The present invention relates to methods and devices for use in spinal surgery, and in particular to rod reduction devices and methods for using the same.
Spinal fixation devices are used in orthopedic surgery to align and/or fix a desired relationship between adjacent vertebral bodies. Such devices typically include a spinal connector, such as a relatively rigid fixation rod, that is coupled to adjacent vertebrae by attaching the element to various anchoring devices, such as hooks, bolts, wires, or screws. The fixation rods can have a predetermined contour that has been designed according to the properties of the target implantation site, and once installed, the instrument holds the vertebrae in a desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
Spinal fixation devices can be anchored to specific portions of the vertebra. Since each vertebra varies in shape and size, a variety of anchoring devices have been developed to facilitate engagement of a particular portion of the bone. Pedicle screw assemblies, for example, have a shape and size that is configured to engage pedicle bone. Such screws typically include a threaded shank that is adapted to be threaded into a vertebra, and a head portion having a rod-receiving element, usually in the form of a U-shaped slot formed in the head. A set-screw, plug, cap, or similar type of fastening mechanism, is used to lock the fixation rod into the rod-receiving head of the pedicle screw. In use, the shank portion of each screw is threaded into a vertebra, and once properly positioned, a fixation rod is seated through the rod-receiving member of each screw and the rod is locked in place by tightening a set screw or other fastener mechanism to securely interconnect each screw and the fixation rod.
While current spinal fixation systems have proven effective, one challenge associated with such systems is mounting the fixation rods into the rod-receiving member of various fixation devices. In particular, it can be difficult to align and seat the rod into the rod receiving portion of adjacent fixation devices due to the positioning and rigidity of the vertebra into which the fixation device is mounted. Thus, the use of a spinal rod reduction device, also sometimes referred to as a spinal rod approximator, is often required in order to grasp the head of the fixation device and reduce the rod into the rod-receiving head of the fixation device.
While several rod reduction devices are known in the art, some tend to be bulky and cumbersome to use. Accordingly, there is a need for improved rod reduction devices and methods for seating a spinal rod in a rod-receiving member of one or more spinal anchors.
The present invention provides methods and devices for placing a spinal fixation rod into a rod-receiving head of a spinal implant. In one embodiment, the device can include a clamping member and a rod-reducing arm. The clamping member can be adapted to removably mate to a rod-receiving head of a spinal implant. The rod-reducing arm can be rotatably matable to the clamping member such that rotation of the rod-reducing arm with respect to the clamping member is effective to reduce a rod into a rod-receiving head of a spinal implant that is mated to the clamping member.
In general, the rod-reducing arm can include an elongate member having first and second opposed arms that are disposed at a distal end thereof. In one embodiment, the first and second opposed arms can be integrally formed on a distal end of the elongate member. In another embodiment, the first and second opposed arms can be pivotably coupled to a distal end of the elongate member. In this embodiment, the device can include an actuator that is operatively associated with the first and second opposed arms and is adapted to pivot the first and second opposed arms between open and closed positions.
In another embodiment, the rod-reducing arm can take the form of forceps that have first and second opposed arms that are movably coupled to one another at a location that is proximal to a distal end of each arm. A telescoping pin can extend between the first and second opposed arms and can be adapted to guide the first and second opposed arms between open and closed positions. The device can also include a ratcheting mechanism that is coupled to the first and second opposed arms and is adapted to lock the opposed arms in a fixed position.
The device can also include a post that extends outward from the rod-reducing arm and is adapted to abut against a rod to reduce a rod into a rod-receiving head of a spinal implant. In one embodiment, the post can include a concave distal surface that is adapted to engage a rod.
A variety of configurations are also available for the clamping member of the reduction device including, for example, first and second clamping jaws that are pivotably coupled to the first and second opposed arms of the rod-reducing arm and are adapted to removably mate to opposed sides of a rod-receiving head of a spinal implant. In one embodiment, the first and second clamping jaws are substantially C-shaped. A mating element can be formed on an inner facing surface of the first and second clamping jaws and be adapted to removably mate the jaws to a rod-receiving head of a spinal implant. The first and second clamping jaws can also be biased such that a force must be applied to the jaws to cause the jaws to pivot. In one embodiment, a pin can extend through the first and second clamping jaws and be adapted to maintain the alignment of the jaws with respect to each other and the opposed arms of the rod-reducing arm.
Exemplary rod reduction systems are also provided. In one embodiment, the rod reduction system can include a spinal implant and a rod reduction device. The spinal implant can include a rod-receiving head and a bone-engaging portion. A variety of configurations are available for the rod reduction device, including those discussed above. The system can further include a spinal rod that is adapted to be received by the rod-receiving head of the spinal implant.
Methods for reducing a rod into a rod-receiving head of a spinal implant are also provided. The method can generally include mating a clamping member of a rod reduction device to a rod-receiving head of a spinal implant and rotating a rod-reducing arm that is pivotally mated to the clamping member to thereby reduce a rod into the rod-receiving head of the spinal implant. In one embodiment, the clamping member can first be mated to the rod-receiving head of a spinal implant and the rod-reducing arm can then be mated to the clamping member to facilitate reduction of a rod into the rod-receiving head.
The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.
Disclosed herein are methods and devices for reducing a rod disposed within or adjacent to a rod-receiving head of a spinal implant. In general, a rod reduction device is provided that can removably mate to the rod-receiving head of a spinal implant and be effective to reduce a rod disposed within or adjacent to the rod-receiving head. In an exemplary embodiment, the rod reduction device can include a clamping member that is adapted to removably mate to a rod-receiving head of a spinal implant and a rod-reducing arm that is rotatably matable to the clamping member. The rod-reducing arm can be configured such that rotation of the arm with respect to the clamping member is effective to reduce a rod into the rod-receiving head of the spinal implant that is mated to the clamping member. The rod reduction device can be used with a variety of spinal implants in addition to various other tools.
As indicated above, the rod reduction device 10 can include a rod-reducing arm 12. While a variety of configurations are available for the rod-reducing arm 12, the arm 12 can generally be an elongate member 13 that includes first and second opposed arms 24, 26 that are disposed at a distal end 13b thereof. In one exemplary embodiment, shown in
In another embodiment, the elongate member 13 can take the form of forceps. For example, as shown in
A variety of configurations are also available for the first and second opposed arms 24, 26 that are disposed at a distal end 13b of the elongate member 13 of the rod-reducing arm 12. In general, the opposed arms 24, 26 can form a substantially U-shaped member 16 at the distal end 12b of the elongate member 13. The U-shaped member 16 can be aligned with the longitudinal axis L of the elongate member 13 (as shown in
For example, in one exemplary embodiment, shown in
The rod-reducing arm 12 of the rod-reduction device 10 can further include a reduction post 32 that is adapted to reduce a rod into a rod-receiving head of a spinal implant. In general, the reduction post 32 can extend outward from a bottom facing surface 38 of the rod-reducing arm 12 and be adapted to abut against a rod that is disposed adjacent to a rod-receiving head of a spinal implant that is mated to the clamping member 14 of the device 10. A variety of configurations are available for the reduction post 32. For example, as shown in
As indicated above, the rod reduction device 10 can also include a clamping member 14. The clamping member 14 of the rod reduction device 10 can have a variety of configurations and is generally adapted to securely grasp a rod-receiving head of a spinal implant. In one exemplary embodiment, shown in
The clamping member 14 can be configured to maintain the parallel alignment of the first and second jaw members 14a, 14b with respect to each other and the opposed arms 24, 26 of the rod-reducing arm 12. A variety of techniques can be used to maintain the alignment of the jaw members 14a, 14b. For example, in one embodiment shown in
In another embodiment, the jaw members 14a, 14b can be biased such that a force must be applied to the jaws 14a, 14b to cause the jaws 14a, 14b to pivot. Several techniques can be used to bias the clamping jaws 14a, 14b including, for example, biasing elements (not shown), such as springs, that are disposed in the first and second opposed arms 24, 26 of the rod-reducing arm 12. The springs can be positioned in a groove or channel formed in the first and second opposed arms 24, 26 and can extend from a proximal portion of the opposed arm 24, 26 to a distal end of the arm. Distal portions of the springs can be disposed in grooves formed in the pivot pins 15a, 15b that mate the jaw members 14a, 14b to the opposed arms 24, 26. In one exemplary embodiment, the springs can apply a downward force to the grooves formed in the pivot pins 15a, 15b to bias the jaw members 14a, 14b at an angle with respect to the opposed arms 24, 26. Such a configuration can maintain the parallel alignment of the of the jaw members 14a, 14b and prevent the jaw members 14a, 14b from pivoting out of alignment while the rod-reduction device 10 is being mated to a rod-receiving head of a spinal implant. In use, the springs can be configured to flex upward to allow the rod-reducing arm 12 to rotate with respect to the clamping jaws 14a, 14b to thereby reduce a rod into the rod-receiving head of the spinal implant that is engaged by the jaw members 14a, 14b. In addition to providing a biasing force, the springs can also facilitate attachment of the jaw members 14a, 14b to the opposed arms 24, 26.
The hemispherical surface 14′ that forms each jaw member 14a, 14b can be configured to mate to the rod-receiving head of a spinal implant. For example, in the exemplary embodiment shown in
As indicated above, in one exemplary embodiment, the rod-reducing arm 12 and clamping member 14 can be separate components that are mated to each other in use. Such a configuration is illustrated in
Methods for reducing a rod 40 into a rod-receiving head 61 of a spinal implant 60 are also provided.
As shown in
Once the clamping member 14 is properly positioned, the handle can be used to move the opposed arms to the closed position to cause the first and second jaw members 14a, 14b to engage the head 61 of the implant 60. A ratchet mechanism that is associated with the first and second opposed arms 24, 26 can be used to maintain the rod reduction device 10 in the closed position. The rod-reducing arm 12 can then be rotated with respect to the clamping member 14 to reduce the rod 40 into the rod-receiving head 61 of the spinal implant 60. As explained above, as the rod-reducing arm 12 is rotated, a reduction post 32 that is disposed on the arm 12 (or another portion of the arm) can abut the spinal rod 40 and apply a downward force to the rod 40 to reduce the rod 40 into the head 61 of the implant 60. When the rod 40 is fully reduced, the rod reduction device 10 can be removed from the spinal implant 60 and a fastener (not shown) can be applied to secure the rod within the head of the implant.
One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.