Complex regional pain syndrome (CRPS type I) is the most likely diagnosis because the child has persistent, function-limiting pain behavior and marked unwillingness to move the entire limb despite a minor fracture that is now healed radiographically and has a normal neurovascular exam. MCCQE objectives emphasize recognizing pain that is disproportionate to tissue injury and persists beyond expected healing, often accompanied by guarding and fear of movement. CRPS can occur after fractures or immobilization and may present with severe allodynia, hyperalgesia, edema, color/temperature changes, and motor dysfunction; however, early cases may primarily show avoidance of movement and pain with otherwise normal objective findings.

An unrecognized scaphoid fracture would cause localized wrist pain (classically snuffbox tenderness) rather than refusal to move elbow, wrist, and fingers, and would not be explained by a distal radius buckle fracture that has united. Ischemic (Volkmann) contracture would involve a tense forearm, fixed flexion deformity, and neurovascular compromise. Median nerve compression would produce sensory changes and thenar weakness. School avoidance alone does not explain the post-injury limb-protective pattern with normal healing. Management focuses on reassurance, early mobilization, physiotherapy, and multidisciplinary pain strategies.