MCQs – Foot/Ankle 3

Modern Study Review (AI-Generated)

High-Yield Summary

Talar neck fractures and their risk of avascular necrosis (AVN) are a staple of the Royal College exam, focusing heavily on Hawkins classification and displacement patterns. The critical clinical decision hinges on the degree of displacement and joint involvement, which dictate AVN risk and urgency of fixation. While the exam emphasizes Hawkins classification for prognosis, modern practice integrates advanced imaging and early fixation to reduce AVN rates. Similarly, foot and ankle trauma classifications (Weber, LisFranc) and deformity management (tibialis posterior insufficiency, hemiplegic foot) are high-yield topics requiring precise anatomical and biomechanical understanding. Surgical approaches for subtalar dislocations and salvage procedures for Freiberg’s infraction reflect evolving operative standards.

High-Yield Decision Matrix

Active Recall Q&A

Talar Neck Fracture AVN Rates

Q: What are the rates of avascular necrosis (AVN) for Hawkins I talar neck fractures?
A: 0-13% AVN.
Related Pearl: Hawkins classification directly correlates with AVN risk, guiding urgency and fixation strategy.

Q: What is the AVN rate for Hawkins II talar neck fractures?
A: 20-50% AVN.
Related Pearl: Subtalar displacement increases vascular compromise, raising AVN risk.

Q: What is the AVN rate for Hawkins III talar neck fractures?
A: 90-100% AVN.
Related Pearl: Complete dislocation disrupts blood supply almost universally, necessitating aggressive management.

Q: What is the approximate AVN risk for undisplaced talar neck fractures?
A: About 10%.
Related Pearl: Minimal displacement preserves vascularity; conservative treatment may be sufficient.

Q: What is the AVN risk for displaced talar neck fractures with subtalar displacement?
A: Approximately 40%.
Related Pearl: Subtalar joint involvement increases vascular injury risk.

Q: What is the AVN risk for displaced talar neck fractures with ankle displacement?
A: Approximately 90%.
Related Pearl: Ankle displacement indicates severe vascular disruption and poor prognosis.

Talar Dislocation and Classification

Q: What defines a Canale IV talar fracture?
A: Dislocation of the talar head from the navicular.
Related Pearl: This injury pattern often requires open reduction due to joint incongruity.

Tibialis Posterior Insufficiency

Q: Where is the avascular region in tibialis posterior insufficiency?
A: Behind the medial malleolus.
Related Pearl: This area is prone to tendon degeneration and rupture.

Q: What demographic is most commonly affected by tibialis posterior insufficiency?
A: Middle-aged females.
Related Pearl: Hormonal and biomechanical factors contribute to tendon degeneration in this group.

Q: What radiographic findings are typical in tibialis posterior insufficiency?
A: Chopart joint valgus; lateral x-ray shows midfoot sagging and loss of longitudinal arch.
Related Pearl: Normal x-rays do not exclude tibialis posterior dysfunction; clinical correlation is essential.

Ankle Fracture Classification

Q: What type of ankle injury is associated with fibular fractures above the syndesmosis?
A: Pronation external rotation injury (Weber C).
Related Pearl: Syndesmotic injury is common, requiring fixation.

Q: What ankle injury is associated with fibular fractures at the joint level?
A: Supination external rotation injury (Weber B).
Related Pearl: These fractures often have intact syndesmosis.

Hemiplegic Foot Deformity

Q: How is dynamic equinovarus in a hemiplegic patient treated?
A: Use an ankle-foot orthosis (AFO) to counter equinus and a lateral T strap to correct forefoot varus.
Related Pearl: Combining orthotic support addresses both sagittal and coronal plane deformities.

Q: What is the treatment for longstanding claw-toes in hemiplegic patients?
A: Flexor tendon release or Girdlestone-Taylor flexor-to-extensor transfer; conservative treatment includes deep toe-box shoes with metatarsal bars.
Related Pearl: Neurologic origin limits conservative success; surgical correction improves function.

Chevron Osteotomy

Q: What should be avoided during a Chevron osteotomy?
A: Adductor hallucis release laterally due to risk to blood supply.
Related Pearl: Medial eminence removal and lateral shift with medial capsule plication preserve vascularity.

LisFranc Injury

Q: What is the keystone bone in LisFranc injuries?
A: The second metatarsal.
Related Pearl: Stability of the LisFranc joint depends on the second metatarsal’s articulation.

Q: What factors influence outcomes in LisFranc injuries?
A: Injury severity and achieving anatomic reduction with fixation.
Related Pearl: Both factors are critical; poor reduction leads to chronic instability.

Flatfoot Etiology

Q: What is the most common cause of acute acquired flatfoot?
A: Tibialis posterior tendon rupture.
Related Pearl: Early diagnosis prevents progression to rigid deformity.

Rheumatoid Tibialis Posterior

Q: What is the preferred treatment for tibialis posterior insufficiency in rheumatoid arthritis?
A: Bony procedures starting with subtalar arthrodesis; triple arthrodesis if deformity is severe.
Related Pearl: Soft tissue reconstruction fails due to chronic inflammation and poor tissue quality.

Foot Crush Injury

Q: What amputation is preferred for major crush injuries across the foot?
A: Trans-metatarsal amputation; if not possible, Symes amputation.
Related Pearl: Preserving limb length improves prosthetic function.

Subtalar Dislocation

Q: How do medial subtalar dislocations typically present and reduce?
A: Easier closed reduction; obstructions include talar head impaction fracture, extensor tendons, and capsule.
Related Pearl: Medial dislocations are twice as common as lateral.

Q: What makes lateral subtalar dislocations more difficult to reduce?
A: Obstructions include tibialis posterior tendon flipped over medial malleolus, talar head impaction fracture, and flexor digitorum longus tendon.
Related Pearl: Often require open reduction due to soft tissue interposition.

Q: What surgical approach is used for medial and lateral subtalar dislocations?
A: Medial approach for both.
Related Pearl: Provides optimal access to obstructing structures.

Q: What approach is recommended for anterior subtalar dislocations?
A: Anterolateral approach due to peroneal tendon involvement.
Related Pearl: Anterior dislocations are rare and require tailored exposure.

Freiberg’s Infraction

Q: What is the appropriate salvage procedure for Freiberg’s infraction?
A: Fusion; Swanson arthroplasty is inappropriate.
Related Pearl: Fusion provides durable pain relief and maintains foot stability.

Talar Neck Fracture X-ray Technique

Q: What is the Canale and Kelly radiographic technique for talar neck fractures?
A: Maximal plantarflexion, 15° pronation or eversion, with x-ray tube angled 75° cephalad from horizontal.
Related Pearl: This view optimally visualizes the talar neck and detects varus deformity.

Classic Clinical Notes

• Rates of AVN for talar neck fractures: Hawkins I – 0-13%, Hawkins II – 20-50%, Hawkins III – 90-100%. Nonunion of talar neck fractures is uncommon; they tend to heal in varus.

• So for undisplaced talar neck – guess about 10% AVN.

• For the displaced talar neck with subtalar displacement – guess about 40%.

• For the displaced talar neck with ankle displacement – guess about 90%.

• The Canale IV is where the talar head dislocates from the navicular.

• In tib post insufficiency – there is an avascular region behind the medial malleolus.

• In tib post insufficiency – it is most common in middle aged females; the Chopart joint is in valgus, and the lateral x-ray is often abnormal, showing the sagging of the midfoot with loss of longitudinal arch – don’t count on the x-rays being normal!!

• The ankle injuries with fibular fractures above the syndesmosis are often pronation external rotation injuries (Weber C). The supination external rotation injuries often lead to fibular fractures at the level of the joint (Weber B).

• For the hemiplegic man with dynamic equinovarus, use an AFO to counter the equinus, and a lateral T strap to pull his forefoot out of varus.

• In a longstanding hemiplegic with claw-toes – treat with flexor tendon release or Girdlestone-Taylor flexor to extensor transfer. You can treat conservatively I suppose, but this will not get better because it has a neurologic origin. The conservative treatment would be a deep toe-box shoe with a metatarsal bar.

• In the Chevron – do not do an adductor hallucis release – going laterally endangers the blood supply. You do remove the medial eminence and shift the distal fragment laterally and plicate the medial capsule.

• In LisFranc injuries, the 2nd MT is the keystone. Some say that the severity of injury is in fact the most important factor in the final outcome; others argue that achieving anatomic reduction and fixing it there is more important. There certainly are a lot of different types (divergent, homolateral, isolated).

• The most common cause of acute acquired flatfoot is tib post rupture.

• In rheumatoids, you’d be crazy to try soft tissue reconstruction of tib post – they need bony procedures, starting with subtalar arthrodesis if possible; if there is more severe deformity, they need a triple.

• For the major crush injury across the foot – try for a trans-met amputation; if not, Symes.

• For medial subtalar dislocations (acute acquired clubfoot): they are usually easier to reduce closed than the lateral dislocations. The obstructions include: impaction fracture of the talar head, the extensor tendons (the talar head bursts through them dorsally), capsule. They are about twice as common as lateral dislocations.

• For lateral subtalar dislocations (acute acquired vertical talus): these are more often impossible to get back in than the medial dislocations. Obstructions include: tibialis posterior (flips over the medial malleolus), impaction fracture of the talar head, and sometimes the flexor digitorum longus tendon.

• Both medial and lateral subtalar dislocations can be approached medially.

• For the highly unusual anterior subtalar dislocation, it probably pulls the peroneals with it and these need to be approached anterolaterally.

• It would be inappropriate to use a Swanson arthroplasty in Frieberg’s infraction – if they need salvage – fuse it!

• For talar neck fractures: Many of the minimally displaced fractures assume a varus deformity at the fracture site that cannot be appreciated on standard x-ray projections. Canale and Kelly described the best x-ray technique to demonstrate the entire talar neck in the AP direction. With the ankle in maximal equinus, the foot is placed on a cassette and pronated 15o; the x-ray tube is directed upwards at a 75o angle from horizontal.

• Canale and Kelly View
• Maximal plantarflexion
• Pronation or eversion of 15 degrees
• Aim x-ray cephalad 75 degrees from horizontal

Last Updated on January 25, 2026 by Christian Veillette