A three-step strategy is proposed to characterize the phenomenon by assessing (i) brain response to direct pressure stimulation on the painful knee, which will reflect the combination of peripheral and central sensitization; (ii) brain response to pressure stimulation on a non-arthritic hyperalgesic area (i.e., the anterior surface of the tibia), which will mostly reflect central sensitization mediated at the spinal cord level, and (iii) brain response to moderately painful heat stimulation on a healthy skin area (i.e., volar forearm), which will reflect central sensitization occurring in the brain and involving the highest-level pain modulatory mechanisms. An additional evaluation is proposed using resting-state fMRI to assess potential alterations in baseline brain functional organization.