Discectomy and cage placement

The discectomy is performed entirely through the access portal. Disk material is removed first with a drill and then with a rotating cutter, ring curette, and long pituitary. The endplates are prepared with serial dilation of the rotating curette. Tactile feedback from the curette indicates when the endplates are reached, and it is important to ensure the endplates are free. Light violation of the endplates is desirable to aid in fusion and slight bleeding is not uncommon at this point. Next, the disk space is packed with tricalcium phosphate (TCP) (Berkeley Advanced Biomaterials Inc., CA, USA) soaked in autologous bone marrow aspirate, drawn from a Jamshidi needle in one of the pedicles.

A K-wire is placed once again and the access portal removed. At this stage, cage width and height can be determined using a trial spacer. However, with some experience, the cage dimensions can also be determined during discectomy through tactile feedback from the rotating cutter which has markings that indicate how wide the blades are spread.

Next, the cage (Figure ​(Figure4,4, PEEK Zeus-O cage (Amendia, Inc., GA, USA)) is inserted over the K-wire aided by fluoroscopy (Figure ​(Figure1).1). The conical shape of the cage ensures it passes through muscle and fascia and gently pushes the nerve root out of the way. With mallet taps, the cage is entered until 1/3 of the cage is past the midline. Some electrophysiological activity is not unusual during cage entry.

Compared to OLLIF, the final position of the cage is more horizontal as seen in Figure ​Figure66.