Kazuhiro Yoshimitsu

Locomotion Assistance for the Person with Mobility Impairment: Fuzzy Control of Cycling Movement by Means of Surface Electrical-Stimulation

Since a wheelchair was originally designed as a transportation vehicle for people who can not walk well due to the degenerative muscles of legs in the case elderly and disabled persons, it was not considered to use lower limbs to drive a wheelchair. Wheelchairs driven by arms cause a shoulder disorder, atrophy of leg muscles and a contracture of leg joints. On the other hand, while wheelchairs driven by legs can prevent or alleviate those symptoms in daily life, it is difficult to drive a wheelchair if the muscles are not strong enough. To solve this problem the functional electrical stimulation is carried out on leg muscles to pedal the wheelchair, and to stabilize the speed a motor is equipped. The leg cycling movement in this paper is controlled by fuzzy logic. Experiments of cycling using three healthy young men are performed on a level surface, and prove the effectiveness of smooth cycling movement. The electrical stimulation is also added to the external oblique of subjects sitting on a chair to examine the possibility to become effective exercise instead of treadmill training by keeping balance.

Electrically Stimulated Antagonist Muscle Contraction Increased Muscle Mass and Bone Mineral Density of One Astronaut - Initial Verification on the International Space Station.

Background Musculoskeletal atrophy is one of the major problems of extended periods of exposure to weightlessness such as on the International Space Station (ISS). We developed the Hybrid Training System (HTS) to maintain an astronaut’s musculoskeletal system using an electrically stimulated antagonist to resist the volitional contraction of the agonist instead of gravity. The present study assessed the system’s orbital operation capability and utility, as well as its preventative effect on an astronaut’s musculoskeletal atrophy. Methods HTS was attached to the non-dominant arm of an astronaut staying on the ISS, and his dominant arm without HTS was established as the control (CTR). 10 sets of 10 reciprocal elbow curls were one training session, and 12 total sessions of training (3 times per week for 4 weeks) were performed. Pre and post flight ground based evaluations were performed by Biodex (muscle performance), MRI (muscle volume), and DXA (BMD, lean [muscle] mass, fat mass). Pre and post training inflight evaluations were performed by a hand held dynamometer (muscle force) and a measuring tape (upper arm circumference). Results The experiment was completed on schedule, and HTS functioned well without problems. Isokinetic elbow extension torque (Nm) changed -19.4% in HTS, and -21.7% in CTR. Isokinetic elbow flexion torque changed -23.7% in HTS, and there was no change in CTR. Total Work (Joule) of elbow extension changed -8.3% in HTS, and +0.3% in CTR. For elbow flexion it changed -23.3% in HTS and -32.6% in CTR. Average Power (Watts) of elbow extension changed +22.1% in HTS and -8.0% in CTR. For elbow flexion it changed -6.5% in HTS and -4.8% in CTR. Triceps muscle volume according to MRI changed +11.7% and that of biceps was +2.1% using HTS, however -0.1% and -0.4% respectively for CTR. BMD changed +4.6% in the HTS arm and -1.2% for CTR. Lean (muscle) mass of the arm changed only +10.6% in HTS. Fat mass changed -12.6% in HTS and -6.4% in CTR. Conclusions These results showed the orbital operation capability and utility, and the preventive effect of HTS for an astronaut’s musculoskeletal atrophy. The initial flight data together with the ground data obtained so far will be utilized in the future planning of human space exploration.

The modified massive cuff stitch: functional and structural outcome in massive cuff tears

BackgroundThe massive cuff stitch (MCS) is known to be a strong suture, suitable for rotator cuff repair. We modified this technique for massive cuff tears by employing a horizontal medial mattress suture from an anchor as well as a vertically crossing transosseous suture.MethodsWe included 42 patients with massive cuff tears suitable for repair: 22 were treated with the modified MCS (MCS group), and 20 with a simple transosseous suture (STS group). The range of motion (ROM), muscle strength, visual analog scale, and the Japanese Orthopaedic Association (JOA) scores were evaluated pre-operatively and 12 and 24 months post-operatively. The incidence of post-operative re-tears was examined at least 1 year post-operatively using Sugayas classification.ResultsThe ROM, muscle strength, degree of pain, and the JOA scores were much improved after surgery in both groups, and there was no significant intergroup difference throughout the pre- and post-operative periods. In contrast, post-operative MRI revealed a significantly lower re-tear rate in the MCS group than in the STS group (9.1% vs. 40%, P = 0.0296).ConclusionsThe techniques tested were comparable in terms of functional outcome after surgical repair of massive cuff tears; however, the modified MCS repair technique produced superior structural outcomes with a significantly lower re-tear rate.