Patent Application
20150201987
The disclosure is directed to a driver instrument for screwing a bone screw into a bony structure. More particularly, the disclosure is directed to a driver instrument configured to facilitate quick alignment and engagement between a bone screw assembly and a driver instrument advanced into the driver socket of the bone screw.
Bone anchors, such as bone screws, are commonly used in surgical procedures to attach constructs to a bony structure of a patient. For example, spinal stabilization constructs configured to stabilize a spinal segment may utilize bone screws to secure spinal rods or other elongate members to one or more vertebrae of a spinal column by means of a housing fixed to the vertebrae by the bone screw. The bone anchors may be screwed into the bony structure with a driver instrument.
It is desirable to quickly secure the housing and bone screw of a bone screw assembly to a driver instrument such that the screw extends generally coaxially from the driver instrument and is retained coupled to the distal end of the driver instrument during initial engagement of the screw with the bony structure; during advancement of the screw into the bony structure; and may be quickly decoupled from the distal end of the driver instrument following final positioning of the bone screw.
In one embodiment, this disclosure relates to a driver instrument adapted to engage and drive bone screw assemblies which include a bone screw and an associated housing, said driver instrument comprising an elongate shaft having a proximal end and a distal end, the distal end further comprising a driver engagement feature adapted to engage and rotationally drive a head of a bone screw and one or more lugs protruding radially therefrom, said one or more lugs being adapted to engage a housing of a bone screw assembly to limit axial rotation thereof relative to said elongate shaft; and a sleeve having a proximal end, a distal end, and being adapted for coaxial rotation about a common longitudinal axis with the elongate shaft, wherein the distal end of the sleeve includes an engagement feature adapted to rotationally engage a mating engagement feature of the housing of a bone screw assembly.
In another embodiment, this disclosure relates to a method of engaging and a driver instrument with a bone screw assembly comprising:
inserting a distal tip of a driver instrument having an elongate shaft including a driver engagement feature into a driver socket of a bone screw of a bone screw assembly;
inserting one or more lugs of the elongate shaft into mating channels of a housing of the bone screw assembly, wherein inserting one or more lugs of the elongate shaft into mating channels of the housing of the bone screw assembly limits rotation of the housing relative to the elongate shaft;
inserting a sleeve coaxially disposed about the elongate shaft into the housing of the bone screw assembly with the sleeve in a first position, said sleeve including an engagement feature being adapted to rotationally engage a mating engagement feature of the housing of the bone screw assembly; and
rotating the sleeve relative to the elongate shaft and the housing of the bone screw assembly to a second position while positioned in the housing of the bone screw assembly, wherein upon relative rotation of the sleeve with respect to the elongate shaft, the engagement feature of the sleeve couples with the mating engagement feature of the housing of the bone screw assembly.
The above summary of some example embodiments is not intended to describe each disclosed embodiment or every implementation of the aspects of the disclosure.
The aspects of the disclosure may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which:
While aspects of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.
All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many embodiments, the term “about” may be indicative as including numbers that are rounded to the nearest significant figure.
The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).
Although some suitable dimensions, ranges and/or values pertaining to various components, features and/or specifications are disclosed, one of skill in the art, incited by the present disclosure, would understand desired dimensions, ranges and/or values may deviate from those expressly disclosed.
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the disclosure. The illustrative embodiments depicted are intended only as exemplary. Selected features of any illustrative embodiment may be incorporated into an additional embodiment unless clearly stated to the contrary. It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described, unless clearly stated to the contrary.
A bone screw assembly, as described herein, may be a polyaxial, monoaxial or uniplanar bone screw, for example, comprising a threaded shank body having a head portion (e.g., a partial spherical head) and a driver socket, the head portion may be pivotably positioned in a housing, the housing defining an open channel and having a base with a seating surface partially defining a cavity, said housing further comprising two leg portions together defining generally U-shaped channels on opposing sides of the housing adapted to receive and retain an elongate stabilization member. Many such bone screw assemblies include a threaded region within the open channel which extends along the inner surface of the legs of the housing, said threaded region adapted to receive a screw which serves to secure the elongate stabilization member within the two generally U-shaped channels. Other bone screw assemblies include an engagement region configured to engage with another configuration of a locking member inserted between the leg portions to secure an elongate stabilization member therein. The partial spherical surface of the head portion and the seating surface may cooperate to allow rotation and a degree of angulation between the housing and the bone screw. It will be appreciated that a number of variations of bone screw assemblies are known and many such assemblies include retainer structures which hold the bone screw and the housing together as an assembly. Bone screw assemblies suitable for use with the instant driver instruments may include one or both of a protrusion and a groove associated with the legs of the housing which provides a mating engagement feature for an engagement feature of the sleeve of the driver instruments as will be described herein. In some embodiments, the housing may include a plurality of projections or a plurality of grooves which provide the mating engagement feature. In other embodiments, the driver instruments may be adapted to engage a threaded region within the open channel of the housing rather than a separate feature of the housing. In describing the engagement feature of the instant driver instruments and the mating engagement feature of the bone screw assemblies for use therewith, the singular form “feature” will be used as a collective term for all projections, grooves, and combinations thereof which serve to provide an engagement between the sleeve of the driver instrument and the housing of the bone screw as described in detail herein.
An exemplary driver instrument 10 is illustrated at
In some embodiments, the handle 12 may be removably coupled to a proximal end 16 of the elongate shaft 14, such as with a quick-connect feature such as a ball detent. In such embodiments, the quick connect feature optionally may engage a motor-driven element (not shown) associated with the handle 12. In other embodiments, the handle 12 may be permanently coupled to the proximal end 16 of the elongate shaft 14.
As illustrated in
Exemplary aspects of the distal end 18 of the elongate shaft 14 and sleeve 40 are further illustrated in
Referring to
Furthermore, the distal tip 22 may be a tapered distal tip extending from the driver engagement feature 20 to the distal extremity of the driver instrument 10. In some embodiments, the tapered distal tip 22 may be tapered at an angle B from the longitudinal rotational axis X. In some embodiments, the angle B may be in the range of about 25 degrees to about 75 degrees, about 30 degrees to about 60 degrees, or about 45 degrees to about 60 degrees, such as about 30 degrees, about 45 degrees or about 60 degrees.
Accordingly, the second angle B of the tapered distal tip 22 may be greater than the first angle A between the engagement surfaces 30 and the longitudinal rotational axis X. Thus, the driver engagement feature 20 may be tapered toward the distal tip 22 a first amount, and the distal tip 22 may be tapered toward the distal extremity of the elongate shaft 14 a second amount greater than the first amount.
Returning to
As discussed later herein, the distal end of the sleeve 40 may include one or more engagement features 44 configured to engage with the interior of the housing 56 of the bone screw assembly 50 through rotational movement of the sleeve 40 relative to the housing 56 of the bone screw assembly 50. For example, the engagement features 44 of the sleeve 40 may be tabs or protrusions extending in opposite directions from the sleeve 40. In some instances, the engagement features 44, e.g., tabs or protrusions, may extend generally perpendicular to the longitudinal axis of the sleeve 40.
The embodiment of
The housing 56 may be adapted to receive and retain an elongate stabilization member (e.g., a spinal rod, a flexible member, etc., not shown) therein for constructing a stabilization system. For example, the housing 56 may include a pair of legs 58 defining a pair of opposed channels 57, such as U-shaped channels, (see
In some embodiments, the housing 56 may be movably coupled to the typically spherical head 54 of bone screw 52 such that the housing 56 may be pivoted and/or rotated relative to the threaded shank 55 of the bone screw 52. For example, the bone anchor assembly 50 may be a polyaxial screw in which the housing 56 may be pivoted and rotated in a plurality of orientations relative to the bone screw 52. For example, the bone screw 52 may have a longitudinal rotational axis Y (shown in
As will be seen in
During subsequent rotation of the sleeve 40 and the engagement feature 44 relative to the housing 56 from the configuration of
In alternate embodiments of the engagement feature 44 of sleeve 40 and mating engagement feature 70 of housing 56, shown in
Although the engagement feature 44 and mating engagement feature 70 have been characterized as projections and channels or grooves, respectively, including external threaded regions and internal threaded regions, respectively, it will be appreciated that the engagement feature 44 may comprise one or more channels or grooves and the mating engagement feature 70 may comprise one or more projections. Similarly, one of ordinary skill in the art will appreciate that functionally equivalent embodiments (not shown) may be formed in which the engagement feature 44 of the sleeve 40 is present on an inner surface of the sleeve 60 while the mating engagement feature 70 of the housing 56 may be present on an exterior surface thereof.
In certain embodiments, the projections and channels or grooves of the engagement feature 44 and mating engagement feature 70 may lie in a transverse plane substantially perpendicular to the axis of the housing 56 as illustrated in
The sleeve handle 42 may also include an actuation mechanism including an actuator, such as a button 80, actuatable between a first position and a second position in which the elongate shaft 14 and the sleeve 40 are rotationally coupled and decoupled, respectively. In the first position, the button 80 or other actuator selectably engages elongate shaft 14 in a manner which prevents relative rotation between the elongate shaft 14 and the sleeve 40. In the second position, the button 80 or other actuator of the sleeve handle 42 selectably decouples from the elongate shaft 14 and allows relative rotation between the elongate shaft 14 and the sleeve 40 about the central longitudinal axis of the elongate shaft 14. Coupling/decoupling between the elongate shaft 14 and the sleeve 40 and/or sleeve handle 42 may be effected by any convenient means known in the art. An illustrative, non-limiting example, shown in
In addition, the actuation mechanism, such as the button 80 and/or the sleeve handle 42, may be adapted to limit rotation of the sleeve 40 relative to the elongate shaft 14. In certain embodiments, an interaction between the elongate shaft 14 and the aperture 82 of the button 80 suffices to limit rotation of the sleeve 40 relative to the elongate shaft 14 to increments of 90 degrees. In such embodiments, relative rotation of the shaft 14 and the sleeve 40 from a first configuration, in which engagement feature 44 may axially enter channels 57 of the housing 56 when the button is in the first position, to a second configuration allows rotation of engagement feature 44 into engagement with mating engagement feature 70 associated with the legs 58 of the housing 56, while the button 80 is in the second position. In the second configuration, engagement between engagement feature 44 and mating engagement feature 70 effectively couple the sleeve 40, elongate shaft 14, housing 56, and bone screw 52 into a single coaxial unit when the button 80 returns to the first position, such that the driver engagement feature 20 is seated in the driver socket 53 of the head 54 of the bone screw 52, said single coaxial unit being adapted to advance the bone screw 52 into a bony structure 100 when the elongate shaft 14 and sleeve 40 are turned by rotating one or both of the handle 12 and the sleeve handle 42.
In some embodiments, rotation also may be limited by the inclusion of a pin 43 of the sleeve handle 42 which engages an arcuate groove 28 in the elongate shaft 14 as shown in
The driver instrument 10 may be used to select and quickly engage a polyaxial bone anchor assembly 50 comprising a housing 56 and bone screw 52 from an assortment of such screws held in a surgical kit. In the alternative, a single polyaxial screw may be held between the fingers of an operator while the driver instrument 10 is engaged and coupled to the screw.
In use, the distal end 18 of the elongate shaft 14 may be inserted through the housing 56 and into the driver socket 53 in the head 54 of the bone screw 52 which positions the lugs 26 of the elongate shaft 14 in the channels 57 of the housing 56. The lugs 26 limit rotation of the elongate shaft 14 within the housing 56 while interactions among the elongate shaft 14, lugs 26, the driver engagement feature 20 and the driver socket 53 of the bone screw 52 coaxially align the elongate shaft 14, sleeve 40, housing 56, and bone screw 52. Engagement feature 44 of the sleeve 40 follows the lugs 26 into the channels 57 of the housing 56 and is initially positioned within the channels 57. In the illustrated embodiments, the distal end of the sleeve 40 may be inserted between the legs 58 of the housing 56; however in some embodiments the distal end of the sleeve 40 may surround the housing 56 if desired. When the button 80 of the sleeve handle 42 is depressed, the sleeve 40 is free to rotate relative to the elongate shaft 14 thereby allowing the engagement feature 44 of the sleeve 40 to rotate into engagement with the mating engagement feature 70 of the housing 56 while the lugs 26 of the elongate shaft 14 limit rotation of the housing 56. As noted herein, rotation of the engagement feature 44 of the sleeve 40 relative to the elongate shaft 14, and thus relative to the housing 56, may be limited to about 90 degrees by cooperating features of the elongate shaft 14 and the sleeve 40 or sleeve handle 42. Releasing the button 80 of the sleeve handle 42 couples the elongate shaft 14 relative to the sleeve 40 such that turning one of the handle 12, the elongate shaft 14, or the sleeve handle 42 turns both the housing 56 and the bone screw 52 allowing the driver instrument 10 to drive the bone screw 52 into a bony structure 100.
Once the bone screw 52 is properly seated in the bony structure 100, the button 80 may again be depressed allowing the sleeve 40 and thus the engagement feature 44 to counter-rotate to disengage the engagement feature 44 from the mating engagement feature 70 of the housing 56. Once the engagement feature 44 is repositioned within the channels 57 of the housing 56 thereby releasing the sleeve 40 and the elongate shaft 14 from the housing 56, the sleeve 40 and the elongate shaft 14 may be removed from the housing 56 and the bone screw 52.
Those skilled in the art will recognize that aspects of the present disclosure may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the present disclosure as described in the appended claims.
