expanding the medical implant and locking the implant in place is disclosed. The medical implant may include an expandable body defined by a superior endplate and an inferior endplate that are hingedly coupled and may be expanded and lordosed. The implant may include a wedge disposed between the superior and inferior endplates that is configured to slide across a channel on inferior endplate and along an inclined groove on superior endplate. In at least some embodiments, an expansion screw is operative coupled to the threaded portion of the wedge that when expansion screw is rotated, the wedge is translated thereby expanding the implant.
1 . An expandable implant movable between a contracted position and an expanded position, comprising:
a body extending from a proximal end to a distal end in a proximal-to-distal direction and extending from a first lateral side to a second lateral side in a widthwise direction, the body being defined by a superior endplate and an inferior endplate that are pivotally connected;
wherein the superior endplate includes an inside surface that comprises an inclined ramp;
wherein the inferior endplate comprises a support frame, an inside superior-facing surface including a channel, wherein the support frame includes a frame portion having a proximal surface and a distal surface, wherein an aperture extends through the proximal surface and the distal surface;
wherein a distal end of the inferior endplate comprises a hinge member that is disposed within an arcuate channel of the superior endplate, the hinge member forming a single pivoting axis between the superior endplate and the inferior endplate;
a groove disposed on an interior sidewall of the superior endplate;
a wedge disposed between the superior endplate and the inferior endplate, the wedge including: a bearing surface on an upper end thereof configured to slide across the inclined ramp and a tang positioned opposite the bearing surface on a lower end thereof configured for disposal within the channel;
a pin extending from the wedge and being configured to slide within the groove upon linear movement of the wedge, wherein the pin and the wedge are configured to prevent an overexpansion of the implant about the single pivoting axis and to maintain an angular position of the superior endplate relative to the inferior endplate; and
an expansion screw extending through the aperture and being operatively coupled to a threaded portion of the wedge, wherein the expansion screw is configured to rotate and thereby linearly translate the wedge in a longitudinal direction;
wherein proximal movement of the wedge causes the superior endplate to rotate away from the inferior endplate.
2 . The expandable implant of claim 1 , further comprising:
a recess formed within the support frame portion, and
wherein a head portion of the expansion screw resides within the recess.
3 . The expandable implant of claim 2 , further comprising:
a retaining clip seated within the recess, the retaining clip being coupled to a groove portion of the expansion screw;
wherein the retaining clip is configured to prevent the expansion screw from linearly translating while permitting the expansion screw to rotate; and
wherein the retaining clip is configured to provide friction on the expansion screw to prevent the expansion screw from inadvertently rotating after insertion and expansion of the expandable implant.
4 . The expandable implant of claim 1 , further comprising:
at least one bone screw aperture extending through one of the superior endplate or the inferior endplate; and
at least one retention tab having a hook portion and an anchor portion;
wherein the at least one retention tab is configured to automatically deflect away from the at least one bone screw aperture during installation of a corresponding bone screw and return to a retaining position upon full seating of the bone screw within the at least one bone screw aperture.
5 . The expandable implant of claim 1 , further comprising:
a first bone screw aperture extending through the superior endplate;
a second bone screw aperture extending through the inferior endplate;
a first retention tab having a first hook portion and a first anchor portion, the first retention tab being configured to: (a) cover at least a portion of the first bone screw aperture in a neutral position, and (b) deflect away from the neutral position upon driving of a first bone screw into the first bone screw aperture when a head portion of the first bone screw contacts an inclined surface of the first hook portion; and
a second retention tab having a second hook portion and a second anchor portion, the second retention tab being configured to: (a) cover at least a portion of the second bone screw aperture in a neutral position, and (b) deflect away from the neutral position upon driving of a second bone screw into the second bone screw aperture when a head portion of the second bone screw contacts an inclined surface of the second hook portion.
6 . The expandable implant of claim 1 , wherein the frame portion further comprises a first gripping groove and a second gripping groove, wherein:
the first gripping groove comprises a notch on one lateral side of the frame portion; and
the second gripping groove comprises a notch on an opposite lateral side of the frame portion.
7 . The expandable implant of claim 1 , wherein:
the superior endplate comprises a first plurality of engagement features that are angled about 20 degrees to about 40 degrees with respect to a proximal end of the superior endplate; and
the inferior endplate comprises a second plurality of engagement features that are angled about 20 degrees to about 40 degrees with respect to a proximal end of the inferior endplate.
8 . The expandable implant of claim 1 , wherein the channel extends in the proximal-to-distal direction and has a size and shape generally corresponding to a size and shape of the tang to couple the wedge within the channel.
9 . The expandable implant of claim 1 , wherein: the expansion screw comprises a threaded portion at a distal end, a drive feature portion at proximal end, and a groove portion connecting the threaded portion and the drive feature portion, and a retaining clip is coupled to the groove portion.
10 . The expandable implant of claim 1 , wherein:
the superior endplate comprises a first bone screw aperture configured to orient a first bone screw in a cephalad direction and a first bone screw relief cutout; and
the inferior endplate comprises a second bone screw aperture configured to orient a second bone screw in a caudal direction and a second bone screw relief cutout;
wherein the first bone screw relief cutout is configured to provide additional clearance to the second bone screw during an installation process and the second bone screw relief cutout is configured to provide additional clearance to the first bone screw during an installation process.
11 . The expandable implant of claim 1 , wherein the channel is positioned behind the support frame and extends along a medial portion of the inside lower surface in a proximal-to-distal direction such that the tang linearly slides within the channel thereby linearly translating the wedge in the longitudinal direction.
12 . A system including a medical implant and a surgical tool, the system comprising:
an expandable implant movable between a contracted position and an expanded position, comprising:
a body extending from a proximal end to a distal end in a proximal-to-distal direction and extending from a first lateral side to a second lateral side in a widthwise direction, the expandable body being defined by a superior endplate and an inferior endplate that are pivotally connected;
the superior endplate includes an inside surface that comprises an inclined ramp;
the inferior endplate comprises a support frame, an inside superior-facing surface including a channel, and a frame portion having a proximal surface and a distal surface, wherein an aperture extends through the proximal surface and the distal surface of the frame portion;
wherein a distal end of the inferior endplate comprises a hinge member that is disposed within an arcuate channel of the superior endplate, the hinge member forming a single pivoting axis between the superior endplate and the inferior endplate;
a groove disposed on an interior sidewall of the superior endplate;
a wedge disposed between the superior endplate and the inferior endplate, the wedge including: a bearing surface on an upper end thereof configured to slide across the inclined ramp and a tang positioned opposite the bearing surface on a lower end thereof configured for disposal within the channel;
a pin extending from the wedge and being configured to slide within the groove upon linear movement of the wedge, wherein the pin and the wedge are configured to prevent an overexpansion of the implant about the pivoting axis and to maintain an angular position of the superior endplate relative to the inferior endplate; and
an expansion screw extending through the aperture and being operatively coupled to the wedge;
wherein the expansion screw is configured to rotate and thereby linearly translate the wedge in a longitudinal direction; and
a surgical tool for moving the expandable implant from the contracted position to the expanded position;
wherein rotation of a driver of the surgical tool causes the wedge to move proximally and causes the superior endplate to rotate away from the inferior endplate.
13 . The system of claim 12 , wherein:
the inferior endplate comprises a first gripping groove located at a first lateral side of the frame portion, and a second gripping groove located at a second lateral side of the frame portion;
the surgical tool comprises a mounting jaw configured to engage with the first gripping groove and the second gripping groove; and
wherein in an insertion configuration, the first gripping groove and the second gripping groove of the expandable implant are engaged by the mounting jaw of the surgical tool.
14 . The system of claim 13 , wherein the surgical tool comprises:
a plunger having a jaw actuator configured to cause the mounting jaw to affirmatively engage and disengage with the gripping grooves of the expandable implant;
wherein activating the jaw actuator moves the mounting jaw to an open configuration by a distance that is greater than a distance between the first gripping groove and the second gripping groove of the frame portion of the expandable implant;
a drive shaft disposed within the plunger having a drive end configured to engage a drive feature of the expansion screw;
wherein the jaw actuator is configured to engage with the first gripping groove and the second gripping groove by pushing the drive shaft against the expansion screw;
a turn shaft coupled to the drive shaft and being configured to rotate the drive shaft by actuation of a turn knob coupled to the turn shaft;
wherein actuating the turn knob rotates the drive shaft and the expansion screw to cause the superior endplate to pivotally separate away from the inferior endplate;
an angle indicator ring operatively coupled with the turn shaft;
wherein rotation of the drive shaft translates the angle indicator ring along the turn shaft thereby incrementally identifying a corresponding angle of expansion of the expandable implant throughout rotation of the turn shaft;
an outer body surrounding the plunger and the drive shaft; and
a handle enclosing the turn shaft and the angle indicator ring.
15 . The system of claim 14 , wherein rotation of the expansion screw causes the wedge disposed in the channel to slide within the inferior endplate towards the proximal end of the expandable implant thereby causing the bearing surface of the wedge to engage the inclined ramp to separate the superior endplate from the inferior endplate along a pivoting axis.
16 . The system of claim 15 further comprising a depth stop coupled perpendicularly to the mounting jaw, the depth stop configured to engage surrounding vertebrae and prevent over-insertion of the expandable implant thereby preventing the mounting jaw from releasing the implant.
17 . The system of claim 16 , wherein an expanded angle between the superior endplate from the inferior endplate is identified by indicator ring of the surgical tool.
18 . The system of claim 17 , further comprising a retaining clip engaged in a recess of the frame portion, wherein the retaining clip is configured to engage a corresponding slot of the expansion screw to prevent the expansion screw from linearly translating while permitting the expansion screw to be rotated by a driver.
19 . The system of claim 18 , wherein the retaining clip is configured to provide friction on the expansion screw to prevent the expansion screw from inadvertently rotating in absence of the driver preventing unwanted expansion and contraction of the implant after insertion and expansion.