Patent Application
20070191856
The distraction of adjacent vertebrae is a common requirement when treating trauma or disease to the spine. For example, reconstruction of a damaged joint with a functional joint prosthesis to provide motion and to reduce deterioration of the adjacent bone and adjacent joints is a desirable treatment option for many patients. For the surgeon performing the joint reconstruction, specialized instrumentation and surgical methods may be useful to facilitate precise placement of the prosthesis.
In one embodiment, a distractor assembly for preparing an intervertebral disc space between a first vertebra and a second vertebra comprises a cross bar and first and second distracting arms connected to the cross bar. Each of the distracting arms comprises a base portion and a moveable portion connected to the base portion via a length adjustment assembly operable to cause translation of the moveable portion relative to the base portion, thereby to adjust a length of the distracting arm.
In another embodiment, a method of using a distractor assembly to prepare an intervertebral disc space between a first vertebra and a second vertebra includes attaching first and second distractor arms of the distractor assembly to anchoring devices connected to the vertebrae and adjusting a length of one of the distractor arms using a length adjustment assembly connecting a base portion of the distractor arm to a moveable portion of the distractor arm.
The present disclosure relates generally to the field of orthopedic surgery, and more particularly to a distraction device for use during vertebral reconstruction using an intervertebral prosthesis. For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments or examples 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 invention is thereby intended. Any alteration and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
Referring first to
In other embodiments, various different reasons may exist for accessing the intervertebral disc 12, or the disc space. These include such procedures as inserting one or more fusion implants, injecting material into the disc space, examining the disc space treated in a prior procedure, and so forth.
Continuing with the prior example, during a surgical technique for repairing the damaged disc 12, all or a portion of the disc may be excised. This procedure may be performed using an anterior, anterolateral, lateral, or other approach known to one skilled in the art, however, the following embodiments will be directed toward a generally anterior approach. Generally, the tissue removal procedure may include positioning and stabilizing the patient. Fluoroscopic or other imaging methods may be used to assist with vertebral alignment and surgical guidance. Imaging techniques may also be used to determine the proper sizing of the intervertebral prosthesis 18. In one embodiment, a sizing template may be used to pre-operatively determine the correct prosthesis size. The tissue surrounding the disc space may be retracted to access and verify the target disc space. The area of the target disc may be prepared by removing excess bone, including osteophytes which may have developed, and other tissues which may include portions of the annulus and all or portions of the nucleus pulpous. The tissue removal procedure, which may include a discectomy procedure, may alternatively or additionally be performed after alignment and/or measurement procedures have been taken.
After the tissue is removed, various alignment procedures may be conducted to align the intervertebral space in preparation for the disc prosthesis 18. These alignment procedures may include introduction of a distractor assembly, such as that shown in
Each of the distracting arms 26 includes an arm base 28 and a moveable arm portion 30 moveably connected to the arm base by a length adjustment mechanism 32 for maintaining a selected length of the distracting arm, and thereby a selected height of the distractor assembly 20, as will be described. In one embodiment, as best illustrated in
Continuing with reference to
As illustrated in
In an alternative embodiment, the shaft 36 may be partially or totally removable from the distracting arms. For example, the shaft 36 may have an engaging mechanism such as a square, hex, or Phillips drive that selectively connects to the helical screw 34. In these embodiments, the shaft 36 may not be flexible. In yet another embodiment, a first portion of the shaft 36 may extend just beyond the arm base 28. A second portion of the shaft 36 may then be selectively coupled to the first portion when a change in the amount of distraction is to be performed, and then removed from the first portion during other procedures.
Referring again to
Referring now to
The anchoring devices 60, 70 may be of a configuration which attaches to the vertebral bodies 14, 16 and permits independent movement of the vertebral bodies 14, 16 in the sagittal plane while maintaining alignment of the vertebral bodies 14, 16 in the transverse and coronal planes.
A variety of alternative anchoring devices with alternative means for attaching to a distractor assembly may be selected which permit at least some movement of the vertebral bodies 14, 16 in a single plane, such as a sagittal plane. In some embodiments, the connection between the distractor assembly and the anchoring devices may be selectably fixed, pivotable, or movable in a linear direction.
It will be recognized that, although particular embodiments of attachment mechanisms 42 and corresponding anchoring devices are described herein, it is anticipated that there will be will be any number of different types of attachment mechanisms and corresponding anchoring devices that may be practiced with the invention. Moreover, the detailed description herein of particular embodiments of such mechanisms and corresponding devices does not evince an intent to limit the practice of the invention to only to those embodiments so described.
With the vertebral bodies 14, 16 distracted and the anchoring devices 60, 70 attached to the vertebral bodies 14, 16, various measurements, such as a depth measurement, may be performed at the disc site to determine the proper sizing of instrumentation and devices to be used throughout the remainder of the surgical technique. Next, further preparation of the vertebral endplate surfaces is performed using a cutting instrument, such as a burr or other cutting surface known in the art. The cutting instrument may also include a telescoping shaft to permit lengthening of the cutting instrument. After the vertebral endplates are prepared, the intervertebral prosthesis 18 may be inserted into the prepared space using any of a variety of insertion methods. After the prosthesis 18 is implanted, the tension on the distractor assembly 20 may be released and the distractor assembly 20 removed. With all instrumentation removed from the disc site, the wound may be closed.
Referring now to
Each of the distracting arms 86 includes an arm base 88 and a moveable arm portion 90 moveably connected to the arm base by a length adjustment mechanism 92 for maintaining a selected length of the distracting arm, as will be described. In the embodiment illustrated in
Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.
