A surgical manipulator system that can answer a wide range of surgical needs is described. We have ever developed a surgical manipulator system HUMAN (Hyper-Utility Mechatronic Assista Nt). It provides minimally invasive neurosurgery in a clinical setting. Besides the obvious restriction of only being able to use this system on the brain, the operative field that this system could treat was circular within a diameter of 1cm. We therefore developed an advanced system based on HUMAN, which we call AMATERAS. This new surgical manipulator system enables precise and minimally invasive surgery on not only the brain but also on such areas as the abdomen. The setting of the manipulator needs to be usable for more than the brain and to have a treatable operative field of3cm minimum. We developed two new mechanisms: a positioning arm that has a five-bar linkage mechanism for pivoting the manipulators and a mechanism that puts some manipulators on a stand for an operating microscope, one that does not hit the surgical bed or the patient's body. With these functions, AMATERAS provides precise and minimally invasive surgery for many area of the body.
To reduce the invasiveness of surgery, we developed an outer sheath for flexible devices in endoscopic surgery. The outer sheath is switched to two statuses, flexible and rigid. Operator inserts the sheath through tissues or organs from a narrow gap in flexible mode. After insertion, operator switches the sheath to the rigid mode. Then operator can insert devices and reach devices the target of the deep area easily. This sheath consists of a set of frame units connected serially, and each unit has a link, a slider, a stopper, and an air channel inside the instrument. When air is added to the sheath, it can be switched to the rigid mode, and when the air pressure is off, the sheath is switched to the flexible mode. We made the prototype whose diameter is 16mm and length is 290mm. We evaluated the performance of switching two modes, and the performance of insertion via a silicone phantom experiment and an animal experiment. The experimental results show that this device switches from flexible mode to rigid mode when air is added over 200kPa pressure, the sheat was possible to go through the curved path with a curving radius of more than 7.5cm, and the sheath was possible to be inserted into the narrow gap where conventional laparoscopic tools can't reach.
A simulation system that is capable of analyzing wheelchair propulsion using a human model which incorporates muscles and bones has been developed. The system calculates the driving force and muscular force for input movements applied to the wheelchair. In this study, three types of sitting arrangements were evaluated, namely a wheelchair in normal seat position which has no cushion, one in upward sitting position which has a seat cushion and one in forward sitting position which has a backrest cushion. This was done to determine the effect of varying the sitting position. The velocity and force applied to the driving wheel were measured by the wheelchair for propelling ability evaluation. The motion of the human body while propelling the wheelchair was captured using a three-dimensional measurement system and muscular forces were measured using the average rectified value of a surface electromyogram (ARV EMG). Measurements were performed on the following muscles: the clavicula and acromion of the deltoids, the pectoralis majors, the infraspinatus, the flexor and extensor of the carpi radialis, the biceps and the triceps. The results of the measurement were compared with the calculated muscular force. Only the acromion of the deltoids was active during the recovery phase, while the other muscles were mainly active during the drive phase of propulsion. In addition, the biceps were active in the early stage of drive phase, while the triceps were active in the latter stage. The switching point between these stages was brought forward when the sitting position was changed. The trend of the calculated muscular force variation corresponded with that of the ARV EMG.These results demonstrate the potential of the developed system. However, there were several discrepancies between the calculated and measured data. The flexor carpi radialis functioned as an agonist during the drive phase and the biceps and triceps, which are antagonist muscles, functioned alternately in the calculated results. In contrast, the biceps functioned as an agonist during the driving phase and functioned simultaneously with the triceps for some periods in the ARV EMG results.Solving these problems is remained for the future study.
It is generally recognized that the optic surgical navigation system is a useful tool that provides accurate anatomical information in neurosurgery and orthopedic surgery. However, at present, this system is not used in maxillofacial surgery in Japan. We report a patient with postoperative maxillary cyst treated by cystectomy using an optical navigation system. A 68-year-old female visited our department due to swelling in the right maxillary area. CT scanning showed a cystic lesion extending from the maxillary tuberosity to the nasal cavity. The lesion was surgically resected using an optical navigation system. In this patient, the use of a navigation system allowed objective confirmation of the portion of the lesion close to the nasal cavity and that surrounding the root of the second molar. In the future, the optic navigation system is expected to become a useful tool for safe and accurate surgery by oral surgeons.