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8. Foot and Ankle MCQs

Practice Set 47 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 921

Topic: Ankle Trauma & Sports
According to the Lauge-Hansen classification, what is the precise sequential order of ligamentous and osseous injury in a Supination-External Rotation (SER) stage IV ankle fracture?
. AITFL, short oblique fibula fracture, PITFL/posterior malleolus, deltoid ligament/medial malleolus
. Deltoid ligament/medial malleolus, AITFL, short oblique fibula fracture, PITFL/posterior malleolus
. AITFL, high fibula fracture above syndesmosis, PITFL, medial malleolus
. PITFL, short oblique fibula fracture, AITFL, deltoid ligament/medial malleolus
. Transverse fibula fracture below plafond, vertical medial malleolus fracture

Correct Answer & Explanation

. AITFL, short oblique fibula fracture, PITFL/posterior malleolus, deltoid ligament/medial malleolus

Explanation

The SER sequence begins anterolaterally with the Anterior Inferior Tibiofibular Ligament (Stage I), progresses to a short oblique fibula fracture (Stage II), then the Posterior Inferior Tibiofibular Ligament or posterior malleolus (Stage III), and finishes medially with the deltoid/medial malleolus (Stage IV).

Question 922

Topic: 8. Foot and Ankle

A 45-year-old male falls from a ladder and sustains a displaced, intra-articular calcaneus fracture. He undergoes open reduction and internal fixation via a standard extensile lateral approach. Which of the following is the most frequently encountered complication specific to this surgical approach?

. Sural nerve transection
. Superficial peroneal nerve neuropraxia
. Wound edge necrosis and dehiscence
. Tibial nerve palsy
. Flexor hallucis longus entrapment

Correct Answer & Explanation

. Wound edge necrosis and dehiscence

Explanation

The extensile lateral approach to the calcaneus has a high rate of wound complications (up to 25%), specifically necrosis at the apex of the flap. Meticulous "no-touch" technique and full-thickness subperiosteal dissection are crucial to preserve the blood supply to the flap.

Question 923

Topic: 8. Foot and Ankle

A 25-year-old male sustains a twisting injury to his ankle. Radiographs show a widened medial clear space but no fracture of the lateral malleolus. Full-length tibia-fibula films reveal a proximal third fibula fracture (Maisonneuve injury). Disruption of which of the following structures is primarily responsible for the lateral talar shift and widening of the medial clear space?

. Deltoid ligament
. Anterior talofibular ligament
. Calcaneofibular ligament
. Spring ligament
. Interosseous membrane

Correct Answer & Explanation

. Deltoid ligament

Explanation

In a Maisonneuve fracture pattern, widening of the medial clear space implies failure of the medial stabilizing structures. Complete rupture of the deltoid ligament removes the primary restraint to lateral talar excursion.

Question 924

Topic: 8. Foot and Ankle
When evaluating a lateral radiograph of the foot for a suspected calcaneus fracture, Böhler's angle is measured. Which of the following correctly describes the anatomical landmarks used to draw the two intersecting lines for this angle?
. Highest point of the anterior process to the highest point of the posterior facet; and highest point of the posterior facet to the highest point of the calcaneal tuberosity
. Lowest point of the anterior process to the highest point of the posterior facet; and lowest point of the posterior facet to the superior edge of the tuberosity
. Superior edge of the calcaneocuboid joint to the lowest point of the posterior facet; and lowest point of the posterior facet to the plantar tuberosity
. Highest point of the sustentaculum tali to the lowest point of the posterior facet; and highest point of the posterior facet to the calcaneal tuberosity
. Highest point of the anterior process to the lowest point of the subtalar joint; and lowest point of the subtalar joint to the plantar fascia origin

Correct Answer & Explanation

. Highest point of the anterior process to the highest point of the posterior facet; and highest point of the posterior facet to the highest point of the calcaneal tuberosity

Explanation

Böhler's angle (normally 20-40 degrees) is formed by a line from the highest point of the anterior process to the highest point of the posterior facet, intersecting a line from the highest point of the posterior facet to the superior tuberosity. It is typically flattened in intra-articular calcaneus fractures.

Question 925

Topic: 8. Foot and Ankle

A 25-year-old male sustains an ankle injury during a rugby match. Radiographs reveal an irreducible fracture-dislocation.

Intraoperatively, closed reduction maneuvers fail completely. What is the primary anatomic block to reduction in this specific injury pattern?

. Interposition of the posterior tibial tendon into the medial clear space
. The proximal fibular fragment is entrapped behind the posterior tubercle of the distal tibia
. The medial malleolus fragment blocks the lateral translation of the talus
. Interposition of an avulsed deltoid ligament into the mortise
. The anterior inferior tibiofibular ligament remains intact and tethered

Correct Answer & Explanation

. The proximal fibular fragment is entrapped behind the posterior tubercle of the distal tibia

Explanation

A Bosworth fracture-dislocation is characterized by the proximal fibular fragment becoming incarcerated behind the posterior tubercle of the distal tibia. This structural entrapment creates a mechanically irreducible deformity requiring urgent open reduction.

Question 926

Topic: 8. Foot and Ankle

A 45-year-old male smoker presents to the emergency department after a fall from a ladder. Examination reveals significant swelling and severe blanching of the skin over the posterior heel. Radiographs demonstrate a displaced tongue-type calcaneus fracture. What is the most appropriate definitive management to prevent catastrophic soft tissue failure?

. Immediate application of a short leg cast in maximal equinus
. Urgent percutaneous reduction and screw fixation
. Elevation, strict bed rest, and delayed ORIF at 10-14 days once 'wrinkle sign' appears
. Immediate open reduction and internal fixation via an extensile lateral approach
. Primary subtalar arthrodesis via a limited sinus tarsi approach

Correct Answer & Explanation

. Urgent percutaneous reduction and screw fixation

Explanation

Tongue-type calcaneus fractures with posterior skin blanching represent an orthopedic emergency due to the high risk of rapid, full-thickness skin necrosis. Urgent percutaneous reduction and screw fixation relieve the severe mechanical pressure on the posterior soft tissues while stabilizing the fracture.

Question 927

Topic: 8. Foot and Ankle

A 30-year-old male undergoes internal fixation of a pronation-external rotation ankle fracture. After fibular plating, the surgeon performs a Cotton test and suspects syndesmotic instability. When using intraoperative fluoroscopy, which parameter on the mortise view is the most reliable indicator of syndesmotic malreduction compared to the uninjured contralateral ankle?

. Tibiofibular clear space greater than 5 mm
. Medial clear space greater than 4 mm
. Talocrural angle less than 75 degrees
. Asymmetry of the anterior and posterior fibular gaps relative to the incisura on a true lateral view
. Tibiofibular overlap less than 1 mm

Correct Answer & Explanation

. Asymmetry of the anterior and posterior fibular gaps relative to the incisura on a true lateral view

Explanation

Direct assessment of the fibula within the incisura fibularis by evaluating anterior and posterior gap asymmetry on a true lateral fluoroscopic view (or CT) is highly accurate for syndesmotic reduction. Traditional plain radiographic AP/Mortise lines (like overlap or clear space) are highly dependent on rotation and are less reliable.

Question 928

Topic: 8. Foot and Ankle

A 50-year-old male sustains a high-energy pelvic injury, including a sacral fracture. During surgical planning for percutaneous sacroiliac screw fixation, the surgeon is concerned about potential injury to the L5 nerve root. Which of the following anatomical considerations is most relevant to preventing this specific complication?

. A. The proximity of the S1 nerve root to the superior aspect of the SI joint.
. B. The course of the L5 nerve root draping over the ventral surface of the sacral ala.
. C. The location of the superior gluteal artery exiting the greater sciatic notch.
. D. The relationship of the internal iliac artery to the anterior sacrum.
. E. The position of the sciatic nerve within the posterior pelvis.

Correct Answer & Explanation

. B. The course of the L5 nerve root draping over the ventral surface of the sacral ala.

Explanation

Correct Answer: B. The course of the L5 nerve root draping over the ventral surface of the sacral ala.The case discussion highlights that the pelvic inlet view helps avoid anterior breach and 'lower lumbar root injury, which drapes over the ventral surface of the sacral ala,' leading to iatrogenic foot drop. Foot drop is typically caused by injury to the peroneal nerve, which receives innervation from the L5 nerve root. Therefore, the L5 nerve root's course over the ventral sacral ala is the most relevant anatomical consideration for preventing iatrogenic foot drop during sacroiliac screw placement.Option A (The proximity of the S1 nerve root to the superior aspect of the SI joint):While S1 nerve root injury is a concern with SI screw placement, the question specifically asks about 'foot drop,' which is more directly linked to L5 injury.Option C (The location of the superior gluteal artery exiting the greater sciatic notch):Injury to the superior gluteal artery is a known complication of SI screw placement, particularly with posterior breach or screws directed too laterally, but it does not directly cause foot drop.Option D (The relationship of the internal iliac artery to the anterior sacrum):The internal iliac artery and its branches are anterior to the sacrum and are at risk with anterior cortical breach, but the L5 nerve root is the primary structure associated with foot drop in this context.Option E (The position of the sciatic nerve within the posterior pelvis):The sciatic nerve is a major structure at risk with posterior breach of the sacrum or screws placed too far posteriorly/inferiorly, but the L5 root's vulnerability to anterior breach is specifically linked to the foot drop complication mentioned in the case.

Question 929

Topic: 8. Foot and Ankle

A 45-year-old female presents after a high-speed MVC. Imaging shows a vertical fracture through the sacral ala lateral to the neural foramina. If the patient exhibits a neurologic deficit, which of the following is most likely expected?

. Loss of anal sphincter tone
. Foot drop and weakness in great toe extension
. Absent ankle reflex and weak plantarflexion
. Urinary retention
. Loss of sensation over the medial thigh

Correct Answer & Explanation

. Foot drop and weakness in great toe extension

Explanation

Denis Zone I fractures occur lateral to the neural foramina. They carry a 6% risk of neurologic deficit, most commonly involving the L5 nerve root (causing foot drop) due to compression against the L5 transverse process.

Question 930

Topic: Midfoot & Hindfoot

The patient's definitive reconstruction involves a dual incision strategy, including a posteromedial approach to address the posterior malleolar extension and the medial column. Which of the following describes the correct internervous plane for the deep dissection of this posteromedial approach and the neurovascular structures to protect?

. Between the Tibialis Anterior and the Extensor Hallucis Longus; protect the deep peroneal nerve and anterior tibial artery.
. Between the Peroneus Longus and the Peroneus Brevis; protect the superficial peroneal nerve.
. Between the Flexor Digitorum Longus and the Flexor Hallucis Longus; protect the sural nerve.
. Between the Posterior Tibial Tendon and the Flexor Digitorum Longus; protect the saphenous nerve and vein anteriorly.
. Between the Gastrocnemius and Soleus; protect the posterior tibial nerve and artery.

Correct Answer & Explanation

. Between the Posterior Tibial Tendon and the Flexor Digitorum Longus; protect the saphenous nerve and vein anteriorly.

Explanation

Correct Answer: DThe case explicitly states for the posteromedial approach: 'The saphenous nerve and vein are protected anteriorly. The deep dissection proceeds between the posterior tibial tendon and the flexor digitorum longus, allowing access to the posterior aspect of the medial malleolus and the Volkmann fragment.' This accurately describes the internervous plane and the key neurovascular structures to protect during this approach.Option A is incorrectas this describes an anterior approach.Option B is incorrectas this describes a lateral approach.Option C is incorrectbecause while the Flexor Digitorum Longus and Flexor Hallucis Longus are in the deep posterior compartment, the primary internervous plane for the posteromedial approach is between the Posterior Tibial Tendon and the Flexor Digitorum Longus. The sural nerve is lateral.Option E is incorrectbecause while the Gastrocnemius and Soleus are posterior, the approach for the distal tibia is typically deeper, and the posterior tibial nerve and artery are deep to the flexor tendons, not directly between the gastrocnemius and soleus for this specific approach to the medial malleolus/Volkmann fragment.

Question 931

Topic: 8. Foot and Ankle

A 35-year-old male is evaluated for a high-energy pilon fracture. CT imaging reveals significant comminution of the posterior tibial plafond (Volkmann fragment). The surgeon plans a posterolateral approach to the ankle for direct reduction and fixation. Which of the following describes the correct internervous/intermuscular interval for this approach?

. Between the tibialis anterior and extensor hallucis longus
. Between the peroneus brevis and flexor hallucis longus
. Between the flexor digitorum longus and tibialis posterior
. Between the Achilles tendon and the peroneus longus
. Between the extensor digitorum longus and the peroneus tertius

Correct Answer & Explanation

. Between the peroneus brevis and flexor hallucis longus

Explanation

The posterolateral approach to the distal tibia and posterior malleolus utilizes the interval between the peroneal tendons (peroneus brevis) laterally and the flexor hallucis longus (FHL) medially. This provides excellent visualization of the posterior tibial plafond while protecting the posteromedial neurovascular bundle.

Question 932

Topic: 8. Foot and Ankle

A 40-year-old patient sustains a severe pilon fracture from a fall from height. The axial load was applied while the ankle was in a strongly plantarflexed position. Based on the mechanism of injury, which region of the tibial plafond is most likely to exhibit the maximum comminution and displacement?

. Anterior plafond
. Posterior plafond
. Medial malleolus
. Anterolateral (Chaput) fragment
. Central articular die-punch

Correct Answer & Explanation

. Posterior plafond

Explanation

The position of the foot at the time of axial impact dictates the primary fracture pattern in pilon fractures. A plantarflexed ankle directs the force into the posterior aspect of the tibial plafond, leading to predominant posterior comminution and displacement.

Question 933

Topic: 8. Foot and Ankle

During the definitive surgical staging of a highly comminuted, AO/OTA type 43-C3 pilon fracture, the surgeon elects to fix the fibula first to restore limb length. However, achieving accurate fibular length proves difficult. If the fibula is fixed in a shortened position, what is the most likely consequence for the tibial articular reduction?

. Anterior subluxation of the talus
. Valgus malalignment of the tibial plafond
. Varus malalignment of the tibial plafond
. Procurvatum deformity of the distal tibia
. Over-distraction of the medial malleolar fragment

Correct Answer & Explanation

. Valgus malalignment of the tibial plafond

Explanation

In complex pilon fractures, plating the fibula first can inadvertently dictate the length and alignment of the tibia. If the fibula is fixed short, the intact syndromotic ligaments will tether the lateral aspect of the tibia, pulling the tibial block into a valgus malreduction.

Question 934

Topic: Midfoot & Hindfoot

A 32-year-old male presents to the Emergency Department following a high-energy motor vehicle accident. He reports immediate pain and deformity in his left foot after an axial load through a plantarflexed foot with a severe inversion component. Clinical examination reveals an 'acquired clubfoot' deformity with significant varus angulation of the hindfoot, supination, plantarflexion, and a prominently palpable talar head dorsolaterally. The skin overlying the talar head is stretched and blanched. Based on this presentation, what is the most likely diagnosis?

. Lateral Subtalar Dislocation
. Talar Neck Fracture with Dislocation
. Medial Subtalar Dislocation
. Chopart Joint Dislocation
. Pantalar Dislocation

Correct Answer & Explanation

. Medial Subtalar Dislocation

Explanation

Correct Answer: CThe patient's presentation is classic for a medial subtalar dislocation. The mechanism of injury (axial load through a plantarflexed foot with severe inversion) directly correlates with the pathomechanics of this injury. Clinically, the 'acquired clubfoot' deformity, significant varus angulation of the hindfoot, supination, plantarflexion, and the prominent dorsolateral talar head are pathognomonic findings for a medial subtalar dislocation. The skin tension over the talar head is a critical sign of impending soft tissue compromise. Lateral subtalar dislocations present with the foot in valgus and pronation, and the talar head prominent medially. Talar neck fractures involve a fracture line through the talar neck, often with variable hindfoot deformity. Chopart joint dislocations involve disarticulation at the talonavicular and calcaneocuboid joints, with an intact subtalar joint. Pantalar dislocations involve simultaneous dislocation of the tibiotalar, subtalar, and talonavicular joints, which is a much more severe and unstable injury.

Question 935

Topic: 8. Foot and Ankle

Following the initial clinical assessment, emergent plain radiographs of the left foot and ankle were obtained. The lateral view is provided below. Based on the provided image and the case description, which of the following radiographic findings is most characteristic of this patient's injury?

. The talus is dislocated from the distal tibia within the ankle mortise.
. The navicular is displaced laterally relative to the talar head.
. The calcaneus is displaced medially and anteriorly relative to the talus.
. There is significant widening of the ankle syndesmosis.
. A comminuted fracture of the lateral malleolus is evident.

Correct Answer & Explanation

. The calcaneus is displaced medially and anteriorly relative to the talus.

Explanation

Correct Answer: CThe provided image and case description confirm a medial subtalar dislocation. In this injury, the talus remains perfectly congruent with the distal tibia within the ankle mortise, ruling out option A. The anteroposterior view (described in the text, though not shown) would confirm the navicular resting medial to the talar head, not laterally, ruling out option B. The text explicitly states that 'The calcaneus was displaced medially and anteriorly relative to the talus,' which is a hallmark of a medial subtalar dislocation. The ankle views demonstrated no concomitant tibiotalar subluxation, widening of the syndesmosis (ruling out D), or obvious malleolar fractures (ruling out E). The image clearly shows the talus articulating with the tibia, but disarticulated from the calcaneus and navicular, with the foot (including calcaneus and navicular) displaced relative to the talus.

Question 936

Topic: 8. Foot and Ankle

During an attempt at closed reduction for this patient's medial subtalar dislocation in the emergency department, the orthopedic resident is struggling to achieve reduction despite adequate sedation and longitudinal traction. Which specific maneuver is highlighted in the case as critical for successful reduction by addressing a common impediment?

. Applying sustained traction with the knee fully extended to maximize hamstring stretch.
. Exaggerating the foot's dorsiflexion and eversion to disengage the talonavicular joint.
. Flexing the knee to 90 degrees to relax the gastrocnemius-soleus complex.
. Applying direct manual pressure to the plantar aspect of the calcaneus to lever the talus.
. Administering a neuromuscular blocking agent without concurrent general anesthesia.

Correct Answer & Explanation

. Flexing the knee to 90 degrees to relax the gastrocnemius-soleus complex.

Explanation

Correct Answer: CThe case explicitly states under 'Clinical Pearls and Pitfalls': 'Pearl Knee Flexion is Mandatory: The most common reason for a failed closed reduction in the emergency department is inadequate relaxation of the gastrocnemius-soleus complex. Always flex the knee to 90 degrees during the reduction maneuver to eliminate this massive deforming force.' This relaxation is crucial for allowing the calcaneus to be manipulated effectively. Options A and B describe incorrect or incomplete steps. Option A would increase gastrocnemius tension. Option B describes part of the reduction but not the initial disengagement. Option D is not a primary maneuver for muscle relaxation. Option E is unsafe and not the specific maneuver highlighted for muscle relaxation in this context.

Question 937

Topic: 8. Foot and Ankle

Following successful closed reduction of the patient's medial subtalar dislocation, the foot is stable on clinical assessment. What is the most important next diagnostic step, and what is its primary purpose?

. Magnetic Resonance Imaging (MRI) to evaluate for avascular necrosis of the talus.
. Repeat plain radiographs to confirm concentric reduction and assess stability.
. Non-contrast Computed Tomography (CT) scan of the foot and ankle to rule out occult fractures.
. Arteriography to assess for occult vascular injury to the dorsalis pedis artery.
. Electromyography (EMG) to evaluate for deep peroneal nerve neuropraxia.

Correct Answer & Explanation

. Non-contrast Computed Tomography (CT) scan of the foot and ankle to rule out occult fractures.

Explanation

Correct Answer: CThe case clearly states, 'While plain radiographs are sufficient for diagnosing the dislocation and guiding the immediate closed reduction, computed tomography is an absolute requirement following the reduction of any subtalar dislocation.' It further emphasizes, 'A post-reduction non-contrast CT scan of the foot and ankle with fine axial, coronal, and sagittal reformats is mandatory. The primary indications for this CT scan include evaluating for osteochondral shear fractures of the talar dome, talar head, or navicular,' and other periarticular fractures. Plain radiographs (Option B) are typically obtained immediately post-reduction but are insufficient for detecting occult fractures. MRI (Option A) is rarely indicated acutely and is more for subacute/chronic issues like AVN. Arteriography (Option D) and EMG (Option E) are not routinely indicated unless specific vascular or neurological deficits persist after reduction.

Question 938

Topic: Midfoot & Hindfoot

Despite two well-executed attempts at closed reduction under adequate sedation, the patient's medial subtalar dislocation remains irreducible. The decision is made to proceed with emergent open reduction. For an irreducible medial subtalar dislocation, which of the following soft tissue structures is most commonly implicated as an interpositional block to reduction?

. Posterior tibial tendon
. Flexor hallucis longus tendon
. Extensor digitorum brevis muscle belly
. Deltoid ligament
. Peroneus brevis tendon

Correct Answer & Explanation

. Extensor digitorum brevis muscle belly

Explanation

Correct Answer: CThe case explicitly details the indications for operative intervention: 'In medial dislocations, the most common blocks to closed reduction include the buttonholing of the talar head through the extensor digitorum brevis muscle belly, the extensor retinaculum, or the talonavicular joint capsule.' The other options (posterior tibial tendon, flexor hallucis longus tendon, deltoid ligament, peroneus brevis tendon) are less common or not typically involved in blocking reduction of a medial subtalar dislocation. The EDB muscle belly, located dorsolaterally, is directly in the path of the prominent talar head during a medial dislocation.

Question 939

Topic: 8. Foot and Ankle

The patient undergoes successful open reduction and stabilization of his medial subtalar dislocation. During the post-operative rehabilitation phase, the patient asks about potential long-term complications. Based on the case information, which of the following is the most common long-term complication associated with high-energy subtalar dislocations, even after successful reduction?

. Avascular necrosis of the talar body
. Chronic ankle instability
. Post-traumatic subtalar arthritis
. Recurrent subtalar dislocation
. Tarsal tunnel syndrome

Correct Answer & Explanation

. Post-traumatic subtalar arthritis

Explanation

Correct Answer: CThe case highlights under 'Pitfall Underestimating Long Term Complications': 'Furthermore, post-traumatic subtalar arthritis occurs in up to 50 percent of high-energy cases, regardless of the quality of reduction, due to the initial chondral insult.' While avascular necrosis (Option A) is a concern, its rate is significantly lower in isolated subtalar dislocations compared to talar neck fractures. Chronic ankle instability (Option B) and recurrent dislocation (Option D) are less common if the reduction is stable and appropriate rehabilitation is followed. Tarsal tunnel syndrome (Option E) is a rare complication and not the most common long-term issue.

Question 940

Topic: Midfoot & Hindfoot

A different patient presents with a severe midfoot deformity after a high-energy twisting injury. Radiographs show complete disarticulation at the talonavicular and calcaneocuboid joints, but the subtalar joint remains intact. Based on the provided differential diagnosis table, what is the most likely injury?

. Medial Subtalar Dislocation
. Lateral Subtalar Dislocation
. Talar Neck Fracture with Dislocation
. Chopart Joint Dislocation
. Pantalar Dislocation

Correct Answer & Explanation

. Chopart Joint Dislocation

Explanation

Correct Answer: DThe differential diagnosis table explicitly defines 'Chopart Joint Dislocation' as having 'Disarticulation at talonavicular and calcaneocuboid joints, subtalar joint intact.' This perfectly matches the clinical scenario described in the question. Medial and Lateral Subtalar Dislocations involve disarticulation of the talonavicular and talocalcaneal joints. Talar Neck Fractures involve a fracture line through the talar neck. Pantalar Dislocation involves dislocation of the tibiotalar, subtalar, and talonavicular joints simultaneously. Therefore, Chopart Joint Dislocation is the correct answer.

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