Fibular Shaft Fractures

Fibular shaft fractures involve the diaphysis of the fibula. They can occur as isolated injuries (direct blow) or as part of a complex ankle or leg injury (Maisonneuve, Tibia-Fibula fracture).

Mechanism of Injury

• Direct Blow: "Nightstick" fracture. Isolated transverse fracture. Stable. This is typically sustained in contact sports like soccer or rugby where a direct kick or impact occurs to the lateral leg.
• Rotational Force: External rotation of ankle. Energy transmits through syndesmosis → proximal fibula fracture (Maisonneuve). Unstable. The medial structures (deltoid) fail first, then the syndesmosis, then the fibula.
• Axial Load: Fall from height. Usually associated with tibial fracture. The fibula fails under compression, often resulting in comminution.

Epidemiology

• Incidence: Common fracture in active adults. Fibula fractures (including malleolar) constitute a significant portion of ankle trauma.
• Isolated: Football/Soccer (direct kick) is the most common cause.
• Prognosis: Isolated = Excellent union rates. Associated = Depends on other injuries (tibial alignment, chondral damage).
• Risk Factors: Contact sports, osteoporosis in elderly. In the elderly population, fibula fractures may be part of fragility fractures of the ankle.

Anatomy

The fibula acts as a strut for muscle attachment and ankle stability, but plays a minor role in weight transmission.

• Fibula Structure: Long, slender bone. The head is proximal, articulating with the tibia. The neck is just distal to the head (nerve risk). The shaft is triangular in cross-section. The distal end forms the lateral malleolus.
• Weight Bearing: The fibula bears approximately 6-17% of the body's load. This minimal load-bearing allows for fibular resection (e.g., for bone grafts) without significant functional deficit, provided the distal syndesmosis is intact.
• Interosseous Membrane (IOM): A strong fibrous sheet connecting the tibia and fibula. It provides stability for the ankle mortise and serves as an origin for muscles. The fibers run obliquely from proximal-medial (tibia) to distal-lateral (fibula), resisting distal migration of the fibula.
• Common Peroneal Nerve (CPN): The nerve winds around the neck of the fibula, passing from the popliteal fossa into the anterior and lateral compartments. It is highly susceptible to injury here from direct trauma, casts, or surgical retractors.
  • Deep Peroneal Nerve: Supplies the Anterior compartment (Tibialis Anterior, EHL, EDL). Function: Dorsiflexion. Sensation: First dorsal web space.
  • Superficial Peroneal Nerve: Supplies the Lateral compartment (Peroneus Longus/Brevis). Function: Eversion. Sensation: Dorsum of the foot (except 1st web space). Pierces the deep fascia in the distal third of the leg.
• Syndesmosis: The distal tibiofibular joint is maintained by the Anterior Inferior Tibiofibular Ligament (AITFL), Posterior Inferior Tibiofibular Ligament (PITFL), Transverse Ligament, and the distal IOM. It prevents diastasis (widening) of the ankle mortise.

Vascular Supply

• Peroneal Artery: The nutrient artery typically enters the middle third of the fibular shaft.
• Periosteal Supply: The fibula receives a rich blood supply from its multiple muscle attachments (Soleus, Peroneals, Tibialis Posterior, EHL).
• Clinical Relevance:
  • The robust vascularity contributes to high union rates, even in displaced fractures.
  • The middle third of the fibula is the "workhorse" donor site for vascularized bone grafts (e.g., for mandibular or tibial reconstruction) because of its predictable pedicle (peroneal vessels).
  • The distal third has a relatively poorer blood supply, closer to the watershed area of the ankle, which can impact wound healing in surgical cases.

Pathophysiology

• Stability: The fibular shaft itself is not essential for weight bearing stability in the mid-diaphysis. However, the proximal and distal ends are critical for knee (LCL attachment) and ankle stability.
• Ankle Mortise: The Lateral Malleolus (distal fibula) acts as a buttress to prevent lateral shift of the talus. Even 1mm of lateral shift can reduce tibio-talar contact area by 42%, leading to early osteoarthritis.
• Maisonneuve Fracture: A spiral fracture of the proximal third of the fibula associated with a rotational ankle injury. The fracture line location is an indicator of the exit point of the rotational force. If the force exits proximally, it implies that the energy has traveled through the interosseous membrane and syndesmosis, rupturing them.
• Healing: The fibula has a rich muscle envelope (peroneals, soleus, tibialis posterior) which provides excellent blood supply. Non-union is rare. Malunion is generally well tolerated unless it affects the ankle mortise.

History

• Mechanism: Was it a direct blow (e.g., hockey stick, kick)? This suggests an isolated fracture. Was it a twisting injury? This suggests a rotational component and possible syndesmotic injury.
• Pain: Location of pain is key. Mid-calf pain vs Ankle pain. Patients with Maisonneuve fractures may complain only of ankle pain and the proximal fibula tenderness is missed if not palpated.
• Ambulation: Patients with isolated fibula fractures can often bear weight, though painful. Patients with unstable syndesmotic injuries usually cannot.

Physical Examination

• Inspection: Look for deformity, swelling, and bruising. Note any skin tenting or open wounds (rare in isolated fibula). Look specifically for medial ankle bruising ("ecchymosis").
• Palpation:
  • Fibula: Palpate the entire length. The "Squeeze test" (compressing tibia and fibula together at mid-calf) causing distal pain suggests syndesmosis injury.
  • Medial Ankle: Tenderness over the deltoid ligament or medial malleolus is the "red flag" for Maisonneuve.
  • Syndesmosis: Tenderness over the AITFL (anterior ankle).
• Neurovascular Status:
  • Motor: Check Dorsiflexion (Tib Ant) and Great Toe Extension (EHL) for Deep Peroneal Nerve. Check Eversion (Peroneals) for Superficial Peroneal Nerve.
  • Sensory: Check first web space (Deep) and dorsum of foot (Superficial).
  • Pulses: Dorsalis Pedis and Posterior Tibialis.
• Knee: Always assess the knee to rule out associated injuries (LCL, PLC) or proximal tib-fib joint dislocation.

The "lateral leg / ankle pain after a twist or blow" presentation has several mimics. The critical task is separating a benign isolated shaft fracture from an unstable rotational injury.

Missed Syndesmosis

Leading cause of poor outcome in "isolated" fibula fractures. Results in chronic instability, Talar shift, and early post-traumatic arthritis. Requires reconstruction with graft (e.g., semitendinosus) or arthrodesis if late degeneration occurs.

Compartment Syndrome

Check in high-energy injuries or crush injuries. Be vigilant in "tight" leg compartments (Anterior/Lateral). Pain out of proportion to injury, pain with passive stretch of toes. Isolated fibula compartment syndrome is rare but can occur with direct crush.

Superficial Peroneal Nerve Entrapment

• Pathology: The Superficial Peroneal Nerve (SPN) pierces the deep fascia in the distal third of the leg, making it vulnerable to tethering in fracture callus or surgical scar tissue.
• Risk: Higher risk with lateral approaches or percutaneous pin placement.
• Presentation: Patients complain of burning pain over the dorsum of the foot, often exacerbated by inversion and plantarflexion (stretching the nerve).
• Signs: Positive Tinel's sign over the scar/fracture site. Sensation may be altered over the dorsum of the foot.
• Management: Desensitization massage, Gabapentin. Surgical neurolysis is reserved for refractory cases.

Complex Regional Pain Syndrome (CRPS)

Can occur after any ankle trauma. Early mobilization and Vitamin C may reduce risk.

Nerve Injury

The Superficial Peroneal Nerve is at risk during lateral approaches (distal third), and the Common Peroneal Nerve is at risk during proximal approaches or from the injury itself. Symptomatic neuromas may require surgical excision.

Non-Operative (Isolated)

• 0-2 Weeks: Boot, WBAT with crutches for comfort. Elevate to reduce swelling.
• 2-6 Weeks: Wean boot. Transition to supportive shoe/brace. Start Physio for ROM (Ankle alphabet) and strengthening (Peroneals/Calf).
• 6+ Weeks: Return to impact activities as pain allows. Most patients return to full sports by 8-12 weeks.
• Milestones:
  • Full weight bearing without pain.
  • Equal ankle dorsiflexion/plantarflexion.
  • Ability to perform single leg hop.

Operative (Syndesmosis)

• 0-2 Weeks: Non-weight bearing (NWB) cast/splint using crutches. Elevation. Wound check at 2 weeks.
• 2-6 Weeks: NWB in tall boot. Range of Motion exercises allowed (Active dorsiflexion/plantarflexion). Avoid external rotation. Protocol varies widely: Suture buttons (TightRope) often allow earlier weight bearing (e.g., WBAT at 2 weeks) compared to rigid screws.
• 6-12 Weeks: Progressive weight bearing. Proprioception training (wobble board). Strengthening (theraband).
• Hardware Removal:
  • Rigid Screws: Traditionally removed at 3-4 months before full unrestricted activity to prevent screw breakage. Activity is restricted until removal and then screw holes heal (6 weeks).
  • Suture Buttons: Stay in permanently unless symptomatic (knot irritation). No activity restriction once healed.

Rehabilitation Protocol Details (Syndesmosis)

• Phase 1 (0-6 Weeks): Protection and Edema Control
  • Goals: Heal soft tissues, protect fixation.
  • Exercises: Toe curls, Knee ROM, Hip strengthening (Straight Leg Raises).
  • Precautions: No weight bearing (for screws). No external rotation torque.
• Phase 2 (6-10 Weeks): Mobility and Strength
  • Goals: Restore full ROM, normalize gait.
  • Exercises: Calf stretching (gastroc/soleus), Ankle 4-way theraband strengthening, Stationary bike (low resistance).
  • Proprioception: Single leg stance eyes open/closed.
• Phase 3 (10+ Weeks): Return to Function
  • Goals: Power, Agility, Sport-specific skills.
  • Exercises: Heel raises (bilateral to single), Plyometrics (box jumps, hopping), Running progression (Walk-Jog-Run).
  • Testing: Hop test (greater than 90% of contralateral side) required for cleared return to play.

Isolated Fibula

• Excellent. 95%+ of patients return to pre-injury level of activity.
• Rapid healing. Pain resolves by 3-4 months usually.
• Long-term functional deficits are rare.

Maisonneuve

• Good, if syndesmosis reduced accurately.
• Risk: Ankle arthritis if reduction is poor (fibula malreduced or syndesmosis widened).
• Stiffness: Stiffer ankle compared to isolated fractures.
• Recovery: Takes longer (6-9 months) for full sports return compared to isolated injuries.

• Screw vs suture button for the syndesmosis: Level I meta-analysis favours suture buttons for function and lower reoperation, but a long-term RCT found malreduction and osteoarthritis rates comparable between the two. Reduction quality may matter more than the implant chosen.
• Routine syndesmosis screw removal: Traditionally removed before return to full activity, yet many intact screws are asymptomatic. Practice is shifting to removing only symptomatic implants.
• Which "isolated" fibula fractures are truly stable: Static radiographs miss latent instability. Reliance on gravity/external-rotation stress views versus weight-bearing radiographs versus MRI to declare stability remains debated.
• Number, size and cortices of screws: Quadricortical vs tricortical, 3.5 vs 4.5mm, one vs two screws - no consensus; the trend is toward fewer, smaller, or flexible constructs.
• Ankle position during syndesmotic fixation: The old teaching to hold maximal dorsiflexion to avoid "over-tightening" is now largely discredited; clamp position and rotation are the real determinants of malreduction.
• Significance of fibular shortening/malunion: Mid-diaphyseal fibula malunion is usually well tolerated, but the threshold of shortening that alters ankle mechanics is poorly defined.
• Thromboprophylaxis for boot-treated isolated fractures: Routine chemical prophylaxis is not supported for low-risk patients; risk-stratified use is recommended but thresholds vary by guideline.

• Protective Gear: Shin guards (Soccer) are effective in preventing direct blow fractures ("Nightstick").
• Return to Play:
  • Isolated: 4-8 weeks. Criteria: Pain-free hopping, full strength, full ROM.
  • Maisonneuve: 4-6 months. Requires solid syndesmotic healing and rehab.

Global Epidemiology

• Ankle fractures (of which the fibula is the most frequently involved bone) occur at roughly 100-180 per 100,000 person-years, with a bimodal distribution: young men from sport/high-energy injury and older women from fragility fractures.
• Isolated diaphyseal ("nightstick") fibula fractures are most common in contact and kicking sports (soccer/football, rugby, hockey) where a direct blow strikes the lateral leg.
• Maisonneuve fractures represent a small but high-stakes subset; they are disproportionately represented among "missed" rotational ankle injuries.

Side-by-side Guidance

Registry and System Notes

• National arthroplasty/trauma registries (AOANJRR, NJR, SHAR) track ankle fracture fixation as a high-volume procedure; metalwork removal (notably syndesmosis screws) is a frequent secondary procedure, a burden that suture-button fixation aims to reduce.
• Routine removal of intact syndesmosis screws is now questioned; many systems remove only symptomatic implants.

High- vs Limited-resource Practice

• Well-resourced settings: stress radiographs or CT for equivocal syndesmosis, suture-button options, formal physiotherapy-led rehabilitation, early weight-bearing protocols.
• Limited-resource settings: reliance on plain radiographs and clinical examination (proximal fibula palpation, medial tenderness, calf squeeze); cast or boot immobilisation; syndesmotic screws preferred over costlier suture-button devices, with later removal where feasible.
• The universal, resource-independent priority is the same: do not miss the unstable medial side or a proximal (Maisonneuve) fibula fracture.