Functional analysis of the trunk flexion-extension through Gaussian functions fitting of the movement profile

A healthy mobility of the trunk plays a fundamental role in the activities of daily living. The flexion-extension movement is one of the main tasks evaluated in clinical practice to assess the functionality of the spine. Nevertheless, no fully shared methods are currently available for the clinician to perform quantitative evaluations on the movement quality. In this paper, the trunk flexion-extension task performed by 36 healthy adult subjects, for a total of 104 acquisitions, was acquired with an optoelectronic system of 8 cameras and 32 skin passive optical markers. The absolute displacement of the subject's seventh thoracic vertebra (T7) was fitted with an asymmetric Gaussian function, comparing the performance of four alternative cost functions in the optimization process. A set of descriptive parameters for the quantitative evaluation of the profile, suitable for the everyday use in the clinical practice, was designed and applied on the current dataset. Statistical analysis was performed on residuals of the fitting process, coefficients of the optimal fitting functions and proposed descriptive parameters, outlining a preliminary description of the trunk flexion-extension movement in the healthy adult.