Surgical cutter instrument with trial

1. A surgical cutting instrument comprising:

an instrument shaft having a distal end and a proximal end;

an instrument handle on the proximal end of the instrument shaft;

a trial sizer head configured to attach to the distal end of the instrument shaft and to correspond in size to an intervertebral implant, wherein the trial sizer head comprises at least one longitudinal slot; and

a cutter configured to attach to the instrument shaft and axially translatable within the at least one longitudinal slot in the trial sizer head,

wherein in a retracted and locked position, the cutter is positioned proximally of the trial sizer head and is locked in position.

2. The surgical cutting instrument of claim 1 , wherein the instrument shaft includes an inner shaft and an outer shaft movable with respect to one another.

3. The surgical cutting instrument of claim 2 , wherein the cutter is configured to attach to the inner shaft.

4. The surgical cutting instrument of claim 1 , wherein in a released cutting position, the cutter is movable with respect to the trial sizer head into and through the at least one longitudinal slot.

5. The surgical cutting instrument of claim 1 , wherein the at least one longitudinal slot extends along a midline of the instrument between two opposite lateral edges.

6. The surgical cutting instrument of claim 1 , wherein the at least one longitudinal slot comprises a pair of slots on opposite superior and inferior surfaces of the trial sizer head.

7. The surgical cutting instrument of claim 1 , further comprising a removable adjustable stop attachable to the instrument shaft and configured to limit motion of the trial sizer head.

8. A set of surgical cutting instruments according to claim 1 , comprising a plurality of surgical cutting instruments each having a different size trial sizer head.

9. A surgical method comprising:

inserting a first combined trial sizer head and cutter instrument into a vertebral disc space to check a fit of the first trial sizer head for the vertebral disc space, wherein the vertebral disc space is disposed adjacent to at least two bones;

removing the first combined trial sizer head and cutter from the vertebral disc space and inserting a second combined trial sizer head and cutter instrument of a different size; and

unlocking a cutter on the second combined trial sizer head and cutter instrument to allow the cutter to be axially translatable with respect to the trial sizer head; and

cutting at least one of the bones adjacent to the vertebral disc space with the cutter.

10. The surgical method of claim 9 , wherein the cutting step comprises cutting a slot into at least one of the bones adjacent to the vertebral disc space.

11. The surgical method of claim 10 , wherein the slot is a midline slot.

12. The surgical method of claim 9 , further comprising attaching a removable adjustable stop to the second combined trial sizer head and cutter instrument and limiting motion of the trial sizer head during cutting by contacting at least one of the bones adjacent to the vertebral disc space with the adjustable stop.

13. A surgical method of cutting bone for insertion of an intervertebral disc prosthesis, the surgical method comprising:

sequentially inserting one or more different size combined trial sizer head and cutter instruments into a vertebral disc space to check a fit of the trial sizer head for the vertebral disc space;

unlocking a cutter on a selected combined trial sizer head and cutter instrument while the cutter is in the vertebral disc space to allow the cutter to be movable with respect to the trial sizer head; and

cutting at least one of the bones adjacent to the vertebral disc space with the cutter by moving the cutter distally with respect to the trial sizer head.

14. The surgical method of claim 13 , wherein the cutting step comprises cutting a slot into at least one of the bones adjacent to the vertebral disc space.

15. The surgical method of claim 14 , wherein the slot is a midline slot.

16. The surgical method of claim 13 , further comprising attaching a removable adjustable stop to the combined trial sizer head and cutter instrument and limiting motion of the trial sizer head during cutting by contacting at least one of the bones adjacent to the vertebral disc space with the adjustable stop.