Differential Diagnosis for Undisplaced Fracture Involving the Lateral Malleolus
- Single Most Likely Diagnosis
- Salter-Harris Type I fracture: This is the most likely diagnosis given the description of the fracture extending to the physis, which is a characteristic feature of Salter-Harris fractures. The fact that it's an undisplaced fracture also aligns with the typical presentation of these fractures.
- Other Likely Diagnoses
- Salter-Harris Type II fracture: Although the fracture is described as extending to the physis, if there's a small amount of metaphyseal bone involved, it could be classified as a Salter-Harris Type II fracture. The vertical orientation and involvement of the lateral malleolus could still fit this diagnosis.
- Triplane fracture: This type of fracture occurs in adolescents and involves the lateral malleolus, but it typically has components in multiple planes. However, an early or less complex triplane fracture might initially present similarly to the described fracture.
- Do Not Miss Diagnoses
- Pathologic fracture: Although less common, a fracture in this location could be pathologic in nature, especially if there's an underlying bone lesion or condition such as osteogenesis imperfecta. Missing this diagnosis could lead to inadequate treatment and further complications.
- Stress fracture: While stress fractures are more common in the metatarsals or other weight-bearing bones, they can occur in the ankle. A stress fracture of the lateral malleolus could present with similar symptoms and would be important not to miss due to the different treatment approach.
- Rare Diagnoses
- Osteochondritis dissecans: This condition involves a fragment of cartilage and bone becoming detached from the surrounding bone, typically in the knee but can occur in the ankle. It might present with pain and could potentially mimic a fracture on imaging, especially if the fragment is not clearly visible.
- Infection or osteomyelitis: Although rare, an infection could cause destruction of bone that might mimic a fracture on imaging. This would be a critical diagnosis not to miss due to the need for urgent antibiotic treatment.