The strategies behind “inside-out” and “outside-in” endoscopy of the lumbar spine: treating the pain generator

Two conceptually different transforaminal endoscopic methods of accessing and decompressing the lumbar intervertebral discs have emerged over the years: the “inside-out,” and the “outside-in” technique. While the distinction between these two methods driven by the initial placement of the endoscopic working cannula either inside the intervertebral disc (inside-out) or into the neuroforamen (outside-in) seems somewhat trivial on the surface, it is far from it when one looks beyond the access issue. The differences go much deeper than the initial starting point, considering which of the common pain generators can be directly visualized and treated.