The present invention relates to an apparatus (1) and a method for determining one or more values of functional physiological parameters for a vessel structure around a joint structure of a living being in a non-invasive manner taking into account the impact of anatomical motion onto the vessel structure. A representation determination unit (11) is adapted to determine a deformation of a first representation of the vessel structure based on a deformation model and first and second postures of the joint structure, and to determine a second representation based on the first representation and the determined deformation. A parameter value determination unit (13) is adapted to determine a value of the functional physiological parameter based on a hemodynamical simulation model and the second representation. The apparatus thus provides for an improved severity classification of functional physiological parameter for a vessel structure.