Kiyomi Matsuo

Development of a new adaptation system for a manual wheelchair based on human body function

In this paper, we propose a new adaptation system for a manual wheelchair to reduce the load on the upper extremity of the user during wheelchair manipulation and also to increase the efficiency of the wheelchair propulsion. The proposed adaptation system is designed to provide optimal position of the handrim and the desired angular position of seat and backrest of the wheelchair based on the users body function. Electromyogram signals from the user muscles, heart rate signals, oxygen uptake, amount of applied pressure on the seat and backrest, force/moment applied on the handrim, joint force/moment of the upper extremity and analytical results using the dynamic manipulating force ellipsoid and the driving force contribution figure are used as index parameters for the proposed adaptation system.

The effect of different positions on lower limbs skin perfusion pressure

We have encountered situations of patients with critical limb ischemia accompanied by pain at rest and necrosis, who hang their legs down from the bed during sleep. This lower limb position is known to be a natural position, which reduces pain in the lower extremity induced by ischemia. However, the effect of this position on blood flow of the lower extremity is poorly understood. We studied whether measurements of skin perfusion pressure (SPP) changes by leg position and the difference between healthy adults and patients with critical limb ischemia. The subjects of this study were 10 healthy adults and 11 patients with critical limb ischemia. Patients with critical limb ischemia, including both dorsum of foot and plantar of foot, having SPP of lower limbs of less than 40 mmHg (supine position) were the object of this study. SPP was measured on four positions (supine position, lower limbs elevation position, sitting position, and reclining bed elevation of 20° position). In sitting position, both the number of healthy adults and critical patients show significant increases in SPP compared with the other three positions. These results suggest that sitting position is effective to keep good blood stream of lower limbs not only in healthy adults but also in patients with critical limb ischemia. However, an appropriate leg position should not have lower limbs hang downwards for long periods time because edema is caused by the fall in venous return in lower limbs, and the wound healing is prolonged. Our clinical research could be more useful in the future, particularly in developing countries, for surgeons managing wounds in leg and foot and preserving ischemic limbs.

Effects of Wheelchair Seat-height Settings on Alternating Lower Limb Propulsion With Both Legs.

This study investigated the effects of seat-height settings of wheelchairs with alternating propulsion with both legs. Seven healthy individuals with no orthopedic disease participated. Flexion angles at initial contact (FA-IC) of each joint, range of motion during propulsion period (ROM-PP), and ground reaction force (GRF) were measured using a three dimensional motion capture system and force plates, and compared with different seat-height settings. Statistically significant relationships were found between seat-height and speed, stride length, knee FA-IC, ankle FA-IC, hip ROM-PP, vertical ground reaction force (VGRF), and anterior posterior ground reaction force (APGRF). Speed, hip ROM-PP, VGRF and APGRF increased as the seat-height was lowered. This effect diminished when the seat-height was set below −40 mm. VGRF increased as the seat-height was lowered. The results suggest that the seat-height effect can be attributed to hip ROM-PP; therefore, optimal foot propulsion cannot be achieved when the seat height is set either too high or too low. Efficient foot propulsion of the wheelchair can be achieved by setting the seat height to lower leg length according to a combination of physical characteristics, such as the user’s physical functions, leg muscles, and range of motion.