A 34-year-old trail runner arrives limping, one hand wrapped around the outside of his right knee and the other around a swollen ankle. His sock is dusty, and every attempt to rotate the foot produces a sharp wince that travels up the leg. He says he “only twisted the ankle,” but the proximal fibula is exquisitely tender. The question is whether the injury ends at the ankle—or whether the entire interosseous membrane has failed.

— What’s your move? Read on.

Before you read
  • Which ankle instability pattern defines this injury?
  • When is reduction urgent even if the skin is intact?

When to Think of It

Think of it with an ankle external-rotation injury plus proximal fibular tenderness, medial malleolar fracture or medial tenderness, widened medial clear space, syndesmotic widening, or an apparently “minor” ankle injury with pain extending up the leg. Examine the entire fibula, ankle mortise, skin, pulses, sensation, and compartment firmness.

Sick or Not Sick

The key call is stable versus unstable ankle mortise with threatened neurovascular status or skin. Dislocation, gross deformity, open injury, absent pulses, progressive neurologic deficit, or compartment syndrome requires immediate reduction and orthopedic involvement; otherwise, instability on imaging still generally requires operative management.

The First Fifteen Minutes

  • Immobilize in a well-padded posterior short-leg splint with a stirrup; repeat pulses, sensation, and motor function after splinting.
  • For moderate pain and no contraindication: acetaminophen 1,000 mg PO, because central analgesia reduces pain without impairing the neurovascular examination.
  • If additional pain control is needed: fentanyl 1 mcg/kg IV, typically 25–100 mcg, because rapid opioid analgesia facilitates examination and reduction; reassess ventilation and sedation.
  • If the ankle is dislocated, skin is tented, or pulses are impaired: perform immediate closed reduction with procedural sedation; ketamine 1 mg/kg IV, or 4–5 mg/kg IM if IV access is unavailable, provides dissociative analgesia while usually preserving spontaneous respirations. Follow local sedation protocol.
  • If the injury is open: cefazolin 2 g IV now, because early gram-positive coverage reduces infection risk; add broader gram-negative or anaerobic coverage according to Gustilo grade and institutional protocol.
  • If tetanus is not up to date for an open wound: tetanus vaccine 0.5 mL IM; add tetanus immune globulin 250 IU IM for dirty wounds with unknown or incomplete primary vaccination.
  • If reduction is required and ketamine is unsuitable: propofol 0.5–1 mg/kg IV initially, titrated in 0.25–0.5 mg/kg increments, with airway-capable monitoring; dosing varies with age, frailty, and co-ingestants.

Definitive Care & Disposition

Obtain AP, lateral, and mortise ankle radiographs plus full-length tibia-fibula films; image the knee if proximal pain or another injury is suspected. CT may define complex ankle or posterior malleolar involvement. Maintain reduction and non-weight-bearing status. Orthopedics should evaluate unstable syndesmotic disruption, talar shift, open fracture, or irreducible dislocation—most require operative fixation. Admit if open injury, neurovascular compromise, severe swelling, unreliable follow-up, or associated injuries; a reduced, closed injury with preserved perfusion may await timely orthopedic follow-up only when the mortise is stable and specialist-directed.

How This One Kills

The classic failure is diagnosing an “ankle sprain” from a nondisplaced ankle film while never palpating the proximal fibula. The syndesmosis then heals malaligned, producing chronic talar instability and early arthritis.
The Differential — What Else Looks Like This
  • Isolated lateral ankle sprain — no proximal fibular tenderness or mortise instability; treating a Maisonneuve injury as a sprain permits displacement.
  • Proximal fibula fracture alone — ankle stress or mortise imaging shows syndesmotic injury; missing it leaves the ankle unstable.
  • Ankle dislocation without fracture — alignment and fracture pattern differ, but both require urgent reduction; delay risks skin and neurovascular injury.
  • Peroneal nerve injury at the fibular neck — foot-drop or dorsal foot sensory loss may accompany either injury; missing it loses a time-sensitive neurologic baseline.

The Second-Day Story

Older adults, patients with neuropathy, and partially analgesic-treated patients may report only vague ankle discomfort and walk into the department. The proximal fibular fracture may be subtle or absent on initial ankle films. Deliberately palpate the fibula from the fibular head to the ankle, compare the mortise, and obtain full-length tibia-fibula imaging when the mechanism or examination is discordant.
Back to Our Patient
Back to our 34-year-old trail runner: the proximal fibular tenderness and external-rotation mechanism trigger recognition of a Maisonneuve injury, so full-length tibia-fibula and mortise films are obtained. They show a proximal fibular fracture, widened medial clear space, and syndesmotic disruption; his pulses and sensation remain intact, and the skin is closed. He receives analgesia, a well-padded short-leg splint, remains non-weight-bearing, and is admitted for urgent orthopedic evaluation and operative stabilization rather than discharged as an ankle sprain.
Patient Presentation to Attending
How you’d present this patient on the floor — tight, pertinent positives and negatives, no rambling
“This is a 34-year-old previously healthy trail runner with a right ankle inversion-external rotation injury and pain extending to the proximal fibula. He has marked ankle swelling and focal proximal fibular tenderness, with no open wound, compartment firmness, or knee tenderness. Dorsalis pedis and posterior tibial pulses are palpable, capillary refill is normal, and sensation and ankle motor function are intact but limited by pain. Ankle films show medial clear-space and syndesmotic widening, and tibia-fibula films show a proximal fibular fracture. This is an unstable Maisonneuve-pattern ankle injury without current neurovascular compromise. I’ll maintain reduction and non-weight-bearing immobilization, provide analgesia, repeat the neurovascular exam, and consult orthopedics for operative management.”

Study Directive

  • Draw the Maisonneuve injury pattern from memory: proximal fibula, interosseous membrane, syndesmosis, and medial-sided injury.
  • Review three ankle mortise radiographs and identify medial clear-space and tibiofibular overlap abnormalities.
  • Practice a complete pre- and post-reduction neurovascular documentation template.
  • Read your institutional open-fracture antibiotic and procedural-sedation protocols.

Recent Literature