The main goal of my PhD is to investigate the risk factors of chronicity in the chronic regional pain syndrom (CRPS) and in the futur, be able to have an impact on its secondary prevention. We already know some risk factors of onset of CRPS but what's about the chronicity? Through an observational longitudinal study at CUSL, we would like to study some risks factors and then, as in the low back pain, be able to determine which patients are at higher risk of chronicity and which therapeutic interventions to suggest.