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[Purpose] The purpose of this study was to clarify the characteristic of gait of elderly people with kyphosis. [Subjects] The subjects were 12 healthy elderly persons and 12 elderly persons with kyphosis. [Methods] We measured the index of kyphosis as a quantitative assessment of kyphosis, and divided the subjects into two groups using the index of kyphosis. We employed a 3-dimensional motion analysis system and 6 force platforms to capture kinetic and kinematic data of gait. The experimental condition was walking at a self-selected speed. We repeated the measurements in three trials. [Results] Elderly people with kyphosis decreased maximum hip abduction moment in the late stance phase and increased pelvic posterior tilt and pelvic rotation. [Conclusion] These results suggest that alignment changes of elderly people with kyphosis cause biomechanical changes in the frontal plane. [ABSTRACT FROM AUTHOR]

Hydrogels have attracted much attention as potential soft and wet materials because of their unique properties, such as low surface friction and volume phase transition. However, conventional hydrogels are mechanically too weak and unsuitable for practical uses. Inspired by the structure of articular cartilage, a natural tough hydrogels, we have created novel hydrogels with extremely high mechanical strength. The gels are a kind of interpenetrating networks (IPN) consisting of rigid polyelectrolyte and soft neutral polymers, and show a compressive fracture stress of 60 MPa, 3000% of tensile strain and 2500 J/m² of fracture energy. Such mechanical properties cannot be explained by the standard theories about fracture of soft polymer systems. In this paper, we discuss, based on our recent papers, the synthesis conditions to obtain the tough hydrogels and physical mechanism under the high toughness. The essential point is that partial breakage of the rigid component causes formation of yielding zone around crack tip, which leads to a large dissipation for the crack propagation. We also describe several results on tissue engineering application of the hydrogels. [ABSTRACT FROM AUTHOR]