How can I differentiate between a sprain and a fracture in a patient with an ankle injury?

Differentiating between an ankle sprain and a fracture in a patient presenting with an ankle injury primarily relies on a thorough clinical assessment, although definitive diagnosis often requires imaging NICE NG38 Wedmore & Charette 2000.

Key indicators that may suggest a fracture over a sprain include:

• Inability to bear weight: If the patient cannot bear weight immediately after the injury and in the emergency department, this raises suspicion for a fracture Wedmore & Charette 2000.
• Localized bony tenderness: Significant tenderness upon palpation over specific bony prominences, such as the posterior edge or tip of either malleolus, the navicular bone, or the base of the fifth metatarsal, is a strong indicator for a potential fracture Wedmore & Charette 2000. Foot fractures are frequently misdiagnosed as ankle sprains, emphasizing the need for careful palpation Judd & Kim 2002.
• Gross deformity: Any visible deformity of the ankle or foot is highly suggestive of a fracture or dislocation Wedmore & Charette 2000.

Both sprains and fractures can present with pain, swelling, and bruising, making initial differentiation challenging based solely on these symptoms Wedmore & Charette 2000.

For a definitive diagnosis, especially when clinical suspicion for a fracture is high based on these criteria, X-rays are typically required Wedmore & Charette 2000. In children, ankle injuries can involve growth plates, and careful evaluation is necessary Solove 2020.

If a fracture is confirmed, management will follow specific guidelines for non-complex or complex fractures NICE NG38,NICE NG37. Rehabilitation is a crucial part of recovery for both sprains and fractures NICE NG211.