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![Posterolateral percutaneous endoscopic discectomy with free-running electromyography monitoring under general anesthesia](https://image.oaes.cc/482e904c-a2df-4aa9-a5f4-95168f835847/2200.fig.2.png)
Figure 2. Preoperative design of entry points of skin (P) for L5/S1 lumbar disc herniation. (A) Axial computed tomography paralleled with target intervertebral disc (blue line) is scanned; (B) axial trajectory (pink line) is drawn with 25 degree angle against P-I line; (C, D) cranial (y) and dorsal (z) deviations of P from the entry point of annulus fibrosus (O) are also calculated