Cervical intervertebral prosthesis
A cervical intervertebral prosthesis includes at least one cover plate that is configured to be connected to one of two adjacent vertebral bodies and an instrument for positioning a fastening device at one of the vertebral bodies in order to secure the intervertebral prosthesis. The instrument is separate from the fastening device and includes a drill gauge and arms with projections for holding the cervical intervertebral prosthesis at a predetermined position relative to the drill gauge. The drill gauge has an orientation pointing towards the cover plates at an oblique angle α.
1 . An instrument for positioning a fastening device at a vertebral body in order to secure an intervertebral prosthesis that is separate from the fastening device and comprises two cover plates configured to be connected to adjacent vertebral bodies and a prosthesis core which forms an articular joint with one of the cover plates,
the instrument comprising a drill gauge for the fastening device which is configured to be connected to the prosthesis or a prosthesis model in a predetermined relative position, wherein the drill gauge is configured for connection so as to be slanted to point at an oblique angle towards the cover plates.
2 . The instrument of claim 1 , wherein the drill gauge has a passageway formed therein.
3 . The instrument of claim 2 , wherein the passageway has a length greater than its width.
4 . The instrument of claim 2 , wherein the passageway is curved.
5 . The instrument according to claim 1 , 2 3 or 4 , further comprising a second drill gauges, the drill gauge and the second drill gauge being oriented towards each other.
6 . A cervical intervertebral prosthesis system, comprising
two cover plates having a first dimension in an anterior-posterior direction and being configured to be connected to adjacent vertebral bodies,
a prosthesis core which forms an articular joint with one of the cover plates, a fastening device and
an instrument separate from the fastening device for positioning the fastening device at one of the adjacent vertebral bodies in order to secure the intervertebral prosthesis,
the instrument comprising a drill gauge and arms with projections for holding the cervical intervertebral prosthesis at a predetermined position relative to the drill gauge, the drill gauge having a direction of orientation pointing towards the cover plates at an oblique angle.
7 . The system of claim 6 , wherein the direction of orientation of the drill gauge is selected so such that the direction intersects with an exterior surface of at least one of the cover plates at a predetermined distance from the drill gauge.
8 . The system of claim 7 , wherein the predetermined distance is between one third and two thirds of the first dimension.
9 . The system of claim 7 , wherein the at least one of the cover plates has a recess on its exterior surface at the predetermined distance.
10 . The system of claim 6 , wherein the drill gauge has a passageway formed therein.
11 . The system of claim 10 , wherein the passageway has a length greater than its width.
12 . The system of claim 10 , wherein the passageway is curved.
13 . The system of claim 6 , wherein the drill gauge comprises at least two parallel passageways formed therein.
14 . The system of claim 6 , 7 , 8 , 9 , 10 , 11 , 12 or 13 , further comprising a second drill gauges, the drill gauge and the second drill gauge being oriented towards each other.
15 . The system of claim 6 , wherein the fixation device is a screw.
16 . The system of claim 6 , wherein the fixation device is a wire.
17 . The system of claim 6 , wherein the fixation device is a Steffee nail.
18 . The system of claim 15 , 16 or 17 , wherein the fixation device is curved.