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.

The photocycloaddition of thiobenzophenone to acrylonitrile at 366 nm has been studied kinetically. The quantum yields for thietane formation decreased with increasing the concentration of thiobenzophenone and increased with increasing the concentration of acrylonitrile. It has been shown, using biacetyl quenching, that the reactive state at 366 nm is the second excited ( , *) singlet. Its lifetime is the order of magnitude of 10-11 sec. It has been found that the 1,3-dithiane is the only intermediate to give the thietane under the experimental conditions used (0.5 > [So] > 0.05 M), and that the energy wasting process partly responsible for the low quantum yields was the reaction of the immediate precursor for 1,3-dithiane formation with the ground state of thiobenzophenone.The study of aromatic ketones dates back to the earliest days of organic photochemistry and has continued with increasing enthusiasm for the last 50 years. In contrast, the corresponding thioketones have, until recently, been virtually ignored. Nonetheless such compounds and their alicyclic equivalents do give rise to many interesting reactions: photocycloaddition,3-6 photocyclization,7 photodimerization,6a•8 photooxidation, and photoreduction.9Ohni, Tsuchihashi, and their coworkers reported that the photoaddition of thiobenzophenone to acrylonitrile induced by excitation in the , * band (366 nm) yielded a thietane (1), but that at longer wavelength, that is by excitation through the , * band, no reaction was observed.4a Our own studies confirmed the obtention of 1 in high yield at short wavelength, but showed, further, that the thietane (1) was not the primary product, but derived from the thermal breakdown of the unstable 1,3-dithiane (2).5 6Under such circumstances, arguments deriving from the stereospecificity in the addition which were used to support the contention that the reaction was a singlet process required reinterpretation.4a We were also able to show that products were obtained by irradiation at (1) Photochemical Synthesis. 49. This is the ninth in a sequence on thione photochemistry. Publication No.

This paper describes the difficult machinability of nickel titanium alloy (NiTi alloy) and its mechanism. As a result of examining the difficult cutting machinability via a turning experiment, NiTi alloy cutting showed larger cutting force, higher cutting temperature, and severe tool wear with plastic deformation of the tool compared to Ti-6Al-4V. In addition, the discharged chips were tangled with the jaw chuck and the cutting tool. As a result of investigating the cause of these difficult machining properties by orthogonal cutting, it was found that the progression of severe flank wear is affected by the elastic recovery due to the super elasticity of the material. The verification of the results according to the shear plane theory suggest that the large deformation resistance of the material is the cause of the increase in cutting temperature. Furthermore, because the cutting temperature exceeds the shape memory transformation temperature, the generated chips are shape memory processed. It was also found that because the generated chips are super elastic, chips are not easily broken and they are lengthened, and are easily entangled with a cutting tool and a jaw chuck.

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.

This study deals with the cutting characteristics of titanium materials when milled by a small-diameter end mill, or a micro end mill. It is well known that titanium is difficult to cut by conventional means. However, its cutting characteristics have not yet been made sufficiently clear in cases where a micro end mill less than 1 mm in diameter is used. This study chiefly involves the experimental investigation of tool wear and surface roughness of micro-end milling of Ti-6Al-4V. The findings were that tool wear did not increase much when the cutting speed was increased from 50 m/min to 200 m/min. Furthermore, the cutting force required to cut decreased at high speeds and during wet cutting. In wet cutting, the surface had a roughness (Rz) of only 0.3 μm at 200 m/min in contrast to 0.6 μm at 50 m/min.