LAUSR

Reliably and accurately estimating joint/segmental kinematics from optical motion capture data has remained challenging. Studies objectively characterizing human movement patterns have typically involved inverse kinematics and inverse dynamics techniques. Subsequent research has included scaled cadaver-based musculoskeletal (MSK) modeling for non-invasively estimating joint and muscle loads. As one of the ways to enhance confidence in the validity of MSK model predictions, the kinematics from the preceding step that drives such a model needs to be checked for agreement or compared with established models. This study rigorously compares the upper-extremity joint kinematics calculated by the Dutch Shoulder Model implemented in the AnyBody Managed Model Repository (Multibody Kinematics Optimization) with those estimated by the Vicon Plug-in Gait model (Single-body Kinematics Optimization). Ten subjects performed three trials of Reaching tasks in a three-dimensional marker-based optical motion capture laboratory setting. Joint angles, processed marker trajectories, and reconstruction residuals corresponding to both models were compared. Scatter plots and Bland-Altman plots were used to assess the agreement between the two model outputs. Results showed the largest differences between the two models for shoulder, followed by elbow and wrist, with all RMSDs <10deg (although this limit might be unacceptable for clinical use). Strong-to-excellent Spearman's rank correlation co-efficients were found between the model outputs. The Bland-Altman plots showed a good agreement between most of the outputs. In conclusion, results indicate that these two models with different kinematic algorithms broadly agree, albeit with few key differences.