Surgical instruments for spinal disc implants and related methods

1. A trial for spinal surgery, comprising:

a trial implant portion having a shape corresponding to an implantable spinal disc implant;

a shaft connected to the trial implant portion; and

at least one axially extending cutting guide attached to the shaft at a position that is axially spaced apart from the trial implant portion, the cutting guide configured to releasably slidably receive and guide a cutting member toward vertebral bone,

wherein the at least one cutting guide comprises a superior cutting guide and an inferior cutting guide, each with a respective cutting guide slot, wherein the trial further comprises an upper and lower trial implant portion stop with a respective alignment window residing respectively above and below the bearing surfaces on an anterior side of the trial implant portion, whereby the upper and lower alignment windows are configured to allow cutting members to extend therethrough while held in a desired orientation by the corresponding superior and inferior cutting guide slot.

2. A trial according to claim 1 , wherein the trial implant has superior and inferior bearing surfaces that are devoid of cutting guide slots.

3. A trial according to claim 1 , wherein the at least one axially extending cutting guide comprises an upper cutting guide slot and a lower cutting guide slot, the upper and lower guide slots residing on diametrically opposed sides of the shaft.

4. A trial according to claim 1 , wherein the at least one cutting guide comprises a slot with a geometry configured to maintain positive orientation of a cutting blade as the cutting member slidably advances therein, and wherein the at least one cutting guide slot is configured to define a non-adjustable fixed cutter stop that engages a stop portion of a cutting member that slidably advances therethrough to prevent further forward movement of the cutting member.

5. A trial according to claim 1 , further comprising first and second outwardly projecting anchoring portions residing on a side of the trial implant portion stop facing the trial implant portion, the anchoring portion configured to engage an anterior side of a target vertebral body, thereby limiting motion of the trial and/or maintaining trial position during formation of keelways into the vertebral body.

6. A trial according to claim 1 , further comprising a shallow groove on the superior and inferior bearing surfaces of the trial implant portion, the shallow groove configured so as to avoid contact with the cutting blade during formation of a keelway.

7. A trial according to claim 1 , in combination with a chisel, the chisel being the cutting member that slides in the cutting guide, the chisel having a stop portion residing axially away from a forward edge portion of the chisel, wherein the chisel stop portion cooperates with a leading edge portion of a slot in the cutting guide to prevent forward motion of the chisel when the chisel stop portion engages the leading edge portion of the slot of the cutting guide.

8. A trial according to claim 7 , in further combination with a reamer, the reamer being the cutting member that slides in the cutting guide, the reamer having a stop portion residing axially away from a forward edge portion of the reamer, wherein the reamer stop portion cooperates with a leading edge portion of a slot in the cutting guide to prevent forward motion of the reamer when the reamer stop portion engages the leading edge portion of the slot of the cutting guide.

9. A trial according to claim 1 , in combination with a pair of universal reamers and a pair of universal chisels, wherein the at least one cutting guide is two cutting guides, one for directing one of the reamers and chisels to form a superior keelway and the other for directing the other one of the reamers and chisels to form an inferior keelway, wherein the reamers and the chisels are cutting members that releasably and slidably engage the cutting guides.

10. A trial according to claim 1 , wherein the shaft merges into a handle, and wherein the handle and shaft are releasably attached to the trial implant portion.