Proximal Fibula (Maisonneuve)

The Maisonneuve fracture is a proximal fibular fracture associated with a disruption of the ankle syndesmosis and interosseous membrane, with or without a medial-sided ankle injury. It is a high-energy equivalent ankle injury that is frequently missed on initial presentation because the fracture is remote from the ankle, and plain ankle radiographs may appear deceptively benign.

• Named after Jules Germain François Maisonneuve (1840), who described the spiral fracture of the proximal fibula caused by external rotation of the foot
• The mechanism is external rotation of the foot with a fixed leg — force propagates proximally through the interosseous membrane from a medial ankle injury to fracture the proximal fibula
• The interosseous membrane tears from distal to proximal up to the level of the fracture
• Medial-sided injury is almost always present: deltoid ligament rupture, medial malleolus fracture, or both
• The anterior inferior tibiofibular ligament (AITFL) and posterior inferior tibiofibular ligament (PITFL) are disrupted — complete syndesmotic instability results
• The ankle mortise is unstable despite a normal or near-normal appearance on ankle radiographs — this is the key diagnostic pitfall
• Associated injuries: posterior malleolus fracture (Volkmann fragment), anterior tibial lip avulsion (Chaput fragment)

The Maisonneuve fracture represents the most proximal variant of the Supination-External Rotation (SER) or Pronation-External Rotation (PER) patterns in the Lauge-Hansen classification. Understanding this context clarifies why the syndesmosis is always disrupted.

• Maisonneuve = Pronation-External Rotation (PER) pattern — medial injury occurs first, then force propagates through interosseous membrane
• The entire interosseous membrane from the ankle to the fibula fracture is disrupted — this is why the ankle is completely unstable despite the fracture being at the knee level
• Weber classification: Maisonneuve = Weber C (fibula fracture above syndesmosis) — syndesmosis always disrupted in Weber C injuries

• Clinical examination: ankle pain and swelling; medial ankle tenderness (deltoid ligament or medial malleolus); proximal fibula pain and tenderness — ALWAYS palpate the entire fibula in any ankle injury; positive external rotation stress test of ankle
• Squeeze test (Hopkinson): compression of fibula and tibia at mid-calf — pain at ankle or along interosseous membrane = positive; suggests syndesmotic disruption
• External rotation stress test: foot in neutral, externally rotate — reproduction of ankle pain; lateral talar shift on stress radiograph confirms instability
• Plain radiographs: always include full-length tibia-fibula views when Maisonneuve suspected; standard ankle views may show: widened medial clear space (>4 mm), widened syndesmosis (>5 mm at 1 cm above plafond on AP), tibiofibular overlap <10 mm on AP or <1 mm on mortise, medial malleolus fracture
• Medial clear space >4 mm = deltoid rupture or medial malleolus fracture = ankle instability until proven otherwise
• CT scan: useful to define posterior malleolus involvement, fibula fracture comminution, and articular congruity; assess for anterolateral tibial lip fractures (Chaput fragment)
• MRI: can confirm deltoid ligament and syndesmotic ligament integrity; useful when clinical diagnosis uncertain

The Maisonneuve fracture is an unstable ankle injury requiring surgical stabilisation of the syndesmosis. The proximal fibula fracture itself rarely requires direct fixation.

• Medial malleolus fracture (if present): ORIF with lag screws or tension band wiring — restores medial buttress; performed before syndesmotic fixation
• Deltoid ligament rupture: if medial malleolus intact but deltoid torn — repair vs no repair is debated; most contemporary evidence supports repair of deltoid in presence of syndesmotic instability to prevent residual medial instability
• Syndesmotic stabilisation: mandatory in all Maisonneuve fractures — the proximal fracture = complete syndesmotic disruption
• Reduction of syndesmosis: reduce fibula into tibial incisura anatomically under direct vision or fluoroscopy; clamp from fibula to tibia with ankle in dorsiflexion; confirm reduction on mortise view — fibula must be reduced into incisura; CT can confirm post-reduction congruity

Syndesmotic Fixation Options:

• Ankle must be in dorsiflexion during syndesmotic fixation — prevents overtightening and malreduction of fibula in dorsiflexion; plantarflexion at time of screw insertion risks fibula being fixed in an anterior position
• Proximal fibula fracture: does not require direct fixation in most cases — the fibula will heal with conservative management once the ankle is stabilised; only fix proximally if there is significant displacement threatening neurovascular structures or peroneal nerve
• Peroneal nerve at risk with proximal fibula fracture — assess pre- and postoperatively; immediate neurolysis if nerve is compressed
• Posterior malleolus (>25% articular surface or unstable): requires ORIF — posterolateral approach; fixes the PITFL attachment and stabilises the syndesmosis posteriorly

• Non-weight bearing in below-knee cast for 6–8 weeks; progressive weight bearing thereafter
• Syndesmotic screw: remove at 8–12 weeks before full weight bearing to prevent screw breakage — or leave if asymptomatic (debate exists)
• Suture button: no removal required; allows progressive weight bearing earlier in some protocols
• Complications: syndesmotic malreduction (most critical — leads to ankle incongruity and early arthritis); implant breakage; loss of reduction; post-traumatic ankle arthritis; chronic syndesmotic instability if undertreated
• Syndesmotic malreduction is the most preventable and most consequential complication — intraoperative CT or fluoroscopic assessment of reduction is strongly recommended
• Peroneal nerve palsy: common with proximal fibula fractures; most recover spontaneously over 3–6 months; EMG/NCS at 6 weeks if no recovery

• Syndesmotic reduction accuracy: multiple studies demonstrate that up to 30–50% of syndesmotic reductions assessed as adequate on fluoroscopy are malreduced on CT — intraoperative CT or post-reduction CT is increasingly recommended as the standard of care
• Fibula must be reduced into the incisura fibularis — external rotation, shortening, or posterior displacement of the fibula are common malreduction patterns; each changes ankle kinematics and leads to early arthritis
• Deltoid repair debate: recent RCT data (REFIX trial and others) suggests that deltoid ligament repair in the setting of syndesmotic fixation improves medial stability and functional outcomes — repair is increasingly recommended in Maisonneuve injuries with deltoid disruption
• Suture button vs screw: multiple RCTs now support suture button as equivalent or superior to screw fixation — allows physiological tibiofibular motion, avoids obligate screw removal, and may reduce malreduction rate due to dynamic self-correction
• Chronic syndesmotic instability: missed Maisonneuve fracture leads to chronic ankle instability, pain, and progressive arthritis; late reconstruction with ligament repair and bony realignment is complex; emphasis on not missing the diagnosis acutely

• Always palpate the entire fibula in any ankle injury — proximal tenderness = Maisonneuve until proven otherwise
• Maisonneuve = PER pattern = medial injury first, then interosseous membrane tear propagating proximally to proximal fibula fracture
• Medial clear space >4 mm = ankle instability; tibiofibular overlap <10 mm AP = syndesmosis widened
• Weber C = fibula above syndesmosis = syndesmosis always disrupted = syndesmotic fixation required
• Proximal fibula fracture does not need fixation — stabilise the ankle and syndesmosis; fibula heals
• Fix syndesmosis with ankle in dorsiflexion — prevents overtightening and anterior fibular malreduction
• Suture button = physiological motion, no routine removal — increasingly preferred over screw
• Syndesmotic malreduction: most consequential complication — intraoperative CT recommended
• Peroneal nerve at risk with proximal fibula fracture — document pre- and postoperatively
• Posterior malleolus >25% articular surface — ORIF required; stabilises PITFL and posterior syndesmosis