Kinematics-Based Prediction of Chronic Pain After Combat-Related Extremity Trauma

Combat-related extremity trauma frequently results in persistent pain, including neuropathic, residual limb, and phantom limb pain. The kinematics of injury-including energy level, direction of force, and dominant force components-may independently predict tissue deformation, nerve stress, and the transition from acute to chronic- pain. This prospective observational cohort study will assess whether kinematics-only variables predict chronic pain outcomes after combat-related upper and lower limb injuries. Pain outcomes will include pain intensity, pain extent (surface/area), neuropathic pain features, and mechanical pain sensitivity measured using von Frey filaments.

Adults with combat-related limb trauma will be enrolled within 72 hours of injury. Baseline assessment will include a standardized kinematics classification documenting (1) energy class, (2) dominant direction of force, (3) dominant force component, and (4) kinematics severity grade (K0-K3). Participants will be followed at 6 weeks, 3 months, and 6 months. The primary endpoint is chronic limb pain at 3 months. Secondary endpoints include chronic pain at 6 months, pain area, neuropathic features, and mechanical pain thresholds using von Frey testing at standardized limb sites (injured and contralateral control). This is a non-interventional study; no treatment decisions are dictated by the protocol.