Comparison of modelling and tracking methods for analysing elbow and forearm kinematics

This study aimed to find an optimal measurement protocol of elbow and forearm kinematics using different modelling and tracking methods. Kinematic data of elbow flexion/extension and forearm pronation/supination was acquired using optical motion capture from 12 healthy male volunteers. Segment coordinate systems for humerus, forearm, radius, ulna, and hand were defined. Different tracking methods, using anatomical markers or rigid or point maker clusters, were used to compute the three-dimensional rotations. Marker placement errors were assessed to evaluate the rigid body assumption. Multiple comparisons demonstrated statistical differences between tracking methods: compared to using only anatomical markers, tracking using clusters reduced the estimated range of pronation/supination by 14.9%-43.2%, while it estimated increased flexion/extension by 5.3%-9.1%. The study suggests using only anatomical markers exerts the optimal estimation of elbow and forearm kinematics. Modelling using the coordinate systems of the humerus and forearm and of the humerus and ulna, respectively, demonstrated good consistency with literature and are correspondingly regarded as the most appropriate approach for measuring pronation/supination and flexion/extension. The results are valuable in establishing a measurement protocol for analysing elbow and forearm kinematics, avoiding confusions and misinterpretations in communicating results from different methodologies.