Differential Diagnosis for Undisplaced Fracture Involving the Lateral Malleolus
- Single Most Likely Diagnosis
- Salter-Harris Type I fracture of the distal fibula: This diagnosis is the most likely due to the presence of a vertically oriented, undisplaced fracture extending to the physis, minimal bone marrow edema superior to the distal fibular physis, and the maintenance of the ankle mortise without evidence of ligamentous injury. These findings are consistent with a Salter-Harris Type I fracture, which is a separation of the epiphysis from the metaphasis through the growth plate.
- Other Likely Diagnoses
- Salter-Harris Type II fracture of the distal fibula: Although the physis is not widened, the presence of a fracture extending to the physis and the minimal bone marrow edema could also suggest a Type II fracture, where the fracture extends through the growth plate and into the metaphasis.
- Distal fibular metaphyseal fracture: Given the vertical orientation of the fracture and its extension to the physis, it could be considered a metaphyseal fracture of the distal fibula, especially if the involvement of the physis is considered more as an extension of the fracture rather than a primary component.
- Do Not Miss Diagnoses
- Pathologic fracture due to an underlying bone lesion: It is crucial to consider the possibility of a pathologic fracture, especially if there is any history or suspicion of an underlying bone lesion such as osteogenesis imperfecta, bone cysts, or tumors. Missing this diagnosis could lead to inadequate treatment and potential complications.
- Infection or osteomyelitis: Although less likely given the description, infection or osteomyelitis could present with similar findings, including bone marrow edema. Missing this diagnosis could lead to severe consequences if not treated promptly with antibiotics.
- Rare Diagnoses
- Non-accidental trauma: In certain cases, especially in pediatric patients, it is essential to consider non-accidental trauma as a cause for the fracture, especially if the history provided does not match the injury pattern or if there are other signs of abuse.
- Osteochondritis dissecans: This condition involves the separation of a piece of cartilage and bone from the joint, which could potentially present with similar findings, especially if the fragment involves the area near the physis. However, this would be less likely given the description of the fracture extending to the physis.