Combined Effects of Graded Foraminotomy and Annular Defect on Biomechanics after Percutaneous Endoscopic Lumbar Decompression: A Finite Element Study

Figure 2

Schematic view of the graded decompression surgery of percutaneous endoscopic lumbar foraminotomy. (a) The nerve root was compressed by the facet and herniated disc in the red circle region. The facet, bulging disc, and free fragments can be removed by using a bevelled working sleeve. (b) The nerve root in the green circle region was exposed and decompressive after only the removal of the extruded disc (AUF-0). The postsurgical annular defect was left on the left posterolateral side of the annulus fibrosus and surrounded by a black dotted line. (c) The nerve root was exposed and decompressive after the removal of the extruded disc and 25% left superior articular process (AUF-25). (d) The extruded disc and 50% left superior articular process were removed (AUF-50). (e) The extruded disc and 75% left superior articular process were removed (AUF-75). (f) The extruded disc and total left superior articular process were removed (AUF-100). The dotted line on the superior articular process represents the dividing line of foraminotomy.