Differential Diagnosis for a 2-year-old Boy with Refusal to Walk After a Fall

• Single most likely diagnosis:
  • Toddler's fracture (a type of stress fracture in young children): This is a common injury in toddlers who are learning to walk or run, and it often occurs without a significant fall. The anterior tibia is a typical location for this type of fracture, and the normal X-ray does not rule out this diagnosis, as these fractures may not be visible on initial X-rays.
• Other Likely diagnoses:
  • Contusion or bruise of the anterior tibia: Direct trauma to the area could result in pain and refusal to walk, even without a fracture.
  • Soft tissue injury (e.g., muscle or ligament strain): Although less common in this age group, a strain could cause significant pain and lead to refusal to bear weight.
• Do Not Miss diagnoses:
  • Non-accidental trauma: Although the history provided suggests an accidental injury, it's crucial to consider the possibility of non-accidental trauma, especially if there are inconsistencies in the history or other suspicious findings on examination.
  • Osteomyelitis or septic arthritis: Infection in the bone or joint can cause severe pain and refusal to move the affected limb. While less likely given the acute onset after a fall, these conditions are medical emergencies and must be considered.
  • Pathologic fracture (fracture through a bone weakened by an underlying condition, such as a cyst or tumor): Although rare, a pathologic fracture could occur with minimal trauma and would require prompt diagnosis and treatment.
• Rare diagnoses:
  • Bone cyst or tumor: Conditions like unicameral bone cysts or osteoid osteomas could cause pain and lead to a fracture with minimal trauma.
  • Rickets or other metabolic bone diseases: These conditions can weaken bones and predispose to fractures with minimal trauma, though they would typically be associated with other signs and symptoms.