Derotation apparatus for treating spinal irregularities

#The present disclosure generally relates to treatment of spinal irregularities. In particular, in one or more embodiments, the present disclosure relates to derotation apparatus and systems that can be used to reduce the rotation of vertebral bodies

#Many types of spinal irregularities can cause pain, limit range of motion, or injure the nervous system within the spinal column. These irregularities can result from, without limitation, trauma, tumor, disc degeneration, and disease. By way of example, scoliosis and kyphosis are irregularities that can result in a complex, three-dimensional problem with lateral curvature of the spine and segmental vertebral rotation. Advances in medicine and engineering have provided doctors with a plurality of devices and techniques for correcting these deformities or irregularities.

#One technique for treating scoliosis is the Harrington rod. The Harrington rod operates on a distraction system attached by hooks to the spine that when distracted, straightens the curve in the spine. Until the 1970's, the Harrington rod was the preferred method of treatment for scoliosis. Follow-up studies of these rods documented the negative effects of using distraction rods alone for correction of spinal deformities, including “flat back syndrome” and the resulting degenerative changes in the lower lumbar spine. Other methods of management, including spinal fixations systems that include segmental wires, hooks, rods and/or bone fasteners (e.g., pedicle screws) have revolutionized the treatment of spinal deformities. The advent and availability of smaller and stronger bone fasteners has further advanced treatment, allowing for effective application of corrective forces to posterior systems into the high thoracic spine.

#FIG. 1 illustrates a derotation apparatus in accordance with one embodiment of the present invention.

#FIG. 2 illustrates an exploded view of a derotation apparatus in accordance with one embodiment of the present invention.

#FIG. 3 illustrates an embodiment of a tube assembly of a derotation apparatus.

#FIGS. 1 and 2 illustrate a derotation apparatus 10 in accordance with an embodiment of the present invention. As illustrated, derotation apparatus 10 comprises a tube assembly 20, a ball joint assembly 30, and a handle assembly 40. Tube assembly 20 may comprise an inner sleeve 50 and an outer sleeve 60 disposed over inner sleeve 50 with inner sleeve 50 having a distal end 70 configured and adapted for attachment to an implant (not illustrated). In an embodiment, the implant may be attached to a vertebral body. Ball joint assembly 30 may comprise at least one ball joint 80. As illustrated, ball joint assembly comprises two ball joints 80. As will be discussed in more detail below, force may be applied to handle assembly 40 to derotate the vertebral body to which the implant is attached. This should result in reducing the rotation between vertebral bodies in a patient's spine. In addition, rotation of the vertebral bodies may also straighten curvature of the spine.

#Referring now to FIGS. 1-5, tube assembly 20 of derotation apparatus 10 will be described in more detail in accordance with one embodiment of the present invention. FIG. 3 illustrates tube assembly 20 with ball joint assembly 30 and handle assembly 40 removed. In general, tube assembly 20 should attach derotation apparatus 10 to the implant (not illustrated). As previously mentioned, tube assembly 20 includes inner sleeve 50 and outer sleeve 60 disposed over inner sleeve 50.

#Inner sleeve 50 includes distal end 70 configured and adapted for attachment to an implant (not illustrated). In an embodiment (not illustrated), distal end 70 fits over at least a portion of an implant. While not illustrated, the inner surfaces of distal end 70 may include features configured and adapted for attachment to the implant. For example, distal end 70 may include a connection that when allows for coupling the inner sleeve 50 to the implant by applying some force. In another embodiment, a dovetail-type connection, such that placement of distal end 70 over the implant with rotation should couple the inner sleeve 50 to the implant, thus preventing separation. Other suitable mechanisms may be used to prevent separation of distal end 70 from the implant. The implant may include any of a variety of surgical implants that may be secured to a vertebral body, including, for example, a spine stabilization system that includes a bone fastener (e.g., a pedicle screw) coupled to a rod. By way of example, distal end 70 may fit over the head of the bone fastener. Distal end 70 may include slots 90 through which the rod extends when distal end 70 is fitted over the bone fastener, for example. Distal end 70 may further include a beveled surface 100.