What clinical signs and symptoms should I assess to differentiate between a mild and severe ankle sprain?

To differentiate between a mild and a severe ankle sprain, assess the following clinical signs and symptoms:

• Pain severity and location: Mild sprains typically present with localized pain and tenderness, whereas severe sprains may have intense pain that is out of proportion to the injury mechanism.
• Swelling and bruising: Mild sprains usually have mild to moderate swelling, while severe sprains often show marked swelling and extensive bruising.
• Weight-bearing ability: In mild sprains, patients can usually bear weight with some discomfort; severe sprains often result in inability or significant difficulty to bear weight.
• Range of motion and joint stability: Mild sprains have minimal loss of range of motion and no joint instability; severe sprains may have significant loss of motion and clinical signs of ligament instability (e.g., positive anterior drawer test), best assessed after 4–5 days when swelling subsides.
• Presence of complications: Severe sprains may be associated with complications such as fractures, dislocations, nerve or vascular injury, tendon rupture, or haemarthrosis, which require urgent referral.

Clinical reassessment after 4–5 days is recommended to better evaluate severity, as early examination can be misleading due to pain and swelling.

Referral to emergency or orthopaedics should be considered if symptoms worsen, do not improve as expected, or if severe signs such as inability to weight-bear, suspected fracture, or neurovascular compromise are present.

Early mobilization and functional assessment are important for recovery, with return to activity when full, painless range of motion and strength are restored.

References: NICE CKS