Patent Application
20200253645
The present invention relates to bone fixation devices, and more particularly to anterior cervical plates and systems.
In the treatment of various spinal conditions, including the treatment of fractures, tumors, and degenerative conditions, it is necessary to secure and stabilize the anterior column of the spine following removal of a vertebral body or part. Various devices for internal fixation of bone segments in the human or animal body are known in the art.
Following such removal made using a thoracotomy, thoracoabdominal, retroperitoneal, or similar approach, the normal anatomy is reconstructed using tricortical iliac crest or fibular strut grafts. Not only are removals performed on the thoracic spine, as is the case for the above procedures, but also the cervical spine. Once bone matter is removed, it is then necessary to secure and stabilize the graft, desirably in such a manner as to permit rapid mobilization of the patient. Such objectives can be accomplished by a bone plate. However, to accomplish this service in the optimum manner, it is necessary that the plate be reasonably congruent with the bone to which it is applied, that it have as low a profile as possible, that it be firmly secured to the spinal column so that it is not torn out when the patient places weight and stress upon it and that it be capable of placement and fixation in a manner that is convenient for the surgeon.
In this context it is necessary to secure the plate to the spinal body and also, in some cases, to the graft. After the insertion of a graft and a plate, the graft placed in the patient tends to subside. Traditional cervical plates are designed to limit motion within the fusion mass. However, a German doctor by the surname of Wolff demonstrated that bone grows when in compression and resorbs in the absence thereof. Consequently, cervical plate technology has attempted to limit motion of the coupled spinal areas in all directions but compression; theorizing that the natural weight of the head would provide sufficient load to stimulate bone growth in the fusion mass. As disclosed in U.S. Pat. No. 7,993,380 to Hawkes, incorporated herein by reference, certain cervical plates have been provided that provide active compression to supplement passive compression provided by the patient's head weight.
Unfortunately, previous orthopedic plates, including anterior cervical plates, have numerous disadvantages in their configuration and use. The prior systems require a separate system for distraction during the removal of the vertebral body or part. Prior plates are difficult to locate properly on the vertebrae due to limited visualization, and often require the use of specialized instruments and Caspar pins. The use of removable Caspar pins increases bone damage and bleeding that requires further treatment. It is also difficult to correctly size prior plates, and limitations on available sizes may require less than ideal plate placement.
With prior systems, cumbersome drill and screw guides are often needed to place and angle screws correctly relative to the plate. Furthermore, even once holes are drilled in the vertebrae, the introduction of the prior plates into the wound interferes with visualization needed to achieve proper screw placement. Even today, most orthopedic plates fail to adjust to bone remodeling or subsidence. Prior plates utilize separate screw-plate retention mechanisms. Such retention mechanisms add bulk, increase costs, add surgical steps, and may restrict screw angulation during placement.
For all these reasons, existing orthopedic plates, including cervical plates, include deficiencies that reduce positive outcomes for patients and cause difficulties for surgeons. It would be an improvement for orthopedic plates to address these deficiencies.
Implementation of the invention provides orthopedic plates, plate systems, and methods of use that address deficiencies of prior orthopedic plates, plate systems, and methods of use thereof. Orthopedic plates as described herein include anterior cervical plates. The new plates and plate systems allow screws to be placed with full visualization. The increased visualization allows screw placement even without use of specialized locating instruments or pins. The new plates are introduced to the surgical wound after the screws are placed; the wound is empty during screw placement when compared with prior screw placement methods. Additionally, because the screws are placed before the plates are introduced, the screws function as attachment points for distraction implements, and separate Caspar pins are not required.
The new plates and plate systems also obviate the need to achieve a particular position and angulation of screws. The screws allow more angulation than many prior devices allowed, and plate eyes of implementations of the invention adjust to screw position.
New plates in accordance with implementations of the invention include plate eyes that translate so as to match the effective plate size to the screw placement, thereby allowing each plate to fit multiple screw spacings. The new plates thereby reduce or eliminate difficulties associated with properly sizing prior art plates.
In accordance with implementations of the invention, plates are adapted to adjust to bone remodeling or subsidence. Screw eyes can slide to maintain graft contact. Some implementations of the invention provide unidirectional regulation of eye movement to help maintain graft compression.
Implementations of the invention reduce system bulk, as typical screw-plate retention mechanisms are not necessary. No ring, propeller, or wire screw retention mechanisms need be located above the screw heads. Implementations of the invention also decrease costs. New plates and plate systems have reduced locking-related parts count as screw retention is inherent rather than secondary. Implementations of the invention also reduce surgical steps. Caspar pin placement, pre-drilling of screw holes, actuating of screw locking mechanisms, and/or treatment of bone bleeding are eliminated using methods in accordance with implementations of the invention. Implementations of the invention permit a greater range of screw angulation during placement. Retention of the screws in implementations of the plate is inherent and independent of screw angulation up to the point of the screw neck contacting the plate; a wide range of screw angulation is achieved without the screw neck contacting the plate.
According to implementations of the invention, an orthopedic plate is provided. In some implementations, the orthopedic plate is a cervical plate for a cervical spine fixation procedure. The orthopedic plate includes an eye member. The eye member includes a biocompatible material formed to define a cylindrical passage through the eye member, the cylindrical passage being sized to receive an orthopedic screw head therein and to provide an interference fit with the orthopedic screw head. The eye member also includes a first frame member engagement contour and a second frame member engagement contour formed on opposite sides of the eye member. The orthopedic plate also includes a plate member. The plate member includes a channel formed by a first frame leg and a second frame leg, both of a biocompatible material. The first frame leg includes a first eye member engagement contour formed on a channel side of the first fame leg that is adapted to engage the first frame member engagement contour of the eye member in sliding engagement. The second frame leg includes a second eye member engagement contour formed on a channel side of the second fame leg that is adapted to engage the second frame member engagement contour of the eye member in sliding engagement. The eye member is contained within and adapted to slide within the channel.
In some implementations, the first frame member engagement contour and the second frame member engagement contour each include an extension extending laterally away from a center of the eye member, and the first eye member engagement contour and the second eye member engagement contour each include a slot sized and shaped to slidingly receive one extension of the eye member. In some implementations, the extension of the first frame member engagement contour and the second frame member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions.
In some implementations, the first eye member engagement contour and the second eye member engagement contour each include an extension extending laterally toward the other frame leg, and the first frame member engagement contour and the second frame member engagement contour each include a slot sized and shaped to slidingly receive one extension of the plate member. In some implementations the extension of the first eye member engagement contour and the second eye member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions. The orthopedic plate of claim 1, wherein the plate member further includes a static cylindrical passage sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head.
Some implementations further include another eye member. The other eye member includes a biocompatible material formed to define a cylindrical passage through the other eye member, the cylindrical passage through the other eye member being sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head. The other eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the other eye member. In such embodiments, the plate member further includes another channel formed by a third frame leg and a fourth frame leg, both of a biocompatible material. The third frame leg includes a third eye member engagement contour formed on a channel side of the third fame leg that is adapted to engage the third frame member engagement contour of the other eye member in sliding engagement. The fourth frame leg includes a fourth eye member engagement contour formed on a channel side of the fourth fame leg that is adapted to engage the fourth frame member engagement contour of the other eye member in sliding engagement. The other eye member is contained within and adapted to slide within the other channel.
Some implementations also include another eye member. The other eye member includes a biocompatible material formed to define a cylindrical passage through the other eye member, the cylindrical passage through the other eye member being sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head. The other eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the other eye member that are adapted to engage the first and second eye member engagement contours of the first and second frame legs. The other eye member is contained within and adapted to slide within the channel (the channel formed by the first and second legs).
According to some implementations, the orthopedic plate also includes a force-generating mechanism adapted to apply a compressive force between the eye member and the other eye member. According to some implementations, the force-generating mechanism includes one of a spring, a compliant mechanism, or a nickel-titanium alloy (nitinol) wire.
Some implementations also include orthopedic screws each having the orthopedic screw head sized to provide an interference fit with the cylindrical passage to thereby form an orthopedic plate system. In some implementations, each of the orthopedic screws includes a driving feature and a wand-attachment feature adapted to permit retention of the orthopedic screw against a force directed against the orthopedic screw head during interference fitting of the orthopedic screw head in the cylindrical passage.
According to some implementations, a method of using the orthopedic plate system includes steps of inserting one orthopedic screw into a first anterior portion of a vertebral body of a first vertebra and inserting another orthopedic screw into a second anterior portion of a vertebral body of a second vertebra. The method also includes using the orthopedic screws to distract the disc space for a discectomy and insertion of an interbody implant or graft. The method also includes determining a proper length for the plate member using a distance between the orthopedic screw heads and inserting and positioning the plate member in the wound with the cylindrical passage over one orthopedic screw head. The method further includes locking the plate member to one of the orthopedic screws by drawing the orthopedic screw head into the cylindrical passage of the eye member while pushing the eye member toward the orthopedic screw head until an interference fit is achieved between the orthopedic screw head and the eye member.
In some implementations, the orthopedic plate further including a motion-stopping structure adapted to at least selectively inhibit sliding motion of the eye member within the channel. In some implementations, the motion-stopping structure is a structure such as a cylindrical roller clutch structure, a sprag clutch structure, a ball clutch structure, a cylindrical roller clutch structure with an energizing spring, a sprag clutch structure with an energizing spring, a ball clutch structure with an energizing spring, a toothed ratchet mechanism, a self-energizing wedge, an integrated camming member, or an interference fit between the eye member and the channel caused by expansion of the eye member upon insertion of the orthopedic screw head into the cylindrical passage.
In some implementations, the channel has either an open-ended shape or a closed-ended shape. In some implementations, the orthopedic plate is sized for use in a cervical vertebra fixation procedure. In some implementations, the orthopedic plate is part of an orthopedic plate system including an orthopedic screw having the orthopedic screw head. In some implementations, the orthopedic plate system also includes one or more tools or instruments for driving the orthopedic screw and/or for applying force between the orthopedic screw and the plate member.
According to further implementation, an orthopedic plate system is provided. The orthopedic plate system is a cervical plate system for a cervical spine fixation procedure. The orthopedic plate system includes a first orthopedic screw having a first threaded shaft extending from a first orthopedic screw head and a second orthopedic screw having a second threaded shaft extending from a second orthopedic screw head. The orthopedic plate system also includes a first eye member. The first eye member includes a biocompatible material formed to define a first cylindrical passage through the first eye member, the first cylindrical passage being sized to receive the first orthopedic screw head therein and to provide an interference fit with the first orthopedic screw head. The first eye member also includes a first frame member engagement contour and a second frame member engagement contour formed on opposite sides of the first eye member.
The orthopedic plate system also includes a second eye member. The second eye member includes a biocompatible material formed to define a second cylindrical passage through the second eye member, the second cylindrical passage through the second eye member being sized to receive the second orthopedic screw head therein and to provide an interference fit with the second orthopedic screw head. The second eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the second eye member.
The orthopedic plate system also includes a plate member. The plate member includes a first channel formed by a first frame leg and a second frame leg, both of a biocompatible material. The first frame leg includes a first eye member engagement contour formed on a channel side of the first fame leg that adapted to engage the first frame member engagement contour of the first eye member in sliding engagement. The second frame leg includes a second eye member engagement contour formed on a channel side of the second fame leg that is adapted to engage the second frame member engagement contour of the first eye member in sliding engagement. The plate member also includes a second channel formed by a third frame leg and a fourth frame leg, both of a biocompatible material. The third frame leg includes a third eye member engagement contour formed on a channel side of the third fame leg that is adapted to engage the third frame member engagement contour of the second eye member in sliding engagement. The fourth frame leg includes a fourth eye member engagement contour formed on a channel side of the forth fame leg that is adapted to engage the fourth frame member engagement contour of the second eye member in sliding engagement. The first eye member is contained within and adapted to slide within the first channel and the second eye member is contained within and adapted to slide within the second channel.
According to some implementations, the orthopedic plate system further includes motion-stopping structures adapted to at least selectively inhibit sliding motion of the first and second eye members within the first and second channels. According to some implementations, the first frame leg, the second frame leg, the third frame leg, and the fourth frame leg are integrally formed from a unitary piece of biocompatible material. According to some implementations, the first channel and the second channel are unitarily formed as a continuous closed-loop channel that is divided by an insert affixed near a center of the continuous closed-loop channel.
According to some implementations, the orthopedic plate system also includes a force-generating mechanism adapted to apply a compressive force between the first eye member and the second eye member. According to some implementations, the force-generating mechanism includes one of a spring, a compliant mechanism, or a nickel-titanium alloy (nitinol) wire.
In some implementations, the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour each includes an extension extending laterally away from a center of the respective eye member, and the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour each include a slot sized and shaped to slidingly receive one extension of the respective eye member. In some implementations, the extension of the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions.
In some implementations, the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour each include an extension extending laterally toward the other frame leg, and the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour each include a slot sized and shaped to slidingly receive one extension of the plate member. In some implementations the extension of the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions. The orthopedic plate of claim 1, wherein the plate member further includes a static cylindrical passage sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head.
In some implementations, each of the orthopedic screws includes a driving feature and a wand-attachment feature adapted to permit retention of the orthopedic screw against a force directed against the orthopedic screw head during interference fitting of the respective orthopedic screw head in the respective cylindrical passage.
In some implementations, the orthopedic plate further including a motion-stopping structure adapted to at least selectively inhibit sliding motion of each of the first eye member and the second eye member within their respective channels. In some implementations, the motion-stopping structure is a structure such as a cylindrical roller clutch structure, a sprag clutch structure, a ball clutch structure, a cylindrical roller clutch structure with an energizing spring, a sprag clutch structure with an energizing spring, a ball clutch structure with an energizing spring, a toothed ratchet mechanism, a self-energizing wedge, an integrated camming member, or an interference fit between the eye member and the channel caused by expansion of the respective eye member upon insertion of the respective orthopedic screw head into the respective cylindrical passage.
According to some implementations, a method of using the orthopedic plate system includes steps of inserting the first orthopedic screw into a first anterior portion of a vertebral body of a first vertebra and inserting the second orthopedic screw into a second anterior portion of a vertebral body of a second vertebra. The method also includes using the first orthopedic screw and the second orthopedic screw to distract the disc space for a discectomy and insertion of an interbody implant or graft. The method also includes determining a proper length for the plate member using a distance between the first orthopedic screw head and the second orthopedic screw head and inserting and positioning the plate member in the wound with the first cylindrical passage over the first orthopedic screw head and the second cylindrical passage over the second orthopedic screw head. The method further includes locking the plate member to the first orthopedic screw and the second orthopedic screw by drawing the first orthopedic screw head into the first cylindrical passage of the first eye member while pushing the first eye member toward the first orthopedic screw head until an interference fit is achieved between the first orthopedic screw head and the first eye member and drawing the second orthopedic screw head into the second cylindrical passage of the second eye member while pushing the second eye member toward the second orthopedic screw head until an interference fit is achieved between the second orthopedic screw head and the second eye member.
The objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
A description of embodiments of the present invention will now be given with reference to the Figures. It is expected that the present invention may take many other forms and shapes, hence the following disclosure is intended to be illustrative and not limiting, and the scope of the invention should be determined by reference to the appended claims.
Embodiments of the invention provide orthopedic plates, plate systems, and methods of use that address deficiencies of prior orthopedic plates, plate systems, and methods of use thereof. Orthopedic plates as described herein include anterior cervical plates. The new plates and plate systems allow screws to be placed with full visualization. The increased visualization allows screw placement even without use of specialized locating instruments or pins. The new plates are introduced to the surgical wound after the screws are placed; the wound is empty during screw placement when compared with prior screw placement methods. Additionally, because the screws are placed before the plates are introduced, the screws function as attachment points for distraction implements, and separate Caspar pins are not required.
The new plates and plate systems also obviate the need to achieve a particular position and angulation of screws. The screws allow more angulation than many prior devices allowed, and plate eyes of embodiments of the invention adjust to screw position.
New plates in accordance with embodiments of the invention include plate eyes that translate so as to match the effective plate size to the screw placement, thereby allowing each plate to fit multiple screw spacings. The new plates thereby reduce or eliminate difficulties associated with properly sizing prior art plates.
In accordance with embodiments of the invention, plates are adapted to adjust to bone remodeling or subsidence. Screw eyes can slide to maintain graft contact. Some embodiments of the invention provide unidirectional regulation of eye movement to help maintain graft compression.
Embodiments of the invention reduce system bulk, as typical screw-plate retention mechanisms are not necessary. No ring, propeller, or wire screw retention mechanisms need be located above the screw heads. Embodiments of the invention also decrease costs. New plates and plate systems have reduced locking-related parts count as screw retention is inherent rather than secondary. Embodiments of the invention also reduce surgical steps. Caspar pin placement, pre-drilling of screw holes, actuating of screw locking mechanisms, and/or treatment of bone bleeding are eliminated using methods in accordance with embodiments of the invention. Embodiments of the invention permit a greater range of screw angulation during placement. Retention of the screws in embodiments of the plate is inherent and independent of screw angulation up to the point of the screw neck contacting the plate; a wide range of screw angulation is achieved without the screw neck contacting the plate.
According to embodiments of the invention, an orthopedic plate is provided. In some embodiments, the orthopedic plate is a cervical plate for a cervical spine fixation procedure. The orthopedic plate includes an eye member. The eye member includes a biocompatible material formed to define a cylindrical passage through the eye member, the cylindrical passage being sized to receive an orthopedic screw head therein and to provide an interference fit with the orthopedic screw head. The eye member also includes a first frame member engagement contour and a second frame member engagement contour formed on opposite sides of the eye member. The orthopedic plate also includes a plate member. The plate member includes a channel formed by a first frame leg and a second frame leg, both of a biocompatible material. The first frame leg includes a first eye member engagement contour formed on a channel side of the first fame leg that is adapted to engage the first frame member engagement contour of the eye member in sliding engagement. The second frame leg includes a second eye member engagement contour formed on a channel side of the second fame leg that is adapted to engage the second frame member engagement contour of the eye member in sliding engagement. The eye member is contained within and adapted to slide within the channel.
In some embodiments, the first frame member engagement contour and the second frame member engagement contour each include an extension extending laterally away from a center of the eye member, and the first eye member engagement contour and the second eye member engagement contour each include a slot sized and shaped to slidingly receive one extension of the eye member. In some embodiments, the extension of the first frame member engagement contour and the second frame member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions.
In some embodiments, the first eye member engagement contour and the second eye member engagement contour each include an extension extending laterally toward the other frame leg, and the first frame member engagement contour and the second frame member engagement contour each include a slot sized and shaped to slidingly receive one extension of the plate member. In some embodiments the extension of the first eye member engagement contour and the second eye member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions. The orthopedic plate of claim 1, wherein the plate member further includes a static cylindrical passage sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head.
Some embodiments further include another eye member. The other eye member includes a biocompatible material formed to define a cylindrical passage through the other eye member, the cylindrical passage through the other eye member being sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head. The other eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the other eye member. In such embodiments, the plate member further includes another channel formed by a third frame leg and a fourth frame leg, both of a biocompatible material. The third frame leg includes a third eye member engagement contour formed on a channel side of the third fame leg that is adapted to engage the third frame member engagement contour of the other eye member in sliding engagement. The fourth frame leg includes a fourth eye member engagement contour formed on a channel side of the fourth fame leg that is adapted to engage the fourth frame member engagement contour of the other eye member in sliding engagement. The other eye member is contained within and adapted to slide within the other channel.
Some embodiments also include another eye member. The other eye member includes a biocompatible material formed to define a cylindrical passage through the other eye member, the cylindrical passage through the other eye member being sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head. The other eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the other eye member that are adapted to engage the first and second eye member engagement contours of the first and second frame legs. The other eye member is contained within and adapted to slide within the channel (the channel formed by the first and second legs).
According to some embodiments, the orthopedic plate also includes a force-generating mechanism adapted to apply a compressive force between the eye member and the other eye member. According to some embodiments, the force-generating mechanism includes one of a spring, a compliant mechanism, or a nickel-titanium alloy (nitinol) wire.
Some embodiments also include orthopedic screws each having the orthopedic screw head sized to provide an interference fit with the cylindrical passage to thereby form an orthopedic plate system. In some embodiments, each of the orthopedic screws includes a driving feature and a wand-attachment feature adapted to permit retention of the orthopedic screw against a force directed against the orthopedic screw head during interference fitting of the orthopedic screw head in the cylindrical passage.
According to some embodiments, a method of using the orthopedic plate system includes steps of inserting one orthopedic screw into a first anterior portion of a vertebral body of a first vertebra and inserting another orthopedic screw into a second anterior portion of a vertebral body of a second vertebra. The method also includes using the orthopedic screws to distract the disc space for a discectomy and insertion of an interbody implant or graft. The method also includes determining a proper length for the plate member using a distance between the orthopedic screw heads and inserting and positioning the plate member in the wound with the cylindrical passage over one orthopedic screw head. The method further includes locking the plate member to one of the orthopedic screws by drawing the orthopedic screw head into the cylindrical passage of the eye member while pushing the eye member toward the orthopedic screw head until an interference fit is achieved between the orthopedic screw head and the eye member.
In some embodiments, the orthopedic plate further including a motion-stopping structure adapted to at least selectively inhibit sliding motion of the eye member within the channel. In some embodiments, the motion-stopping structure is a structure such as a cylindrical roller clutch structure, a sprag clutch structure, a ball clutch structure, a cylindrical roller clutch structure with an energizing spring, a sprag clutch structure with an energizing spring, a ball clutch structure with an energizing spring, a toothed ratchet mechanism, a self-energizing wedge, an integrated camming member, or an interference fit between the eye member and the channel caused by expansion of the eye member upon insertion of the orthopedic screw head into the cylindrical passage.
In some embodiments, the channel has either an open-ended shape or a closed-ended shape. In some embodiments, the orthopedic plate is sized for use in a cervical vertebra fixation procedure. In some embodiments, the orthopedic plate is part of an orthopedic plate system including an orthopedic screw having the orthopedic screw head. In some embodiments, the orthopedic plate system also includes one or more tools or instruments for driving the orthopedic screw and/or for applying force between the orthopedic screw and the plate member.
According to further embodiment, an orthopedic plate system is provided. The orthopedic plate system is a cervical plate system for a cervical spine fixation procedure. The orthopedic plate system includes a first orthopedic screw having a first threaded shaft extending from a first orthopedic screw head and a second orthopedic screw having a second threaded shaft extending from a second orthopedic screw head. The orthopedic plate system also includes a first eye member. The first eye member includes a biocompatible material formed to define a first cylindrical passage through the first eye member, the first cylindrical passage being sized to receive the first orthopedic screw head therein and to provide an interference fit with the first orthopedic screw head. The first eye member also includes a first frame member engagement contour and a second frame member engagement contour formed on opposite sides of the first eye member.
The orthopedic plate system also includes a second eye member. The second eye member includes a biocompatible material formed to define a second cylindrical passage through the second eye member, the second cylindrical passage through the second eye member being sized to receive the second orthopedic screw head therein and to provide an interference fit with the second orthopedic screw head. The second eye member also includes a third frame member engagement contour and a fourth frame member engagement contour formed on opposite sides of the second eye member.
The orthopedic plate system also includes a plate member. The plate member includes a first channel formed by a first frame leg and a second frame leg, both of a biocompatible material. The first frame leg includes a first eye member engagement contour formed on a channel side of the first fame leg that adapted to engage the first frame member engagement contour of the first eye member in sliding engagement. The second frame leg includes a second eye member engagement contour formed on a channel side of the second fame leg that is adapted to engage the second frame member engagement contour of the first eye member in sliding engagement. The plate member also includes a second channel formed by a third frame leg and a fourth frame leg, both of a biocompatible material. The third frame leg includes a third eye member engagement contour formed on a channel side of the third fame leg that is adapted to engage the third frame member engagement contour of the second eye member in sliding engagement. The fourth frame leg includes a fourth eye member engagement contour formed on a channel side of the forth fame leg that is adapted to engage the fourth frame member engagement contour of the second eye member in sliding engagement. The first eye member is contained within and adapted to slide within the first channel and the second eye member is contained within and adapted to slide within the second channel.
According to some embodiments, the orthopedic plate system further includes motion-stopping structures adapted to at least selectively inhibit sliding motion of the first and second eye members within the first and second channels. According to some embodiments, the first frame leg, the second frame leg, the third frame leg, and the fourth frame leg are integrally formed from a unitary piece of biocompatible material. According to some embodiments, the first channel and the second channel are unitarily formed as a continuous closed-loop channel that is divided by an insert affixed near a center of the continuous closed-loop channel.
According to some embodiments, the orthopedic plate system also includes a force-generating mechanism adapted to apply a compressive force between the first eye member and the second eye member. According to some embodiments, the force-generating mechanism includes one of a spring, a compliant mechanism, or a nickel-titanium alloy (nitinol) wire.
In some embodiments, the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour each includes an extension extending laterally away from a center of the respective eye member, and the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour each include a slot sized and shaped to slidingly receive one extension of the respective eye member. In some embodiments, the extension of the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions.
In some embodiments, the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour each include an extension extending laterally toward the other frame leg, and the first frame member engagement contour, the second frame member engagement contour, the third frame member engagement contour, and the fourth frame member engagement contour each include a slot sized and shaped to slidingly receive one extension of the plate member. In some embodiments the extension of the first eye member engagement contour, the second eye member engagement contour, the third eye member engagement contour, and the fourth eye member engagement contour includes a cross-sectional shape such as a rectangular shape, a rectangular shape with rounded corners, a dovetail shape, a partially circular shape, a partially ellipse shape, a triangular shape, a trapezoidal shape, a polygonal shape, or a shape with one or more out-of-plane protrusions. The orthopedic plate of claim 1, wherein the plate member further includes a static cylindrical passage sized to receive another orthopedic screw head therein and to provide an interference fit with the other orthopedic screw head.
In some embodiments, each of the orthopedic screws includes a driving feature and a wand-attachment feature adapted to permit retention of the orthopedic screw against a force directed against the orthopedic screw head during interference fitting of the respective orthopedic screw head in the respective cylindrical passage.
In some embodiments, the orthopedic plate further including a motion-stopping structure adapted to at least selectively inhibit sliding motion of each of the first eye member and the second eye member within their respective channels. In some embodiments, the motion-stopping structure is a structure such as a cylindrical roller clutch structure, a sprag clutch structure, a ball clutch structure, a cylindrical roller clutch structure with an energizing spring, a sprag clutch structure with an energizing spring, a ball clutch structure with an energizing spring, a toothed ratchet mechanism, a self-energizing wedge, an integrated camming member, or an interference fit between the eye member and the channel caused by expansion of the respective eye member upon insertion of the respective orthopedic screw head into the respective cylindrical passage.
According to some embodiments, a method of using the orthopedic plate system includes steps of inserting the first orthopedic screw into a first anterior portion of a vertebral body of a first vertebra and inserting the second orthopedic screw into a second anterior portion of a vertebral body of a second vertebra. The method also includes using the first orthopedic screw and the second orthopedic screw to distract the disc space for a discectomy and insertion of an interbody implant or graft. The method also includes determining a proper length for the plate member using a distance between the first orthopedic screw head and the second orthopedic screw head and inserting and positioning the plate member in the wound with the first cylindrical passage over the first orthopedic screw head and the second cylindrical passage over the second orthopedic screw head. The method further includes locking the plate member to the first orthopedic screw and the second orthopedic screw by drawing the first orthopedic screw head into the first cylindrical passage of the first eye member while pushing the first eye member toward the first orthopedic screw head until an interference fit is achieved between the first orthopedic screw head and the first eye member and drawing the second orthopedic screw head into the second cylindrical passage of the second eye member while pushing the second eye member toward the second orthopedic screw head until an interference fit is achieved between the second orthopedic screw head and the second eye member.
The frame member 12 of this embodiment of the plate 10 is formed as a unitary construction having a first leg 16 and a second leg 18 defining a first channel 20, and a third leg 22 and a fourth leg 24 defining a second channel 22. The first channel 20 receives and slidingly secures a first of the eye members 14 therein, and the second channel receives and slidingly secures a second of the eye members 14 therein. In some embodiments, the frame member 12 is substantially planar, and in other embodiments, the frame member 12 has a curve to it that generally matches a curve of an anticipated implant location, such as the anterior portion of the cervical spine.
To allow the first channel 20 and the second channel 26 to receive and slidingly secure the eye members 14 therein, each of the legs 16, 18, 22, and 24 has a channel or eye member engagement contour 28 formed on a channel side thereof (a channel-facing or channel defining side of the respective leg 16, 18, 22, or 24). The eye members 14 each have a corresponding frame member engagement contour 30 formed on opposite sides of the eye member 14 such that the contours 30 slidingly engage the contours 28 as shown in
This movement between eye members 14 provides several functions to the plate 10. First, the plate 10 shown in
The eye members 14 each are formed as a unitary construction defining a cylindrical passage 32 therethrough. The cylindrical passage 32 is defined by an inner surface 34 of the eye member 14. In some embodiments, the cylindrical passage 32 defined by the inner surface 34 has a substantially equal diameter throughout a thickness of the eye member 14. In other embodiments, the cylindrical passage 32 has one or more rounded edges and/or has a portion of slightly larger diameter near one or more termini of the cylindrical passage 32. In general, however, the diameter of the cylindrical passage 32 (or of a major portion thereof) is sized to be slightly smaller than a maximum diameter of an orthopedic screw head 36 (not shown in
As used herein, the terms “press fit” or “interference fit” shall be interpreted broadly as including the joining of any two mating parts such that one or the other (or both) parts slightly deviate in size from their nominal dimension, thereby deforming each part slightly, each being compressed, the interface between the two parts creating a union of extremely high friction. The word interference refers to the fact that one part slightly interferes with the space that the other is occupying in its nominal dimension. According to embodiments of the invention, the difference in sizes between the maximum diameter of the screw head 56 and the diameter of the cylindrical passage 32 is sufficiently large that a force sufficient to overcome the resulting interference fit or press fit between the screw head 36 and the eye member 14 is larger than a force sufficient to pull the screw 38 out of a bone. In some embodiments, such a force is at least approximately 200 pounds (approximately 900 Newtons), though those of ordinary skill in the art will recognize that any desirable force of removal may be achieved by way of materials and relative sizing choices.
The frame member 12 of
As illustrated in
In the embodiment labeled E, the contour 28 forms a slot with out-of-plane protrusions extending upward and downward within the slot, while the contour 30 forms an extension with corresponding out-of-plane extensions to engage the slot's extensions. In the embodiment labeled F, the contour 28 forms a slot with a trapezoidal shape and the contour 30 forms an extension with a corresponding trapezoidal shape. The embodiments labeled G and H illustrate that the contour 30 can form a slot while the contour 28 forms an extension (as opposed to the embodiments labeled A-F). It should be noted that while only two shapes are shown in the embodiments labeled G and H, any shape, including the shapes of the embodiments labeled A-F and other shapes not shown could be provided with an extension on contour 28 and a slot on contour 30. In the embodiment labeled G, the contour 28 forms an extension with a rectangular shape (with or without rounded corners), while the contour 30 forms a slot with a corresponding rectangular shape (with or without rounded corners). In the embodiment labeled H, the contour 28 forms an extension with a semicircular end, and the contour 30 forms a slot with a corresponding semicircular end.
While
Other structures may be provided to inhibit or stop attempted outward motion, such as a sprag clutch structure, either with or without an energizing structure such as a spring, a ball clutch structure, again either with or without an energizing structure such as a spring, versions of the wedge 44 discussed with respect to
During manufacture of the embodiment of the plate 10 of
The screw 38 also includes a driving feature 82. The driving feature 82 of this embodiment is illustrated as a hexalobe internal driving feature, but the screw 38 may be provided with any of a variety of internal and external driving features, and embodiments of the invention are not limited to any particular driving feature of the screw 38. The screw 38 also incorporates a wand attachment feature 84, which in this embodiment is illustrated as an undercut spherical diameter formed in the screw head 36. The screw 36 may be provided with any of a variety of internal attachment points, such as threaded and other undercut shapes, and embodiments of the invention are not limited to any particular engagement feature of the screw 38. The attachment feature 38 serves as an attachment point for a locking wand, but may also serve as a retaining feature for drivers, calipers, distractors, and other instruments.
In the embodiment of
Once the screws 38 have been placed, the screws 38 can be used in a manner similar to which Caspar pins had been used previously to facilitate distraction of the disc space, preparation of the disc/disc space, and placement/insertion of a bone graft or interbody spacer/implant. Thus, according to embodiments of the invention, the surgeon may use a distraction instrument that is inserted into the wand attachment feature of the screws 38 and is used to distract the vertebral bodies. Once the discectomy has been performed along with any other disc space preparation, and once the bone graft or interbody spacer has been placed, the distraction may be released and the distraction instrument or instruments are removed. Because no Caspar pins were used, there is nothing to be removed from the bone itself, and there is no need to perform any treatment to minimize bone bleeding.
Either at this point or previously, the surgeon uses a measurement technique to determine an appropriate spacing between the screw heads 36. The appropriate spacing may involve some measure of distraction, although typically once the graft or interbody implant is in place no additional distraction is required. The measurement technique may be any desirable technique. By way of example, the measurement technique may involve taking a radiograph and measuring a spacing of the screw heads 36 in situ. As another example, the spacing of the screw heads 36 in situ may occur through use of a caliper or other measurement tool inserted into the wand attachment features 84 of the screw heads 36. As another example, the spacing of the screw heads 36 may be measured by an app running on a computing device (even as simple as a smart phone) using a photograph of the surgical site and the screw heads 36, as a diameter of the screw heads 36 is known. As discussed previously, embodiments of the plate 10 accommodate a variety of screw spacings, so the measurement of screw spacing need not be as precise as with prior-art orthopedic plates, but a generally accurate measurement facilitates selection of a most-appropriately sized plate 10.
In contrast to prior-art methods, the selection of the size of the plate 10 occurs after the screws 38 have been placed. The size of the plate 10 can be selected based on the optimal placement and orientation of the screws 38 after they have already been placed. Prior-art orthopedic plates and techniques required selection of a desired plate size along with use of individual drilling guides and other tools specifically sized for each plate and that limited placement and orientation of the screws. Accordingly, prior-art devices often resulted in less-than-optimal placement of anchoring screws, which represents a significant risk of adverse results. Embodiments of the invention thus provide significant advantages with respect to screw placement and selection of an optimally sized plate 10.
At this point in the procedure, wands are locked into one or more of the wand attachment features 84 of the screw heads 36, and the plate 10 is passed over and down the wands with the wands in the passage(s) 32 and/or passage 76 until the plate 10 approaches or contacts the screw heads 36 as shown in
The plate 10 is locked to the screw heads 36 by application of forces between the plate 10 and the screw heads 36 that forces the screw heads 36 into the passage(s) 32 and/or passage 76 until an interference fit is achieved between the screw heads 36 and the eye member(s) 14 and/or frame member 12. The forces for locking each screw 38 to the plate 10 may be applied serially or in parallel.
As may be seen in
In summary, embodiments of the invention provide many advantages over prior-art orthopedic plates. The embodiments of the plate 10 allow screws to be placed with full visualization. The plate 10 is guided onto the screws 38 by wands 90 without need for locating instruments or pins. The embodiments of the plate 10 allow eye members 14 to translate within the frame members 12 to match the plate size to the screw placement, without requiring an exact plate size match. Accordingly, inventory carrying requirements can be reduced.
Embodiments of the invention obviate the need to achieve a particular position and angulation of the screws 38. The screws 38 allow more angulation than prior-art orthopedic plates, and the eye members 14 of the plate 10 adjust to the screw position. Accordingly, cumbersome drill and screw guides that were needed previously to place and angle screws correctively relative to the prior-art plates are no longer needed. Furthermore, embodiments of the new plate 10 are introduced into the surgical wound after the screws 38 are placed, so the wound is comparatively empty during screw placement, whereas prior-art orthopedic plates required the plate to be present in the wound during screw placement, interfering with the visualization needed to achieve proper screw placement.
Embodiments of the plate 10 allow the eye members 14 to slide to maintain graft contact. Optional unidirectional regulation of movement of the eye members 14 of certain embodiments assists in maintaining graft compression. Prior-art orthopedic plates, however, typically did not adjust to bone remodeling or subsidence. Embodiments of the plate 10 also allow the implanted screws 38 to function as attachment points for other instruments such as distraction instruments, so separate Caspar pins are not required for distraction, as was often required with prior-art systems. Accordingly, there is less injury done to surrounding bone that must be treated.
Many prior-art orthopedic plates require separate screw-plate retention mechanisms that add bulk to the systems, increase cost of manufacture of the systems, add surgical steps, and that may restrict screw angulation during placement. Embodiments of the plate 10 address these deficiencies. The eye members 14 lock directly onto the screw heads 36 by an interference or press fit and do not require the typical prior-art ring, propeller or wire to sit above the screw head. As a result, the thickness of the system is reduced. The embodiments of the plate 10 also have a reduced locking-related parts count because the retention of the screws 38 is inherent to the eye members 14 rather than secondary. Surgical steps are reduced, as the embodiments of the plate 10 obviate the need for actuating a locking mechanism. Finally, as retention of the screw heads 36 in the plate 10 is inherent and independent of screw angulation up to the point of the screw neck 80 contacting the eye members 14, a wide range of angulation of the screws 38 is permitted.
Surgical techniques associated with embodiments of the plate 10 are significantly simplified with respect to surgical techniques utilized with prior-art systems. A prior-art surgical technique, after creation of the surgical wound to expose the anterior cervical spine would typically involve a number of steps. Such steps would include inserting Caspar-style pins into the vertebral bodies, followed by use of a distractor attached to the pins to distract the disc space. A discectomy would be performed, followed by insertion of an interbody spacer and/or graft. Then, a plate would be trialed in the wound to determine if the plate was appropriately sized. In some instances, multiple plates would be trialed (at an increased cost in sanitation requirements and/or plates considered used and to be destroyed after the surgery). Once a plate size is determined, the plate is positioned and a screw hole is predrilled. The first screw is inserted, the plate is recentered, and the second hole is predrilled and the second screw is inserted. The third and fourth screws are then predrilled and inserted. Typically, a screw-locking procedure is followed for each screw. Thereafter, the Caspar-style pins are removed and bone wax is used to control bleeding.
In some alternate prior-art orthopedic plate insertion procedures, the trialing steps are performed using drill/screw guides. With such systems, a drill guide is positioned after which the first screw hole is pre-drilled, followed by predrilling of the other three screw holes. Care must be taken not to allow the drill guide to move during this procedure, which could cause misalignment such that the plate would not fit properly. Then, the plate is positioned in the wound, and the screws are inserted. Again, a screw-locking procedure is followed for each screw. The steps of removing the Caspar-style pins and using bone wax to control bleeding are similar.
In contrast, the surgical procedure for use with embodiments of the plate 10 is simplified. No Caspar-style pins are used. Instead, the procedure begins, after creation of the surgical wound to expose the anterior cervical spine, with insertion of the two screws 38 into the vertebral bodies with full visualization and with allowance for a greater degree of flexibility in screw placement and angulation. The screws 38 themselves then serve as attachment points for the distractor, and distraction follows with the discectomy and insertion of the interbody spacer and/or graft. The plate length is estimated off of an image (fluoroscopy and/or visual imagery), the plate 10 is inserted into the wound, and the plate 10 is locked to the screw heads 36, whereupon the procedure is done. No separate screw-locking procedure is necessary, and there are no Caspar-style pin wounds to be treated.
While embodiments of the invention have been described herein, it is envisioned that alternate embodiments may also be provided. In one alternate style of the plate 10, the plate 10 is formed of two integrated frame/eye members that incorporate mutual sliding features whereby they slide with respect to each other and not as two eye members 14 sliding with respect to a separate frame member 12 as with certain embodiments previously discussed. The one-eye-member embodiment discussed with respect to
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims the benefit of U.S. Provisional Application No. 62/804,049, filed Feb. 11, 2019, which is incorporated by reference for all it discloses.
| Number | Date | Country | |
|---|---|---|---|
| 62804049 | Feb 2019 | US |
