Preop

You will need lead for this case. C arm will be used extensively. You will need a C armor. 

Measure the preoperative disk angle to give you a sense for the degree of lordosis of the future graft. 

Indication

Best for L5/S1, sometimes applicable to L4/5 depending on the location of the bifurcation of the descending aorta into the common iliacs. The location of the venous bifurcation is more important than the arterial bifurcation since these are more delicate structures and more difficult to mobilize. In the image below, the L4/5 disk space is above the bifurcation and this space was not accessible during surgery. 

Pay attention to the angle of the L5/S1 disk relative to the pubic symphysis. This will dictate whether you have the angle to approach the disk space. 

Positioning

Supine with arms at right angles to the body on arm boards. Red boxes demonstrate where to attach the brackets for the retractor. 

Place a bump transversely beneath the pelvis such that the top of the bump is at the top of the iliac crests. 

Incision

Vertical incision below the belly button. The circular retractor is attached to the brackets. 

Exposure

Done by the abdominal surgeon. They will call when they are ready. 

Localization

Make sure you understand from the abdominal surgeon the location of delicate structures such as veins tucked under retractors.

Place the needle with the ball stop in the candidate disk space then go straight to a lateral shot. 

Procedure

Once you have verified the correct level, complete the annulotomy with the long-handle 15-blade. 

Remove disk material with Kerrison and pituitary rongeurs. 

Remove cartilaginous end plate with curettes. 

Ask for a trial. The width of the trial is determined by the width of visible disk space. 

Take lateral C-arm shots to determine the depth of the trial. 

Once you know the depth and width, i.e. the dimensions of the "footplate", these do not change. 

The rest is about determining the height of the graft and the angle of lordosis. The degree of lordosis is constrained by the height of the graft. Decreasing the height may constrain you to lesser degrees of lordosis. 

For the Stryker graft, place the graft such that the two holes are pointing down, towards the lower vertebral body. 

Use the awl to penetrate the bony end plate before placing the screws. You may have to use an angled awl and  screw driver to get the appropriate angle. Verify this with C arm shots. 

Your work is done once all three screws are placed. 

The abdominal surgeon will close.