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 6101
Topic: 8. Foot and Ankle
The artery of the tarsal canal is a crucial contributor to the blood supply of the talar body, making it vulnerable in talar neck fractures. This artery classically originates as a branch of which major vessel?
Correct Answer & Explanation
. Posterior tibial artery
Explanation
The artery of the tarsal canal typically arises from the posterior tibial artery about 1 cm proximal to its bifurcation. It gives off the deltoid branch and provides the dominant blood supply to the talar body.
Question 6102
Topic: 8. Foot and Ankle
A 35-year-old sustains a displaced talar neck fracture. The artery of the tarsal canal provides the predominant blood supply to the talar body. From which major vessel does this artery originate?
Correct Answer & Explanation
. Posterior tibial artery
Explanation
The artery of the tarsal canal is a branch of the posterior tibial artery and provides the dominant blood supply to the talar body. It anastomoses with the artery of the tarsal sinus, which originates from the anterior tibial and peroneal arteries. Disruption of this blood supply in talar neck fractures heavily contributes to avascular necrosis.
Question 6103
Topic: 8. Foot and Ankle
A 50-year-old male presents with a Lisfranc injury (tarsometatarsal fracture-dislocation) after a fall. Initial radiographs are equivocal, but there is significant midfoot pain and swelling. What is the most appropriate next imaging study to confirm the diagnosis?
Correct Answer & Explanation
. CT scan of the foot.
Explanation
When plain radiographs are equivocal for a Lisfranc injury but clinical suspicion is high (midfoot pain, swelling, ecchymosis, especially plantar ecchymosis), a CT scan of the foot (C) is the gold standard for definitive diagnosis. It provides detailed bony anatomy, allowing visualization of subtle diastasis, avulsion fractures, and articular incongruity at the tarsometatarsal joints. Weight-bearing radiographs (A) might reveal subtle instability if the patient can tolerate them, but CT is superior for complex bony anatomy. MRI (B) is excellent for soft tissue (ligament) injury but less precise for subtle bony disruption than CT, and is typically reserved for assessing the integrity of the Lisfranc ligament if bony injury is unclear or for persistent pain after fixation. Bone scan (D) is not specific. Ultrasound (E) is not used for this diagnosis.
Question 6104
Topic: 8. Foot and Ankle
Which of the following describes a 'Maisononneuve fracture'?
Correct Answer & Explanation
. A fracture of the proximal fibula with an associated unstable ankle syndesmosis and often a deltoid ligament rupture or medial malleolar fracture.
Explanation
A Maisonneuve fracture (B) is a specific type of ankle injury characterized by a fracture of the proximal fibula (near the fibular neck), often associated with an unstable syndesmosis (disruption of the tibiofibular ligaments) and a medial injury (either a deltoid ligament rupture or a medial malleolar fracture). This injury results from external rotation and pronation forces transmitted up the interosseous membrane. It is crucial to diagnose because the proximal fibular fracture indicates instability at the ankle, requiring syndesmotic fixation even if the ankle joint itself appears less obviously displaced on plain radiographs.
Question 6105
Topic: 8. Foot and Ankle
A 25-year-old male sustains a spiral fracture of the distal tibia and fibula. Radiographs suggest an unstable ankle fracture. Which imaging view is most crucial for assessing syndesmotic integrity?
Correct Answer & Explanation
. Mortise view of the ankle.
Explanation
The mortise view of the ankle (C) is the most crucial standard plain radiographic view for assessing syndesmotic integrity. It is an AP view with the foot internally rotated 15-20 degrees to open up the ankle mortise. This view allows for evaluation of the tibiofibular clear space, tibiofibular overlap, and medial clear space. Widening of these parameters suggests syndesmotic disruption. While stress radiographs (E) can be used to dynamically assess syndesmotic stability, the mortise view is the standard static image. AP (A) and lateral (B) views provide additional information but are less specific for syndesmotic assessment. Oblique (D) is less commonly used for syndesmosis.
Question 6106
Topic: 8. Foot and Ankle
Which of the following is an indication for operative management of an acute Achilles tendon rupture?
Correct Answer & Explanation
. Gap in the tendon palpable (>1 cm).
Explanation
A palpable gap in the tendon (>1 cm) (D) after an acute Achilles tendon rupture is a strong indication for operative management, as it suggests significant retraction and difficulty achieving good apposition with non-operative treatment, leading to higher rates of re-rupture. Operative repair typically leads to a lower re-rupture rate and better functional outcomes, especially in active individuals. Elderly patients with low demands (A) and patients with significant comorbidities (B) might be better managed non-operatively. Partial tears (C) are often managed conservatively if the functional deficit is minimal. Non-compliant patients (E) are often poor candidates for surgical repair due to the demanding post-operative rehabilitation.
Question 6107
Topic: 8. Foot and Ankle
A 20-year-old male sustains a Lisfranc injury. Intraoperatively, a significant gap between the medial cuneiform and the base of the second metatarsal is noted after reduction. What is the most appropriate method of fixation across the Lisfranc joint?
Correct Answer & Explanation
. Suture button fixation system.
Explanation
For a Lisfranc injury with a significant diastasis after reduction, particularly involving the Lisfranc ligament complex, a suture button fixation system (e.g., TightRope) (D) has become increasingly popular. It provides dynamic stabilization, restores the normal biomechanics of the midfoot by allowing micro-motion, and reduces the need for hardware removal compared to traditional transarticular screws. While transarticular screws (A) from the medial cuneiform to the second metatarsal base were historically the gold standard, they create a rigid construct and are often removed. K-wires (B) are temporary and not strong enough. Plate and screw fixation (C) is typically for comminuted fractures. Fixation of only the first TMT joint (E) is insufficient for a significant injury.
Question 6108
Topic: 8. Foot and Ankle
What is the most serious long-term complication of a neglected or inadequately treated Lisfranc injury?
Correct Answer & Explanation
. Post-traumatic midfoot arthritis.
Explanation
The most serious and debilitating long-term complication of a neglected or inadequately treated Lisfranc injury is post-traumatic midfoot arthritis (D). Persistent instability, malreduction, or articular damage at the tarsometatarsal joints leads to progressive degenerative changes, chronic pain, and significant functional disability. This often necessitates reconstructive surgery, such as midfoot fusion. Chronic ankle instability (A) is not a direct consequence. DVT (B) is an acute complication. Foot drop (C) is related to nerve injury, not typically Lisfranc. Calcaneal spur (E) is not related.
Question 6109
Topic: 8. Foot and Ankle
Which of the following is the hallmark radiological sign of an acute Lisfranc injury on a weight-bearing AP view of the foot?
Correct Answer & Explanation
. Increased space between the medial cuneiform and the base of the second metatarsal.
Explanation
The hallmark radiological sign of an acute Lisfranc injury on a weight-bearing AP view of the foot is an increased space (diastasis) between the medial cuneiform and the base of the second metatarsal (C). This widening indicates disruption of the Lisfranc ligament complex, which connects these two bones and is crucial for midfoot stability. Options A and B describe other potential midfoot disruptions but are not the primary diagnostic sign for the Lisfranc joint itself. Loss of arch height (D) can be a general sign but is less specific. Navicular fracture (E) is a separate injury.
Question 6110
Topic: Midfoot & Hindfoot
What is the primary goal of surgical management for an intra-articular calcaneal fracture?
Correct Answer & Explanation
. Achieve anatomical reduction of the posterior subtalar facet.
Explanation
The primary goal of surgical management for an intra-articular calcaneal fracture is to achieve anatomical reduction of the posterior subtalar facet. Restoration of this articular surface is critical to minimize the risk of post-traumatic subtalar arthritis, which is the most common long-term complication. While restoring Bรถhler's and Gissane's angles are important indicators of overall calcaneal morphology, they are secondary to the articular reduction. Rigid fixation is a means to achieve the goal, not the goal itself. Decompressing peroneal tendons might be an associated step but not the primary goal. Preventing DVT is a general post-operative concern.
Question 6111
Topic: 8. Foot and Ankle
A 65-year-old male presents with an ankle fracture-dislocation. The foot is severely deformed, and the skin is tented, blanching, and in danger of necrosis. There are palpable pulses. What is the most urgent next step?
Correct Answer & Explanation
. Perform a closed reduction of the dislocation.
Explanation
Any fracture-dislocation causing skin compromise (e.g., tenting, blanching, impending necrosis) or neurovascular compromise is an orthopedic emergency. Even with palpable pulses, prolonged skin tension can lead to necrosis and conversion of a closed injury to an open one, increasing infection risk. The most urgent step is to perform a gentle, emergent closed reduction to relieve tension on the skin and soft tissues, irrespective of the need for future definitive fixation (which might be ORIF). CT and antibiotics are important but follow limb salvage. Elevation and ice are supportive but insufficient for impending skin loss.
Question 6112
Topic: 8. Foot and Ankle
A 40-year-old male sustains a spiral fracture of the proximal fibula. Which of the following associated nerve injuries should be specifically assessed?
Correct Answer & Explanation
. Common peroneal nerve
Explanation
The common peroneal nerve (also known as the common fibular nerve) courses superficially around the fibular neck, making it vulnerable to injury with proximal fibula fractures. Injury to the common peroneal nerve typically results in foot drop (weakness of ankle dorsiflexion and eversion) and sensory loss over the dorsum of the foot and lateral leg. The deep and superficial peroneal nerves are branches of the common peroneal nerve. The tibial nerve is in the posterior compartment, and sural and saphenous nerves are cutaneous sensory nerves not typically injured with this fracture pattern.
Question 6113
Topic: 8. Foot and Ankle
A 20-year-old male sustains a twisting injury to his foot. X-rays are inconclusive for a Lisfranc injury, but he has severe pain over the midfoot, swelling, and ecchymosis on the plantar aspect of the foot. What is the next most appropriate imaging study to rule out a subtle Lisfranc injury?
Correct Answer & Explanation
. CT scan of the foot.
Explanation
Clinical suspicion for a Lisfranc injury, especially with plantar ecchymosis and midfoot pain, warrants thorough evaluation. If initial non-weight-bearing X-rays are inconclusive, weight-bearing views are often the next step to unmask subtle instability. However, a CT scan of the foot is considered the gold standard for diagnosing subtle or difficult-to-visualize Lisfranc injuries, providing detailed bony anatomy and allowing for precise measurement of fragment displacement and diastasis. While MRI can visualize soft tissue injuries (ligaments), CT is superior for initial bony assessment. Bone scan is less specific and ultrasound is generally not used for these fractures.
Question 6114
Topic: 8. Foot and Ankle
A 30-year-old male falls and sustains a comminuted fracture of the tarsal navicular. What is the primary concern for long-term complications with this specific bone injury?
Correct Answer & Explanation
. Avascular necrosis (AVN).
Explanation
The tarsal navicular bone has a tenuous blood supply, primarily entering dorsally and laterally. Fractures, especially comminuted or displaced fractures, can disrupt this blood supply, placing the bone at high risk for avascular necrosis (AVN). AVN of the navicular can lead to collapse, deformity, and severe midfoot arthritis. While nonunion and malunion leading to flatfoot are also complications, AVN is a particularly significant concern due to the unique vascularity of this bone. Nerve entrapment and Achilles rupture are not direct complications of a navicular fracture.
Question 6115
Topic: 8. Foot and Ankle
A 50-year-old male presents with acute onset of foot drop following a traumatic knee dislocation. Which of the following nerves is most likely injured, and what is its primary motor function affected?
Correct Answer & Explanation
. Common peroneal nerve; ankle dorsiflexion and eversion.
Explanation
Foot drop, characterized by the inability to dorsiflex the ankle and evert the foot, is a classic sign of common peroneal (fibular) nerve injury. The common peroneal nerve courses superficially around the fibular neck and is vulnerable in knee dislocations. The tibial nerve innervates plantarflexors and foot intrinsics. The saphenous nerve is purely sensory. The femoral nerve innervates the quadriceps (knee extension) and iliopsoas (hip flexion). The sural nerve is sensory only to the lateral foot.
Question 6116
Topic: 8. Foot and Ankle
A 28-year-old snowboarder presents with lateral ankle pain and swelling after falling. She describes a sensation of her ankle 'giving way' and pain posterior to the lateral malleolus. Physical exam reveals tenderness and snapping when the ankle is moved from dorsiflexion to plantarflexion/eversion. This is most indicative of:
Correct Answer & Explanation
. Peroneal tendon subluxation/dislocation.
Explanation
The clinical presentation of lateral ankle pain, a sensation of 'giving way,' pain posterior to the lateral malleolus, and especially the snapping sensation with ankle movement (dorsiflexion to plantarflexion/eversion) is classic for peroneal tendon subluxation or dislocation. This occurs when the superior peroneal retinaculum (SPR) is torn, allowing the peroneal tendons to subluxate or dislocate anteriorly over the lateral malleolus. Ligamentous ruptures (ATFL, CFL) cause instability but not typically snapping. Achilles rupture involves loss of plantarflexion and a palpable gap. High ankle sprain causes pain proximal to the ankle joint and with external rotation.
Question 6117
Topic: 8. Foot and Ankle
A 40-year-old male sustains a displaced intra-articular calcaneus fracture. Bohler's angle on the injured side measures 5 degrees (normal 20-40 degrees). What does this measurement primarily indicate?
Correct Answer & Explanation
. Degree of calcaneal shortening and collapse.
Explanation
Bohler's angle (also known as the 'tuber joint angle') is measured on a lateral radiograph of the foot and reflects the height of the posterior facet of the calcaneus relative to the posterior tuberosity and anterior process. A decreased Bohler's angle (e.g., 5 degrees as opposed to the normal 20-40 degrees) indicates collapse of the calcaneus, particularly the posterior facet, and shortening of the calcaneus. This correlates with the severity of the intra-articular depression and prognosis. While it doesn't directly indicate talar head displacement, AVN risk of the calcaneus, or ligamentous integrity, it is a key measure of the extent of calcaneal collapse.
Question 6118
Topic: 8. Foot and Ankle
What is the most common mechanism of injury for a talus neck fracture?
Correct Answer & Explanation
. Hyperdorsiflexion with axial load.
Explanation
Talus neck fractures are classically caused by a forceful hyperdorsiflexion of the ankle with an axial load. This mechanism typically occurs during events like motor vehicle accidents (driver's foot hitting the floorboard) or falls from height. In this position, the talus neck is impinged between the anterior tibia and the calcaneus, leading to fracture. Direct falls on the heel cause calcaneus fractures. Inversion sprains cause ankle ligamentous injury or 5th metatarsal fractures. Hyperplantarflexion is less common for talus neck fractures.
Question 6119
Topic: Midfoot & Hindfoot
A 7-year-old child undergoes limb salvage surgery for Ewing's Sarcoma of the distal femur. What is a primary long-term concern related to growth in this patient?
Correct Answer & Explanation
. Development of significant limb length discrepancy
Explanation
In growing children undergoing limb salvage surgery, particularly around long bones like the distal femur, removing or irradiating a significant portion of the growth plate or replacing it with an endoprosthesis that does not grow can lead to substantial limb length discrepancy over time. This requires careful planning, sometimes using expandable prostheses, or subsequent lengthening procedures. DVT is an acute surgical complication, not a long-term growth issue. Accelerated growth of the contralateral limb is not a direct consequence. Premature fusion of all growth plates is too general. Charcot arthropathy is a neuropathic joint condition, unrelated to growth after Ewing's surgery.
Question 6120
Topic: Ankle Trauma & Sports
A 25-year-old male sustains an ankle injury while playing basketball. Radiographs show a transverse fracture of the distal fibula at the level of the syndesmosis and widening of the syndesmosis. The medial clear space is also increased. This injury pattern most closely corresponds to which Weber classification type?
Correct Answer & Explanation
. Weber C
Explanation
The Weber classification for ankle fractures describes the level of the fibular fracture relative to the syndesmosis. A Weber C fracture involves a fibular fracture proximal to the syndesmosis, often with syndesmotic disruption and medial injury (deltoid ligament tear or medial malleolus fracture). A transverse fibular fracture at the level of the syndesmosis combined with syndesmotic widening and increased medial clear space (indicating medial ligamentous injury or fracture) is the hallmark of a Weber C injury, specifically indicating syndesmotic instability. Weber A is distal to syndesmosis, Weber B is at the level. A Maisonneuve fracture is a specific type of Weber C where the fibular fracture is very high, near the fibular head.
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