Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-04-07
2002-08-06
Garbe, Stephen P. (Department: 3727)
Surgery
Instruments
Orthopedic instrumentation
C623S017120
Reexamination Certificate
active
06428541
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to surgical procedures for spinal stabilization and more specifically to instrumentation adapted for inserting a spinal implant within the intervertebral disc space between adjacent vertebra. More particularly, while aspects of the invention may have other applications, the present invention is especially suited for disc space preparation and inmplant insertion into a disc space form a generally anterior approach to the spine.
Various surgical methods have been devised for the implantation of fusion devices into the disc space. Both anterior and posterior surgical approaches have been used for interbody fusions. In 1956, Ralph Cloward developed a method and instrumentation for anterior spinal interbody fusion of the cervical spine. Cloward surgically removed the disc material and placed a tubular drill guide with a large foot plate and prongs over an alignment rod and then embedded the prongs into adjacent vertebrae. The drill guide served to maintain the alignment of the vertebrae and facilitated the reaming out of bone material adjacent the disc space. The reaming process created a bore to accommodate a bone dowel implant. The drill guide was thereafter removed following the reaming process to allow for the passage of the bone dowel which had an outer diameter significantly larger than the reamed bore and the inner diameter of the drill guide. The removal of the drill guide left the dowel insertion phase completely unprotected.
More recent techniques have advanced this concept and have provided further protection for sensitive tissue during disc space preparation and dowel insertion. Such techniques have been applied to an anterior approach to the lumbar spine. In one approach, a unilateral template has been provided to evaluate the space in the disc space. For bilateral implant placement, the template entire device must be rotated and visually aligned to approximately 180 from the previous position. Thus, there is the chance for operator error in rotating the device to the correct position. Further, there is little
More recent techniques have advanced this concept and have provided further protection for sensitive tissue during disc space preparation and dowel insertion. Such techniques have been applied to an anterior approach to the lumbar spine. In one approach, a unilateral template has been provided to evaluate the space in the disc space. For bilateral implant placement, the template entire device must be rotated and visually aligned to approximately 180 from the previous position. Thus, there is the chance for operator error in rotating the device to the correct position. Further, there is little guidance to ensure proper alignment of cutting instruments extending through the template.
One approach to provide such alignment is the use of a guide wire extending through a cannulated cutting instrument, such as a trephine. However, for instruments with hollow cutting heads, there is typically no engagement between the inner walls of the hollow cutting head and the guide wire. Thus, the guide wire may bend between the portion extending into the tissue and the guide wire entrance into the cannula of the instrument. As a result, the hollow cutting head may not remain in substantial alignment with the guide wire, resulting in improper opening formation. Therefore, there remains a need for improved guiding mechanisms for cutting instruments.
Once an initial opening or openings have been made in the disc space, the height of the disc space is normally distracted to approximate the normal height. Typically, a first distract or with a height estimated by CT or MRI examination is inserted. If additional distraction is required, the first distractor is removed and a second, larger distractor is inserted. However, since the positioning of the distractors is usually performed without the benefit of protective guide sleeves, the switching of distractors increases the potential for damage to neurovascular structures and may increase the time of the procedure.
For bilateral procedures, a double barrel sleeve may be inserted over a pair of previously placed distractors with a central extension extending into the disc space to maintain distraction. One limitation on guide sleeve placement is the amount of neurovascular retraction that must be achieved to place the guide sleeves against the disc space. For some patients, a double barrel sleeve may not be used because there is insufficient space to accept the sleeve assembly. Further, although the distal end of the sleeve assembly may be configured to engage the vertebral surface, if material has been removed from the disc space, there is the potential that adjacent neurovascular structures may encroach on the working channels in the disc space, resulting in damage to these structures caused by contact with instruments. While visualization windows on the guide sleeve may assist in better visualization of procedure steps and verifying unobstructed working channels prior to tool insertion, the windows themselves may allow tissue to come into contact with instruments in the working channels. Thus, there remains a need for guide sleeves requiring reduced neurovascular retraction for proper placement and providing greater protection to adjacent tissue.
With guide sleeves in place, the disc space and end plates may be prepared for receipt of an implant. Typically, cutting instruments are advanced to remove disc material and bone. Such operations may be time consuming since it is often necessary to adjust depth stop equipment and to remove the instruments to remove cutting debris. Since it is desirable to shorten the time of the operative procedure, there remains a need for improved cutting instruments and depth stop mechanisms.
While the above-described techniques are advances, improvement is still needed in the instruments and methods. The present invention is directed to this need and provides more effective methods and instrumentation for achieving the same.
SUMMARY OF THE INVENTION
The present invention relates to methods and instrumentation for vertebral interbody fusion. In one form, the method contemplates gaining access to at least a portion of the spine, marking the entrance point or points in the disc space, creating an initial opening in the disc space through a template, distracting the disc space and positioning an outer sleeve defining an interior working channel adjacent the disc space. In a preferred embodiment, the template can be inserted in a reduced sized configuration, with a first portion engaging the tissue. The template may then be manipulated to a larger configuration for bilateral insertion procedures by movement of a second portion, without repositioning the first portion. Additionally, a template according to the present invention may include trephine guides that accommodate a variety of different diameter trephine cutting heads. Specifically, trephines according to the present invention may include an upper shaft having a uniform diameter regardless of trephine cutting head diameter. Thus, the upper guides of the template maintain the trephine in axial alignment regardless of whether the lower guide engages the trephine head. In another aspect of the invention, an improved guide member is provided to maintain alignment of cutting instruments.
Once an initial opening or openings have been defined in the disc space, a distractor may be inserted to distract the disc space to the desired height. Various distractors according to the present invention may be used to distract the disc space. One such distractor has a first position that provides a first working distraction height in the disc space and a second position that provides a greater second working distraction height. Should the first working distraction height be insufficient, the distractor according to the present invention may be rotated one quarter turn to create a second greater distraction height in the disc space. Additionally, in a further preferred aspect of the invention, a modular dis
Boyd Lawrence M.
Estes Bradley T.
Liu Mingyan
Ray, III Eddie
Garbe Stephen P.
Ngo Lien
SDGI Holdings Inc.
Woodard Emhardt Naughton Moriarty & McNett
LandOfFree
Method and instrumentation for vertebral interbody fusion does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and instrumentation for vertebral interbody fusion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and instrumentation for vertebral interbody fusion will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2945123