A study of the external forces and moments at the shoulder and elbow while performing every day tasks

OBJECTIVES: To establish a database of upper limb kinematics and kinetics to support the development of a biomechanical model of the shoulder and elbow. DESIGN: Ten unimpaired subjects were studied when performing 10 different tasks of every day living. BACKGROUND: The development of biomechanical models of the upper limb to support the design of total joint replacements requires data on the commonly performed activities. Unlike the lower limb, this involves the selection of the tasks believed to be the most common. METHODS: Kinematic data were collected using four video cameras to track the movements of reflective markers attached to the upper limb and trunk. The rigid body kinematics was then analysed and the external forces and moments at the shoulder and elbow were calculated using inverse dynamics. RESULTS: The greatest ranges of motion at the shoulder occurred during reaching and lifting tasks as did the greatest shoulder moment (14.3 Nm flexion). The greatest elbow flexion occurred while reaching the back of the head but the greatest moment (5.8 Nm) occurred while lifting a block to head height. CONCLUSIONS: A database of ranges of motion and external forces and moments has been established to support the development of biomechanical models of the upper limb. RELEVANCE: The development of biomechanical models to support the design of upper limb joint replacements requires detailed knowledge of the types and magnitudes of forces and moments at the joints.