A METHOD FOR KINEMATIC ANALYSIS OF MOTIONS OF THE SHOULDER, ARM, AND HAND COMPLEX

The literature of kinesiology, body mechanics, physical anthropology, and osteometry presents an array of facts about muscle, bone, and tendon relatioriships in the human shoulder, arm, and hand, both in the static and dynamic state. Generally, these expositions are descriptive and qualitative. Only on certain portions of the mechanism have precise geometrical and quantitative data been obtained. There is lacking from these sources a comprehensive but practically feasible scheme for analysis of the kinematics of the system. The methods of motion study, widely applied to occupationai and other human activities, similarly have failed to provide the desired rationale. While the therblig and similar techniques of motion study off er a semi-quantitative approach, they involve a mixture of hand-arm movements and job elements which describe the biokinematics only in a very general sense. The need for a practical but precise method for shoulder-arm-hand motion analysiç immediately arises from research to establish the functional requirements for arm and hand prostheses. Here, the substitution of mechanical equipment for the lost members, enormously complicated by the limited number of controls available from shoulder harness, muscle tunnel, and accessory mechanical controls, poses for the engineer the perplexing problem of putting the functional regain where it will be most effective. It is necessary, for his guidance, to establish the frequency and extent of motions in the natural mechanism as they are involved in the performance of the common activities of daily Iiving. Such data, therefore, figure prominently in the design and evaluation of the prosthesis. A workable method for kinematic analysis should not long await application to many fields of human biology. It opens the way to dynamic analysis of a11 types of manual work. The calorimetric techniques for measurement of the energy in such work have long been recognized to lack the specificity and sensitivity necessary for a scientific formulation of the vast array of light activity types. They fail to differentiate clearly the work done in moving the body structures from that done against externa1 loads. Hence, it is expected that the physical analysis of biomechanics will contribute in a very fundamental way to the investigation of human energetics in manual work. Thr purpose of this paper is to describe a method of kinematic analysis of the motions of çhoulder, arm and hand. There are six steps involved, as follows: (1) Measurement and calibration of the standard experimental subject. (2) Fitting of the subject with visual landmarks. (3) Cinematography of the subject performing the activities under study. (4) Obtaining the Cartesian earth coordinates of the visual landmarks