Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-03-15
2001-06-19
Mancene, Gene (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06248107
ABSTRACT:
This invention relates to orthopaedics and spinal surgery, and more particularly to a method and apparatus for reducing the extent of displacement between adjacent vertebrae.
BACKGROUND OF THE INVENTION
An apparatus for reducing the extent of displacement between adjacent vertebrae is shown in U.S. Pat. No. 4,611,581 to Steffee. That apparatus includes a pair of rigid plates, which are attached to opposite sides of the spinous process of the human spine. The plates are attached to the spine by bolts with coarse threads on one end and machine threads on the other. The coarse threads of the bolts are first screwed into the spine. The plates are then placed over the machine-threaded portion of the bolts, which are then held in place by nuts, threaded over the top of the plates. A displaced vertebra is relocated by pulling the vertebra toward the plate by tightening the nut on the bolt that holds the displaced vertebra.
A problem with this design is that it leaves a rather high profile of metal extending above the spine. The following invention is one solution to this problem.
SUMMARY
In one aspect, this invention is a reduction assembly for a spinal implant clamp that is used to connect a bone bolt to a spinal implant rod. The reduction assembly has a reduction bolt with machine threads on one end and coarse threads on the other end. A nut is then threaded on the machine threads over a collar. The collar open is open at both ends and is of a size to readily slide over the reduction bolt. The posterior face of the collar has a notch to accept a non-horizontal face on a spinal implant clamp and the nut and collar have mutually engageable male and female contacts that allow the nut to rotate in respect to the collar.
In another aspect, this invention is an assembly for reducing a displaced vertebra and connecting the displaced vertebra to a spinal implant rod. The assembly has a reduction bolt with machine threads on one end and coarse threads on the other. The assembly also has a connection unit to attach a spinal rod to the reduction bolt, and until it is tightened, the connection unit allows the reduction bolt to slide in the connection unit. The connection unit also includes a washer that rides against the side of the reduction bolt. A nut is threaded onto the machine threads of the reduction bolt over a collar. The collar is open at both ends and is of a size to readily slide over the reduction bolt. The posterior face of the collar has a notch to accept a portion of the lateral side of the washer as the washer presses against the reduction bolt. Hence, the notch is part of the open end of the collar into which one slides the collar over the reduction bolt and down onto the connection unit.
In another aspect, this invention is an apparatus for use in reducing a displaced vertebra. The apparatus has at least one longitudinal member positionable along the longitudinal axis of the spine, two vertebral anchors, three clamps and a reduction bolt. Two of the clamps fixedly secure each of the vertebral anchors to the longitudinal member. The third clamp is used to hold the reduction bolt to the longitudinal member, and when loose, allows a reduction bolt to slide within the clamp. The apparatus also includes a washer on the third clamp that rest against the side of the reduction bolt. A nut is threaded onto the machine threads of the reduction bolt over a collar. The collar is open at both ends and is of a size to readily slide over the reduction bolt. The posterior face of the collar has a notch to accept a portion of the lateral side of the washer as the washer presses against the reduction bolt. Hence, the notch is part of the open end of the collar into which one slides the collar over the reduction bolt and down onto the connection unit. Positioned in this fashion the nut can be tightened against the collar to pull the reduction bolt, previously threaded into a displaced vertebra, and thereby move the displaced vertebra toward the longitudinal member. The third clamp can be tightened to secure the reduction bolt to the longitudinal member, and then the nut and the collar can be removed from the patient without the vertebra moving away from the longitudinal member.
In yet another aspect, this invention is also a method for aligning a displaced vertebra. In general, the method includes the steps of attaching a bolt to a displaced vertebra; positioning a spinal rod along the longitudinal axis of the spine; positioning a clamping device on the bone bolt and the spinal rod, with clamping device having a compression member that, when engaged, simultaneously tightens the bone bolt and the spinal rod to the clamping device; sliding a collar over the bone bolt and allowing the collar to rest against the clamping device; threading a nut over the machine threads on the bone bolt and against the collar to move the displaced vertebra toward the spinal rod; tightening the compression member on the clamping device to hold the bone bolt and the spinal rod; and removing the nut and collar from the bone bolt.
An advantage of this invention is that it allows the nut that is typically used to hold a longitudinal member to a longitudinal member to be removed after a displaced vertebra has been relocated to its proper position by the surgeon.
REFERENCES:
patent: 4175555 (1979-11-01), Herbert
patent: 4456005 (1984-06-01), Lichty
patent: 4611581 (1986-09-01), Steffee
patent: 4696290 (1987-09-01), Steffee
patent: 4854311 (1989-08-01), Steffee
patent: 5254118 (1993-10-01), Mirkovic
patent: 5312404 (1994-05-01), Asher et al.
patent: 5545166 (1996-08-01), Howland
patent: 5643263 (1997-07-01), Simonson
patent: 5653708 (1997-08-01), Howland
patent: 5782831 (1998-07-01), Sherman et al.
patent: 5885285 (1999-03-01), Simonson
patent: 6123707 (2000-09-01), Wagner
Brumfield David L.
Foley Kevin T.
Morrison Matthew M.
Mancene Gene
Robert Eduardo C.
SDGI Holdings Inc.
Woodard Emhardt Naughton Moriarty & McNett
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