Patent Application
20160324654
The present invention relates to orthopedic implants and, in particular, it concerns orthopedic implants and corresponding methods in which a change of form of the implant is achieved after insertion of the implant by operation of one or more worm gear.
It is known to provide various types of orthopedic implant which change form after insertion, typically to allow introduction of the implant into the body in a collapsed or small-cross-section form prior to deployment of the implant within the body. Various deployment mechanisms are used to effect the change of form during or after introduction of the implant into the body.
US Patent Application Pre-Grant Publication No. US 2013/0079883 A1 to Butler et al. discloses an expandable spinal interbody device with a worm gear deployment mechanism. A small solid worm element in a blind hole at the proximal side of the implant engages teeth at the base of a pivotally mounted arm to effect lateral displacement of the arm.
The present invention is an orthopedic implant and corresponding method in which a change of form of the implant is achieved after insertion of the implant by operation of one or more worm gear.
According to the teachings of the present invention there is provided, a device comprising: (a) a base having a length defining a direction of elongation of the base; (b) an arm pivotally connected to the base, the arm having a length defining a direction of elongation of the arm; (c) a worm gear configuration comprising: (i) a worm mounted within the base so as to be rotatable about a central axis of the worm, and (ii) a set of gear teeth associated with the arm, the set of gear teeth being deployed to sequentially engage, and be driven by, the worm, such that, when the worm is rotated about its central axis, the arm is driven through a range of pivotal motion relative to the base so as to change an angle of inclination between the direction of elongation of the arm and the direction of elongation of the base, wherein the device is at least part of an orthopedic implant, and wherein the worm is hollow along at least part of a length of the worm so as to define part of a filling channel for introducing biocompatible material into the orthopedic implant.
According to a further feature of an embodiment of the present invention, the arm has a region distanced from the pivotal connection by at least half the length of the arm, the device further comprising a displaceable element, the displaceable element being interconnected with the region of the arm such that displacement of the arm through the range of pivotal motion from an initial position towards a final position causes displacement of at least part of the displaceable portion away from the base.
According to a further feature of an embodiment of the present invention, the displaceable element is interconnected with the region of the arm via a pin-and-slot engagement.
According to a further feature of an embodiment of the present invention, the displaceable element is pivotally interconnected with the base.
According to a further feature of an embodiment of the present invention, a second aim interconnects the displaceable element with the base, the second arm being pivotally interconnected with the base.
According to a further feature of an embodiment of the present invention, there is also provided a second worm gear configuration deployed for driving motion of the second arm relative to the base.
According to a further feature of an embodiment of the present invention, where the arm is referred to as the first arm and the worm is referred to as the first worm, there is also provided: (a) a second arm pivotally connected to the base, the second arm having a length defining a direction of elongation of the second arm; (b) a second worm gear configuration comprising: (i) a second worm mounted within the base so as to be rotatable about a central axis of the second worm, and (ii) a set of gear teeth associated with the second arm, the set of gear teeth being deployed to sequentially engage, and be driven by, the second worm, such that, when the second worm is rotated about its central axis, the second arm is driven through a range of pivotal motion relative to the base so as to change an angle of inclination between the direction of elongation of the second arm and the direction of elongation of the base.
According to a further feature of an embodiment of the present invention, the first worm and the second worm are integrated into a common actuator element so as to rotate together about a common central axis, and wherein the first and second worms have opposing helical handedness and are configured such that, on rotation of the common actuator element, the first and second arms are driven simultaneously in opposing rotation.
According to a further feature of an embodiment of the present invention, the first worm and the second worm are deployed coaxially and are independently rotatable, and wherein the second worm is configured to be rotated by engagement of an actuating tool inserted via the part of the filling channel passing through the first worm.
According to a further feature of an embodiment of the present invention, there is also provided a bridging element bridging between the first and second arms.
According to a further feature of an embodiment of the present invention, the bridging element is a rigid bridging element, and wherein the bridging element is interconnected with at least one of the first and second arms via a pin-and-slot engagement.
According to a further feature of an embodiment of the present invention, the bridging element is a flexible bridging element.
According to a further feature of an embodiment of the present invention, where the arm is referred to as the first arm, there is also provided: (a) a second arm pivotally connected to the base, the second arm having a length defining a direction of elongation of the second arm; (b) a set of gear teeth associated with the second aim, the set of gear teeth being deployed to sequentially engage, and be driven by, the worm, wherein the first aim and the second arm are deployed on opposite sides of the base such that, when the worm is rotated about its central axis, the first and second arms are driven simultaneously through a range of pivotal motion in opposite directions.
According to a further feature of an embodiment of the present invention, where the worm is referred to as the first worm, there is also provided: (a) a third arm pivotally connected to the base; (b) a fourth arm pivotally connected to the base; (c) a second worm gear configuration comprising: (i) a second worm mounted within the base so as to be rotatable about a central axis of the second worm, and (ii) a set of gear teeth associated with each of the third and the fourth arms, the set of gear teeth being deployed to sequentially engage, and be driven by, the second worm, wherein the third arm and the fourth arm are deployed on opposite sides of the base such that, when the second worm is rotated about its central axis, the third and the fourth arms are driven simultaneously through a range of pivotal motion in opposite directions.
There is also provided according to the teachings of an embodiment of the present invention, a device comprising: (a) a base having a length defining a direction of elongation of the base; (b) a first arm pivotally connected to the base, the first arm having a length defining a direction of elongation of the first arm; (c) a second arm pivotally connected to the base, the second arm having a length defining a direction of elongation of the second arm; (d) a first worm gear configuration comprising: (i) a first worm mounted within the base so as to be rotatable about a central axis of the first worm, and (ii) a set of gear teeth associated with the first arm, the set of gear teeth being deployed to sequentially engage, and be driven by, the first worm; and (e) a second worm gear configuration comprising: (i) a second worm mounted within the base so as to be rotatable about a central axis of the second worm, and (ii) a set of gear teeth associated with the second arm, the set of gear teeth being deployed to sequentially engage, and be driven by, the second worm, such that rotation of the first and second worms about their central axes drives the first and second arms through respective ranges of pivotal motion relative to the base so as to change angles of inclination between the directions of elongation of the first and second arms and the direction of elongation of the base, wherein the device is at least part of an orthopedic implant.
According to a further feature of an embodiment of the present invention, the first worm and the second worm are deployed coaxially.
According to a further feature of an embodiment of the present invention, the first worm and the second worm are integrated into a common actuator element so as to rotate together about a common central axis, and wherein the first and second worms have opposing helical handedness and are configured such that, on rotation of the common actuator element, the first and second arms are driven simultaneously in opposing rotation.
According to a further feature of an embodiment of the present invention, the first worm and the second worm are deployed coaxially and are independently rotatable, and wherein the first worm is formed with an inner access channel for allowing insertion of an actuating tool for rotating the second worm via the inner access channel of the first worm.
According to a further feature of an embodiment of the present invention, there is also provided a bridging element bridging between the first and second arms.
According to a further feature of an embodiment of the present invention, the bridging element is a rigid bridging element, and wherein the bridging element is interconnected with at least one of the first and second arms via a pin-and-slot engagement.
According to a further feature of an embodiment of the present invention, the bridging element is a flexible bridging element.
There is also provided according to the teachings of an embodiment of the present invention, a device comprising: (a) a base having a length defining a direction of elongation of the base; (b) an aim pivotally connected to the base, the arm having a length defining a direction of elongation of the arm; (c) a worm gear configuration comprising: (i) a worm mounted within the base so as to be rotatable about a central axis of the worm, and (ii) a set of gear teeth associated with the arm, the set of gear teeth being deployed to sequentially engage, and be driven by, the worm, such that, when the worm is rotated about its central axis, the arm is driven through a range of pivotal motion relative to the base so as to change an angle of inclination between the direction of elongation of the arm and the direction of elongation of the base, wherein the device is at least part of an orthopedic implant, and wherein the worm is located in a distal half of the base.
The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
The present invention is an orthopedic implant and corresponding method in which a change of form of the implant is achieved after insertion of the implant by operation of one or more worm gear.
The principles and operation of implants and methods according to the present invention may be better understood with reference to the drawings and the accompanying description.
Referring now to the drawings,
In general terms, each of the devices shown has a base 10 with a length defining a direction of elongation 12 of the base and at least one arm 14, pivotally connected to base 10, typically by engagement of a pivot pin 15. Each arm 14 has a length defining a direction of elongation 16 of the arm. The device includes at least one worm gear configuration having a worm 18 mounted within base 10 so as to be rotatable about a central axis of the worm, and a set of gear teeth 20 associated with arm 14. The set of gear teeth 20 is deployed to sequentially engage, and be driven by, the worm, such that, when the worm 18 is rotated about its central axis, the arm 14 is driven through a range of pivotal motion relative to the base so as to change an angle of inclination between the direction of elongation 16 of the arm 14 and the direction of elongation 12 of the base 10.
In certain preferred embodiments, the worm (or one of a plurality of worms) is located at or near a proximal end of the base, i.e., with at least part of the worm lying within 20% of the length of the base from the proximal end of the base. In such cases, certain particularly preferred implementations of the invention employ a worm which is hollow along at least part of its length so as to define part of a filling channel for introducing biocompatible material into the orthopedic implant.
In certain preferred embodiments, the worm (or one of a plurality of worms) is located in a distal half of the base, i.e., with the worm lying within 50% of the length of the base from the distal end of the base. In such cases, rotation of the distally-located worm is achieved either by integration of the worm with a core element extending along the length of the base or by use of an elongated tool, such as a hex key or screwdriver, inserted along an access channel through the base. These implementations facilitate a range of geometrical configurations and clinical procedures which would not be possible with only a proximally-located worm, as will be exemplified below.
In certain preferred embodiments, a pair of worms, typically deployed coaxially along the base, is used to deploy two or more arms.
Specific non-limiting examples of all of the above aspects of the invention, and other innovative features, will be presented below with reference to specific drawings.
Before addressing features of the preferred embodiments in more detail, it will be helpful to define certain terminology as used herein in the description and claims. The term “worm” is used herein in the description and claims to refer to a rotatable element with a helical thread or groove. The “worm” is used as part of a “worm gear configuration” in which an adjacent arm with teeth engaging the worm is rotated by operation of the worm to rotate around a pivot axis perpendicular to a central axis of the worm. Where the worm is part of an elongated structure extending axially beyond the region of the helical groove, the term “worm” is used to refer only to the region in which the helical groove engages the adjacent teeth.
The term “handedness” is defined herein as the property of a helix or helical channel of being either right-handed (like a normal screw thread) or left-handed (like a reverse screw thread).
The “inclination” between two lines is defined herein as the angle formed by one line relative to an intersecting line which is parallel to the second line, even if actual lines do not intersect or are even non-coplanar.
Where reference is made to introducing a biocompatible material “into” the implant, it should be noted that this includes cases where the material is introduced into, and remains within, the implant as well as cases where the material is introduced into, and passes through, the implant. In certain preferred embodiments, the implant once deployed at least partially defines an enclosed volume which may be partially or entirely filled, depending upon the intended application, by introduction of suitable biocompatible material, such as for example bone particles or other material for encouraging bone growth.
Turning now to device 100 as illustrated in
Proximal worm 18a is shown here formed with a central channel 28, aligned with a corresponding opening 30 in the proximal end of base 10, thereby rendering proximal worm 18a hollow. Channel 28 here provides one or more of a number of functions. Firstly, channel 28 is preferably formed with a hexagonal (or other non-circular) cross-section such that it acts as a socket for engagement by a corresponding hex-key (or other complementary) tool (not shown) to allow application of a torque to turn the actuator element 22 with its two associated worms 18a and 18b. Additionally, after reaching the desired degree of deployment and removing the tool, channel 28 forms part of a channel for introducing a biocompatible material into the implant. For this purpose, a medial region of actuator element 22 is preferably formed with lateral openings 32, which form a contiguous filling channel with opening 30 and channel 28, thereby allowing introduction of biocompatible material into interior volumes, enclosed volumes and/or spaces adjacent to the orthopedic implant.
In the example shown here, a displaceable element 34 is interconnected with a region of arms 14a and 14b in the half of the arms further from the connection with base 10, and typically near the ends of the arms. In the case shown here, displaceable element 34 is a rigid bridging element interconnected to arms 14a and 14b via a pin-and-slot engagement. Specifically, each of the arms is shown here with a laterally (here bilaterally) projecting pin 36 which engages corresponding slots 38 in displaceable element 34. It will be appreciated that this engagement can be reversed, and/or the arms may be forked and pass externally to a central bridging element.
Proximal and distal worms 18a and 18b preferably have opposing helical handedness and are configured such that, on rotation of actuator element 22 as illustrated by arrow 40 in
The geometry of the worm gear configuration is such that arms 14a and 14b are locked at all stages of deployment. In other words, due to frictional locking of the teeth 20a, 20b within the corresponding worm grooves, force applied to the arms will not rotate the worms. The implant is thus stable in all states, and can be opened to a greater or lesser degree according to the requirement of each particular case while ensure structural stability and load-bearing capabilities in whatever state the device has reached.
The available range of angular displacement of the arms may vary between implementations. In most cases, the initial insertion state has the direction of elongation of the arms near parallel (e.g., inclined by no more than 20 degrees) to the direction of extension of base 10, thereby forming a compact form for insertion in a minimally invasive procedure. A fully deployed state of each arm is typically at an inclination of at least 30 degrees, and may reach angles of 60 degrees or even 90 degrees. In certain implementations, as exemplified below in
In the embodiment illustrated here, a threaded bore 50 allows detachable engagement between a threaded holder (not shown) and the device during introduction of the device into the body and manipulation into the desired position. One or more tool (not shown) for actuating the worm(s) may be part of an integrated delivery system together with the holder, or may be an independent tool introduced separately.
Turning now to
The ability to control the worms individually allows for one arm to be opened to a greater or lesser extent than the other. Most preferably, reverse handedness of the worms is still used in order to allow equal opening of the two arms when the two engagement elements are rotated together. The ability to achieve a variable degree of opening of each arm individually is particularly useful in a range of procedures. By way of example, if used as an upright expanding cage structure between adjacent vertebral endplates, the independent adjustment allows the surgeon to choose a suitable combination of intervertebral height restoration plus lordotic (or scoliosis) correction.
In all other respects, the structure and function of device 200 will be understood by analogy to device 100 described above.
Turning now to
In the case of device 300, the worm gear configuration is located in the proximal region of base 10. In this case, a hollow worm 18 is used, with structure and function analogous to that of worm 18a of device 100 described above.
In the case of device 350, the worm gear configuration is located in the distal half of the base. In this case, actuation of the worm may be either by insertion of an actuating tool along an open channel through base 10 (analogous to operation of worm 18b of device 200), or else the worm may be integrated with a hollow rotatable plug 56 with a proximal shaped socket for allowing operation by a suitable key.
One particularly preferred but non-limiting exemplary application for device 400 is illustrated schematically in.
Turning now to
Turning now to
Turning now to
Turning now to
Finally,
It is understood that the teeth/ridges/pyramids may be included on the surfaces (of any/all embodiments shown) that come in contact with bony tissue in order to minimize migration and/or improve fixation of the device to the anatomy.
It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the scope of the present invention as defined in the appended claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2014/066823 | 12/11/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61914435 | Dec 2013 | US | |
| 61951566 | Mar 2014 | US |
