Three-Dimensional Biomechanical Model of Wrist Dynamics during Activities of Daily Living

Current upper-extremity models are task-limited due to sensor constraints. In this study, we describe pilot data acquired for development and evaluation of a three-dimensional dynamic model for quantification of wrist dynamics. Wrist kinematics were determined during unconstrained tasks, while both kinematics and kinetics were determined during constrained (closed chain) tasks. Standardized tasks evaluated were typical activities of daily living (ADLs). The model is composed of four anatomic segments: trunk, upper arm, forearm, and hand. Task reaction forces (static and dynamic) were obtained from a six-axis dynamometer with interchangeable attachments. Ten healthy subjects provided informed consent to participate in the model application study in accordance with our institutional review board requirements. Kinematics during unconstrained motion were demonstrated through wrist flexion/extension, radial/ulnar deviation, and pronation/supination tasks. Despite being performed to isolate a single planar motion as much as possible, all tasks demonstrated multiplanar motion. Wrist flexion/ extension was the most uniplanar task, while radial/ulnar deviation was highly biplanar. Wrist dynamics were demonstrated during jar-opening, door-opening, and isometric pushing tasks, which displayed biplanar kinematics and triplanar kinetics. Peak wrist kinetics occurred during the isometric task. The model demonstrates flexibility and quantitative output suitable for clinical assessment, activity modification monitoring, and longer-term follow-up care