Robotic Positioning in Percutaneous Transforaminal Endoscopic Discectomy Based on X-ray Image and DLT Algorithm

Percutaneous transforaminal endoscopic discectomy (PTED) is a decompression surgery on patients with lumbar disc herniation and spinal canal stenosis in a minimally invasive environment, which greatly shorten the rehabilitation cycle of patients. However, the puncture of traditional PTED is performed under non-direct vision, which relies on the surgeon’s clinical experience heavily and can easily cause collateral damage. In this paper, we propose a robotic positioning method in PTED based on X-ray image and DLT algorithm. The end-effector with three rings (EETR) for PTED positioning has been specially designed. During the operation, the 3D-2D transformation matrix is calculated by direct linear transform (DLT) algorithm. Finally, the motion parameters are calculated to control the robot. Based on our method, only one X-ray image is needed to complete the positioning, which also works well in a large range of deflection angle between EETR and target puncture channel. Thus, it greatly simplifies the surgical process and reduces the radiation exposure time. By conducting a series of comparative experiments on the positioning of model bones, the translation error is less than l.lmm and rotation error is less than 0.8°, when the deflection angle is less than 30°. And the translation error is 1.61mm and rotation error is 1.98°, when the angle reached 60°. It meets the requirements for PTED positioning, and has improved the positioning accuracy.