Surgery – Instruments – Orthopedic instrumentation
Patent
1995-10-19
1997-12-30
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 72, 606 73, A61B 1770
Patent
active
057023948
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of assembly pieces used in ostheosynthesis, in particular of the spine, and it relates more particularly to a piece for assembling two rods together.
Publication EP-A-0 383 992 discloses an assembly piece used in ostheosynthesis of the spine and serving to interconnect transversely two longitudinal rods that are fixed at several points along their length to the vertebrae. That piece comprises two identical clamp-forming elements for assembling one against the other on a longitudinal rod by means of a threaded rod and two nuts. The assembly pieces are positioned in pairs on the longitudinal rods and the two threaded rods assembling their elements are united by a tapped sleeve for connecting the longitudinal rods together transversely. Installation of the assembly pieces thus makes use of a large number of different elements (nuts, threaded rods, clamp-forming elements, tapped sleeve) which are fiddly to assembly together. In addition, those various elements present projecting angles that run the risk of damaging surrounding tissue.
The present invention seeks to remedy those drawbacks and its object is to provide an improved assembly piece which can be installed easily and quickly and which does not risk damaging surrounding tissue.
According to a first characteristic of the invention, this improved assembly piece comprises: two portions, and two bores on transverse axes passing obliquely through the slot, each adapted to receive a respective rod to be assembled; and locks the two rods in place by clamping them between said portions.
In an advantageous embodiment of the invention, said body is generally spherical in shape, said axes are orthogonal, and said portions are interconnected by a bridge of material defined on the outside by a flat and on the inside by the bottom of the slot, with the slot extending parallel to the flat. Still in an advantageous embodiment of the invention, the screw has a head for coming axially into abutment against a shoulder formed on one of the portions and the screw has a thread for engaging tapping formed in the other portion.
Other characteristics and advantages of the present invention appear on reading the following description of a non-limiting embodiment of the invention, and on examining the accompanying drawings, in which:
FIG. 1 is a perspective view of an assembly piece of the invention with two rods to be assembled together passing through it;
FIG. 2 is a view from above of the piece shown on its own resting via its flat on a plane surface;
FIG. 3 is a view from beneath of the assembly piece with the two rods passing through it;
FIG. 4 is a view taken in a direction orthogonal to the axes of the rods; and
FIG. 5 is a section through the assembly piece on a section plane containing the axis of the screw, and perpendicular to the flat.
The assembly shown in the figures is made from a solid body 1 that is preferably constituted by a titanium alloy. The outside surface of the body 1 is generally in the form of a truncated sphere having a flat 12. The body 1 is split on an equatorial plane P perpendicular to the flat 12 to form a slot 2 separating two generally hemispherical portions 1a and 1b that are connected together by a bridge of material 1c extending between the flat 12 and the bottom 13 of the slot 2. Preferably, as shown, the slot 2 is of constant thickness and its bottom 13 is plane and parallel to the flat 12.
The assembly piece is bored to receive a first rod T.sub.1. The bore 5 formed in this way passes through the body 1 along an axis A that intersects both the plane P and the plane tangent to the flat 12 obliquely. The bore 5 opens out at one end in the outside surface of the portion 1a where it intersects the flat 12 on an elliptical arc 12a, and at its other end it opens out on either side of the plane P in the outside surfaces of the portions 1a and 1b.
The body 1 is also bored to receive a second rod T.sub.2 for assembly with the first T.sub.1. The bore 6 formed in this way passes through the body 1 on an axi
Henry Patrick
Lapresle Philippe
Missenard Gilles
Buiz Michael
Shai Daphja
Stryker Corporation
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