Causes / typical injury mechanism: Proximal fibula fractures are most commonly caused by trauma, particularly associated with twisting of the leg or foot and with blunt force to the lateral leg. Fractures of the proximal fibula rarely occur as isolated injuries and are often associated with damage to other structures such as the proximal tibia, knee ligaments, and nearby neurovascular structures (eg, common peroneal nerve).

Classic history and presentation: Presentation of proximal fibula fractures varies based on the severity of the trauma and presence of associated ligament and neurovascular injuries. Typically, proximal fibula fracture presents with local edema and tenderness on palpation of the lateral leg over the proximal fibula and can sometimes result in antalgic gait and discoloration and deformity of the lateral leg.

Depending on the associated injuries, these fractures may also present with:

• Knee instability due to ligament damage
• Avulsion of the lateral collateral ligament (LCL)
• Weakness (eg, foot drop) and sensory issues distal to the injury due to peroneal nerve damage
• Hemarthrosis
• Pain over the medial malleolus suggestive of a Maisonneuve fracture

Prevalence: Rare.

• Age – This is usually seen in athletes younger than 25 years and individuals with decreased bone density who are older than 50 years.
• Sex / gender – This most commonly affects young male athletes and postmenopausal women.

Risk factors: A major risk factor for fibula fractures is decreased bone density. For this reason, fibula fractures are most prevalent in older individuals, especially postmenopausal women, cigarette smokers, and physically inactive people. Additionally, people who participate in contact sports involving cutting and twisting, such as soccer, American football, and downhill skiing, are at a higher risk for proximal fibula fractures. Direct trauma to the region is a known risk factor.

Pathophysiology: This is typically a direct injury to the proximal fibula. There can alternatively be a twisting injury to the ankle that transmits through the interosseus membrane where the force exits through the proximal fibula. There can also be an association with a multiligamentous knee injury in which there is a high amount of energy transmitted to the knee through a motor vehicle accident, direct trauma, or a twisting injury.