Introduction: Hemophilic arthropathy is characterized by functional alterations, disabling physical sequelae, and chronic pain. Conditioned pain modulation describes the net effect of endogenous pathways that enhance or diminish the effects of afferent noxious stimuli.

Objectives: To describe conditioned pain modulation in patients with hemophilia and identify the best predictive model of conditioned pain modulation in these patients

Methods: Cross-sectional cohort study. 51 patients with hemophilic arthropathy will be recruited in 3 regions of Spain. The main study variable will be the conditional pain modulation (Conditioned Pain Modulation Index, using an ischemic technique of the arm using the pain pressure threshold as a test stimulus), with age being the dependent variable. The secondary variables, estimated as modifying or confounding variables, will be kinesiophobia (Tampa Scale for Kinesiophobia), catastrophizing (Pain Catstrophizing Scale), trait and state anxiety (State-Trait Anxiety Inventory) and the main clinical, anthropometric, and sociodemographic. Expected results: Identify the degree of modulation conditioned by pain in patients with hemophilic arthropathy. Identify the best predictive model for conditioned pain modulation in these patients based on the study variables