Advances in endoscopic disc and spine surgery: foraminal approach.

Endoscopic spine surgery is evolving rapidly due to improvements in surgical technique, endoscope design, and instrumentation. The current technique expands on the basic features and principles of Kambin's access to the spine through the triangular zone. A standardized method for foraminal surgery, the Yeung Endoscopic Spine System (YESS) (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA) technique is proposed: (1) A protocol for optimal instrument placement by identifying the skin window, annular window, anatomic disc center, and disc inclination plane through topographical coordinates calculated by lines drawn on the skin from the C-Arm image. Adjustments in the trajectory are made to accommodate individual anatomic considerations and the pathologic disorders to be accessed. (2) Evocative Chromo-Discography (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA). (3) Selective Endoscopic Discectomy (Richard Wolf Surgical Instrument Company, Vernon Hills, Illinois, USA). (4) Thermal discoplasty and annuloplasty. (5) Endoscopic foraminoplasty. (6) Accessing the epidural space in the axilla between the traversing and exiting nerve root. (7) Partially resecting the posterior annulus to get beneath the herniated fragment, if needed. This technique allows access to the epidural space from the lumbar disc as far cephalad as the middle of the vertebral body or approximately 2-3 mm caudally. The foraminal approach is routinely accessible from T-10 to L4-5. L5-S1 can be accessed with special techniques that include foraminoplasty of the lateral facet. Surgical results continue to improve, consistent with refinement of indications and techniques for specific conditions treatable by this endoscopic method.