Sagittal balance systems and methods of use thereof

A system for dilating tissue includes a retractor having a pair of retractor blades that are movable towards and away from each other to retract tissue of a patient. The retractor blades have longitudinal guide channels. A first pin is attachable to a first vertebra. The system also includes an interbody spacer insertion device that has a guide channel for slidably engaging the longitudinal channel guide and is releasably attachable to an interbody spacer. The interbody spacer insertion device is configured to guide the interbody spacer into a space between adjacent vertebrae. A method for using the system includes advancing the retractor blades towards first and second vertebrae. The first retractor blade is attached to the first vertebra using the first pin and the retractor blades are moved away from each other. The interbody spacer insertion device is translated towards the vertebrae to position the interbody spacer between the vertebrae.

BACKGROUND

Technical Field

The present disclosure relates generally to systems and methods for performing lumbar surgical procedures.

Related Art

The human spine includes twenty-four vertebrae coupled sequentially to one another to form a spinal column that houses and protects critical elements of the nervous system. Each vertebra has a cylindrical body (vertebral body), two pedicles extending from the vertebral body, a lamina extending from the pedicles, two wing-like projections extending from the pedicles, a spinous process extending from the lamina, a pars interarticularis, two superior facets extending from the pedicles, and two inferior facets extending from the lamina. The vertebrae are separated and cushioned by thin pads of tough, resilient fiber known as inter-vertebral discs that provide flexibility to the spine and absorb shock during physical activity.

A small opening (i.e., a foramen) located between each vertebra allows for passage of nerves through the vertebrae. However, when the vertebrae are not properly aligned (e.g., are offset or constricted), the nerves may be compressed, leading to neurological disorders such as back pain, leg pain, numbness, tingling, diminished strength, a decrease in a range of motion of an individual, etc. Additionally, over time the intervertebral discs can deteriorate, tear, or herniate (where inner portions of the disc protrude through a tear), leading to constriction and/or misalignment of the discs and vertebrae, again causing chronic pain, degenerative disc disease, or even tearing or herniation.

Surgical procedures were developed to correct these issues, including procedures that remove and replace damaged intervertebral discs with prosthetics. Initially, during these procedures, access to a compromised disc and the corresponding vertebrae is achieved by creating an incision in a patient, guiding a retractor along a pathway to the target surgical site, and engaging the retractor to separate tissue between the initial incision and the target surgical site. After a partial or complete removal of the damaged disc (commonly referred to as a discectomy), the resulting empty space between the corresponding vertebrae may collapse and/or become misaligned due to the partial or complete absence of the disc. To prevent such collapse or misalignment clinicians may insert a prosthetic spacer between the vertebrae to maintain normal spacing and curvature of the affected region. Once the prosthetic is secured, the retractor is removed, and the initial incision closed.

Accordingly, improved systems and methods for performing surgical procedures to replace damaged intervertebral discs are desirable.

SUMMARY

According to aspects of the present disclosure, a method for performing a surgical procedure may include advancing a pair of retractor blades of a retractor toward a first vertebra and a second vertebra of a patient, fixing the retractor to the first vertebra with a first pin, moving the retractor blades away from each other, fixing the retractor to the second vertebra with a second pin, translating a distal portion of an interbody spacer insertion device toward the vertebrae along a longitudinal guide channel of the retractor blade, positioning an interbody spacer between the vertebrae of the patient, and disengaging the interbody spacer from the interbody spacer insertion device.

In aspects of the present disclosure, translating the interbody spacer insertion device may include translating an insertion guide along a fixed trajectory toward a disc space of the patient.

According to aspects of the present disclosure, the interbody spacer may be operably coupled to the interbody spacer insertion device.

In aspects of the present disclosure, operably coupling the interbody spacer may include moving a first arm of the interbody spacer insertion device from a first position to a second position away from a second arm of the interbody spacer, positioning the first arm about a plate, and moving the first arm back to the first position to engage the plate. The interbody spacer may be coupled to the plate. The plate may be coupled to the interbody spacer via a screw configured to rotatably engage a threaded aperture of the interbody spacer. The screw may be rotated in a first direction to release the screw from the interbody spacer. Force may be applied proximally to the interbody spacer insertion device to remove the interbody spacer insertion device from the patient.

According to aspects of the present disclosure, the first arm may be moved from the first position to the second position to move the first arm away from the second arm after removing the interbody spacer insertion device. The plate may be decoupled from the interbody spacer insertion device.

According to aspects of the present disclosure, a system for inserting an interbody spacer between vertebrae of a patient is disclosed. The system includes a retractor having a first retractor blade and a second retractor blade, the first and second retractor blades configured to move away from each other to retract tissue of a patient, a first pin configured to be fixed to a first vertebra of a patient, and an interbody spacer insertion device having a channel guide disposed thereon, the interbody spacer insertion device configured to slidably engage the first retractor blade during insertion of an interbody spacer. The first retractor blade may have a longitudinal guide channel configured to receive the channel guide of the interbody spacer insertion device therein. The first retractor blade may be a caudal retractor blade, a cephalad retractor blade or an auxiliary retractor blade oriented medially or laterally.

According to aspects, the interbody spacer insertion device is coupled to the longitudinal guide channel of the first retractor blade and translatable along a fixed trajectory toward the first and second vertebrae of the patient.

In aspects, the interbody spacer insertion device further includes a first arm and a second arm disposed along a distal portion of the interbody spacer insertion device, the first and second arms configured to move between a first configuration and a second configuration. In the first configuration, the first and second arms of the interbody spacer insertion device are approximated relative to one another, and in the second configuration, the first and second arms of the interbody spacer insertion device are expanded relative to one another. The interbody spacer insertion device may be configured to engage a plate coupled to the interbody spacer. The plate may be coupled to the interbody spacer via a screw configured to rotatably engage a threaded aperture of the interbody spacer.

According to aspects of the present disclosure, an expandable interbody spacer includes a first body portion and a second body portion rotatably coupled to the first body portion, such as via a rod, the first body portion having an engagement wall extending toward the second body portion. The expandable interbody spacer includes a pawl beam rotatably coupled to the second body portion via a pawl rod, and a plurality of teeth extending from the pawl beam. Transitioning the expandable interbody spacer from a closed configuration to an open configuration may cause the pawl beam to engage the plurality of teeth to prevent the expandable interbody spacer from transitioning to the closed configuration.

In aspects of the present disclosure, a method of placing an expandable interbody spacer includes advancing an expandable interbody spacer coupled to an interbody spacer insertion device toward vertebrae of a patient, the expandable interbody spacer maintained in a closed configuration by the expandable interbody spacer insertion device, positioning the expandable interbody spacer, in the closed configuration, between vertebrae of the patient, and releasing, with the interbody spacer insertion device, the expandable interbody spacer. Upon release, the expandable interbody spacer is configured to transition toward an open configuration to match a natural lordosis of the patient.

According to aspects, advancing includes advancing the interbody spacer insertion device along at least a portion of the longitudinal guide channel of a retractor blade. Advancing may include aligning a channel guide of the interbody spacer insertion device to the longitudinal guide channel of the retractor blade. The method may include moving or cutting the anterior longitudinal ligament (“ALL”) of the patient after the expandable interbody spacer is positioned between and secured to the vertebrae, so that the expandable interbody spacer may be expanded or permitted to expand after the ALL is released prior to expanding the expandable interbody spacer.

In aspects of the present disclosure, a method of performing a surgical procedure is disclosed. The method may include advancing first and second of retractor blades of a retractor towards first and second vertebrae of a patient, fixing the first retractor blade to the first vertebra with a first pin, moving the first and second retractor blades away from each other, translating a distal portion of an interbody spacer insertion device towards the first and second vertebrae with a channel guide associated with the insertion device traversing along a longitudinal guide channel of one of the first or second retractor blades, positioning an interbody spacer associated with the insertion device between the first and second vertebrae of the patient, and disengaging the interbody spacer from the interbody spacer insertion device.

According to aspects, the second retractor blade may be fixed to the second vertebra with a second pin. The distal portion of the interbody spacer may include translating the insertion device with an interbody spacer/plate combination attached to the insertion device. The interbody spacer/plate combination may include an interbody spacer and a plate, the interbody spacer may have an attachment screw receiving hole, the plate may have an attachment bore for receiving an attachment screw inserted therethrough to secure the plate to the interbody spacer. Translating the distal portion of the interbody spacer insertion device may include translating the distal portion of the interbody spacer insertion device with the interbody spacer insertion device secured to the plate and the plate secured to an interbody spacer. The plate may define an axis passing through the attachment bore, the plate may have a pair of bone screw receiving holes with the center of each bone screw receiving hole offset from the axis. Each bone screw receiving hole may be offset from the axis on the same side of the axis. The center of each bone screw receiving hole may be offset from the axis by an angle of from about 5 degrees to about 30 degrees.

In aspects, the method may include inserting screws through the bone screw receiving holes to secure the interbody spacer to the first and second vertebrae. Disengaging the interbody spacer insertion device may include releasing the interbody spacer insertion device from the plate. The method may include removing the attachment screw from the plate and the interbody spacer. Translating the distal portion of the interbody spacer insertion device may include translating the distal portion of the interbody spacer insertion device with an expandable interbody spacer associated with the distal portion of the interbody spacer insertion device. Positioning the interbody spacer between the first and second vertebrae may include positioning the expandable interbody spacer between the first and second vertebrae in an unexpanded state.

According to aspects, screws may be inserted through bone screw receiving holes of the expandable interbody spacer to secure the expandable interbody spacer to the first and second vertebrae.

In aspects, the expandable interbody spacer may be released from the interbody spacer insertion device.

According to aspects, an anterior longitudinal ligament may be released after the expandable interbody spacer is secured to bone.

In aspects, the expandable interbody spacer may be expanded.

According to aspects, an auxiliary blade may be attached to the retractor.

In aspects, translating the distal portion of the interbody spacer insertion device includes engaging a channel guide associated with the distal portion of the interbody spacer insertion device with a longitudinal guide channel of the auxiliary blade and sliding the channel guide in the longitudinal guide channel.

According to an aspect of the present disclosure, a system for inserting an interbody spacer between vertebrae of a patient is disclosed. The system includes a retractor, a first pin, and an interbody spacer insertion device. The retractor has a first retractor blade and a second retractor blade, at least one of the first and second retractor blades has a longitudinal guide channel, the first and second retractor blades configured to move away from each other to retract tissue of a patient. The first pin is configured to be fixed to a first vertebra of a patient. The interbody spacer insertion device includes a channel guide disposed thereon, the channel guide configured to slidably engage the longitudinal guide channel during insertion of an interbody spacer, the interbody spacer insertion device configured to guide an interbody spacer releasably attached thereto into a space between the first and second vertebrae based upon the sliding engagement of the channel guide with the longitudinal guide channel.

In aspects, the interbody spacer insertion device is configured to releasably couple to a plate, the plate securable to the interbody spacer. The plate may have an attachment bore configured to receive an attachment screw to attach the plate to the interbody spacer. The plate may define an axis passing through the attachment bore, the plate may have a pair of bone screw receiving holes with the center of each bone screw receiving hole offset from the axis. The center of each bone screw receiving hole may be offset from the axis on the same side of the axis. The center of each bone screw receiving hole may be offset from the axis by an angle of from about 5 degrees to about 30 degrees.

According to aspects, the system may include an expandable interbody spacer releasably secured to a distal portion of the interbody spacer insertion device. The expandable interbody spacer may have an unexpanded state and an expanded state. The expandable interbody spacer may define a pivot axis and a pair of bone screw receiving holes, the pair of bone screw receiving holes being offset from a plane perpendicular to the pivot axis. The system may include an auxiliary blade securable to the retractor. The auxiliary blade may include a longitudinal guide channel, the channel guide being slidably engageable with the longitudinal guide channel of the auxiliary blade.

In an aspect of the present disclosure, an expandable interbody spacer is disclosed. The expandable interbody spacer includes a first body portion and a second body portion, a pawl beam, and a plurality of teeth extending from an engagement wall. The first body portion and the second body portion are pivotably coupled via a rod. Each of the first body portion and the second body portion defines a bone screw mount offset from a plane perpendicular to the pivot axis defined by the rod. Each bone screw mount includes a bone screw aperture. The pawl beam rotatably couples to the second body portion via a pawl rod. The plurality of teeth extending from the engagement wall is configured to engage the pawl beam. Transitioning the expandable interbody spacer from a closed configuration to an open configuration causes the pawl beam to engage the plurality of teeth to prevent the expandable interbody spacer from transitioning towards the closed configuration.

In aspects of the present disclosure, a combination of a plate and an interbody spacer includes an interbody spacer having an attachment screw receiving hole, and a plate. The plate defines an attachment bore for receiving an attachment screw inserted therethrough to secure the plate to the interbody spacer. The plate further defines an axis passing through the attachment bore and a pair of bone screw receiving holes with a center of each bone screw receiving hole offset from the axis.

According to aspects, the combination further includes a screw configured to extend through the attachment bore and engage the attachment screw receiving hole to secure the plate to the interbody spacer. The center of each bone screw receiving hole may be offset from the axis on the same side of the axis. The center of each bone screw receiving hole may be offset from the axis by an angle of from about 5 degrees to about 30 degrees.

DETAILED DESCRIPTION

Embodiments of the presently described retractor systems and methods are described in detail with reference to the drawings, in which like or corresponding reference numerals designate identical or corresponding elements in each of the several views.

Reference will now be made to terms used throughout the present disclosure to describe the principles of the present disclosure. As used herein, the term “clinician” refers to a doctor, nurse, or other care providers and may include support personnel. As is traditional, the term “distal” refers to structure that is, in use, positioned farther from the clinician, whereas the term “proximal” refers to structure that is positioned closer to the clinician. Further, directional terms such as front, rear, upper, lower, top, bottom, distal, proximal, and the like are used to assist in understanding the description and are not intended to limit the present disclosure. The term “surgical field” refers to the space in which the surgical procedure is performed, and the term “surgical cavity” refers to a cavity at least partially surrounded by tissue.

Referring now toFIG.1, a retractor system10is illustrated. The retractor system10includes a retractor100, a first retractor blade200a, a second retractor blade200b, the first and second retractor blades200a,200bcoupled to and extending distally from the retractor100forming an opening in tissue of a patient. The retractor100has an auxiliary blade300coupled thereon, the auxiliary blade300extending distally from the retractor100. Retractor blades200a,200bmay be oriented in a caudal-cephalad orientation with auxiliary blade positioned in a medial or lateral orientation. The retractor blades200a,200bhave an interbody spacer insertion instrument80disposed between them with a spacer500coupled at a distal portion of the insertion instrument80.

Referring now toFIGS.1A-1C, the retractor100is illustrated. The retractor100allows access to a target disc or target discs positioned between vertebrae “V” (FIG.1), such as thoracic or lumbar vertebrae, and is referred to generally as retractor100. The retractor100includes a first support110having arms130,132extending from the first support110. A second support120is configured to slidably receive and engage the arms130,132, enabling the second support120to operably couple to the first support110at a plurality of locations along the arms130,132. The first and second supports,110,120are configured to receive and support retractor blades200a,200b(FIG.2B) that, when assembled, extend distally from the respective supports110,120. In use, longitudinal movement of the second support120relative to the first support110along the arms130,132allows longitudinal movement of the retractor blades200a,200balong an axis A-A. The retractor blades200a,200bare removably secured to the first and second supports110,120, though it is contemplated that, in embodiments, the retractor blades200a,200bmay be permanently coupled to the first and second supports.

The arms130,132of the retractor100define cavities133,134that extend along an axis A-A at least partially along a length of the arms130132. The cavity133of the arm130includes teeth136that extend along an upper side of the arm130, the teeth136are configured to operatively engage a translation knob122of the second support120. In embodiments, it is contemplated that any portion of the surfaces defined by cavities133,134may have teeth or other grooves disposed thereon that may be engaged by one or more translation knobs associated with each arm130,132, as desired. The translation knob122is configured to secure the second support120at a particular location on the arm130when the translation knob122is rotatably engaged. Additionally, the cavities133,134are configured to accommodate locking wheels135,137that are translatably disposed in respective cavities133,134. Each locking wheel135,137is configured to secure an auxiliary blade300(FIG.2C) at a position along the respective arm130,132.

With additional reference toFIG.1, as noted above, the retractor blades200a,200bpreferably are releasably attached to the first support110and the second support120. An engaging arm202(FIGS.2A,2B) of each retractor blade200a,200bengages an underside of the first or second support110,120. The first and second supports110,120define cavities119,129, that are configured to detachably secure the protruding portions204of the retractor blades200a,200b(FIGS.2A,2B) therein. Both the first and second supports110,120include locking sliders118,128that slidably engage the protruding portion204of the retractor blades200a,200bto releasably secure the protruding portions204of the retractor blades200a,200bwithin the cavities119,129. The locking sliders118,128are operatively coupled to respective biasing members115,125(FIG.1C) such that the locking sliders118,128are biased toward a locked state. Engaging portions121,127(FIG.1C) of the locking sliders118,128engage grooves206(FIG.2A,2B) defined in protruding portions204, thereby releasably securing the retractor blades200a,200bto the first support110and the second support120. The first support110further defines a pair of recessed portions112,114aligned with cavities133,134and configured to accommodate respective locking wheels135,137therein. The locking wheels135,137allow approximation of the first and second supports110,120to a closed cooperative position, with the locking wheels135,137nested in the recessed portions112,114.

As noted above, the second support120includes a translation knob122that is rotatably mounted on, and configured to move, the second support120to a particular position along the arms130,132. A ratchet (not explicitly shown) engages the teeth136of the arm130as the first and second supports110,120move away from one another. Similarly, when moving the second support120toward the first support110, the translation knob122is rotated in the opposite direction when the ratchet is released. The second support120includes a ratchet assembly configured to allow uni-directional movement of the second support120and lock the second support in position along the arms130,132. The ratchet assembly includes a ratchet knob124configured to release and/or disengage the ratchet assembly with arm130to allow selective uni-directional movement of the second support120.

Referring now toFIGS.2A and2B, retractor blades200a,200bare configured to releasably couple to the first support110and the second support120, respectively. Each retractor blade200a,200bhas an engaging arm202and a blade portion208extending therefrom. The engaging arm202is configured to engage the underside of either the first or the second support110,120. The blade portion208is in substantially orthogonal relation to the engaging arm202. By virtue of the relation of the blade portion208to the engaging arm202, the blade portion208extends substantially orthogonally from the first or second support110,120when assembled. It is contemplated that, in embodiments, the blade portion208may be coupled to the engaging arm202at varying angles such that the blade portion208may form a predetermined fixed angle with the engaging arm202, and by extension, the first or second support110,120.

The engaging arm202includes a protruding portion204configured to extend through one of the cavities119,129of the first or second support110,120, respectively. Specifically, each protruding portion204defines a groove206configured to securely engage the respective engaging portions121,127(FIG.1C) of the locking sliders118,128.

One or more longitudinal guide channels209extend substantially along the blade portion208distally from the engaging arm202. The longitudinal guide channels209may extend along the entire length of the blade portion208, though in embodiments the longitudinal guide channels209may extend distally a part of the way along the blade portion208. In use, when the retractor blades200a,200bof the respective first and second supports110,120are in close cooperative alignment, the opposing longitudinal guide channels209of the opposing blade portions208define one or more lumens configured to receive, for example, a guide wire, a guide pin, or other surgical implements therethrough (not shown). The longitudinal guide channels209may be rounded or may be shaped so as to form a semi-elliptical cross section to hold a pin in place therein (via e.g., a friction fit); the pin being removable when sufficient proximal force is applied. The distal portion of the blade portion208may form a concave profile adapted to engage and accommodate the contour of a vertebral body. In some embodiments, the concave recess defines a radius of curvature from about 0.1 inches to about 1.0 inches, and more preferably 0.6 inches. It is contemplated that, in embodiments, the clinician may select a retractor blade200aor200bhaving any particular radius of curvature as desired to accommodate varying vertebral bodies that are engaged by the retractor blade200aor200b.

Referring now toFIG.2C, an auxiliary blade300is shown that is configured to couple to one of the arms130,132of the retractor100in a medial or lateral position. The auxiliary blade300includes an engaging arm302defining an orifice303of varying dimensions and a blade portion308extending from the engaging arm302. The orifice303of the engaging arm302is configured to be secured along the length of the arms130,132. More particularly, the orifice303defines an enlarged portion304and a narrowed portion306(e.g., a keyhole configuration). The enlarged portion304of the orifice303is configured to receive therethrough locking wheel135,137of the first or second arm130,132, respectively, such that the engaging arm302of the auxiliary blade300may be positioned on one of the arms130,132in a superimposed relation and secured by the respective locking wheel135,137. A neck portion139(FIG.1B,1C) of the locking wheel135is configured to be slidably received in the narrowed portion306of the auxiliary blade300. A neck portion (not shown) of locking wheel137is similarly configured to be slidably received in the narrow portion306of the auxiliary blade300. The blade portion308is substantially orthogonal with respect to the engaging arm302, whereby when the auxiliary blade300is secured to one of the arms130,132, the blade portion308is substantially orthogonal to the respective arm130,132. Additionally, each blade portion308includes at least one longitudinal guide channel309extending substantially along the length of the blade portion308, similar to the longitudinal guide channels209of the retractor blade200. Likewise, similar to retractor blades200a,200b, the longitudinal guide channels309of the auxiliary blade300are configured to receive a guide wire, a guide pin, or other surgical implements therethrough.

In embodiments, and with additional reference toFIG.6B, the longitudinal guide channels209,309of retractor blades200a,200band/or auxiliary blade300are shaped to correspond to a shape of a channel guide721c. The retractor blades200a,200bor auxiliary blade300may be configured to enable longitudinal translation of the insertion guides721through at least a portion of the longitudinal guide channel209,309therealong. For example, the insertion guide721, that is configured to couple to the insertion system700, includes a channel guide721cthat further includes a neck portion and a rounded head portion. The neck portion and rounded head portion may be configured for slidable reception by the longitudinal guide channels209,309, each having a corresponding pattern formed along the surface of the longitudinal guide channels209,309. It will be understood that in such embodiments, the shape of the insertion guide721and corresponding longitudinal guide channels209,309are keyed to control motion of the insertion system700and the implant associated with the insertion system so as to prevent unintended movement or “walking” of implants, plates, or combinations thereof during insertion between the vertebrae of patients. It will be further understood that the retractor blade200and/or the auxiliary blade300may be oriented in the cephalad direction (e.g., a cephalad blade), the caudal direction (e.g., a caudal blade), the posterior direction (e.g., a posterior blade) and the anterior direction (e.g., an anterior blade) to enable translation of insertion guides721along the respective portions of the patient as desired by the clinician, further allowing for increased flexibility. It is contemplated that the insertion guide721may be provided in a variety of sizes that allow the spacing between the auxiliary blade300(or blade200) and the outer tubular member712of the insertion system700(FIG.6A) to vary allowing increased flexibility in placement of the spacer500between adjacent vertebrae. Insertion guides721having a variety of sizes may be provided in a kit.

The auxiliary blade300may be adjustably secured to the arms130,132. Specifically, the neck portion139of the locking wheels135,137may be slidably received through the narrowed portions306of the cavities303of corresponding auxiliary blades300to allow the clinician to position the auxiliary blades300in the transverse direction, as well as the longitudinal direction along the axis A-A along the arms130,132. Once positioned along one of the arms130,132the clinician may rotate one of the locking wheels135,137in a first direction to secure the auxiliary blade300to one of the arms130,132. To remove or reposition the auxiliary blade300, the clinician may rotate one of the locking wheels135,137in a second direction opposite the first direction, thereby partially or completely releasing the auxiliary blade300from one of the arms130,132.

Referring now toFIGS.2D and2E, an alternate embodiment of the auxiliary blade300ofFIG.2Cis illustrated and referred to as curved blade300′. The curved blade300′ is substantially similar to the auxiliary blade300. The curved blade300′ includes a hand-grippable portion312, a planar surface307extending distally from the hand-grippable portion312, and an arcuate portion310extending distally from a distal portion of the planar surface307. The planar surface307and the arcuate portion310are configured to slidably receive a shuttle301. More particularly, the shuttle301includes a channel which receives the planar surface307and/or arcuate portion310therethrough. A shuttle pin314extends through the shuttle301, and rotatably engages a bore (not explicitly shown) defining a threaded surface. Longitudinal guide channel309does not extend to the distal end of the auxiliary blade300′ as seen inFIG.2D. This provides a limit stop such that an instrument traveling along the longitudinal guide channel309stops prior to reaching the distal end of the auxiliary blade300′. In situations where a cutter (e.g., knife, scalpel, or other cutting instrument) is used to cut tissue (e.g., the ALL), the distal end of the longitudinal guide channel309limits how far the cutter travels along the auxiliary blade300′ into the working space such that the cutter is inhibited from cutting too far and risking damage to surrounding tissue and vasculature.

The planar surface307and the arcuate portion310have a longitudinal guide channel309extending along at least a portion of both the planar surface307and the arcuate portion310. The arcuate portion310is defined in part by a predetermined radius of curvature. In use, when the curved blade300′ is introduced to a working channel of a patient to retract tissue, by virtue of the curvature of the arcuate portion310the tissue engaged by the arcuate portion310is retracted less than the tissue retracted by the planar surface307. This may allow the clinician to retract the tissue located proximally farther than the tissue located distal to the clinician (when looking toward the vertebra of the patient), thereby reducing the chance for trauma to the distal tissue. The arcuate portion310of the curved blade300′ may also be shaped or toed inward such that, the arcuate portion310approximates the shape of the anterior portion of the vertebra when advanced toward the vertebra during surgical procedures. In embodiments, during surgical procedures, the distal portion of the curved blade300′ may be advanced such that the arcuate portion310extends along a side portion of the vertebra of the patient. The curved blade300′ further includes a cylindrical member311that rotatably couples the planar surface307to the engaging arm302within an engagement channel313. The hand-grippable portion312of the curved blade300′ further includes a plurality of grooves or other ergonomic features disposed thereon to facilitate grip of the curved blade300′ by the clinician during surgical procedures.

To fix the shuttle301and the engaging arm302relative to the planar surface307or arcuate portion310, the shuttle pin314is advanced inward until the shuttle pin314mechanically engages a side portion of either the planar surface307or arcuate portion310. As such, the shuttle pin314enables selective positioning of the engaging arm302along the planar surface307or arcuate portion310. When the shuttle pin314is retracted, it disengages from either the planar surface307or the arcuate portion310, which allows the curved blade300′ to move up and down along the planar surface307and/or the arcuate portion310with respect to the engaging arm302, thereby allowing the clinician to set the height at which the curved blade300′ is positioned with respect to the engaging arm302. A toe screw316extends through an arm315extending from the shuttle301. The toe screw316is configured to rotatably engage the engaging arm302to allow the engaging arm302to toe inwards or outwards relative to the planar surface307. In embodiments, accessories may also be coupled to a shuttle (not shown) such as, without limitation, a light to the auxiliary blade300or curved blade300′. In embodiments, the accessories may also be attached to the retractor blade200.

Referring now toFIGS.3A and3B, a dissector400is illustrated for use with the retractor100. While shown at a certain scale and as extending a predetermined marked distance, it will be understood that the dissector400may be formed to have a wider or narrower cross-section, and may be longer or shorter, depending on the particular needs of a clinician during a surgical procedure. The dissector400has a central passage402extending along the length of the dissector400with open proximal and distal portions. The central passage402is configured such that the dissector400may slidably receive a guide wire or guide pin therethrough (not shown). The guide wire or guide pin may guide the dissector400to the target disc of a patient during a surgical procedure. Additionally, the dissector400may have indicia marked (e.g., etched, printed or printed thereon) to indicate the depth of the body cavity or the distance between the epidermal tissue surface and the vertebral body. The clinician may use such indicia to select an appropriate retractor blade during the surgical procedure. In embodiments, the central passage402is defined by an electrically conductive tube with plastic over molded onto and surrounding the tube. A notch404is formed along the proximal portion of the dissector400in association with an electromyography system in a known manner. A clip from the electromyography system can be contacted with the conductive tube at the notch404with the signals transmitted along the tube inside the insulating plastic outer body, to the distal portion and/or distal tip of the conductive tube that contacts tissue.

Referring now toFIGS.4A-4C, a spinal interbody spacer or spacer500for placement between vertebrae is illustrated. The spacer500includes a pair of opposing side walls510,504, a blunt nose506, and an arcuate proximal wall502. The spacer500may be monolithically formed and may be made of any suitable biocompatible material such as, without limitation, polyetheretherketone (“PEEK”), polyphenylsulfonee (e.g., Radel®), polyetherimide (e.g., Ultem®), stainless steel, cobalt chrome, titanium, titanium alloys, and the like.

The spacer500defines a generally torpedo-shaped profile with an opening “C” extending therethrough to enable bone growth between adjacent vertebrae. Additionally, opening “C” is configured to accommodate additional bone graft material. The blunt nose506includes a substantially contoured, tapered surface to facilitate insertion thereof between the vertebral bodies. The spacer500includes a vertebral body engaging top and bottom surfaces512,514having protrusions configured to facilitate gripping and securing of the spacer500with adjacent vertebrae. In particular, the protrusions include ring-patterned protrusions508concentrically arranged with respect to the opening “C”. Additionally, the ring-patterned protrusions508of the opposing top and bottom surfaces512,514may be configured to allow secure engagement with respect to each other when disposed in superposed relation. In embodiments discussed below, the interbody spacer may have opposing surfaces configured to expand upon mechanical engagement by an interbody spacer insertion system or insertion system700(FIGS.6A,6B) so as to enable the clinician to adjust the lordotic curvature of the patient once the interbody spacer is positioned between the vertebrae of the patient.

With continued reference toFIG.4C, an arcuate proximal wall502includes a recess518defining a threaded aperture516for mating with an insertion system700(FIGS.6A,6B). The top and bottom surfaces512,514of the spacer500are substantially parallel to one another. In embodiments, the top and bottom surfaces may be in angled relation. The spacer500may be tapered laterally and define a generally wedge shaped configuration. Specifically, one sidewall may have a height that is different from the height of the opposing sidewall defining the tapered or lordotic or hyperlordotic configuration. Alternatively, the opposing side walls may have the same height, and thus defining a parallel configuration.

For a detailed description of interbody spacers, including expandable interbody spacers, reference may be made to commonly owned U.S. Patent Application Publication No. 2017/0135824 entitled “Expandable Spinal Implant” and U.S. Pat. No. 9,468,535 entitled “Interbody Spacer” the contents of which are hereby incorporated by reference in their entirety.

Referring now toFIG.4D, an interbody spacer attachment plate or attachment plate520configured to couple to the spacer500(FIGS.4A-4C) when fixing the spacer500to corresponding vertebrae is illustrated. The attachment plate520defines a pair of opposed surfaces522which extend along an axis B-B. A pair of screw bores524extends through the attachment plate520between openings in the opposed surfaces522. The screw bores524are configured to receive bone screws (not shown) therein. The screw bores524are substantially circular. Each screw bore524has a center point and radius extending outward from the center point to an edge of the screw bore524. An attachment bore526is interposed between the screw bores524and extends through the attachment plate520. The attachment bore526has a center which is positioned along the B-B axis, and a radius extending from the center to a threaded surface configured to engage an attachment screw (not shown). In embodiments, the screw bores524and/or the attachment bore526may be tapered such that the radius of the bore decreases between pair of opposed surfaces522in a proximal to distal direction.

The respective centers of the screw bores524are offset relative to the center of the attachment bore526such that an angle θ is formed relative to the axis B-B. In particular, the screw bores524are offset in an anterior-posterior orientation such that the centers of the screw bores524define the angle θ with respect to the center of the attachment bore526, which lies along the axis B-B. The angle θ may be anywhere from about 5 degrees to about 30 degrees, though in embodiments, it is contemplated that the angle may be any suitable angle between about 5 degrees and about 20 degrees. It will be appreciated that the angle θ need not be identical for each of the screw bores, and that one screw bore may be offset from axis B-B by a greater angle than the other screw bore. By virtue of the offset of the screw bores524relative to the attachment bore526, the position of screw bores524is oriented in a direction so that anatomical structures (e.g., nerves, tissue and blood vessels) located on the side of the plate opposite to axis B-B from screw bores524are avoided, and the potential for damage to such structures as screws are inserted through the screw bores is minimized or reduced. In general, the screw bores are oriented in a posterior direction to avoid anteriorly oriented structures. Additionally, by virtue of the offset of the attachment bore526and pair of screw bores524, the attachment plate520may be coupled to an implant (e.g., spacer500shown inFIGS.4A-4C) while being positioned. Such positioning of the attachment plate520relative to the vertebrae of the patient provides the additional benefit of allowing the plate520to, when positioned in certain locations (e.g., along vertebrae associated with the lumbar part of the vertebral column) more closely approximate or match the curvature or lordosis of the associated vertebrae. For additional detail including an example of a suitable bone screw, reference may be made to commonly-owned U.S. Pat. No. 8,137,405, the contents of which are hereby incorporated by reference in their entirety.

Referring now toFIGS.5A-5G, an expandable interbody spacer600is shown. The expandable interbody spacer600includes a first body portion602and a second body portion604configured to rotatably couple to the first body portion602. The first and second body portions602,604are rotatably coupled via a rod606so that the first body portion602and second body portion604pivot relative to one another about an axis B-B defined by the rod606. The first body portion602and the second body portion604have a corresponding first bone screw mount610and a second bone screw mount612disposed at a proximal end of the first and second body portions602,604, respectively. In embodiments, the first and second bone screw mounts610,612may be offset from a central portion of the expandable interbody spacer600when viewed from the proximal portion (e.g., the first and second bone screw mounts610,612may be offset in the anterior or posterior directions) depending on the desired final position of the expandable interbody spacer600. In embodiments where the first and second bone screw mounts610,612are offset from the central portion of the expandable interbody spacer600, such offset may be to increase the distance between the first and second bone screw mounts610,612and tissue, nerves, or other anatomic features of the individual in the opposite direction. In particular, the first and second bone screw mounts610,612may be disposed in a posterior direction as discussed in connection with the screw bores524of attachment plate520so that the screws are spaced from vessels and nerves disposed more anteriorly. A pawl beam614is rotatably coupled to the second body portion604and configured to engage an engagement wall616extending from the first body portion602. For purposes of clarity, reference will be made to a left portion and a right portion of the expandable interbody spacer600, and components associated therewith. The left portion is to be understood as referring to the portion of the expandable interbody spacer600configured to rotatably pivot during expansion of the expandable interbody spacer600. The right portion of the expandable interbody spacer600is to be understood as referring to the portion of the expandable interbody spacer600configured to fix the orientation of the first body portion602relative to the second body portion604when the expandable interbody spacer600is expanded.

The first body portion602has an upper surface620having a plurality of protrusions620aextending upward therefrom and a plurality of micro-apertures620b. The protrusions620aare configured to inhibit expulsion and/or movement of the expandable interbody spacer600by engaging an endplate of the vertebra adjacent the upper surface when the expandable interbody spacer600is positioned between adjacent vertebrae. The micro-apertures620bextend from the upper surface620through the first body portion602downward to a lower surface (not explicitly shown) of the first body portion602, and are configured to enable bone growth therethrough during spinal fusion of the vertebrae of the patient. The first body portion602further defines an opening622located centrally along the upper surface620, the opening622extending downward from the upper surface620toward the second body portion604. While the first body portion602and the opening622are shown forming a substantially elliptical shape, it will be understood that the aperture may take any variety of shapes (e.g., a circle, square, and the like). The opening622allows bone growth between adjacent vertebrae and also provides an area for packing the expandable interbody spacer600with bone growth material.

The first body portion602has the first bone screw mount610disposed along a proximal portion of the first body portion602, the first bone screw mount610extending proximally and upward relative to the upper surface620of the first body portion602. The first bone screw mount610defines an aperture610aconfigured to receive a first bone screw washer610btherein. The first bone screw washer610bis made of a relative soft material (e.g., commercially pure titanium) configured to deform as a bone screw (not explicitly shown), formed of a harder material (e.g., titanium alloy Ti-6Al-4V), is inserted and engages the first bone screw washer610b. The aperture610ais angled so as to direct a screw inserted therethrough into the adjacent vertebral body.

The first body portion602has a rotation cylinder624extending downward along a left portion of the first body portion602. The rotation cylinder624is configured to receive the rod606therein to enable rotation about an axis B-B (FIG.5A). More particularly, the rotation cylinder624is configured to mate with a curved indent626in the second body portion604. The micro-apertures620bwhich are aligned with the rotation cylinder624extend therethrough.

The first plate602has an engagement wall616extending downward from the right portion of the first body portion602. The engagement wall616has teeth616aextending distally from a proximal portion of the engagement wall616. The teeth616afurther extend from the engagement wall616inward toward the aperture of the first and second body portions602,604. The teeth616aof the engagement wall616are configured to engage teeth614aof the pawl beam614to maintain the position of the first body portion602relative to the second body portion604when the expandable interbody spacer600is in an open configuration (FIG.5G).

The second body portion604has an upper surface628including a plurality of micro-apertures630extending from the upper surface620of the second body portion604to a lower surface (not explicitly shown) of the second body portion604. The second body portion604has a plurality of protrusions632extending downward from a lower surface (not explicitly shown) of the second body portion604. Similar to the protrusions620aof the first body portion602, the protrusions632of the second body portion604are configured to inhibit expulsion and movement by the expandable interbody spacer600relative to the vertebrae of the patient by engaging an endplate of an adjacent vertebra.

In embodiments, the micro-apertures620bof the first body portion602vertically align with the micro-apertures630of the second body portion604when in the closed configuration (FIG.5B). The second body portion604has a proximal region634and a distal region636which extend from the upper surface628of the second body portion604. The proximal and distal regions634,636are configured to support the first body portion602when the expandable interbody spacer600is in the closed configuration (FIG.5B), the first body portion602vertically offset from the second body portion604.

The second body portion604has a curved indent or recess638which forms a surface disposed along the left portion of the second body portion604which, as noted above, is configured to mate with the rotation cylinder624of the first body portion602. A pair of apertures640extends proximally and distally from the surface formed by the recess638to form corresponding bores through at least a portion of the proximal and distal regions634,636, respectively. The recess638is configured to rotatably receive the rotation cylinder624therein. The aperture640extending distal from the recess638extends to the distal portion of the second body portion604, enabling insertion of the rotation cylinder624from the distal portion of the expandable interbody spacer600. The apertures640are configured to receive the rod606for pivotally coupling the first body portion602and the second body portion604.

Similarly, a pair of apertures642is disposed on opposing sides of a cavity formed by the proximal and distal regions634,636along the right portion of the second body portion604. The apertures642are in coaxial alignment and form corresponding bores which extend proximally and distally from the cavity through at least a portion of the proximal and distal regions634,636. The bore extending from the aperture of the distal region636extends to the distal portion of the distal region636and is configured to receive a pawl rod608therein.

The first body portion602has an aperture644disposed on the proximal portion of the first body portion. The aperture644defines a corresponding bore which extends distally through the first body portion602. The bore has a threaded surface that is configured to receive a fixation screw (not shown) configured to couple the expandable interbody spacer600to an insertion tool (e.g., the insertion system700(FIG.6A)).

The pawl rod608is configured to rotatably support the pawl beam614in the cavity formed between the proximal and distal regions634,636of the second body portion604. The pawl beam614includes a rotation beam614band an engagement beam614ccoupled to an upper surface of the rotation beam614b. The rotation beam614bhas a pair of apertures614din coaxial alignment, the apertures614ddefining a bore extending through the rotation beam614b. The bore extending through the rotation beam614bis configured to receive the pawl rod608therein and enables rotatable engagement of the pawl beam614and the teeth616aof the engagement wall616. More particularly, the engagement beam614cincludes teeth614aconfigured to engage the teeth616aof the engagement wall616(FIGS.5D and5G) to maintain the orientation of the first body portion602relative to the second body portion604when in an expanded configuration (FIG.5E). Coil springs646are configured to be positioned about proximal and distal portions of the pawl rod608. The coil springs646are configured to apply rotational force to the engagement beam614cto bias the pawl rod608outward toward the engagement wall616of the first body portion602to urge the teeth614ainto engagement with teeth616a. The pawl rod608has a slot formed along the proximal end of the pawl rod608which is accessible through a bore defined by an aperture648, the bore extending through the proximal region634of the second body portion604.

The expandable interbody spacer600may be inserted between the vertebrae of a patient in conjunction with the retractor system10ofFIG.1and/or in a manner similar to the method described with respect toFIG.9. It is contemplated, however, that the expandable interbody spacer600may be inserted between the vertebrae by any other suitable method known in the art. In addition, the expandable interbody spacer600may be inserted without engaging the retractor100as discussed.

Once positioned between the first and second vertebrae, a first bone screw and a second bone screw, as are known in the art, are inserted through the first and second bone screw washers610b,612bthat are positioned in the apertures610a,612aand into the adjacent vertebrae thereby rotatably coupling the expandable interbody spacer600to the first and second vertebrae of the patient. The first and second bone screws may be driven through pre-drilled holes established in the vertebrae of the patient. Alternatively, the first and second bone screws may be self-starting bone screws which do not require pre-drilling vertebrae before fixation thereto. As the first and second bone screws are inserted into the vertebrae, the first and second bone screws deform the corresponding bone screw washers610b,612b, fixing the first and second body portions602,604to the respective vertebrae. Other structures known in the art, such as set screws, cover plates or washers, etc. are also contemplated for securing the screw to the implant.

With continued reference toFIGS.5A-5G, and additional reference toFIGS.8A-8D, engagement of the expandable interbody spacer600will be discussed in detail. Once inserted between the vertebrae of the patient and attached thereto, the first body portion602may be rotated relative to the second body portion604about the rod606. To rotate the first body portion602relative to the second body portion604, the blade808of the expander800(FIG.8A) is inserted between the first and second body portions602,604. The expander800is rotatably engaged by a clinician to cause the edge808bof the blade808to pivot about the rounded portion808ain a first direction, causing the edge808bto come into contact with the first body portion602of the expandable interbody spacer600. As the expander800is rotated further, the first body portion602is rotated upward, causing the teeth614aof the pawl beam614to ratchet and engage the teeth616aof the engagement wall616of the first body portion602. The ratcheting of the first body portion602relative to the second body portion604enables the clinician to transition the expandable interbody spacer600from a closed configuration (FIG.5C) to an open configuration (FIG.5E). Once in the open configuration, and more particularly when a desired amount of lordosis is established between first and second vertebrae of the patient, the expander800is rotated in a second direction different from the first direction, thereby causing the blade808of the expander800to disengage from the expandable interbody spacer600. The teeth616aof the engagement wall616rest on the teeth614aof the pawl beam614, thereby maintaining the position of the first body portion602relative to the second body portion604during spinal fusion of the vertebrae of the patient. This arrangement between the teeth614aand the teeth616ainhibits collapse of the expandable interbody spacer600. Alternative modes of expanding the expandable interbody spacer also are contemplated. In the simplest aspect, the expandable interbody spacer may be permitted to passively expand as the patient is repositioned, with the expandable interbody spacer settling into a natural or desired position of lordosis based on patient positioning. In the alternative, the first and second body portions602,604may be moved apart by expansion mechanisms such as a mechanical scissor jack, hydraulic expander or other known mechanisms.

It will be understood that, in embodiments, the coil springs646may be configured to apply an outward force such that when the expandable interbody spacer600is in a collapsed configuration, when released, the expandable interbody spacer600transitions to an open configuration (seeFIG.5E). More particularly, during a surgical procedure the expandable interbody spacer600may be locked or otherwise held in a closed configuration by the insertion system700prior to positioning between vertebrae of a patient. Once positioned as desired between vertebrae of a patient, the clinician positioning the expandable interbody spacer600may cause the insertion system700to release the expandable interbody spacer600. Upon release, the first and second body portions602,604may be urged to pivot about the rod606toward the open configuration, without being urged apart by the clinician. By allowing the expandable interbody spacer600to expand without the application of force by a clinician, an angle of lordosis maybe achieved without over or under expanding the expandable interbody spacer600by applying too much or too little rotational force.

Referring now toFIGS.6A and6B, illustrated is an interbody spacer translation system or insertion system700for positioning a spacer500between vertebrae of a patient during a surgical procedure. As will be described later in detail, the insertion system700is coupled to a spacer500and guided along one of the retractor blades200,300,300′. While the insertion system700is shown slidably engaging the auxiliary blade300, it will be apparent that the insertion system700may be positioned to engage and translate along the longitudinal guide channels209of the retractor blades200a,200b.

The insertion system700includes a housing704defining a bore that is configured to slidably receive an inner tubular member708therethrough. When assembled, a handle702of the housing704is in orthogonal relation with the inner tubular member708extending distally therefrom. The housing704includes a proximal portion configured to receive a release assembly706that releasably couples to the inner tubular member708.

The inner tubular member708extends distally from the housing704through a bore defined by an outer tubular member712. The outer tubular member712has a hand-grippable portion710with a bore extending therethrough coupled proximally to the outer tubular member712. In embodiments, the hand-grippable portion710includes a plurality of ribs710a, or other ergonomic features that enhance gripping the hand-grippable portion710, extending outward about the hand-grippable portion710to allow the clinician to grip and rotate the hand-grippable portion710. The outer tubular member712may have one or more windows714disposed along the outer tubular member712and extending therethrough to allow visual inspection of the inner tubular member708when inserted through the outer tubular member712. More particularly, the windows714may allow visual inspection of indicia or instrument features of instruments disposed within the bore of the outer tubular member712such as, for example, the inner tubular member708. The windows714also may facilitate cleaning and sterilization of the instrument between uses.

The distal portion of the inner tubular member708has a coupling716disposed at the end thereof. The coupling716is configured to be rotatably engaged by either the hand-grippable portion710or the release assembly706. More particularly, counter-clockwise rotation of the hand-grippable portion710causes the outer tubular member712to rotatably engage the coupling716, causing arms718a,718bto move away from one another. Conversely, clockwise rotation of the hand-grippable portion710when the arms718a,718bare in an expanded configuration causes the arms718a,718bto move toward one another. Such movement of the arms718a,718btowards and away and from one another allows the arms718a,718bto engage the attachment plate520(FIG.4D) or the expandable interbody spacer600(FIG.5A).

With particular reference toFIG.6B, the distal portion of the insertion system700is shown, with parts separated. The coupling716has two arms718a,718bin opposed relation. The arms718a,718bare biased inwards relative to the inner tubular member708and couple to an internal actuation assembly (not shown) that by default maintains the arms718a,718bin a close cooperative position relative to one another. When the release assembly706is engaged, the arms718a,718bare moved away from each other. This outward motion expands the distance between a first hook720aand a second hook720b. A screw engagement mechanism (not shown) has an engagement portion that is configured to be received in an opening of a screw722. The screw engagement mechanism may be a tubular member that extends through a bore defined by the inner tubular member708and may rotate either independent of the inner tubular member708or in concert with the inner tubular member708. In embodiments, the screw engagement mechanism may advance proximally or distally to advance the screw722toward or away from the spacer500.

The screw722includes a head with a recess configured to receive the screw engagement mechanism therein, and a threaded portion extending distally from the head. The threaded portion is configured to extend through the attachment plate520(FIG.4D). As discussed hereinabove, the plate520has a top surface defining the attachment bore526extending through the attachment plate520distally toward the bottom surface, an offset pair of screw bores524configured to receive bone screws (not shown) therein, and a periphery extending distally from the top surface to a bottom surface. The periphery has a pair of indents528extending inward along the periphery of the attachment plate520. The indents528form an L shape indent configured to slidably receive the arms718a,718bwhen the arms are in an approximated configuration. The bottom surface has a pair of flanges530(FIG.6B) extending distally from the attachment plate520, the flanges530are configured to slidably engage the recess518of the spacer500. In embodiments, the flanges530may be configured to approximate the shape of the recess518of the spacer500.

Prior to insertion of the spacer500between vertebrae of a patient, the screw722may be inserted and advanced distally through the attachment plate520. Once advanced through the attachment plate520, the threaded portion of the screw722may rotatably engage the threaded aperture516of the spacer500to secure the attachment plate520to the spacer500.

To couple the coupling716to the attachment plate520, thereby operably coupling the insertion system700to the spacer500, the actuation assembly (not shown) may be actuated by a clinician, thereby causing the arms718a,718bto expand outward. The arms718a,718bmay be advanced such that the first and second hooks720a,720bare aligned with the opposing indents528of the attachment plate520. Upon release of the actuation assembly, the arms718a,718b, and, by extension, the corresponding first and second hooks720a,720b, advance inwards into the indents528, thereby securing the attachment plate520to the insertion system700. In the alternative, arms718a,718bmay be biased apart, with the actuation mechanism compressing the arms together, such as with a compression tube, to grasp and hold the implant. As will be appreciated, the inserter may be configured in the alternative to engage the expandable interbody spacer600, as discussed herein.

With continued reference toFIG.6B, an insertion guide721may be coupled to the insertion system700to guide the insertion system700along the longitudinal guide channel209defined by the retractor blade200a,200bor the longitudinal guide channel309defined by the auxiliary blade300. The insertion guide721has a chassis721ahaving an arcuate surface721band a channel guide721c. The arcuate surface721bis configured to approximate an outer surface of either arm718a,718band/or the outer surface of the outer tubular member712. The channel guide721cextends outward from the chassis721aand forms a pair of concave surfaces that invert and form a convex head. The convex head of the channel guide721cis configured to slidably engage the longitudinal guide channel309defined by the auxiliary blade300. The insertion guide721is coupled to the first or second arm718a,718bvia a screw721d. More particularly, the screw is configured to extend through a bore defined by the chassis721aof the insertion guide721and a threaded aperture719a,719bof the corresponding arm718a,718b. Alternatively, the insertion guide721may be integrally formed with a portion of the insertion device700, or may be welded or otherwise attached thereto by suitable means. In addition, other keyed shapes of engagement between the insertion guide721and the retractor blades200a,200bis contemplated, such as a dovetail joint.

The distal portion of the auxiliary blade300has a transverse bore extending at least partially therethrough, the transverse bore configured to receive a pin309′ therein. The pin309′ may be made of tantalum or any other substance known in the art that provides a clear indication of the position of the pin309′, and by extension the position of the auxiliary blade300, in a fluoroscopic image captured during fluoroscopic imaging of the auxiliary blade300.

Referring now toFIG.7, illustrating the insertion system700engaging the retractor system10ofFIG.1, discussed is a method described with reference toFIG.9that details an illustrative example of a method for replacing a damaged intervertebral disc by the retractor system10. While reference will be made to the insertion of the spacer500in connection with the retractor100, it will be understood that the expandable interbody spacer600may be inserted in a similar manner. It will also be understood by one skilled in the art that the expandable interbody spacer600may be inserted with an insertion system (e.g., insertion system700), without slidably engaging the longitudinal guide channels209of the retractor blades200a,200bor the longitudinal guide channel309of the auxiliary blade300when guiding the expandable interbody spacer600toward the vertebrae of a patient. In this regard, it will be understood that the insertion system700may be used during surgical procedures with retractors known in the art, or during procedures without the use of a retractor.

In use, a clinician positions a patient in a lateral decubitus position with the iliac crest of the patient located directly over a table break. The patient is then secured typically via straps or other known tensioning devices, just below the iliac crest and over the thoracic region of the patient. The legs are likewise secured to the table, so as to prevent movement of the patient during the surgical procedure. Once secured, fluoroscopic images of the patient are captured to obtain images of the targeted disc or discs for replacement.

Referring now toFIG.9, once the clinician is satisfied with the placement of the patient and the obtained fluoroscopic images, an incision is made (block902). In embodiments, when replacing one disc, a transverse incision is made, and when replacing multiple discs, a vertical incision is made relative to the patient, to provide subcutaneous access to the iliac portion of the patient. Once the desired incision is created, the exposed muscle fibers are separated by the clinician as the clinician advances a finger into the retroperitoneal space of the patient. The peritoneum is released anteriorly as the retroperitoneal space is developed, allowing the clinician to gain access to the psoas muscle and/or the anterior tip of the transverse process. Once the clinician verifies development of the retroperitoneal space, a dissector is inserted, advanced through the psoas muscle, and fixed directly to the middle of an intervertebral disc or target disc. The clinician may move the dissector as desired to free soft tissue surrounding the target disc, completing preparation of the path to the spine of the patient (block904).

Once the path is established at block904, an intradiscal guidewire is placed through the dissector and advanced into the disc of the patient. If additional dilation is desired by the clinician, the first dilator may be removed, and a second dilator may be introduced in the place of the first dilator. The second dilator, larger than the first, is guided to the target disc by following the path along the guidewire, keeping the second dilator in line with the muscle fibers of the psoas and safely anterior to the lumbar plexus. The clinician may move the proximal portion of the first and/or second dilator back and forth to further develop the surgical site (block906). Once the dilator is seated in place as desired by the clinician, a measurement may be taken of the exterior tissue or skin of the patient relative to the first or second dilator so as to allow the clinician to select an appropriate pair of retractor blades (e.g., retractor blades that are at the appropriate length) (block908). Once selected, the corresponding retractor blades are attached to the retractor100. The retractor100may be closed such that the retractor blades200a,200bare in close cooperative alignment. After removing the first or second dilator, the retractor100is inserted into the tissue and advanced toward the target disc and associated vertebrae. When the retractor is in position, the retractor100is rotated 90 degrees prior to expansion. Optionally, one or more pins may be inserted through the longitudinal guide channels209of the retractor blades200a,200bonce rotated and fixed to the vertebrae of the patient (block910). In an embodiment, a pin is inserted into the channel of one retractor and anchored in the bone of one vertebra.

Once in place, and optionally secured, the retractor100is expanded (block912). In the case where one pin is inserted into the groove of one blade (e.g., the first retractor blade200a), expanding the retractor100causes the other blade (e.g., the second retractor blade200b) to move away from the first retractor blade (200a) which is fixed by the pin. Once the retractor100has been expanded, the guidewire may be removed, and the retractor100expanded further, as desired by the clinician. As desired, where one or no pin has been used, additional fixation pins may be secured to the vertebrae as desired by the clinician. If additional, transverse, retraction is desired, the auxiliary blades300may be inserted and coupled to the retractor100. Once inserted, the auxiliary blades300may be expanded outward, retracting the corresponding tissue (block914). An intradiscal shim (not shown) may be inserted as desired to prevent or reduce the chance of soft tissue creep into a working channel of the surgical site during the surgical procedure (block916). For additional support, a table-mounted surgical arm (not shown) may be attached to the retractor100to maintain the position of the retractor assembly relative to the surgical table, and by extension, the patient.

Once the working channel is established, a traditional annulotomy and discectomy are performed (block918). The annulotomy and discectomy are performed by first determining an appropriate interbody spacer, or sequence of spacers, to distract the space occupied by the target disc (block920.) In embodiments, trial interbody spacers may be inserted and placed in between the vertebrae (e.g., by advancing the trial interbody spacer with a slap-hammer) to facilitate selection of a spacer500that is appropriate.

When placing the spacer500selected by the clinician, the spacer500is threadably coupled to the insertion system700via the attachment plate520(block922). This allows the clinician to insert the spacer500and attachment plate520into the intervertebral space as a single unit. Alternatively, the spacer500may be inserted into the intervertebral space first and the attachment plate520is coupled to the spacer500subsequent to placement in the intervertebral space. During placement, a handle702may be used (or, where necessary, a slap-hammer (not shown) may be coupled) to the insertion system700. The insertion system700having the spacer500coupled distally thereto is advanced toward the vertebrae by aligning the insertion guide721with the longitudinal guide channels209(or longitudinal guide channels309when using the auxiliary blade300). Once aligned, the channel guide721cis advanced distally along the longitudinal guide channel209(or longitudinal guide channel309) (block924). Once the spacer500is positioned as desired by the clinician, the insertion system700may rotatably engage a screw engagement mechanism to remove the screw722from the threaded aperture516of the spacer500(block926), though removal may not be desired or necessary, depending on the surgical procedure. The clinician places bone screws through screw bores524in attachment plate520or, in the case of expandable interbody spacer600, through apertures610a,612a. It is contemplated that only one bone screw may be used with spacer500. It is also contemplated that when using the expandable interbody spacer600, after the expandable interbody spacer600is positioned between adjacent vertebrae, one bone screw is inserted through one of the apertures610a,612a. Subsequent to inserting the bone screw through one of the apertures610a,612a, the expandable interbody spacer600is allowed to expand and a second bone screw is inserted in the other of the apertures610a,612a, thereby securing the expandable interbody spacer600in position. Preferably, the bone screws are inserted with the plate/implant combination or the expandable interbody spacer600, as the case may be, secured to and under the control of insertion system700which is tethered to the either the first or second retractor blade200a,200b. Attaching the plate/implant combination or the expandable interbody spacer600to bone while attached to and under the control of the insertion system700, which is in turn secured relative to either the first or second retractor blade200a,200bwhich is secured to one or both of the adjacent vertebrae, assures that the position of the spacer500or the expandable interbody spacer600does not shift as the bone screws are inserted and driven into bone. In the case of insertion of expandable interbody spacer600, the implant advantageously may be inserted into the disc space and secured to the vertebrae by bone screws with the ALL intact. It is common to release the ALL prior to inserting and securing an expandable interbody spacer600, but releasing the ALL prior to inserting and securing the expandable interbody spacer600may mobilize the vertebrae and increase the likelihood that the position of the expandable interbody spacer600or bone screws will shift away from the desired position during insertion. Since the expandable interbody spacer600may be inserted in an unexpanded condition and expanded after bone screws are inserted through apertures610a,612ainto bone to secure the expandable interbody spacer600relative to the vertebrae, the ALL may be released after the expandable interbody spacer600has been secured in place with bone screws, thereby assuring that the expandable interbody spacer600and/or bone screw position doesn't shift during insertion due to mobilization caused by release of the ALL. After the ALL is released with the expandable interbody spacer600secured in place, the expandable interbody spacer600may be expanded to adjust for lordosis. It is contemplated that the ALL may be released by cutting the ALL or it may be released upon expansion of the expandable interbody spacer600.

Referring now toFIG.8A, an expander is shown for rotatably engaging and expanding an expandable interbody spacer600(FIGS.5A-5G), the expander designated generally800. The expander800has a handle802, a shaft having a first section804aand a second section804bextending distally from the handle802, and a blade808extending distally from a distal portion of the second section804bof the shaft. The first and second sections804a,804bare removably coupled by a locking collar806coupled to the first section804aof the shaft.

The second section804bof the shaft has the blade808extending distally therefrom. The blade808has a rounded portion808aand an edge808bextending outward from the rounded portion808a. Additionally, the blade808may taper from the rounded portion808atoward the edge808bsuch that the edge808bhas a thinner cross-section than the rounded portion808a.

It will be understood that various modifications may be made to the embodiments of the presently disclosed sensing device. Specifically, while use of the insertion system700, the insertion system700, and the expandable interbody spacer600have been describe in detail in connection with the use of the retractor100, it will be understood that the devices may be used in connection with devices known in the art. For example, the aforementioned devices may be used with known retractors or other known techniques or methods to deliver the spacer500, or expandable interbody spacer600, to the target site. Additionally, the spacer500and expandable interbody spacer600may be used with one or more insertion systems and/or retractors during surgical procedures. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and the spirit of the present disclosure.