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 5621
Topic: 8. Foot and Ankle
A surgeon is performing an anterolateral approach to the distal tibia. Which nerve is most at risk during the superficial dissection, and what compartment of the leg does it primarily motor innervate?
Correct Answer & Explanation
. Deep peroneal nerve; anterior compartment
Explanation
The superficial peroneal nerve lies in the operative field during the anterolateral approach to the ankle and distal tibia. It provides motor innervation to the peroneus longus and brevis in the lateral compartment.
Question 5622
Topic: 8. Foot and Ankle
On an axial MRI of the mid-calf, a soft tissue sarcoma is identified strictly confined within the deep posterior compartment. Which nerve runs in this compartment, and what is its primary sensory distribution?
Correct Answer & Explanation
. Deep peroneal nerve; first web space of the foot
Explanation
The tibial nerve descends through the deep posterior compartment of the leg alongside the posterior tibial vessels. It provides sensory innervation to the plantar aspect of the foot via the medial and lateral plantar nerves.
Question 5623
Topic: 8. Foot and Ankle
In an axial MRI evaluating tarsal tunnel syndrome, the posterior tibial neurovascular bundle is situated between the tendons of which two muscles at the level of the medial malleolus?
Correct Answer & Explanation
. Tibialis posterior and flexor digitorum longus
Explanation
From anterior to posterior behind the medial malleolus, the order is Tibialis posterior, Flexor digitorum longus, Artery, Vein, Nerve, Flexor hallucis longus (Tom, Dick, And Very Nervous Harry). Thus, the bundle lies between the FDL and FHL.
Question 5624
Topic: 8. Foot and Ankle
A 24-year-old football player sustains a high-energy knee dislocation (Schenck KD-IV). The knee is grossly unstable, and on examination, the dorsalis pedis and posterior tibial pulses are absent. Ankle-brachial index (ABI) is 0.7. Following closed reduction of the knee, the pulses remain absent. What is the most appropriate next step in management?
Correct Answer & Explanation
. Observe and re-examine in 2 hours
Explanation
In the setting of a knee dislocation with 'hard signs' of vascular injury (such as absent pulses that do not return after reduction, active hemorrhage, expanding hematoma, or distal ischemia), the most appropriate step is immediate surgical exploration of the popliteal artery in the operating room. Delaying surgical revascularization for imaging (like CT angio) in the presence of hard signs risks irreversible limb ischemia.
Question 5625
Topic: Midfoot & Hindfoot
A 28-year-old snowboarder sustains a Hawkins Type III fracture of the talar neck. Which of the following best describes the fracture pattern and the associated risk of avascular necrosis (AVN) of the talar body?
Correct Answer & Explanation
. Fracture with subtalar and tibiotalar dislocation, AVN risk near 100%
Explanation
The Hawkins classification for talar neck fractures is predictive of the risk of AVN. Type I: nondisplaced (AVN risk 0-15%). Type II: displaced with subtalar subluxation or dislocation (AVN risk 20-50%). Type III: displaced with both subtalar and tibiotalar (ankle) dislocation (AVN risk > 90% or near 100% historically). Type IV: Type III + talonavicular subluxation/dislocation. Therefore, Type III involves dislocation of both the subtalar and ankle joints.
Question 5626
Topic: 8. Foot and Ankle
A 45-year-old construction worker falls from a ladder and sustains a displaced intra-articular calcaneus fracture (Sanders Type III). A decision is made to proceed with open reduction and internal fixation (ORIF) via an extensile lateral approach. Which of the following structures is at greatest risk of injury during the elevation of the full-thickness soft tissue flap?
Correct Answer & Explanation
. Sural nerve
Explanation
The extensile lateral approach to the calcaneus involves creating a full-thickness fasciocutaneous flap containing the sural nerve, peroneal tendons, and the lesser saphenous vein. The sural nerve is at significant risk of injury (either transection, traction neuritis, or entrapment in scar) during the incision and elevation of this flap. The flap must be meticulously elevated in a subperiosteal plane from the lateral wall of the calcaneus.
Question 5627
Topic: 8. Foot and Ankle
A 25-year-old male presents with midfoot pain after missing a step and axially loading a plantarflexed foot. Weight-bearing radiographs reveal a 3 mm diastasis between the base of the first and second metatarsals, and a 'fleck sign' in the medial cuneiform-second metatarsal space. What does the 'fleck sign' represent?
Correct Answer & Explanation
. Avulsion of the anterior tibialis tendon insertion
Explanation
The Lisfranc ligament is a strong interosseous ligament connecting the medial cuneiform to the base of the second metatarsal. It is critical for the stability of the tarsometatarsal joint complex. The 'fleck sign' is a small bony avulsion fragment seen in the space between the medial cuneiform and the base of the second metatarsal on an AP or internal oblique radiograph. It represents a bony avulsion of the Lisfranc ligament and is pathognomonic for a Lisfranc injury.
Question 5628
Topic: 8. Foot and Ankle
A 30-year-old male falls from a ladder, sustaining a Hawkins Type III talar neck fracture. Which of the following describes the most likely mechanism of injury and the approximate risk of developing avascular necrosis (AVN) of the talar body?
Correct Answer & Explanation
. Hyperdorsiflexion; greater than 80%
Explanation
The classic mechanism for a talar neck fracture is hyperdorsiflexion, where the talar neck impacts against the anterior distal tibia (e.g., 'aviator's astragalus'). A Hawkins Type III fracture involves the talar neck with dislocation of both the subtalar and tibiotalar joints. Because of the extensive disruption to the blood supply (artery of the tarsal canal, deltoid branches, and artery of the sinus tarsi), the rate of avascular necrosis approaches 80-100%.
Question 5629
Topic: 8. Foot and Ankle
A 40-year-old male is scheduled for open reduction and internal fixation of a Sanders Type III calcaneus fracture via an extensile lateral approach. During the development of the full-thickness subperiosteal flap, which nerve is at greatest risk of iatrogenic injury?
Correct Answer & Explanation
. Sural nerve
Explanation
The sural nerve courses along the lateral aspect of the hindfoot and is at significant risk during the extensile lateral approach to the calcaneus. The incision must be carefully planned, and a full-thickness subperiosteal flap must be elevated utilizing 'no-touch' retraction techniques to minimize traction injury or transection of the sural nerve.
Question 5630
Topic: 8. Foot and Ankle
A 35-year-old male sustains a Sanders type III calcaneus fracture. He undergoes ORIF via an extensile lateral approach. Which of the following is the most frequent complication associated with this specific surgical approach?
Correct Answer & Explanation
. Wound edge necrosis and dehiscence
Explanation
The extensile lateral approach to the calcaneus is associated with a high rate of wound complications, including wound edge necrosis, dehiscence, and infection (reported up to 10-25%). Careful handling of the full-thickness soft tissue flap, avoiding sharp angles, and delaying surgery until the "wrinkle sign" appears are essential to minimize this risk. Subtalar arthritis is a common complication of the fracture itself, but wound issues are the most frequent complication specifically attributed to the extensile lateral approach.
Question 5631
Topic: 8. Foot and Ankle
A 28-year-old male is brought to the emergency department after a severe motorcycle accident. He has an obvious deformity of his left knee. Radiographs confirm an anterior knee dislocation, which is successfully reduced. Pulses are palpable, but the Ankle-Brachial Index (ABI) on the affected limb is 0.85. What is the most appropriate next step in management?
Correct Answer & Explanation
. Discharge with a knee immobilizer and outpatient follow-up
Explanation
Knee dislocations have a high rate of associated popliteal artery injury. Even if pulses are present after reduction, an Ankle-Brachial Index (ABI) should be performed. An ABI less than 0.90 is highly suspicious for a vascular injury (such as an intimal tear or flow-limiting lesion) and warrants further advanced imaging, typically CT angiography, to evaluate the popliteal artery. Immediate surgical exploration is indicated for hard signs of vascular injury (expanding hematoma, absent pulses, pulsatile bleeding), but an ABI of 0.85 with palpable pulses mandates a CTA.
Question 5632
Topic: 8. Foot and Ankle
A 35-year-old male twisted his midfoot while stepping off a curb. Plain non-weight-bearing radiographs of the foot are interpreted as normal. However, he continues to have severe pain over the tarsometatarsal joints and inability to bear weight. Which of the following imaging modalities or techniques is the most appropriate next step to rule out a subtle Lisfranc injury?
Correct Answer & Explanation
. MRI of the foot
Explanation
Subtle Lisfranc (tarsometatarsal) injuries can be missed on standard non-weight-bearing radiographs in up to 20% of cases. The most appropriate initial step for a suspected subtle Lisfranc injury with normal non-weight-bearing films is to obtain weight-bearing radiographs of both feet to stress the joint dynamically and compare it to the contralateral, normal side. Findings such as widening of the space between the 1st and 2nd metatarsal bases (the 'fleck sign') or subluxation indicate injury. If weight-bearing films are inconclusive, MRI or weight-bearing CT may be used.
Question 5633
Topic: 8. Foot and Ankle
A 42-year-old male falls from a roof, sustaining a closed, displaced intra-articular calcaneus fracture.
He is a heavy smoker. What is the most appropriate management regarding the surgical timing and approach to minimize soft-tissue complications if an extensile lateral approach is chosen?
Correct Answer & Explanation
. Immediate open reduction and internal fixation within 12 hours
Explanation
Calcaneus fractures are associated with significant soft-tissue swelling. Operating through swollen, tense skin, particularly via an extensile lateral approach, dramatically increases the risk of wound dehiscence and infection. Surgery should be delayed until soft-tissue swelling subsides, indicated by the 'wrinkle sign', which often takes 10 to 14 days. This is especially critical in smokers.
Question 5634
Topic: 8. Foot and Ankle
A 40-year-old female sustains a pronation-external rotation (PER) type ankle fracture. Intraoperatively, after fixation of the malleoli, the Cotton test is positive, indicating syndesmotic instability. A syndesmotic screw is planned. At what level relative to the ankle joint line should the syndesmotic screw optimally be placed?
Correct Answer & Explanation
. 1-2 cm below the joint line
Explanation
A syndesmotic screw should be placed parallel to the tibial plafond, typically 2 to 5 cm above the ankle joint line. It should be directed approximately 20 to 30 degrees anteriorly from the fibula to the tibia to account for the relative position of the bones.
Question 5635
Topic: 8. Foot and Ankle
A 25-year-old male sustains a Hawkins type III talar neck fracture following a motor vehicle accident. Which of the following best describes the blood supply to the body of the talus that is disrupted in this injury?
Correct Answer & Explanation
. Artery of the tarsal canal, artery of the tarsal sinus, and deltoid branches
Explanation
A Hawkins type III fracture is a fracture of the talar neck with subluxation or dislocation of both the subtalar and tibiotalar joints. This severe injury pattern disrupts all three major sources of blood supply to the talar body: the artery of the tarsal canal (a branch of the posterior tibial artery), the artery of the tarsal sinus (from the perforating peroneal and dorsalis pedis), and the deltoid branches. Consequently, the risk of avascular necrosis (AVN) approaches 100%.
Question 5636
Topic: 8. Foot and Ankle
A 32-year-old athlete sustains a hyperplantarflexion injury to his foot. Weight-bearing radiographs show a 3 mm diastasis between the base of the first and second metatarsals. What is the key anatomical stabilizer that is most likely disrupted in this classic Lisfranc injury?
Correct Answer & Explanation
. The ligament connecting the lateral aspect of the medial cuneiform to the medial 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. Crucially, there is no direct transverse ligamentous connection between the bases of the first and second metatarsals, making this interval structurally vulnerable to diastasis and dislocation when the Lisfranc ligament is torn.
Question 5637
Topic: 8. Foot and Ankle
A 28-year-old male is brought to the emergency department after a severe dashboard injury. His right knee is grossly deformed and is immediately reduced. Following reduction, distal pulses are palpable but noticeably diminished compared to the contralateral side. An Ankle-Brachial Index (ABI) is calculated as 0.85. What is the most appropriate next step in management?
Correct Answer & Explanation
. Immediate vascular surgery consultation for operative exploration
Explanation
In the setting of a knee dislocation, vascular status must be aggressively evaluated. Hard signs of vascular injury (expanding hematoma, pulsatile bleeding, absent pulses, distal ischemia) warrant immediate operative intervention. Soft signs or an ABI between 0.9 and normal require observation, while an ABI < 0.9 without hard signs is a firm indication for a CT angiogram (CTA) to rule out an intimal flap or popliteal artery occlusion.
Question 5638
Topic: 8. Foot and Ankle
A patient falls from a height and sustains a Hawkins Type III talar neck fracture. Which of the following describes the status of the blood supply to the talar body in this injury?
Correct Answer & Explanation
. The arteries of the tarsal canal, sinus tarsi, and the deltoid branch are all likely disrupted.
Explanation
A Hawkins Type III fracture is characterized by a talar neck fracture with displacement of the talar body from both the subtalar and tibiotalar joints. This extreme displacement typically disrupts all three major sources of blood supply to the talus: the artery of the tarsal canal, the artery of the sinus tarsi, and the deltoid branch, leading to a very high rate of avascular necrosis (AVN), often approaching 100%.
Question 5639
Topic: 8. Foot and Ankle
A 40-year-old roofer falls 15 feet, landing on his heels. Radiographs demonstrate a severely depressed intra-articular calcaneus fracture with a Bohler's angle of 0 degrees.
Which adjacent structure is at greatest risk of impingement secondary to the lateral wall blowout typical of this injury pattern?
Correct Answer & Explanation
. Sural nerve
Explanation
In intra-articular calcaneus fractures, the lateral wall frequently blows out (displaces laterally) due to the impact of the talus. This lateral expansion often impinges on the fibula and traps or irritates the peroneal tendons running posterior and inferior to the lateral malleolus, leading to chronic tenosynovitis or subluxation if not anatomically reduced.
Question 5640
Topic: 8. Foot and Ankle
A 42-year-old female sustains a rare ankle injury known as a Bosworth fracture-dislocation. Closed reduction in the emergency department is unsuccessful. Anatomically, what is blocking the reduction of this specific injury?
Correct Answer & Explanation
. The proximal fibular fragment is trapped behind the anterior tubercle of the tibia (Chaput fragment)
Explanation
A Bosworth fracture is a rare fracture-dislocation of the ankle where the proximal fragment of the fractured fibula dislocates posteriorly and becomes locked or incarcerated behind the posterolateral ridge (posterior tubercle) of the distal tibia. This mechanical block makes closed reduction virtually impossible, requiring emergent open reduction.
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