A proposed test to support the clinical movement analysis laboratory accreditation process

This paper describes a testing methodology and resultant set of four variables that can be used to quickly and easily document the correct installation, configuration, and combined working status of force platform (FP) and three-dimensional (3D) motion capture components of a clinical movement analysis (CMA) laboratory. Using a rigid, rod-shaped testing device, CMA laboratory data are collected simultaneously from the FP and motion capture components (typically, video-based kinematic measurements) as the device is manually loaded while being pivoted broadly about a point on the FP. Using a computational method based on static equilibrium, it is possible to independently measure the rod's orientation and tip position during the moving trial, using FP derived data exclusively, and to compare these estimates to rod orientation and tip position estimates derived exclusively from the motion capture component. The motion laboratory accreditation test (MLAT) variables include: the difference (angle) between the orientation of the long axis of the testing device as independently determined from kinematic measures (motion capture component) and the FP derived data; and the difference (x, y, z) between the center of pressure position (FP derived) and the position of the testing device tip (motion capture derived) that loads the FP. A numerical dynamics model was explored to evaluate the appropriateness of the static equilibrium-based FP data model and to determine guidelines for testing device movement frequency and FP loading. The MLAT technique provides a simple means of detecting the combined presence of errors from many sources, several of which are explored in this paper. The MLAT has been developed to help meet one criteria of the CMA laboratory accreditation process, and to serve as a routine quality assessment tool.