Advancements and Challenges in Robot-Assisted Bone Processing in Neurosurgical Procedures.

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.

Fluid Lubrication and Cooling Effects in Diamond Grinding of Human Iliac Bone.

Background and Objectives: Although there have been research on bone cutting, there have been few research on bone grinding. This study reports the measurement results of the experimental system that simulated partial laminectomy in microscopic spine surgery. The purpose of this study was to examine the fluid lubrication and cooling in bone grinding, histological characteristics of workpieces, and differences in grinding between manual and milling machines. Materials and Methods: Thiel-fixed human iliac bones were used as workpieces. A neurosurgical microdrill was used as a drill system. The workpieces were fixed to a 4-component piezo-electric dynamometer and fixtures, which was used to measure the triaxial power during bone grinding. Grinding tasks were performed by manual activity and a small milling machine with or without water. Results: In bone grinding with 4-mm diameter diamond burs and water, reduction in the number of sudden increases in grinding resistance and cooling effect of over 100 °C were confirmed. Conclusion: Manual grinding may enable the control of the grinding speed and cutting depth while giving top priority to uniform torque on the work piece applied by tools. Observing the drill tip using a triaxial dynamometer in the quantification of surgery may provide useful data for the development of safety mechanisms to prevent a sudden deviation of the drill tip.

Finite element method for nerve root decompression in minimally invasive endoscopic spinal surgery.

INTRODUCTION: Diagnosis is the key to improving spinal surgery outcomes. Improvements in the diagnosis of radiculopathy have created new indications for full-endoscopic spine surgery. We assessed the finite element method (FEM) to visualize and digitize lesions not detected by conventional diagnostic imaging. METHODS: We used FEM in two patients: a lumbar patient and a cervical patient. The lumbar patient was a 67-year-old woman with a history of rheumatoid arthritis; she also had osteoporosis and pulmonary fibrosis. She had left L3 radiculopathy due to an L3 vertebral fracture. The cervical patient was a 61-year-old woman with left C6 radiculopathy due to C5-C6 disc herniation. We performed full endoscopic foraminotomy per the patients's request. Based on preoperative and postoperative CT Digital Imaging and Communications in Medicine data of 0.5-mm slices, 3-D imaging data were reproduced, and kinetic simulation of FEM was performed. RESULTS: Postoperatively, both patients' radiculopathy disappeared, improving their activities of daily living and enabling them to walk and work. Also, the total contact area and maximum contact pressure of the nerve tissue decreased from 30% to 80% and from 33% to 67%, respectively. CONCLUSIONS: A new method for perioperative evaluation and simulation, FEM can be to visualize and digitize the conditions of the lesion causing radiculopathy. FEM that can overcome both time and economic constraints in routine clinical practice is needed.