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8. Foot and Ankle MCQs

Practice Set 164 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 3261

Topic: 8. Foot and Ankle

A 28-year-old male sustains a displaced talar neck fracture following a high-energy snowboard crash. You counsel him on the high risk of avascular necrosis (AVN) of the talar body due to the disruption of its precarious blood supply. Which of the following vessels provides the predominant blood supply to the body of the talus?

. Artery of the tarsal sinus
. Artery of the tarsal canal
. Deltoid artery
. Dorsalis pedis artery
. Peroneal artery

Correct Answer & Explanation

. Artery of the tarsal canal

Explanation

The body of the talus receives its blood supply from an anastomotic vascular ring formed by the artery of the tarsal canal (a branch of the posterior tibial artery) and the artery of the tarsal sinus (derived from the anterior tibial and peroneal arteries). The artery of the tarsal canal provides the predominant blood supply to the talar body. Displaced talar neck fractures often disrupt this supply, leading to high rates of AVN.

Question 3262

Topic: 8. Foot and Ankle

A 22-year-old collegiate football player sustains a severe axial load to a plantarflexed foot. Radiographs reveal widening of the space between the medial and middle cuneiforms, with dorsal displacement of the second metatarsal base. The primary stabilizing structure of the Lisfranc joint complex connects which two bones?

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

Correct Answer & Explanation

. Middle cuneiform to the second metatarsal base

Explanation

The Lisfranc ligament is the strongest and most critical primary stabilizer of the tarsometatarsal joint complex. It is a stout interosseous ligament that connects the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal.

Question 3263

Topic: 8. Foot and Ankle

A 45-year-old male sustains a closed tongue-type calcaneus fracture. Physical examination reveals tense, blanched skin over the posterior heel. What is the most appropriate next step in management?

. Elevation and ice, awaiting the 'wrinkle sign' before surgery
. Immediate reduction to relieve soft-tissue tension
. Application of a short leg cast in severe plantarflexion
. Open reduction via an extensile lateral approach
. Primary subtalar arthrodesis

Correct Answer & Explanation

. Immediate reduction to relieve soft-tissue tension

Explanation

A tongue-type calcaneus fracture involves a fracture line extending posteriorly through the tuberosity. The pull of the Achilles tendon on the superior tuberosity fragment causes it to displace superiorly and posteriorly, creating severe tension on the posterior heel skin. This can rapidly lead to skin blanching, ischemia, and full-thickness necrosis. This presentation is an orthopedic soft-tissue emergency requiring immediate reduction (often via a percutaneous or limited open approach) to relieve skin tension and prevent catastrophic wound complications.

Question 3264

Topic: Midfoot & Hindfoot
A 28-year-old man sustains a talar neck fracture following a high-energy motor vehicle collision. Radiographs demonstrate displacement of the talar neck with subluxation of the subtalar joint, but the tibiotalar and talonavicular joints remain congruent. According to the Hawkins classification, what is the approximate risk of developing avascular necrosis (AVN) of the talar body?
. 0-10%
. 20-50%
. 70-90%
. 90-100%
. 100%

Correct Answer & Explanation

. 20-50%

Explanation

The clinical scenario describes a Hawkins Type II talar neck fracture, which is characterized by a displaced talar neck fracture with subluxation or dislocation of the subtalar joint, while the tibiotalar and talonavicular joints remain normal. The blood supply to the talar body is tenuous, relying heavily on the artery of the tarsal canal. The risk of avascular necrosis (AVN) of the talar body correlates with the Hawkins classification: Type I (nondisplaced) is 0-10%; Type II is approximately 20-50%; Type III (subtalar and tibiotalar dislocation) is 70-90%; and Type IV (Type III plus talonavicular dislocation) approaches 100%.

Question 3265

Topic: 8. Foot and Ankle
A 35-year-old man falls from a 15-foot ladder and sustains a displaced fracture of the talar neck. Imaging reveals subluxation of both the subtalar and tibiotalar joints, but the talonavicular joint remains reduced. What is the approximate reported risk of developing avascular necrosis (AVN) of the talar body in this injury pattern?
. 0-10%
. 20-30%
. 40-50%
. 80-100%
. Depends entirely on the surgical approach

Correct Answer & Explanation

. 80-100%

Explanation

This clinical scenario describes a Hawkins Type III talar neck fracture (fracture of the talar neck with dislocation/subluxation of both the subtalar and tibiotalar joints). The blood supply to the talar body (artery of the tarsal canal, artery of the sinus tarsi, and deltoid branches) is severely compromised. The historical risk of avascular necrosis (AVN) for Hawkins Type III fractures is reported to be between 80% and 100%.

Question 3266

Topic: 8. Foot and Ankle

A 45-year-old roofer undergoes open reduction and internal fixation of a displaced intra-articular calcaneus fracture via an extensile lateral approach. Postoperatively, he complains of significant numbness and burning pain along the lateral aspect of his foot. Which of the following nerves was most likely injured during the surgical approach?

. Deep peroneal nerve
. Superficial peroneal nerve
. Medial plantar nerve
. Lateral plantar nerve
. Sural nerve

Correct Answer & Explanation

. Sural nerve

Explanation

The sural nerve is at significant risk of injury during the extensile lateral approach to the calcaneus. It courses posterior to the fibula and supplies sensation to the posterolateral lower leg and the lateral border of the foot. To minimize risk, the horizontal limb of the incision should be placed precisely at the junction of the glabrous and non-glabrous skin, and a full-thickness flap must be elevated without direct retraction on the soft tissues.

Question 3267

Topic: 8. Foot and Ankle
A 40-year-old man sustains a Hawkins type III fracture of the talar neck after a severe motor vehicle collision. What is the approximate reported risk of developing avascular necrosis (AVN) of the talar body with this specific injury pattern?
. 0-10%
. 15-30%
. 40-50%
. 70-100%
. 100% invariably

Correct Answer & Explanation

. 70-100%

Explanation

Hawkins type III fractures involve a fracture of the talar neck with dislocation of both the subtalar and tibiotalar joints. This injury severely disrupts the delicate, retrograde blood supply to the talar body (artery of the tarsal canal, artery of the sinus tarsi, and deltoid branches). Consequently, the risk of avascular necrosis is exceptionally high, typically cited between 70% and 100%.

Question 3268

Topic: 8. Foot and Ankle

A 22-year-old male football player sustains a spontaneous reduction of a knee dislocation prior to arrival at the emergency department. He has a grossly unstable knee but normal, palpable dorsalis pedis and posterior tibial pulses. What is the most appropriate next step in his management to evaluate for vascular injury?

. Observation with serial pulse checks every 4 hours
. Measurement of Ankle-Brachial Index (ABI)
. Immediate CT Angiography of the lower extremity
. Formal catheter arteriogram in the interventional radiology suite
. Duplex ultrasound of the popliteal artery

Correct Answer & Explanation

. Measurement of Ankle-Brachial Index (ABI)

Explanation

For knee dislocations presenting with normal, palpable pulses, an Ankle-Brachial Index (ABI) should be measured first. An ABI > 0.9 reliably excludes flow-limiting vascular injury and allows for observation. If the ABI is < 0.9 or pulses are asymmetric/absent, advanced imaging such as CT angiography is warranted.

Question 3269

Topic: 8. Foot and Ankle

A 21-year-old collegiate football player suffers a high-energy knee dislocation during a tackle. Upon arrival at the emergency department, his knee has spontaneously reduced. Pedal pulses are palpable, but his Ankle-Brachial Index (ABI) is measured at 0.8. What is the most appropriate next step in his management?

. Routine admission for serial neurovascular examinations every 4 hours
. CT angiography of the lower extremity
. Immediate operative exploration of the popliteal artery
. Application of a spanning external fixator across the knee joint
. Magnetic resonance imaging of the knee to evaluate ligamentous injury

Correct Answer & Explanation

. CT angiography of the lower extremity

Explanation

A knee dislocation carries a high risk of popliteal artery injury. Current guidelines recommend measuring the Ankle-Brachial Index (ABI) after reduction of a knee dislocation. An ABI of less than 0.9 is abnormal and highly suspicious for a vascular injury, even if pulses are palpable. It mandates further objective vascular imaging, typically a CT angiogram or conventional angiogram. Immediate operative exploration is reserved for 'hard signs' of vascular injury, such as absent pulses, expanding hematoma, or pulsatile bleeding.

Question 3270

Topic: 8. Foot and Ankle

A 30-year-old male sustains a talar neck fracture with subluxation of the subtalar joint (Hawkins Type II) after a fall from a height. Which of the following vascular structures provides the primary blood supply to the talar body and is most at risk of injury in this specific fracture pattern?

. Artery of the tarsal canal
. Artery of the tarsal sinus
. Deltoid branches of the posterior tibial artery
. Dorsalis pedis artery
. Peroneal artery

Correct Answer & Explanation

. Artery of the tarsal canal

Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, provides the majority of the blood supply to the body of the talus. Talar neck fractures put this retrograde blood supply at significant risk, leading to avascular necrosis (AVN). Hawkins Type II fractures (talar neck fracture with subtalar dislocation) have an AVN rate of approximately 20-50% due to the disruption of this vascular anastamosis.

Question 3271

Topic: 8. Foot and Ankle

A 42-year-old construction worker falls from a scaffolding, sustaining a severely displaced, closed, intra-articular calcaneus fracture. While evaluating the patient to determine whether operative or nonoperative management is indicated, which of the following patient-specific factors is considered a strong relative or absolute contraindication to open reduction and internal fixation through an extensile lateral approach?

. A sedentary occupation prior to the injury
. Insulin-dependent diabetes mellitus with peripheral neuropathy
. A fracture pattern involving the calcaneocuboid joint
. A measured Bohler's angle of 10 degrees
. The presence of concomitant bilateral calcaneus fractures

Correct Answer & Explanation

. Insulin-dependent diabetes mellitus with peripheral neuropathy

Explanation

Surgical treatment of intra-articular calcaneus fractures via an extensile lateral approach carries a high risk of wound complications and infection. Poor tissue healing and immune response make certain patient populations highly unsuitable for this surgery. Insulin-dependent diabetes mellitus, especially when complicated by peripheral neuropathy, is a strong relative (and in many centers, absolute) contraindication to operative management due to the exceptionally high rates of wound breakdown, deep infection, amputation, and subsequent Charcot arthropathy.

Question 3272

Topic: 8. Foot and Ankle

A 25-year-old woman is brought to the emergency department after a severe traumatic knee dislocation. The knee is successfully reduced. Dorsalis pedis and posterior tibial pulses are palpable but slightly weaker than the contralateral limb. An Ankle-Brachial Index (ABI) is measured at 0.85. What is the most appropriate next step in management?

. Discharge with a hinged knee brace and outpatient follow-up
. Admit for serial neurovascular examinations every 4 hours
. Perform a CT angiogram of the lower extremity
. Immediate operative exploration by vascular surgery
. Apply a spanning external fixator and observe

Correct Answer & Explanation

. Perform a CT angiogram of the lower extremity

Explanation

An ABI less than 0.9 in the setting of a knee dislocation is highly suspicious for a popliteal artery injury. A CT angiogram is indicated to evaluate for an intimal tear or flow-limiting vascular lesion.

Question 3273

Topic: 8. Foot and Ankle

A 45-year-old snowboarder sustains a Hawkins Type II talar neck fracture. She undergoes open reduction and internal fixation. At her 8-week follow-up, an AP radiograph of the ankle demonstrates a subchondral radiolucent band in the dome of the talus. What is the clinical significance of this finding?

. It indicates early onset subtalar osteoarthritis
. It indicates osteonecrosis of the talar body
. It represents intact vascularity to the talar body
. It demonstrates a superficial wound infection
. It signifies nonunion of the talar neck

Correct Answer & Explanation

. It represents intact vascularity to the talar body

Explanation

This radiographic finding is Hawkins sign, which is subchondral osteopenia of the talar dome. It indicates that the talar body retains its blood supply and is undergoing normal disuse osteopenia, making avascular necrosis highly unlikely.

Question 3274

Topic: Ankle Trauma & Sports

A 45-year-old man sustains an ankle injury. Radiographs show a spiral fracture of the distal fibula above the level of the syndesmosis (Weber C). The medial clear space is widened to 6 mm. Which of the following structures is unequivocally torn in this injury pattern?

. Anterior talofibular ligament (ATFL)
. Calcaneofibular ligament (CFL)
. Interosseous membrane up to the level of the fracture
. Spring ligament
. Plantar fascia

Correct Answer & Explanation

. Interosseous membrane up to the level of the fracture

Explanation

A Weber C fracture with widening of the medial clear space indicates a completely unstable syndesmotic injury. The interosseous membrane is torn from the ankle joint up to the level of the fibula fracture.

Question 3275

Topic: 8. Foot and Ankle

A 45-year-old man presents with right leg pain radiating to the dorsum of his foot and isolated weakness in great toe extension. Which nerve root is most likely compressed, and what is the typical associated reflex abnormality?

. L4, diminished patellar reflex
. L4, diminished Achilles reflex
. L5, diminished patellar reflex
. L5, no reliable reflex change
. S1, diminished Achilles reflex

Correct Answer & Explanation

. L5, no reliable reflex change

Explanation

Extensor hallucis longus (EHL) weakness and numbness over the dorsum of the foot indicate an L5 radiculopathy. The L5 nerve root does not have a reliable primary deep tendon reflex.

Question 3276

Topic: 8. Foot and Ankle

A 45-year-old active man sustains an acute, closed Achilles tendon rupture. He is evaluating his treatment options between surgical repair and nonoperative management with early functional rehabilitation. Based on recent high-quality randomized controlled trials, what is the most accurate information to provide regarding his outcomes?

. Surgical repair significantly decreases the re-rupture rate compared to functional rehabilitation protocols.
. Nonoperative management with early functional rehabilitation yields equivalent functional outcomes and re-rupture rates compared to surgery.
. Surgical repair allows for earlier return to baseline activities but has a 15% lower complication rate.
. Nonoperative management requires a minimum of 6 weeks of strict non-weight-bearing in a plantarflexed cast.
. Surgical repair results in significantly greater plantar flexion strength at 2-year follow-up.

Correct Answer & Explanation

. Nonoperative management with early functional rehabilitation yields equivalent functional outcomes and re-rupture rates compared to surgery.

Explanation

Recent RCTs show that nonoperative management utilizing early functional rehabilitation protocols has equivalent functional outcomes, strength, and re-rupture rates compared to surgical repair. Surgery is associated with higher rates of superficial and deep wound complications.

Question 3277

Topic: Midfoot & Hindfoot

A 52-year-old woman presents with severe pes planovarus deformity. She has inability to perform a single-leg heel raise, marked forefoot abduction, and talonavicular uncoverage of 45% on standing AP foot radiographs. The deformity is fully flexible on examination. Which of the following is the most appropriate surgical management?

. Flexor digitorum longus (FDL) transfer to the navicular and medial displacement calcaneal osteotomy (MDCO) only
. FDL transfer, MDCO, and lateral column lengthening
. Spring ligament repair and isolated subtalar arthrodesis
. Triple arthrodesis
. Gastrocnemius recession and isolated talonavicular arthrodesis

Correct Answer & Explanation

. FDL transfer, MDCO, and lateral column lengthening

Explanation

This patient has stage IIb adult-acquired flatfoot deformity (flexible, with significant forefoot abduction/>30% talonavicular uncoverage). Optimal treatment includes an FDL transfer, medial displacement calcaneal osteotomy, and a lateral column lengthening to correct the forefoot abduction.

Question 3278

Topic: 8. Foot and Ankle

A 22-year-old professional ballet dancer complains of chronic posterior ankle pain that is worsened when performing "en pointe" (maximal plantarflexion). Radiographs demonstrate a prominent os trigonum. Nonoperative management has failed. What is the most appropriate next step in management?

. Open excision of the os trigonum via a medial approach
. Endoscopic excision of the os trigonum and flexor hallucis longus (FHL) tenolysis
. Arthroscopic subtalar arthrodesis
. Diagnostic injection of the anterior ankle joint
. Peroneal tendon exploration and repair

Correct Answer & Explanation

. Endoscopic excision of the os trigonum and flexor hallucis longus (FHL) tenolysis

Explanation

Posterior ankle impingement often affects ballet dancers due to extreme plantarflexion. Excision of the os trigonum and FHL tenolysis (commonly performed endoscopically) is the gold standard after failed conservative care, yielding high return-to-sport rates.

Question 3279

Topic: Midfoot & Hindfoot

A 58-year-old man with uncontrolled type 2 diabetes presents with a red, hot, swollen right foot. He recalls no trauma. Radiographs show periarticular fragmentation, subluxation of the tarsometatarsal joints, and bounding pedal pulses. What is the most appropriate initial treatment?

. Urgent irrigation and debridement of the midfoot
. Total contact casting and strict non-weight-bearing
. Intravenous antibiotics and observation
. Primary midfoot arthrodesis
. Below-knee amputation

Correct Answer & Explanation

. Total contact casting and strict non-weight-bearing

Explanation

This is a classic presentation of acute (Eichenholtz stage I) Charcot arthropathy. The mainstay of initial treatment to prevent progressive deformity and collapse is offloading with a total contact cast and strict non-weight-bearing.

Question 3280

Topic: 8. Foot and Ankle

Which of the following represents an absolute contraindication to a total ankle replacement (TAR) for end-stage ankle arthritis?

. Patient age over 65 years
. Mild associated subtalar arthritis
. Avascular necrosis involving >50% of the talar body
. Body mass index of 28
. Correctable varus malalignment of 5 degrees

Correct Answer & Explanation

. Avascular necrosis involving >50% of the talar body

Explanation

Absolute contraindications for TAR include active infection, severe neuroarthropathy (Charcot), lack of lower extremity muscle function, and extensive avascular necrosis of the talus, which precludes adequate component fixation.

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