Working Cannula-Based Endoscopic Foraminoplasty: A Technical Note

Figure 3

(a) Schematic of the Kiss step: the tip of the working cannula should anchor between the superior articular process (SAP) and the posterior wall of the disc or distal vertebra through the foramen. The bevel side should face upward and dorsally, so that the bevel tip can fit perfectly and securely on the ventral-lateral side of the SAP. (b) Schematic of the Hug step: after identifying the location and morphology of the osteophyte, the surgeon rotates the working cannula to shave off the osteophyte on the superior articular process (SAP), utilizing the bevel tip in a piecemeal fashion. The surgeon must ensure that the working cannula does not advance too far into the spinal canal and that the exiting nerve root is kept outside the protective working cannula. (c) Schematic of the Tilt step: the working cannula can be tilted upward, downward, or leveled to address different pathological requirements until sufficient foramen enlargement has been achieved. The exiting nerve root is particularly vulnerable during this step. Excessive manipulation of the working cannula can cause pressure on the dorsal root ganglion, leading to severe intraoperative pain and postoperative dysesthesia. (d) Schematic of the Finishing step: after shaving off the majority of the osteophyte using Kiss-Hug maneuvers, the opening of the foramen window continues. If necessary, other endoscopic tools such as articulate burrs and side-firing lasers could be used to further remove remnant osseous fragments and thickened ligamentous materials.

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