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8. Foot and Ankle MCQs

Practice Set 284 of 353

This practice set contains high-yield board review questions covering key concepts in 8. Foot and Ankle. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5661

Topic: 8. Foot and Ankle
A 26-year-old male is involved in a high-speed motorcycle accident. In the ER, his knee is grossly unstable in multiple planes, and he has a documented knee dislocation (Schenck KD-III). His ankle-brachial index (ABI) is measured at 0.85. What is the most appropriate next step in management?
. Immediate surgical exploration of the popliteal artery
. Observation and repeat ABI in 4 hours
. CT angiography (CTA) of the lower extremity
. Application of a spanning external fixator and discharge
. Immediate popliteal vein repair

Correct Answer & Explanation

. CT angiography (CTA) of the lower extremity

Explanation

In the setting of a knee dislocation, an ABI < 0.9 is highly concerning for a popliteal artery injury. The definitive next step for a subnormal ABI or asymmetric pulses (without hard signs of ischemia requiring immediate OR exploration) is a CT angiogram (CTA) to rule out an intimal flap or vascular occlusion. Hard signs of ischemia (absent pulses, expanding hematoma, active pulsatile bleeding) warrant immediate surgical exploration.

Question 5662

Topic: 8. Foot and Ankle

A 35-year-old recreational basketball player sustains an acute Achilles tendon rupture. He is discussing operative vs. non-operative management. According to recent high-level evidence, if an early functional rehabilitation protocol is utilized, how do the outcomes of non-operative management compare to operative repair?

. Non-operative management has a significantly higher re-rupture rate, regardless of rehab protocol
. Operative management has equivalent re-rupture rates but a much lower risk of soft-tissue complications
. With early functional rehab, re-rupture rates are similar, but operative repair carries a higher risk of wound complications
. Operative management provides significantly better long-term plantarflexion strength
. Non-operative management leads to unacceptably high rates of deep vein thrombosis compared to operative management

Correct Answer & Explanation

. Non-operative management has a significantly higher re-rupture rate, regardless of rehab protocol

Explanation

Recent Level I studies (e.g., Willits et al.) have demonstrated that when acute Achilles tendon ruptures are managed with early functional weight-bearing and range-of-motion rehabilitation protocols, there is no clinically significant difference in re-rupture rates between operative and non-operative groups. However, operative management consistently carries a higher risk of surgical wound complications and infections.

Question 5663

Topic: 8. Foot and Ankle
A 25-year-old football player sustains a high-energy knee dislocation (KD-III). Following closed reduction in the emergency department, his ankle-brachial index (ABI) is measured at 0.85. He has palpable distal pulses. What is the most appropriate next step in management?
. Immediate surgical exploration of the popliteal fossa
. CT angiography of the lower extremity
. Serial clinical examinations every 4 hours for 24 hours
. MR angiography of the lower extremity
. Immediate application of a spanning external fixator

Correct Answer & Explanation

. CT angiography of the lower extremity

Explanation

In the setting of a knee dislocation, an ankle-brachial index (ABI) less than 0.9 is an indication for advanced imaging, preferably CT angiography, to evaluate for popliteal artery injury. Immediate surgical exploration is indicated only if there are 'hard' signs of vascular injury (e.g., absent pulses after reduction, expanding hematoma, pulsatile bleeding).

Question 5664

Topic: 8. Foot and Ankle

A 26-year-old professional soccer player suffers an external rotation injury to his ankle. Radiographs show no fracture.

An MRI demonstrates a complete tear of the anterior inferior tibiofibular ligament (AITFL) and interosseous membrane extending 4 cm proximal to the joint line, with an intact deltoid ligament. Dynamic stress views show no widening of the medial clear space. What is the most appropriate management?

. Immediate open reduction and internal fixation with syndesmotic screws
. Suture button fixation of the syndesmosis
. Nonoperative management in a walking boot or cast
. Primary open repair of the AITFL
. Ankle arthroscopy followed by unyielding casting

Correct Answer & Explanation

. Immediate open reduction and internal fixation with syndesmotic screws

Explanation

Stable syndesmotic injuries (characterized by an intact deltoid ligament and no medial clear space widening on stress views) can be treated nonoperatively, even with proximal extension of the interosseous membrane tear. Operative intervention is reserved for unstable injuries.

Question 5665

Topic: 8. Foot and Ankle

A 24-year-old rugby player falls with his foot plantar flexed and another player lands on his heel.

Radiographs suggest a subtle widening between the first and second rays. MRI confirms a complete tear of the Lisfranc ligament. He undergoes open reduction and internal fixation. Which specific articulation does the primary Lisfranc ligament span?

. Medial cuneiform to the first metatarsal base
. Medial cuneiform to the second metatarsal base
. Middle cuneiform to the second metatarsal base
. Lateral cuneiform to the third metatarsal base
. Navicular to the medial cuneiform

Correct Answer & Explanation

. Medial cuneiform to the first metatarsal base

Explanation

The Lisfranc ligament is a strong interosseous ligament that runs obliquely from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the primary stabilizer of the midfoot.

Question 5666

Topic: 8. Foot and Ankle

A patient presents with a displaced talar neck fracture with complete dislocation of the talonavicular, subtalar, and ankle joints. What is the expected rate of avascular necrosis (AVN) for this Hawkins type?

. 0-10%
. 20-50%
. 50-75%
. 90-100%
. Cannot be determined

Correct Answer & Explanation

. 0-10%

Explanation

This describes a Hawkins Type IV fracture-dislocation. Because all major blood supplies to the talus are disrupted, the AVN rate approaches 100%.

Question 5667

Topic: Midfoot & Hindfoot
A 32-year-old male sustains a displaced talar neck fracture with subluxation of the subtalar joint, but the tibiotalar and talonavicular joints remain congruent. What is the Hawkins classification and the estimated risk of avascular necrosis (AVN)?
. Hawkins I; < 10% risk of AVN
. Hawkins II; 20-50% risk of AVN
. Hawkins III; 80-100% risk of AVN
. Hawkins IV; 100% risk of AVN
. Hawkins II; 80-100% risk of AVN

Correct Answer & Explanation

. Hawkins II; 20-50% risk of AVN

Explanation

A Hawkins II talar neck fracture involves subtalar subluxation or dislocation while the ankle and talonavicular joints remain aligned. The associated risk of avascular necrosis (AVN) is historically cited as 20-50%.

Question 5668

Topic: 8. Foot and Ankle

A 24-year-old rugby player sustains an acute knee dislocation. Following emergent closed reduction, his Ankle-Brachial Index (ABI) is 0.85, and distal pulses are asymmetric. What is the most appropriate next step in management?

. Discharge with a knee immobilizer and out-patient MRI
. Observation and repeat ABI in 4 hours
. Immediate CT angiography (CTA)
. Immediate open exploration of the popliteal artery without imaging
. Application of an external fixator and delayed vascular assessment

Correct Answer & Explanation

. Discharge with a knee immobilizer and out-patient MRI

Explanation

An ABI less than 0.90 or asymmetric pulses following a knee dislocation raises high suspicion for a popliteal artery injury. Immediate CT angiography is indicated to delineate the vascular anatomy and plan potential surgical intervention.

Question 5669

Topic: 8. Foot and Ankle

A 29-year-old female experiences forced plantarflexion of her midfoot. Radiographs show a small avulsion fracture at the medial base of the second metatarsal. What is this sign called, and what does it indicate?

. Thurston Holland sign; indicating a physeal injury
. Fleck sign; indicating a Lisfranc ligament avulsion
. Lauge-Hansen sign; indicating a syndesmotic injury
. Terry Thomas sign; indicating a scapholunate dissociation
. Segond sign; indicating an ACL tear

Correct Answer & Explanation

. Thurston Holland sign; indicating a physeal injury

Explanation

The "Fleck sign" is a small osseous avulsion between the base of the second metatarsal and the medial cuneiform. It is pathognomonic for a disruption of the Lisfranc ligament complex.

Question 5670

Topic: 8. Foot and Ankle

A 40-year-old male is scheduled for open reduction and internal fixation of a joint-depressed calcaneus fracture via an extensile lateral approach. Which of the following technical steps most effectively minimizes the risk of the most common postoperative wound complication?

. Creating a full-thickness subperiosteal "no-touch" flap
. Incising directly over the sural nerve to identify and protect it
. Performing the surgery within 24 hours of the initial injury
. Using a tourniquet for a minimum of 120 minutes
. Placing the horizontal limb of the incision distal to the glabrous junction

Correct Answer & Explanation

. Creating a full-thickness subperiosteal "no-touch" flap

Explanation

Wound necrosis and infection are major risks of the extensile lateral approach. Raising a full-thickness subperiosteal flap and employing a "no-touch" retraction technique with K-wires in the talus preserves the fragile blood supply.

Question 5671

Topic: 8. Foot and Ankle

A 22-year-old football player presents with severe midfoot pain after sustaining an axial load on a plantarflexed foot. Non-weight-bearing AP and lateral radiographs appear completely normal. What is the most appropriate next step to diagnose a subtle Lisfranc injury?

. CT scan of the foot without contrast
. MRI of the midfoot
. Weight-bearing radiographs of both feet
. Radionuclide bone scan
. Diagnostic ultrasound of the dorsal foot

Correct Answer & Explanation

. CT scan of the foot without contrast

Explanation

Subtle Lisfranc injuries can often be missed on non-weight-bearing films. Weight-bearing radiographs of both feet allow for comparison and can demonstrate subtle widening between the medial cuneiform and second metatarsal base.

Question 5672

Topic: 8. Foot and Ankle
A 28-year-old male sustains a completely displaced talar neck fracture with subluxation of the body out of the ankle mortise (Hawkins type III). What is the approximate rate of avascular necrosis (AVN) of the talar body associated with this injury?
. 0-10%
. 15-30%
. 40-50%
. 75-100%
. Cannot be determined

Correct Answer & Explanation

. 75-100%

Explanation

Hawkins type III talar neck fractures involve dislocation of both the subtalar and tibiotalar joints, disrupting all three major blood supplies to the talar body. The risk of AVN is exceptionally high, approaching 75-100%.

Question 5673

Topic: 8. Foot and Ankle
A 25-year-old snowboarder sustains a high-energy dorsiflexion injury to the ankle. Radiographs reveal a displaced talar neck fracture with subluxation of the subtalar joint, while the tibiotalar joint remains congruous. Based on the Hawkins classification, what is the approximate risk of developing avascular necrosis (AVN) of the talar body in this patient?
. 0 to 15%
. 20 to 50%
. 60 to 80%
. 90 to 100%
. Risk is primarily determined by the degree of comminution, not the dislocation pattern

Correct Answer & Explanation

. 20 to 50%

Explanation

This is a Hawkins Type II fracture, defined as a displaced talar neck fracture with subluxation or dislocation of the subtalar joint, while the ankle joint remains aligned. The rate of AVN for a Hawkins Type II fracture is historically reported as 20-50%. Type I (non-displaced) has an AVN rate of 0-15%. Type III (subtalar and tibiotalar dislocation) has an AVN rate approaching 100% in older literature, though modern rates are lower.

Question 5674

Topic: 8. Foot and Ankle

During the extensile lateral approach for open reduction and internal fixation of a displaced intra-articular calcaneus fracture, a full-thickness subperiosteal flap is developed. Which of the following neurologic structures is at greatest risk of iatrogenic injury during the dissection of the inferior limb of the incision?

. Deep peroneal nerve
. Superficial peroneal nerve
. Sural nerve
. Medial calcaneal nerve
. Saphenous nerve

Correct Answer & Explanation

. Deep peroneal nerve

Explanation

The extensile lateral approach to the calcaneus involves an L-shaped incision. The inferior limb runs just superior to the plantar skin transition and the vertical limb runs between the fibula and the Achilles tendon. The sural nerve crosses the lateral border of the foot and is highly vulnerable to injury or entrapment, particularly if the vertical limb is placed too far anteriorly or the inferior limb is carried too far distally without meticulous full-thickness soft tissue handling.

Question 5675

Topic: 8. Foot and Ankle

A 22-year-old football player presents with a midfoot injury and plantar ecchymosis. Weight-bearing radiographs show a 3 mm diastasis between the base of the first and second metatarsals. You suspect a Lisfranc injury. The primary stabilizing ligament of the Lisfranc complex originates on the lateral aspect of the medial cuneiform and inserts on the medial aspect of the base of the second metatarsal. What type of ligament is this primary restraint?

. Dorsal ligament
. Plantar ligament
. Interosseous ligament
. Spring ligament
. Bifurcate ligament

Correct Answer & Explanation

. Dorsal ligament

Explanation

The Lisfranc ligament complex connects the medial cuneiform to the second metatarsal base. It consists of dorsal, interosseous, and plantar components. The interosseous Lisfranc ligament is the thickest and strongest primary restraint to diastasis. There is no direct ligamentous connection between the first and second metatarsal bases.

Question 5676

Topic: 8. Foot and Ankle

A 28-year-old male presents with a knee dislocation that was successfully reduced in the emergency department. His pedal pulses are palpable, but his ankle-brachial index (ABI) is measured at 0.85. What is the most appropriate next step in management?

. Discharge with close follow-up
. Observation with serial ABI measurements
. CT angiography of the lower extremity
. Immediate surgical exploration of the popliteal fossa
. Duplex ultrasonography of the deep veins

Correct Answer & Explanation

. Discharge with close follow-up

Explanation

An ABI less than 0.9 in the setting of a knee dislocation is highly suspicious for a popliteal artery injury, even if pulses are palpable. CT angiography is the gold standard diagnostic step to accurately locate and evaluate the extent of the vascular injury.

Question 5677

Topic: 8. Foot and Ankle
A 31-year-old female sustains a Hawkins Type III talar neck fracture following a severe motor vehicle collision. What is the approximate risk of developing avascular necrosis (AVN) of the talar body?
. 0 to 10%
. 15 to 30%
. 40 to 50%
. 75 to 100%
. Variable depending strictly on the surgical approach

Correct Answer & Explanation

. 75 to 100%

Explanation

A Hawkins Type III fracture involves displacement of the talar body from both the subtalar and tibiotalar joints. This displacement disrupts all three major blood supplies to the talus, leading to an AVN risk approaching 100%.

Question 5678

Topic: 8. Foot and Ankle
A 35-year-old roof worker falls from a height and sustains a severely displaced, intra-articular calcaneus fracture. Assessment of Böhler's angle on a standard lateral foot radiograph will typically demonstrate which of the following?
. An increase greater than 40 degrees
. A decrease to less than 20 degrees or a negative angle
. No change compared to the contralateral side
. A constant angle of 35 degrees regardless of displacement

Correct Answer & Explanation

. A decrease to less than 20 degrees or a negative angle

Explanation

Böhler's angle is normally between 20 and 40 degrees. In displaced intra-articular calcaneus fractures, the collapse of the posterior facet and tuberosity results in a decrease, flattening, or even a negative Böhler's angle.

Question 5679

Topic: 8. Foot and Ankle

A 24-year-old athlete presents with midfoot pain after an axial load to a plantarflexed foot. Radiographs reveal a subtle widening of the first intermetatarsal space and a 'fleck sign'. This pathognomonic finding represents an osseous avulsion of the Lisfranc ligament. Which two structures does this ligament connect?

. Medial cuneiform and the base of the second metatarsal
. Lateral cuneiform and the base of the second metatarsal
. Medial cuneiform and the base of the first metatarsal
. Navicular and the medial cuneiform

Correct Answer & Explanation

. Medial cuneiform and the base of the second metatarsal

Explanation

The Lisfranc ligament is a strong interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial base of the second metatarsal. A 'fleck sign' indicates an avulsion fracture at its insertion.

Question 5680

Topic: 8. Foot and Ankle

A 34-year-old male presents with a posterolateral knee dislocation after a high-energy trauma. The joint is emergently reduced. Post-reduction, the distal pulses are palpable, but the Ankle-Brachial Index (ABI) is calculated to be 0.8. What is the most appropriate next step in management?

. Observation and repeat ABI in 4 hours
. Immediate surgical exploration of the popliteal artery
. CT angiography of the lower extremity
. Duplex ultrasound of the lower extremity
. Application of a hinged knee brace and discharge

Correct Answer & Explanation

. Observation and repeat ABI in 4 hours

Explanation

An ABI less than 0.9 following a knee dislocation is highly suspicious for a vascular injury, even if pulses are palpable. A CT angiogram is indicated to evaluate for an intimal tear or occlusion of the popliteal artery.

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