Patent Application
20090264926
The present disclosure broadly concerns spinal fixation systems and generally relates to a multi-plane adjustment system involving a pivoting screw assembly. The system can be useful for correction of spinal injuries or deformities.
The present disclosure generally relates to a spinal fixation system useful for correction of spinal injuries or deformities. More specifically, but not exclusively, the present disclosure concerns spinal fixation systems allowing for pivotal motion of bone screws and lateral adjustment of spinal rod connectors relative to the bone screws, and providing locking mechanisms for locking the bone screws and connectors at desired positions.
In the realm of orthopedic surgery, it is well known to use implants to fix the position of bones. In this way, the healing of a broken bone can be promoted, and malformations or other injuries can be corrected. For example, in the field of spinal surgery, it is well known to place such implants into vertebrae for a number of reasons, including (a) correcting an abnormal curvature of the spine, including a scoliotic curvature, (b) to maintain appropriate spacing and provide support to broken or otherwise injured vertebrae, and (c) perform other therapies on the spinal column.
Implant and connection systems may include several pieces, which may be associated with only specific other pieces. Bone screws, hooks, clamps or other fixation devices can be connected or adjoined to a particular bone as a connection between the bone and the connection system, which can include a support and/or stabilizing member such as a spinal rod. In such a system, a series of two or more screws may be inserted into two or more vertebrae to be instrumented. A rod is then placed within or coupled to the screws, or is placed within a connecting device that links the rod and a screw, and the connections are tightened. In this way, a rigid supporting structure is fixed to the vertebrae, with the rod providing the support that promotes correction or healing of the vertebral malformation or injury by keeping the vertebrae in a particular position.
A spinal implant system or other similar system may have anchors that can be positioned at a number of angles with respect to the vertebrae or spinal rods. Such a feature allows easier placement of implant systems or correction of positioning of an implant system, in that the bone anchors need not be precisely positioned in angular relation with respect to the vertebrae or spinal rods. Rather, with a multi-axial capability, holes can be drilled in a bone at a convenient location and/or angle, for example, and screws can be inserted therein.
A need remains for spinal fixation systems allowing for multi-plane adjustment and which link elongated member(s) to fixation device(s) and allow for pivoting and other adjustment capabilities of the components of the system.
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claims is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the disclosure as illustrated therein, being contemplated as would normally occur to one skilled in the art to which the disclosure relates.
Referring generally to
In certain embodiments, bone engaging portion 32 can be threaded to engage a bone structure, such as a vertebral body, and solidly anchor screw 22 to the bone structure. In such embodiments, bone engaging portion 32 can include coarse threads readily adapted for solid fixation within the cancellous bone of a vertebral body and can terminate in a tapered tip to assist in the gradual engagement and advancement of the threads into the vertebral body. In alternative embodiments, it should be appreciated that bone engaging portion 32 can have a variety of configurations and/or can be a hook or other such appropriate bone engaging structure. Post portion 34 can also be threaded to engage nut 26 or other such threaded items. In certain embodiments, post portion 34 includes machine threads upon which a surgeon may attach an item, such as a clamp. Nut 26 defines a threaded inner hole 27 to threadedly couple with post portion 34. Nut 26 is operable to lock pivoting post portion 34 at a desired angular position relative to bone engaging portion 32. Turning and tightening nut 26 thereby locks connector 24 at the same desired angular position as post portion 34. In certain embodiments, nut 26 can include locking tabs 28 to further secure and lock system 20 at desired positions.
Additionally, portion 80 can define a through hole 88 in communication with channel 84 configured to receive a retaining member, such as a set screw 85. In certain embodiments, hole 88 can include internal threaded portion(s) to be threadedly coupled with the retaining member to secure an elongate member in channel 84. In such embodiments, the internal threaded portions can include reverse angle threads, i.e. a thread in which the forward face points as disclosed in U.S. Pat. No. 6,296,642, incorporated herein by reference in its entirety. In certain embodiments, retaining member 85 is a generally cylindrical set screw with external threads, but may alternatively be another type of holding or locking mechanism. However, it should be appreciated that the elongate member can be secured in channel 84 by other appropriate methods. In certain embodiments, channel 84 may be non-circular in shape to better allow for a retaining member, such as a set screw, to tightly retain an elongate member in channel 84. It should be appreciated that channel 84 can be configured and shaped differently as would generally occur to one skilled in the art.
In certain embodiments, slot 86 includes a sufficient length along longitudinal axis L to allow for adjustment of post portion 34 and positioning of post portion 34 at any one of a plurality of positions along slot 86. The available positioning of post portion 34 at a plurality of positions along slot 86 thereby allows for the relative positioning of an elongate member received in channel 84 at a plurality of positions relative to bone screw 22. Nut 26 is operable to lock pivoting post portion 34 at a desired position along slot 86.
Referring generally to
To treat the condition or injury of the patient, the surgeon obtains access to the surgical site in a manner well known in the art, e.g. through incision and retraction of tissues. Once access to the surgical site has been obtained, e.g. via an opening such as a midline incision above the affected area, with tissue being resected laterally to the transverse process, or by other surgical procedure, the surgeon may connect one or more implants, such as bone screws, to adjacent or nearby vertebrae that require compression or distraction in order to relieve or improve their condition. For example, pilot holes in vertebrae, e.g. in pedicles, may be made, and anchors (e.g. screws 22) may be inserted into or otherwise connected to two or more vertebrae. In one embodiment, once an appropriate access to a surgical site is obtained, system 20 can be inserted to the surgical site, and may be placed in a desired position at or adjacent certain vertebrae. For example, screw 22 may be inserted into a bony structure, such as a vertebra, at a desired position. Threaded portion 32 of each such screw 22 can be threaded into bone to a desired depth, and connector 24 may be placed on screw 22 so that portion 34 extends through slot 86.
An elongate member (e.g. rod R) is placed in channel 84 of connector 24 either before or after connection of connector 24 to screw 22 or placement of system 20 near vertebrae. Retaining member 85 can be received in hole 88 of connector 24 to loosely hold elongate member R therein, while allowing translational and rotational adjustability. Elongate member R can later be received in another connecting assembly with a bone screw or other implant inserted into another vertebra to secure a section of vertebrae.
In certain embodiments, a user of system 20 can pivot post portion 34 to a desired angular position relative to bone engaging portion 32. In the illustrated embodiment, bottom surface 24b of connector 24 can contact one or more of straight segments 62 of extensions 50 and 52 corresponding to a desired angular position of post portion 34. In alternative embodiments, connector 24 engages extensions 50 and 52 in other manners as would occur to one skilled in the art. Additionally, a user can position post portion 34 at a desired location along slot 86 of connector 24. Prior to locking, connector 24 can pivot with respect to portion 32 of anchor 22, or can be moved around an axis of portion 34 of anchor 22. Connector 24 can also be translated along slot 86 with respect to screw 22. Connector 24 can also be pivoted with respect to or translated along elongated member R.
After multi-plane adjustment of system 20, it can be locked to fix the relative positions of elongated member R, screw 22 and connector 24. In certain embodiments, nut 26 can engage post portion 34 by threading nut 26 down post portion 34 to thereby lock system 20 at the desired position by clamping connector 24 to hinge portion 36 of bone screw 22. In certain embodiments, locking tabs 28 can be used to further engage post portion 24 and lock system 20 and the desired positions. Either before or after locking of system 20, a user can insert portion 32 of anchor 22 in a vertebral body and can insert elongate member R in channel 84. Set screw or other retaining member 85 is tightened in hole 88 to securely hold member R in connector 24. System 20 may generally be assembled prior to use in a surgical procedure. However, it should be appreciated that system 20 can be assembled during the surgical procedure.
As illustrated, hinge portion 136 of bone screw 122 includes extensions 150 and 152. In certain embodiments, extensions 150 and 152 are generally parallel and extend upward from bone engaging portion 132. Additionally, hinge portion 136 can include a hinge pin 54 about which pivoting post portion 134 rotates relative to bone engaging portion 132. Similar to screw 22, post portion 134 and extensions 150 and 152 can include holes to receive hinge pin 54.
Referring generally to
An elongate member (e.g. rod R) is placed in channel 84 of connector 24 either before or after connection of connector 24 to anchor 122 or placement of system 120 near the vertebrae. A retaining member (e.g. set screw 85) can be received in hole 88 of connector 24 to loosely hold elongate member R therein, while allowing translational and rotational adjustability. Elongate member R can later be received in another connecting assembly with a bone screw or other implant inserted into another vertebra to secure a section of vertebrae.
In certain embodiments, a user of system 120 can pivot post portion 134 to a desired angular position relative to bone engaging portion 132. In the illustrated embodiment, bottom surface 24b of connector 24 contacts an upper surface of locking piece 100. Additionally, splines on locking piece 100 contact splines on extensions 150 and 152 at a desired position corresponding to a desired angular position of post portion 134. In alternative embodiments, locking piece 100 engages extensions 150 and 152 in other manners. Additionally, similar to system 20, a user can position post portion 134 at a desired location along slot 86 of connector 24. Connector 24 can pivot with respect to portion 132 and along with portion 134, and can translate along slot 86 with respect to anchor 122. Connector 24 can also be pivoted and/or translated with respect to elongated member R.
After multi-plane adjustment of system 120, it can be locked so as to fix elongated member R, connector 24 and screw 122 with respect to each other. In certain embodiments, engagement of nut 26 to post portion 134 by threading nut 26 down post portion 134 operates to lock system 120 at the desired position by clamping connector 24 between nut 26 and locking piece 100, thereby clamping locking piece 100 to hinge portion 136 of bone screw 122. Additionally, similar to system 120, either before or after locking of system 120, a user can insert bone engaging portion 132 in a vertebra and can insert an elongate member R in channel 84 of connector 24. A retaining member (e.g. set screw 85) may be tightened in hole 88 to securely hold elongated member R to connector 24. System 120 may generally be assembled prior to use in a surgical procedure. However, it should be appreciated that system 120 can be assembled during the surgical procedure.
As illustrated connector 224 can extend along a longitudinal axis L and can include an elongated member engaging portion 280 and an anchor engaging portion 282. Portion 280 defines a substantially C-shaped channel 284 configured for receipt of an elongate member, such as a spinal rod R. In certain embodiments, channel 284 is generally perpendicular to longitudinal axis L. In the illustrated embodiment, channel 284 is a side loading spinal rod channel. However, it should be appreciated that channel 284 can be sized and/or configured differently as would occur to one skilled in the art. Additionally, rod engaging portion 280 can define a through hole 288 in communication with channel 284 configured to receive a retaining member 285, such as a set screw. The retaining member is operable to secure an elongate member in channel 284.
Bone screw engaging portion 282 defines an elongate slot 286 configured for receipt of post portion 134 of bone screw 122. In certain embodiments, slot 286 extends generally along or parallel to longitudinal axis L. Bone screw engaging portion 282 can also define longitudinal grooves 290 adjacent slot 286 configured to engage locking piece 200 (see
Similar to slot 86, slot 286 includes a sufficient length along longitudinal axis L to allow for adjustment of post portion 134 and positioning of post portion 134 at any one of a plurality of positions along slot 286. In certain embodiments, slot 286 includes an upper section 286a having a first length and a lower section 286b having a second length, with upper section 286a adjacent top surface 224a of connector 224 and lower section 286b adjacent bottom surface 224b of connector 224. Additionally, in certain embodiments, lower section 286b includes a greater length along longitudinal axis L than upper section 286a to increase the plurality of positions post portion 134 can occupy in slot 286. The variable positioning of post portion 134 in slot 286 allows for the positioning of an elongate member received in channel 284 at a plurality of distances or positions relative to bone screw 122. In certain embodiments, nut 26 is also operable to lock pivoting post portion 134 at the desired position within slot 286.
Referring generally to
An elongate member (e.g. rod R) is placed in channel 84 of connector 224 either before or after connection of connector 224 to screw 122 or placement of system 220 near the vertebrae. A retaining member (e.g. set screw 85) can be received in hole 288 of connector 224 to loosely hold elongate member R therein, while allowing translational and rotational adjustability. Elongate member R can later be received in another connecting assembly with a bone screw or other implant inserted into another vertebra to secure a section of vertebrae.
In certain embodiments, a user of system 220 can pivot post portion 134 to a desired angular position relative to bone engaging portion 132. In certain embodiments, splines on locking piece 200 can contact splines on extensions 150 and 152 at a desired position corresponding to a desired angular position of post portion 134. In alternative embodiments, locking piece 200 engages extensions 150 and 152 in other manners as would occur to one skilled in the art. Connector 224 can pivot with respect to portion 132 and along with portion 134, and can translate along slot 286 with respect to anchor 122. Connector 224 can also be pivoted and/or translated with respect to elongated member R.
Similar to systems 20 and 120, a user of system 220 can position post portion 134 at a desired location along slot 286 of connector 224 via the sliding engagement of locking piece 200 within connector 224. The positioning of post portion 134 along slot 286 corresponds to the positioning of locking piece 200 along slot 286 by the sliding of fingers 202 along grooves 290.
After multi-plane adjustment of system 220, it can be locked so that elongate member R, connector 224 and anchor 122 are fixed with respect to each other. In certain embodiments, the engagement of nut 26 to post portion 134 by threading nut 26 down post portion 134 thereby locks system 20 at the desired positions by clamping connector 224 and locking piece 200 to hinge portion 136 of bone screw 122. Additionally, similar to systems 20 and 120, a user of system 220 can insert bone engaging portion 132 in a vertebral body and can insert an elongate member in side loading channel 284. System 220 may generally be assembled prior to use in a surgical procedure. However, it should be appreciated that system 220 can be assembled during the surgical procedure.
The parts, features and steps discussed above may be interchanged with each other or among embodiments. Accordingly, anchor 22 may be used with system 220, as one example. The various components of systems 20, 120, and 220 are composed of biocompatible materials such as titanium, stainless steel, certain ceramics or plastics, or others.
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It should be understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.
