Sensitivity of a biomechanical model of the finger to errors in experimental input

Biomechanical models of the fingers are used to gain a greater understanding of internal loading. This can help guide the treatment of injuries and pathologies. However, to be valid these models require accurate measurement of body kinematics, external reaction forces and soft tissue architecture. This study aimed to quantify the sensitivity of one such model, to errors in these inputs. Experimental data was collected from a single subject carrying out a simple gripping activity and the experimental data altered to introduce artificial errors. We found that the correlations between errors in measurement of body kinematics and the model outputs could be used to express errors in motion capture data in terms of internal loading. However, these correlations were specific to grip type, therefore, if the grip changed significantly a new analysis would be required. Sensitivity analysis of the muscle and tendon locations indicated which parameters were most important to measure accurately; outputs were most sensitive to changes in the most highly loaded muscle–tendon units, these results were applicable across different hand orientations.