Objective: Practical applications of nerve decompression using neurosurgical robots remain unexplored. Our ongoing research and development initiatives, utilizing industrial robots, aim to establish a secure and efficient neurosurgical robotic system. The principal objective of this study was to automate bone grinding, which is a pivotal component of neurosurgical procedures.Methods: To achieve this goal, we integrated an endoscope system into a manipulator and conducted precision bone machining using a neurosurgical drill, recording the grinding resistance values across 3 axes. Our study encompassed 2 core tasks: linear grinding, such as laminectomy, and cylindrical grinding, such as foraminotomy, with each task yielding unique measurement data.Results: In linear grinding, we observed a proportional increase in grinding resistance values in the machining direction with acceleration. This observation suggests that 3-axis resistance measurements are a valuable tool for gauging and predicting deep cortical penetration. However, problems occurred in cylindrical grinding, and a significant error of 10% was detected. The analysis revealed that multiple factors, including the tool tip efficiency, machining speed, teaching methods, and deflection in the robot arm and jig joints, contributed to this error.Conclusion: We successfully measured the resistance exerted on the tool tip during bone machining with a robotic arm across 3 axes. The resistance ranged from 3 to 8 Nm, with the measurement conducted at a processing speed approximately twice that of manual surgery performed by a surgeon. During the simulation of foraminotomy under endoscopic grinding conditions, we encountered a -10% error margin.

Keywords: Percutaneous endoscopic lumbar discectomy, electromyography, lumbar disc herniation, posterolateral approach, numeric rating scale, MacNab’s criteria

特発性腰椎硬膜外脂肪腫症はまれである.今回われわれは,外科治療を行った4例を経験した.4例の患者はすべて男性で,平均年齢は65.3歳,平均BMIは27.9kg/m^2,来院時JOAスコアは平均16.3/29点,病悩期間は平均35.0ヵ月あった.症状としては,馬尾性間欠性跛行をいずれの症例も呈していた.3例は他の腰椎変性疾患を伴っていた.MRIやCTMでのYサインは4例全例において認められ,1例においてdynamic myelographyが診断に有用であった.治療はすべて患者に椎弓切除による脂肪摘出が施行され症状の改善を認めたが,1例に7ヵ月後foraminotomyを追加した.特発性腰椎硬膜外脂肪腫症の診断には画像の詳細な検討が必要であり,外科的除圧術は症状の改善に有効と考えられた.