Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-04-07
2001-03-06
Jackson, Gary (Department: 3731)
Surgery
Instruments
Orthopedic instrumentation
C606S064000
Reexamination Certificate
active
06197033
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 vertebrae. More particularly, while there may be other applications, the present invention is especially suited for engaging two vertebral bodies that are offset in an anterior-posterior fashion, as in spondylolisthesis, with respect to each other and providing a protected passageway for the movement of instruments and implants therethrough.
Currently available systems utilize a hollow sleeve having a uniform bone engaging end with teeth extending therefrom to be driven into the vertebrae adjacent the disc space. However, a common condition in spinal abnormalities is that adjacent vertebral bodies have been displaced creating an anterior-posterior offset condition. While offset vertebral bodies may be encountered in any part of the spine as a result of trauma, disease, or degeneration, the condition of spondylolisthesis typically develops in the lumbar spine. With offset vertebral bodies, the uniform bone engaging end of the hollow sleeve in prior systems, adapted to engage anterior-posterior aligned vertebral bodies, fails to completely engage both offset vertebra bodies simultaneously. This incomplete engagement with the offset vertebral bodies creates an unprotected space between one of the vertebral bodies and the end of the hollow sleeve. This unprotected space may allow contact between instruments disposed within the sleeve, such as cutting instruments, and surrounding tissue. Such contact may damage the sensitive tissue adjacent to the vertebral body leading to potential injury or death for the patient.
While the more recent techniques and instrumentation represent an advance over earlier surgical procedures for protecting surrounding tissue during preparation of the disc space and insertion of a fusion device, the need for improvement still remains. The present invention is directed to this need and provides a more effective protective guide sleeve for engaging offset vertebral bodies.
SUMMARY OF THE INVENTION
The present invention provides a guide sleeve having offset bone engaging portions. In one aspect the sleeve comprises a first tube portion having a first bone engaging end and a second tube portion moveably connected to the first tube portion. The second tube portion includes a second bone engaging end disposed proximal to the first bone engaging end. The second tube portion is moveable in relation to the first bone engaging portion to create an offset between the second bone engaging surface in relation to the first bone engaging surface. Preferably, the bone engaging end will include a distraction portion extending distally therefrom. Optionally, the guide sleeve may define one or more windows for visualization.
In another aspect, the invention provides a sleeve composed of a tube having a longitudinal axis and a bone engaging end. The bone engaging end has a first bone engaging portion and a second bone engaging portion. The second bone engaging portion is offset with respect to the first bone engaging portion. Preferably, the offset bone engaging portions are adapted to engage offset vertebral bodies.
Still further, the present invention provides a method of positioning a guide sleeve against a first vertebral body offset from a second vertebral body. The method includes making a determination of the amount of offset between the first vertebral body and the second vertebral body. A guide sleeve is provided that includes a bone engaging portion with a first portion and a second portion longitudinally offset from the first portion, the offset between the first and second portions substantially corresponding to the offset between the first vertebral body and the second vertebral body. The guide sleeve is then positioned adjacent the spine with the first bone engaging portion engaging the first vertebral body and the second bone engaging portion engaging the second vertebral body. Optionally, the guide sleeve may be composed of a first portion slidably connected to a second portion. In this configuration, the amount of offset may be adjusted to correspond to the offset between adjacent vertebra. Additionally, it is contemplated that with a moveable first portion, the extent of offset between the bone engaging portion may be adjusted after insertion into the body.
One object of the present invention is to provide an improved guide sleeve for engaging offset bone segments.
Related objects and advantages of the present invention will be apparent from the following description.
REFERENCES:
patent: 5601556 (1997-02-01), Pisharodi
patent: 5669915 (1997-09-01), Caspar et al.
patent: WO 9627321 (1996-09-01), None
Comey Christopher
Estes Bradley T.
Haid, Jr. Regis W.
Moore Jeffrey D.
Ray, III Eddie F.
Jackson Gary
King Anthony S.
SDGI Holdings Inc.
Woodard Emhardt Naughton Moriarty & McNett
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