Surgery – Instruments – Orthopedic instrumentation
Patent
1991-02-19
1994-11-22
Hafer, Robert A.
Surgery
Instruments
Orthopedic instrumentation
606 60, 606 69, A61B 1700
Patent
active
053664558
DESCRIPTION:
BRIEF SUMMARY
This invention relates to pedicle engaging means for use in spinal surgery.
Pedicle screws are well known for use in systems for internal fixation of the spine. However, problems have arisen in attempting to use pedicle screws in systems for segmental spinal fixation. Some pedicle screws need wires to secure them to rods or other devices used for segmental spinal fixation. An alternative which is sometimes used is to make use of plates (instead of rods) or custom built devices. Pedicle screws may be used when there is no lamina present and when consequently methods of sub-lamina wiring are unsuitable.
The object of the present invention is to provide pedicle engaging means particularly suited to use with existing segmental spinal fixation devices such as "Luque rods" or, more particularly, "Hartshill Rectangles" for posterior spinal surgery.
According to the present invention, pedicle engaging means comprises a bridge member having an arched middle portion with an aperture in each side of the arch, and a pair of generally coplanar end portions each with a hole for rotatably receiving a pedicle screw; and a pair of clip members each having a tip engageable in one aperture in the arched portion of the bridge member, and each having a fixing portion with a hole for rotatably receiving a pedicle screw; the hole in a clip member being in register with the hole in the respective end portion of the bridge member when the tip of the clip member is engaged in the respective aperture in the arched portion of the bridge member, and the portion of the clip member between its tip and its fixing portion being cranked so as to form with the junction between the arched portion and the respective end portion of the bridge member a pair of clamping parts for embracing a rod or rod-like portion of a spinal fixation device.
It is anticipated at present that there are three likely occasions when the pedicle engaging means of the invention will be used: region. intervening levels particularly to reduce slip in spondylolisthesis. sublaminar wiring the level above has to be included in order to gain fixation, whereas with the pedicle engaging means of the invention the internal fixation can be limited to one motion segment.
The bridge member and the two clip members may be formed of any biocompatible material, but a flexible material, such as stainless steel strip, enables the shape of the arched portion to be modified by the surgeons to vary the spacing between the screw holes and/or the alignment of or angularity between the end portions containing the screw holes. However, more than one size of bridge member may be provided, with arched portions of different span and/or height. The width of the arched portion may be reduced between the apertures for engagement by the tips of the clip members, e.g., the edges of the arched portion may be concave in plan view to form a neck having its least width at the middle, to afford clearance with respect to adjacent spinous processes.
The holes in the end portions of the bridge member and/or the holes in the fixing portions of the clip members may be elongated in the lengthwise direction of the bridge member, to allow adjustment of the spacing and/or inclination of pedicle screws with respect to the general plane of the end portions of the bridge member. Formation and elongation of the holes may be effected by means of a ball cutter applied to the remote faces of the end portions of the bridge member and the fixing portions of the clip members respectively and moved towards the arched portion of the bridge member and away from the tips of the clip members respectively.
An embodiment of the invention, and the manner of its use, will now be described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a side elevation of the bridge member of pedicle engaging means in accordance with the invention;
FIG. 2 is a plan of the bridge member;
FIG. 3 is an end elevation of the bridge member;
FIG. 4 is a plan view illustrating a method of simultaneously forming t
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Dove John
Rahmatalla Abdul A.
Sell Philip J.
Hafer Robert A.
Hanlon Brian E.
Surgicraft Limited
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