Ankle fracture 

 

Facts

• One of the most common skeletal injuries seen by physicians
• Fractures of the malleoli are caused by rotational mechanisms, most commonly external rotation with the foot supinated
• Incisura fibularis: groove along the distal lateral tibia in which the fibula lies
• Lateral malleolus: lateral flare of the distal fibula
  • Most commonly fractured
• Medial malleolus: medial flare of the distal tibia
  • Inner surface divided by a groove that defines the anterior (larger) and posterior colliculus
  • Anterior colliculus is the attachment for the superficial deltoid ligament
  • Posterior colliculus is the attachment for the deep deltoid ligament
• Posterior malleolus: posterior flare of the distal tibia
  • Integrity important for posterior joint stability
• Mortise: formed by the distal tibial articular surface (plafond), medial and lateral malleoli
  • Articulates with the talar dome
• Talar dome is wider anteriorly
  • In dorsiflexion, talar dome forces fibula laterally and into ER
  • In plantarflexion, the talar dome rotates internally due to checkrein action of the deltoid ligament
• Normal ROM: dorsiflexion of 30° and plantarflexion of 45°
  • Minimum functional ROM: -10° to 20°
  • Axis of rotation is 20° externally rotated compared to knee
• Leg has 4 compartments:
  • Anterior: tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius, anterior tibial vessels and deep peroneal nerve
  • Lateral: peroneus longus, peroneus brevis and superficial peroneal nerve
  • Deep posterior: flexor digitorum longus, flexor hallucis longus, tibialis posterior, posterior tibial vessels and the tibial nerve
  • Superficial posterior: gastrocnemius, plantaris and soleus
• Local structures:
  • Lateral:
    • Peroneal tendons pass posterior to the lateral malleolus under the peroneal retinaculum
    • Superficial to the peroneals at this level is the sural nerve and lesser saphenous vein
  • Medial:
    • Posterior to the medial malleolus lie the tibialis posterior, flexor digitorum longus and flexor hallucis longus tendons, the posterior tibial vessels and tibial nerve
    • These structures pass under the laciniate ligament (medial malleolus to calcaneus)
    • Anterior to the medial malleolus are the saphenous vein/nerve
  • Anterior:
    • Under the extensor retinaculum (anteromedial tibia to anterolaterlal fibula) lie the tibialis anterior, extensor hallucis longus, extensor digitorum longus and peroneus tertius tendons, the deep peroneal nerve and the anterior tibial vessels
    • Superficial to the extensor retinaculum is the superficial peroneal nerve
  • Posterior:
    • Achilles and plantaris tendons

 

• Ligaments:
  Medial ligament complex: deltoid ligament is the primary stabilizer of the ankle, resists valgus stress and lateral translation of the talus
  • Originates from medial malleolus
  • Superficial portion: originates from anterior colliculus and is comprised of 3 parts:
    • Tibionavicular: attaches to navicular, suspends calcaneonavicular (spring) ligament
    • Tibiocalcaneal: attaches at sustenaculum tali, prevents valgus
    • Tibiotalar ligament: attaches along medial talar body
  • Deep portion: primary medial stabilizer of the ankle, attaches to non-articular portion of medial talus
    • Intraarticular but extrasynovial
  • Disruption of the deltoid (or the medial maleollus) results in abnormal talar motion

Lateral ligament complex: originates from lateral malleolus, not as strong as medial

• Anterior talofibular ligament (ATFL): weakest, often first to fail
  • Attaches at talar neck
  • Prevents anterior subluxation of talus (anterior drawer)
• Posterior talofibular ligament (PTFL): strongest, often results in avulsion rather than rupture
  • Attaches at lateral talar tubercle
  • Prevents posterior subluxation of talus
• Calcaneofibular ligament (CFL): stabilizes subtalar joint and resists inversion
  • Attaches at superior lateral calcaneus

Syndesmosis ligament complex: exists between the distal tibia and fibula at the level of the plafond

• Consists of the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), transverse tibiofibular ligament (TTFL) and interosseous tibiofibular ligament (ITFL)
• Stabilizes the mortise, preventing migration of the talus

 

• Patients typically present with ankle pain and variable amounts of swelling and ecchymosis
• Identify position of foot and direction of injury (e.g. inversion) when posible
• Evaluate entire leg for fibula fractures
• Ottawa ankle rules: radiographs are warranted when pain is present around malleoli and either:
  • Tenderness to palpation of the posterior lateral malleolus (distal 6 cm)
  • Tenderness to palpation of the posterior medial malleolus (distal 6 cm)
  • Inabiltiy to take 4 steps immediately after injury and at presentation
• Isolated syndesmotic injury (high ankle sprain) can mimic regular ankle sprain (involving the lateral ligament complex):
  • Tenderness to palpation of AITFL
  • Squeeze test can be performed by compressing the tibia and fibula together 5 cm proximal to ankle
    • Pain along the syndesmosis is considered positive
  • External rotation test: ER of the ankle with knee flexed and ankle in neutral
    • Pain at the AITFL or PITFL is considered positive
• Tenderness to palpation over the soft tissue anteromedial to medial malleolus may indicate deltoid injury
• Clinically evident ankle dislocations should be reduced immediately and then imaged
  • Ankle dislocations without fracture are very rare
• Diabetic patients with low-energy injuries may have Charcot (neuropathic) arthropathy
• Assess NV status and identify associated injuries, particularly around the hindfoot, navicular and 5th MT
• Compartment syndrome: sustained increase in compartment pressure due to inflammation and edema in one or more of the leg compartments leading to vascular compromise and muscle death
  • Muscle death occurs 6-8 hours after the onset of compartment syndrome
  • Severe pain with passive motion of the toes/foot is often first sign
  • Other signs include tense swelling of the calf, diminished pulses, pain out of proportion to injury and paresthesias
    • Serial neurovascular exams are required as compartment syndrome can develop more than 24 hours after injury
  • Compartment pressures should be measured in patients with clincal signs of compartment syndrome
    • Compartment pressure > 30 mmHg or within 30 mmHg of the diastolic blood pressure warrant urgent fasciotomies of the leg compartments
  • Deep posterior compartment pressure may be elevated in the presence of a soft superficial compartment
    • Missed posterior compartment syndrome can result in claw toe deformity

Imaging

Radiographs

• AP, lateral and mortise views of the ankle are standard examinations
• AP:
  • Tibiofibular overlap: < 10 mm is abnormal and implies syndesmotic injury
  • Tibiofibular clear space: > 5 mm is abnormal and implies syndesmotic injury

Normal AP ankle

• Lateral:
  • Identify posterior malleolus and anterior talar avulsion fractures
  • Talar dome should be centered and congruous under the tibial plafond

 

 

Normal lateral ankle

• Mortise:
  • Taken with foot in 20° of IR
  • Medial clear space: > 4 mm is abnormal and indicates lateral talar shift (deltoid rupture)
  • Talar tilt: distal tibial articular surface should be parallel with superior talar articular surface
    • Difference of > 2° suggests talar tilt and ligamentous disruption
  • Talocrural angle: angle subtended by intermalleolar line (connecting distal-most points of both malleoli) and distal tibial articular surface should be between 8°-15°
    • A smaller angle indicates fibular shortening
  • Tibiofibular overlap: < 1 mm implies syndesmotic disruption

Normal ankle mortise

• Stress view:
  • Performed by applying ER force to the ankle with foot dorsiflexed
  • Widening of the syndesmosis (decrease in tibiofibular overlap) indicates syndesmotic injury
  • Widening of the medial clear space indicates deltoid ligament injury
• CT: may be indicated for complex fractures
  • Can detect impaction injuries to the plafond
    • Impaction of the anteriomedial or anteriolateral corners is a poor prognostic sign
• MRI: can be used to evaluate subtle or stress fractures as well as ligament, capsule and tendon injuries

 

Classification

• Lauge-Hansen: based on mechanism of injury, first word indicates position of foot during injury, second word indicates direction of deforming force
  • Each mechanism is an injury progression with each stage representing increasing severity
  • Injury begins in one location and proceeds around ankle depending on mechanism force

Supination-adduction (10-20%): only type associated with medial talar displacement

3. Transverse/avulsion-type fibular fracture or a lateral ligament rupture
4. Vertical medial malleolar fracture

Supination-external rotation (40-75%)

5. ATFL disruption
6. Spiral fracture of distal fibula (posterosuperior to anteroinferior)
7. PTFL disruption or posterior malleolus fracture
8. Transverse/avulsion-type medial malleolus fracture or a deltoid ligament rupture

Pronation-abduction (5-20%)

9. Transverse/avulsion-type medial malleolus fracture or a deltoid ligament rupture
10. Syndesmotic ligament rupture or avulsion fracture
11. Short oblique distal fibular fracture at/above syndesmosis (lateral comminution/butterfly fragment common

Pronation-external rotation (5-20%)

12. Transverse/avulsion-type medial malleolus fracture or a deltoid ligament rupture
13. ATFL disruption
14. Spiral distal fibular fracture at/above syndesmosis (anterosuperior to posteroinferior)
15. PTFL disruption or avulsion

Lauge-Hansen classification

• Danis-Weber: based on level of fibula fracture - the more proximal, the higher the risk of syndesmotic injury and instability
  Type A: fracture below the level of the plafond
  • Associated with vertical or oblique fracture of the medial malleolus.
  • Corresponds to Lauge-Hansen SA

Type B: fracture at or near the level of the plafond

• Most common ankle fracture
• Often an obliqiue/spiral fracture caused by ER
• 50% associated with rupture of the anterior synesmosis
• Corresponds to Lauge-Hansen SER

Type C: fracture above the level of the plafond

• Results in syndesmotic disruption and commonly a medial injury
• Includes Maisonneuve fractures (see below)
• Corresponds to Lauge-Hansen PA and PER

 

• OTA: tibia/fibula, malleolar segment (44)
  • Based primarily on fracture level in relation to syndesmosis

Type A: infrasyndesmosis

A1: isolated infrasyndesmosis lateral malleolus
A2: infrasyndesmosis lateral and associated medial malleolus injury
A3: infrasyndesmosis lateral and associated posteromedial tibial fracture

Type B: transsyndesmotic

B1: isolated transsyndesmotic lateral malleolus
B2: transsyndesmotic lateral and associated medial malleolus injury
B3: transsyndesmotic lateral with medial lesion and fracture of the posterolateral rim of the tibia

Type C: suprasyndesmotic

C1: simple diaphyseal fibula
C2: complex diaphyseal fibula with associated medial injury
C3: proximal fibular fracture with associated medial injury

 

• Eponyms:
  Maisonneuve: ER type injury to the ankle with associated fracture of the proximal third of the fibula
  • Most resemble Lauge-Hansen PER 3 with anterosuperior to posteroinferior fibula fracture
  • Fibular fracture itself typically does not need fixation but presence indicates energy associated with medial malleolus fracture was dissipated up through the syndesmosis and fibula
  • Should increase suspicion for syndesmosis instability

Tillaux-Chaput: syndesmosis injury associated with AITFL avulsion fracture of the tibia

LeForte-Wagstaffe: syndesmosis injury associated with AITFL avulsion fracture of the fibula

• Associated with Lauge-Hansen SER fracture patterns

 

Treatment

• Goal of treatment is to restore joint alignment and stability
  • Correct fibular length and rotation
  • Restore normal talar mechanics - even slight displacement increases contact force between tibia and talus

 

• Syndesmotic injuries: diagnosed by avulsion fractures of the syndesmotic ligaments, talar shift or physical exam
  • Injuries without static instability (normal non-stress radiographs) but with mild dynamic instability (mild widening on stress view): short period of immobilization with NWB splint/cast followed by rehabilitation
  • Static instability or significant dynamic instability require operative fixation
    • Reduce fibula in the incisura fibularis
    • Place screw through fibula and tibia via lateral approach 2 cm above plafond and engage either 3 or 4 cortices with the foot in maximum dorsiflexion (to prevent over-tightening of the syndesmosis)
    • Controversy exists regarding size of screw and timing/necessity of removal

 

• Acute treatment of all fractures/dislocations: cleanse and dress open wounds or skin abrasions
  • Dislocations should be reduced under conscious sedation or local block
    • With knee in flexion (reduce achilles tension) place hand around hindfoot apply traction and reverse deformity against countertraction on the tibia
  • Reduce displaced fractures and place in a short leg splint (posterior with stir-up) with ankle at 90°
  • Confirm alignment with post-reduction films

 

• Nonoperative indications: nondisplaced/stable patterns with an intact syndesmosis, fractures with stable anatomic reduction, patient who cannot tolerate operative treatment
  • Transition from splint (see above) to SLC when swelling subsides
    • NWB immobilization generally for 6 weeks
    • SER II injuries can be WBAT due to mechanical stability
    • Close follow up to monitor displacement

 

• Operative indications:
  • In general: failure to achieve adequate reduction, displaced/unstable fracture patterns with syndesmotic and/or deltoid injury, open fractures

Lateral malleolus
Weber A:

• Isolated injuries typically do not require fixation and do well with early functional rehabilitation
• Fixation should be considered for large fragments in the presence of a medial fracture

Weber B:

• Presence of talar shift or medial malleolar fracture warrants fixation
• Fractures without talar or medial fracture but signs of deltoid ligament injury (tenderness to palpation or positive stress test) require fixation

Weber C:

• Require fixation due to inherent instability of the injury

Medial malleolus

• Fixation is required when there is a syndesmotic injury, persistent talar displacement despite fibular fixation or medial instability (deltoid rupture)

Posterior malleolus

• Fixation is required when there is > 2 mm of displacement, involvement > 25% of the articular surface or persistent subluxation of the talus posteriorly

 

• Operative treatment:
  • If unable to treat patient acutely, allow patient and soft tissues to stabilize for up to 7 days before attempting ORIF
    • Elevate/ice ankle to reduce swelling
    • In situations of extreme soft tissue injury or expected prolonged delay of surgery, external fixation can maintain a provisional reduction

Lateral malleolus: in general, perform fibular fixation first through a direct lateral incision

• Weber A: lag screw or tension band wiring
• Weber B/C: posterior anti-glide plate or lag screw with lateral 1/3 semitubular neutralization plate
  • After fixation, intraoperative stressing of the syndesmosis complex to determine if syndesmosis fixation is required (see above)
  • Performed by applying ER force to the ankle with the foot dorsiflexed or lateral translation force to the fibula with a towel clip
  • Widening of the syndesmosis (decrease in tibiofibular overlap) under fluoroscopy indicates syndesmotic injury
• In cases of deltoid rupture (medial clear space > 4 mm), the talus generally follows the fibula
  • Fixation of the fibula should restore the talar alignment and deltoid repair is not necessary given intact medial malleolus

Medial malleolus: through a direct medial incision

• Generally fixed with two cancellous screws or a tension band construct

Posterior malleolus: usually reduces with reduction of the fibula

• Can be fixed with one or two lag screws placed percutaneously anterior to posterior or with posterior anti-glide plate

 

Complications

• Ankle stiffness: often due to prolonged immobilization
• Compartment syndrome (~1%): urgent fasciotomies are required to release pressure and avoid muscle death
• Infection: < 2% in closed injuries
• Malunion: commonly a shortened/rotated fibula leading to pain or an elongated medial malleolus leading to instability
• Nonunion: rare but is more commonly associated with a closed treated medial malleolus due to interposed soft tissue
  • Revision or excision may be required
• Posttraumatic arthritis: a consequence of any articular injury, can be theoretically minimized with anatomic reduction
• Reflex sympathetic dystrophy: rare, reduce risk with anatomic reduction and early return to motion
• Wound problems: injuries undergoing operative fixation in the presence of abrasions or fracture blisters are at a 2x increased chance of wound complications