From the Guidelines
Spaced X-rays are the recommended initial imaging modality for this 14-year-old male with a suspected Salter-Harris fracture of the distal fibular physis, rather than Magnetic Resonance Imaging (MRI), due to their high sensitivity for detecting ankle fractures and availability. The American College of Radiology recommends radiography as the initial imaging study for patients who meet the Ottawa Ankle Rules (OAR) criteria, with studies demonstrating a sensitivity of 92-99% for detecting ankle fractures 1.
Initial Evaluation
In this case, with tenderness to palpation (TTP) laterally and potential involvement of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL), initial X-rays should be obtained to evaluate for fracture. The typical radiographic protocol should include three standard views: anteroposterior, lateral, and mortise views to include the base of the fifth metatarsal bone distal to the tuberosity 1.
Follow-up and Special Considerations
If the initial X-rays are negative but clinical suspicion remains high, follow-up X-rays in 7-14 days are recommended as they may reveal periosteal new bone formation or physeal widening that wasn't visible initially. This approach is particularly important in adolescents with open growth plates where Salter-Harris fractures can be subtle. Special scenarios, such as suspected calcaneal fractures or lateral process fracture of the talus, may warrant additional views like the axial Harris-Beath view or Broden view 1.
Comparison with MRI
MRI would be considered only if symptoms persist after appropriate treatment and follow-up X-rays, or if there is concern for significant ligamentous injury that would change management. The standard treatment for a suspected Salter-Harris I fracture includes immobilization with a walking boot or ankle brace for 3-4 weeks, rest, ice, compression, and elevation, with gradual return to activities as symptoms improve. Ultrasound (US) may be useful but is not typically considered the first line of imaging for the evaluation of acute trauma to the ankle with positive OAR 1.
Key Points
- Spaced X-rays are the initial imaging modality of choice for suspected Salter-Harris fractures in adolescents.
- Initial X-rays should include three standard views: anteroposterior, lateral, and mortise views.
- Follow-up X-rays in 7-14 days may be necessary if initial X-rays are negative but clinical suspicion remains high.
- MRI is reserved for cases with persistent symptoms or concern for significant ligamentous injury.
From the Research
Diagnosis and Imaging
- The diagnosis of a Salter-Harris fracture of the distal fibular physis can be challenging, and imaging plays a crucial role in confirming the diagnosis 2.
- Magnetic Resonance Imaging (MRI) is often used to confirm the diagnosis of Salter-Harris fractures, but recent studies suggest that sprains may be more common than previously thought in children with lateral ankle injuries without radiograph-visible fractures 3, 2.
- In fact, one study found that none of the 18 patients with clinically suspected Salter-Harris I fracture of the distal fibula had evidence of fibular growth plate injury on MR imaging, and instead, most had ligamentous sprains and/or bony contusions 2.
Treatment and Management
- The management of Salter-Harris fractures depends on the type and severity of the fracture, as well as the presence of any displacement or phyoreporing 4.
- For Salter-Harris type I and II injuries, surgical management is recommended if acceptable alignment cannot be obtained with closed reduction, especially in those with a physeal gap greater than 3 mm and pronation-abduction injuries 4.
- However, for children with radiograph-negative lateral ankle injuries, treatment with a removable ankle brace and self-regulated return to activities may be sufficient, regardless of whether an MRI confirms a Salter-Harris fracture or a sprain 3.
Specific Considerations for the 14-Year-Old Male
- In the case of a 14-year-old male with a suspected Salter-Harris fracture of the distal fibular physis, spaced x-rays may be recommended instead of MRI to monitor the growth plate and detect any potential premature phyoreporing 5, 4.
- The presence of tenderness to palpation (TTP) laterally and potential involvement of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) should be taken into account when deciding on the appropriate treatment and management plan 3, 2.
- The fact that the patient is 14 years old, which is an age where the distal tibial physis is nearing complete closure, should also be considered, as this may affect the treatment and management of the injury 5, 6.