Placement of the cage is between the traversing and exiting nerve roots (on the back corner of the disc space). There is about 8- 10mm of natural space between these two nerve roots. When you then retract the traversing root (which has about 8mm of natural motion), there is over 14mm of space that can be used to place the cage.
Retracting nerve roots in not inherently dangerous as long as the root is pliable and relaxed. There are times with a TLIF or PLIF that the nerve root is tethered and has to be decompressed prior to retraction or is scarred down (from prior surgery) and will not retract as far as it should.
This is why the microscope is so important. I can visualize the retraction performed by my assistant (as well as he can) and determine if the nerve is mobile or not. Accomodations are taken if the nerve does not mobilize well.
Dr. Corenman
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.