MANUAL MINORS
An avulsion fracture of the base of the 5th metatarsal occurs when a bone fragment is pulled away from the rest of the bone due to tension exerted by the peroneus brevis tendon or surrounding ligaments. This type of injury is common during ankle sprains, especially when the foot is suddenly inverted.
Diagnosis
Diagnosis is based on clinical presentation, with localised pain on the lateral edge of the foot, swelling, and difficulty bearing weight. It is confirmed with anteroposterior, lateral, and oblique X-rays of the foot, showing the fracture at the base of the 5th metatarsal.
Differential Diagnosis
Condition | Key Difference |
|---|---|
Jones fracture | Fracture at the metaphyseal-diaphyseal junction, with poorer healing potential. |
Stress fracture of the 5th metatarsal | Occurs in athletes from overuse, not acute trauma. |
Ankle sprain | More generalised pain in the ankle with less bone-specific tenderness. |
Emergency Management
In the emergency setting, the affected foot should be immobilised with a rigid splint or orthopaedic boot to limit movement and reduce pain. Ice application, NSAIDs, or analgesics can be administered as needed. The patient should avoid weight-bearing on the affected foot.
Definitive Treatment
Most avulsion fractures of the base of the 5th metatarsal are managed conservatively with immobilisation for 4 to 6 weeks and weight-bearing restrictions. In rare cases where the fracture is significantly displaced, surgical fixation may be considered. Physical rehabilitation is key to restoring full foot function post-immobilisation.
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