Patent Application
20080262494
The present disclosure relates generally to surgical tools. More specifically, the present disclosure relates to surgical tools used to distract vertebra and to compress vertebra.
In human anatomy, the spine is a generally flexible column that can take tensile and compressive loads. The spine also allows bending motion and provides a place of attachment for keels, muscles and ligaments. Generally, the spine is divided into three sections: the cervical spine, the thoracic spine and the lumbar spine. The sections of the spine are made up of individual bones (vertebrae) that are separated from each other by intervertebral discs.
The intervertebral discs function as shock absorbers and as joints. Further, the intervertebral discs can absorb the compressive and tensile loads to which the spinal column may be subjected. At the same time, the intervertebral discs can allow adjacent vertebral bodies to move relative to each other a limited amount, particularly during bending, or flexure, of the spine. Thus, the intervertebral discs are under constant muscular and/or gravitational pressure and generally, the intervertebral discs are the first parts of the lumbar spine to show signs of deterioration.
Facet joint degeneration is also common because the facet joints are in almost constant motion with the spine. In fact, facet joint degeneration and disc degeneration frequently occur together. Generally, although one may be the primary problem while the other is a secondary problem resulting from the altered mechanics of the spine, by the time surgical options are considered, both facet joint degeneration and disc degeneration typically have occurred. For example, the altered mechanics of the facet joints and/or intervertebral disc may cause spinal stenosis, degenerative spondylolisthesis, and degenerative scoliosis.
One surgical procedure for treating these conditions is spinal arthrodesis, i.e., spine fusion, which can be performed anteriorally, posteriorally, and/or laterally. The posterior procedures include in-situ fusion, posterior lateral instrumented fusion, transforaminal lumbar interbody fusion (“TLIF”) and posterior lumbar interbody fusion (“PLIF”). Solidly fusing a spinal segment to eliminate any motion at that level may alleviate the immediate symptoms, but for some patients maintaining motion may be beneficial. It is also known to surgically replace a degenerative disc or facet joint with an artificial disc or an artificial facet joint, respectively.
A spinal tool is disclosed and can include a first arm and a second arm. A rack can extend from the first arm. Further, a pinion gear can be coupled to the second arm. The pinion gear can engage the rack. The spinal tool can also include a worm gear engaged with the pinion gear.
In another embodiment, a spinal tool is disclosed and can include a first arm and a second arm. A rack can extend from the first arm. A pinion gear can be located within the second arm and the pinion gear can engage the rack. The spinal tool can further include a worm gear engaged with the pinion gear. The worm gear can substantially prevent relative motion between the first arm and the second arm while the worm gear is stationary.
In yet another embodiment, a spinal tool is disclosed and can include a rack, at least one gear engaged with the rack, and a worm gear engaged with the at least one gear. The worm gear can substantially prevent the at least one gear from moving relative to the rack while the worm gear is stationary. Further, as the worm gear is rotatable to move the at least one gear relative to the rack.
In still another embodiment, a method of using a surgical tool is disclosed and can include disengaging a pinion gear on the surgical tool from a rack on the surgical tool. Further, the method can include sliding a second arm relative on the surgical tool relative to a first arm and re-engaging the pinion gear with the rack.
In another embodiment, a method of altering a distance between a first vertebra and a second vertebra using a surgical tool is disclosed. The method can include attaching a first arm of the surgical tool to the first vertebra and attaching a second arm of the surgical tool to the second vertebra. The surgical tool can include a rack extending from the first arm and a pinion gear coupled to the second arm and engaged with the rack. Further, the surgical tool can include a worm gear engaged with the pinion gear. The method can also include rotating the worm gear to move the pinion gear along the rack and to move the second arm relative to the first arm.
In yet still another embodiment, a method of enlarging a space within tissue is disclosed and can include engaging a first arm of the surgical tool with a first side of the space and engaging a second arm of the surgical tool with a second side of the space. The surgical tool can include a rack extending from the first arm and a pinion gear coupled to the second arm and engaged with the rack. Further, the surgical tool can include a worm gear engaged with the pinion gear. The method can also include rotating the worm gear to move the pinion gear along the rack and to move the second arm relative to the first arm. As the second arm moves relative to the first arm, the space can enlarge.
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In a particular embodiment, the first arm 500 can include a base 502. An intermediate segment 504 can extend from the base 502. Further, a distal segment 506 can extend from the intermediate segment 504. The base 502 of the first arm 500 can have a proximal end 510 and a distal end 512. The distal end 512 can include a distal groove 514 that is flanked by a first distal end portion 516 and a second distal end portion 518. As indicated, the first distal end portion 516 can be formed with a first distal hole 520 and the second distal end portion 581 can be formed with a second distal hole 522.
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The rack 572 can include a proximal end 574 and a distal end 576. The proximal end 574 of the rack 572 can be attached to the base 502 of the first arm 500. Further, as shown, the rack 572 can be formed with a plurality of teeth 578. As described in detail below, the second arm 600 can move linearly along the rack 572 to enlarge a space within tissue or to reduce a space within tissue. For example, the second arm 600 can move linearly along the rack 572 in order to distract vertebra or compress vertebra.
In a particular embodiment, the second arm 600 can include a base 602. An intermediate segment 604 can extend from the base 602. Further, a distal segment 606 can extend from the intermediate segment 604. The base 602 of the second arm 600 can have a proximal end 610 and a distal end 612. The distal end 612 can include a distal groove 614 that is flanked by a first distal end portion 616 and a second distal end portion 618. As indicated, the first distal end portion 616 can be formed with a first distal hole 620 and the second distal end portion 681 can be formed with a second distal hole 622.
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Commencing at block 900, the pinion gear can be disengaged from the rack. The pinion gear can be disengaged from the rack by sliding a shaft connected to the pinion gear relative to the rack. As such, the pinion gear can be slid off of the rack and disengaged from the rack. At block 902, the second arm can be slid along the rack relative to the first arm. The second arm can be slid toward the first arm or away from the first arm.
Moving to block 904, the pinion gear can be re-engaged with the rack. The pinion gear can be re-engaged with the rack by releasing the shaft and allowing a spring to bias the pinion gear back into position relative to the rack. The shaft can also be rotated in order to properly align the gears on the pinion gear with the rack. At block 906, the first arm can be attached to a first vertebra. Alternatively, the first arm can be attached to a first implant, or a first portion of an implant. The implant can be attached to, or otherwise engaged with, the first vertebra. As such, the first arm can be directly or indirectly attached to, or engaged with, a first vertebra.
Also, at block 908, the second arm can be attached to a second vertebra. Alternatively, the second arm can be attached to a second implant, or a second portion of an implant. The implant can be attached to, or otherwise engaged with, the second vertebra. As such, the second arm can be directly or indirectly attached to, or engaged with, a second vertebra. In a particular embodiment, each arm can be connected to a respective vertebra using a bone screw that can extend through a collar that extends from each arm.
Proceeding to block 908, the handle on the spinal tool can be rotated in order to move the second arm relative to the first arm. In a particular embodiment, rotating the handle in a first direction can move the second arm toward the first arm. Further, rotating the handle in a second direction can move the second arm away from the first arm. At decision step 912, a surgeon can determine whether a correct distance between the vertebra has been reached. If not, the method can return to block 910 and the handle can be rotated further. If a correct distance is reached at block 912, the method can proceed to block 914 and the handle can be released. When the handle is released, the worm gear connected to the handle can prevent the pinion gear from moving relative to the rack. As such, the second arm can be locked in place relative to the first arm and the spinal tool can substantially prevent a distance between the first vertebra and the second vertebra from changing.
At block 916, a spinal device can be installed along the vertebra. In a particular embodiment, the spinal device can be a spinal fixation device, a spinal fusion device, an intervertebral prosthetic disc, a nucleus implant, another spinal device, or a combination thereof. Continuing to decision step 918, it can be determined whether the installation of the spinal device is complete. If not, the method can return to block 916 and the installation of the spinal device can continue. On the other hand, if the installation of the spinal device is complete, the method can continue to block 920 and the pinion gear can be disengaged from the rack, e.g., as described above. In a particular embodiment, disengaging the pinion gear from the rack can relieve any tension on the spinal tool and can allow the spinal tool to be removed from the patient.
Moving to block 922, the first arm of the spinal tool can be disengaged from the first vertebra, e.g., by removing the bone screw connecting the first arm to the first vertebra. Also, at block 924, the second arm of the spinal tool can be disengaged from the second vertebra, e.g., by removing the bone screw connecting the second arm to the second vertebra. Thereafter, at block 926, the spinal tool can be removed from the surgical field. The method can then end at state 928.
With the configuration of structure described above, the spinal tool provides a device that can be used distract vertebra. Further, the device can be used to compress vertebra. The configuration of the gearing allows the spinal tool to be self-locking and the need for an additional locking mechanism, e.g., a pawl, is obviated. Further, the spinal tool can be used to enlarge a space within other tissue, e.g., the spinal tool can be used a rib spreader or as a retractor. In such a case, the arms of the spinal tool may be modified so that each arm includes a paddle and each paddle can be engaged with a portion of the space. As the handle on the spinal tool is rotated, the arms can move relative to each other and the paddles can cause the space in which the tool is installed to enlarge. When rotation of the handle is ceased, the worm gear can prevent the pinion gear from moving along the rack and can substantially lock the tool and prevent relative motion between the arms - except for any motion caused by deflection of the arms due to external forces placed thereon.
The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments that fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
