Surgery – Instruments – Orthopedic instrumentation
Patent
1996-11-08
2000-08-22
Tucker, Guy V.
Surgery
Instruments
Orthopedic instrumentation
606 69, A61B 1770
Patent
active
061065269
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a member for stabilizing cervical vertebrae.
The German patent 39 23 995 discloses a stabilizing member for stabilizing cervical vertebrae. This member comprises a plate, which is bent to adapt it to the desired shape of the cervical spinal column. Thereafter, a plurality of bolts are screwed into the individual adjacent vertebrae. If the surgeon determines that the bending line is not perfect or must be changed for medical reasons, all screws must again be unscrewed in order to rebend the plate. This should be followed by again screwing in the bolts; For stability reasons of the vertebrae such a renewed screwing operation is hardly possible because of the weak anchoring in the bone so that in practice it must be done without such a later correcting alignment. The U.S. Pat. No. 5,312,404 discloses a member for stabilizing vertebrae which comprise a body with a plate-shaped portion and a bore extending perpendicular to the plane of the plate. A bone screw with a threaded portion and a head is provided, whereby the threaded portion extends through the bore towards a first side of the plane of the plate and the head of a bone screw is supported by the plate-shaped portion. The member has a second portion which is laterally offset with respect to the bore in the plane of the plate adjacent to the plate-shaped portion. The second portion comprises a bore for receiving a rod. A threaded bore for receiving a screw is provided perpendicular to the axis of this bore. The rod is fixed by means of a screw screwed into this threaded bore.
The U.S. Pat. No. 5,360,429 discloses a member for stabilizing vertebrae which consists of a body with a plate-shaped portion and a laterally offset second portion. The second portion comprises a slit which is provided with an external screw thread and serves for receiving a rod to be supported therein. A nut cooperating with the external screw thread serves for locking the rod to be placed therein.
It is the object of the invention to provide a member for stabilizing cervical vertebrae wherein the rod to be received is permanently locked.
This object is achieved by the member for stabilizing cervical vertebrae characterized in claim 1. Further developments of the invention are characterized in the subclaims.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention will be apparent from the description of an embodiment with reference to the Figures. In the Figures:
FIG. 1 is an enlarged sectional view along line I--I of FIG. 2;
FIG. 2 is a top view of the member shown in FIG. 1; and
FIG. 3 is a side view of a part of the member shown in the FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE INVENTION
As best shown in the FIGS. 1 and 2 the member comprises a plate-shaped body 1 which has a substantially rectangular form.
The body has a bore 2 which is provided about centrally in one half thereof and aligned perpendicular to the plane of the plate. A bone screw comprising a threaded portion 4 and a head 5, as for example known from the cited German patent 39 23 995, is disposed in the bore 2. The threaded portion 4 extends through the bore in direction of the first side 6 of the plate-shaped body 1. The bore has an edge portion formed as a spherical segment shaped recess at the second side 7 of the plate-shaped body opposite to the first side 6. The head 5 has a corresponding convex spherical segment shape at its lower side facing the threaded portion 4. The radius of the spherical segment shaped recess and of the corresponding convex spherical segment shaped portion of the spherical segment shaped head are substantially equal and match each other so that the bone screw can pivot around the axis 8 within the conical region indicated by the dotted lines for conveniently screwing the bone screw into the vertebrae.
The second half of the body comprises a cylindrical projection 9 extending towards the second side 7. The cylindrical projection 9 comprises an external screw thread 10. Its symmetry or thread axis, r
REFERENCES:
patent: 5261912 (1993-11-01), Frigg
patent: 5312404 (1994-05-01), Asher et al.
patent: 5360429 (1994-11-01), Jeanson et al.
Biedermann Lutz
Harms Jurgen
Neuner George W.
Tucker Guy V.
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