Fibula fractures

Romesh, a 6-year-old boy, was playing on some monkey bars at school when he slipped and landed on his legs and has been unable to bear weight since. The bars were approximately 1m high, and on examination, positive findings include an area of bruising over the lateral aspect of the right lower leg and marked tenderness on palpation.

Incidence

Isolated fibula shaft fractures are rare. They are more commonly associated with tibia fractures or with an ankle fracture affecting the distal fibula.

How might the patient present?

History

The mechanism is crucial to the injury pattern identified:

• Direct trauma to the lateral aspect of the lower leg results in a transverse or comminuted fracture.
• Twisting injuries produce a spiral fracture.
• Repeated stress, such as in long-distance runners, can cause a fatigue fracture, usually just above the inferior tibiofibular ligament. Think of the cross-country running teenager who usually wouldn’t present but has new lower leg pain or antalgic gait.

Examination

• After an initial history, the normal process of looking, feeling, and moving is a good step. Always examine the knee and ankle and evaluate for other areas of injury. Assessing gait is helpful, as isolated fractures will likely be treated conservatively.

Investigations

• X-ray is the initial imaging modality of choice
• Point-of-care ultrasound could confirm the presence of a fracture, but given the risk of other associated bony injuries, patients will still require imaging.
• Patients with complex injuries involving other bones or joints may warrant cross-sectional imaging
• Does the history match the injury – is there a risk for NAI?

Classification

Fibula fractures are classified by fracture type, whether there is an associated tibial fracture, whether they’re displaced or not and whether they’re open or closed,

• Displacement i.e. 0-50% displaced, >50% displacement with bony contact, or fully displaced
• Open/Closed
• Greenstick-type patterns can occur
• Toddler’s fracture (Spiral fracture of the tibia) may uncommonly have an associated fibula fracture.

Treatment

1. Analgesia
2. Remove significant contaminants from open wounds and administer antibiotics early
3. Isolated shaft fractures – treat with either a supportive dressing, a cast or a boot
4. As the fibula is rarely fractured in isolation, the need for surgical management (such as open reduction and internal fixation) if usually dictated by that of any associated tibial fractures

Potential complications

As with any fracture, union issues (delayed, malunion and non-union) is a risk, made worse if there’s infection. Compartment syndrome is a risk, but is more relevant if there is an associated tibial fracture. Be suspicious of an isolated spiral fracture at the proximal fibula; it may be associated with a distal tibia fracture, called a Maisonneuve fracture. These do poorly with conservative treatment, meaning the ankle must be imaged in those with an apparently isolated fibula fracture to prevent a missed tibial fracture. Although rare, these can occur in older adolescents with closed physes.

Ensure associated nerves (common peroneal if the fibular neck is fractured), arterial territory (the anterior tibial pulse) and lateral collateral ligament is intact with normal function. The lateral collateral ligament joins the femur and fibula, so whilst not as important as the other collateral ligaments, if damaged, it has a high co-incidence of stiffness or pain in other areas such as knee, ankle and foot can delay full rehabilitation.

Do not miss…

• Compartment syndrome
• Other associated fractures – namely at the ankle and tibia
• Fibular head dislocation – the mechanism is usually a fall on a flexed knee, and can be managed with closed or open reduction.

And a bit of trivia

Some patients can be born without a fibula (fibula hemimelia). This will be picked up on ultrasound screening or on newborn screening, but may be relevant for those patients who haven’t presented to healthcare or have migrated.

Romesh was given loading doses of paracetamol and ibuprofen, as well as intranasal diamorphine. His lower leg x-ray, which also included ankle views, and his right lower leg showed a minimally angulated greenstick fracture of the distal fracture. He was managed in a cast and followed up in fracture clinic.

References

Emergency Care of Minor Trauma in Children, 1^st Edition, Davies F

Lecture Notes Orthopaedics and Fractures, 4^th Edition, Duckworth T and Blundell CM

Essential Orthopaedics and Trauma, 5^th Edition, Dandy DJ and Edwards D