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Ankle-Foot Orthoses (AFO) are orthotics for patients having pathological gait represented by the stroke. In this study three-dimensional digital data from a physical object was extracted by using 3D-digitizer. If we have a 3D digitized orthotic model, the shape can be modified easily and Finite Element Analysis (FEA) and Stereo-Lithography (Rapid-Prototyping System: RPS) can be easily done. Continuing the research, we then focused on patients suffering from hemiplegics stroke in order to develop a method of fabricating the AFO, which fit patients even more. The major purpose of this study is to produce an orthotic design method for fitting each patient by measuring spastic muscle action and by deducing parameters for an orthosis from the data. We will have to consider how the outcomes of measurements should be processed as parameters in the design of 3DCAD.

Publisher Summary Although some variability is present in normal gait, particularly in the use of the muscles, there is an identifiable ‘normal pattern’ of walking, and a ‘normal range’ can be defined for most of the measurable parameters. Pathology of the locomotor system produces abnormal patterns of movement or applied force. Some of these abnormalities can be identified by eye, but others can only be identified by the use of appropriate measurement systems. The pattern of gait is the outcome of a complex interaction between the many neuromuscular and structural elements of the locomotor system. Abnormal gait might result from a disorder in any part of this system, including the brain, spinal cord, nerves, muscles, joints, and skeleton. Abnormal gait might also result from the presence of pain, so that although physically capable of walking normally, the subject finds it more comfortable to walk in some other way.

Publisher Summary Mechanics analysis of the gait of normal and disabled subjects enables to characterize normal and pathological gait and to provide specifications for artificial limbs, joints, and bone grafts. In analyzing gait, it is useful to (1) study the basic aspects of the neuromuscular coordination of movement, the contribution of various muscle forces in different phases of the stride and the loss of certain muscle functions for subjects with paralytic disabilities, so as to best design a format of rehabilitation or programmed stimulation in paralytic patients; (2) provide specification of forces, which a skeletal implant or a lower limb prosthesis might be subjected to and must be designed for; and (3) obtain information concerning the instantaneous stresses in the skeleton of the lower limbs, for prescription of the strength of bone grafts and the choice of graft material and its dimension. The kinematics of the various body segments, the reaction forces acting at the joints and inertia forces acting on the segments, the muscle lengths and forces, and the coordination of the instantaneous lower limb muscle forces during walking, need to be determined.

Publisher Summary This chapter presents a study conducted to elucidate the behavioral characteristics of force, length, velocity, and the electrical activity in lower limb muscles during pathological gait. In this study, a method and model for describing three dimensional gait was developed, and the behavior of muscles in pathological gait was examined for its kinematic and electrical properties. The gaits of a group of children were examined for these characteristics and for the effects of surgery. For this study, the behavior of muscle was derived from subject motion recorded on film. Markers were placed on each subject at the joints and other significant anatomical landmarks. Using a finite impulse response digital filter with the muscle length data, the rates of change of length for the muscle were computed. The results of the study showed that abnormality in a one joint muscle coupled with normality in a two joint muscle sharing the same tendon can affect abnormal changes in two joints.