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8. Foot and Ankle MCQs

Practice Set 263 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 5241

Topic: 8. Foot and Ankle

A 60-year-old diabetic patient with a history of peripheral neuropathy presents with a rapidly progressive, warm, swollen, erythematous, and painful right foot. X-rays reveal disorganization of the midfoot joints, fragmentation of articular surfaces, and a 'rocker-bottom' deformity. There are no systemic signs of infection (normal WBC, CRP). What is the most critical immediate management strategy?

. Immediate surgical fusion of the midfoot joints.
. Administration of broad-spectrum intravenous antibiotics.
. Strict non-weight bearing with total contact casting (TCC).
. Elevation and application of ice packs to the foot.
. Conservative management with over-the-counter pain relievers.

Correct Answer & Explanation

. Strict non-weight bearing with total contact casting (TCC).

Explanation

This clinical presentation is characteristic of acute Charcot neuroarthropathy. While infection must always be ruled out in a diabetic foot, the absence of systemic signs and the specific radiographic findings point towards Charcot. The most critical immediate management is to protect the foot from further collapse and deformity by offloading. Strict non-weight bearing with a total contact cast (TCC) is the gold standard for acute Charcot foot. This immobilizes the joints, distributes pressure evenly, and reduces the inflammatory response, preventing further bone destruction. Surgical fusion is considered for stable deformities or non-bracable feet after the acute phase. Antibiotics are not indicated unless infection is confirmed. Elevation and ice are insufficient. Over-the-counter pain relievers do not address the progressive destruction.

Question 5242

Topic: 8. Foot and Ankle

A newborn is diagnosed with congenital vertical talus (CVT), also known as 'rocker-bottom foot.' Physical examination reveals a rigid foot with a prominent plantar convex deformity, dorsiflexion of the forefoot, and hindfoot equinus. What is the primary underlying anatomical abnormality in CVT, and what is the typical initial management approach?

. Talonavicular subluxation with the navicular dorsally dislocated on the talar head; serial casting (Ponseti method).
. Abnormal development of the talus causing a 'vertical' orientation; early surgical release of soft tissues.
. Fixed equinus deformity of the hindfoot; serial casting to stretch the Achilles tendon.
. Dorsal dislocation of the navicular on the talar head; serial casting in reverse Ponseti method followed by surgery.
. Adduction and supination of the forefoot; manipulation and casting in a clubfoot protocol.

Correct Answer & Explanation

. Dorsal dislocation of the navicular on the talar head; serial casting in reverse Ponseti method followed by surgery.

Explanation

Congenital vertical talus (CVT) is characterized by a fixed dorsal dislocation of the navicular on the talar head, making the talus appear vertical. This leads to the characteristic 'rocker-bottom' foot deformity, with a rigid hindfoot equinus and forefoot dorsiflexion. The initial management typically involves a modified or 'reverse Ponseti' serial casting technique to gradually reduce the forefoot and stretch the contracted structures, followed by surgical intervention (often a one-stage release) to achieve full reduction of the talonavicular joint and maintain correction. The standard Ponseti method is for clubfoot (talipes equinovarus). Early surgical release is often required but casting usually precedes it to improve soft tissue conditions. Fixed equinus is part of it, but the talonavicular dislocation is key. Adduction and supination of the forefoot are characteristic of clubfoot, not CVT.

Question 5243

Topic: 8. Foot and Ankle

A 48-year-old male with poorly controlled diabetes mellitus presents with a swollen, erythematous, and warm right foot without ulceration. He denies trauma. Radiographs reveal fragmentation of the navicular, subchondral debris, and loss of the medial longitudinal arch. Inflammatory markers are mildly elevated. According to the Eichenholtz classification, what is the most appropriate initial management?

. Immediate surgical arthrodesis of the midfoot
. Intravenous antibiotics and bone biopsy
. Total contact casting and strict non-weight bearing
. Custom orthotics and full weight-bearing
. Below-knee amputation

Correct Answer & Explanation

. Total contact casting and strict non-weight bearing

Explanation

The patient is in Eichenholtz Stage 1 (Developmental/Fragmentation phase) of Charcot neuroarthropathy, characterized by erythema, swelling, warmth, and radiographic fragmentation and debris. The gold standard treatment is rigid immobilization and offloading, typically with a total contact cast (TCC), until the acute inflammatory phase resolves and the foot progresses to Stage 2 (Coalescence).

Question 5244

Topic: 8. Foot and Ankle
A 55-year-old female presents with a progressive flatfoot deformity and medial ankle pain. Examination reveals a flexible flatfoot, an inability to perform a single-limb heel rise, and greater than 50% uncovering of the talonavicular joint on weight-bearing AP radiographs. She has a positive Silfverskiold test demonstrating isolated gastrocnemius tightness. What is the most appropriate surgical management for this Johnson and Strom Stage IIb posterior tibial tendon dysfunction?
. Posterior tibial tendon debridement and synovectomy
. Flexor digitorum longus transfer, medial displacement calcaneal osteotomy, lateral column lengthening, and gastrocnemius recession
. Triple arthrodesis and Achilles tendon lengthening
. Tibiotalocalcaneal (TTC) arthrodesis
. Spring ligament repair without osseous intervention

Correct Answer & Explanation

. Flexor digitorum longus transfer, medial displacement calcaneal osteotomy, lateral column lengthening, and gastrocnemius recession

Explanation

Stage IIb PTTD is characterized by a flexible deformity with significant forefoot abduction (>40% talonavicular uncovering). Surgical treatment typically requires soft tissue reconstruction (FDL transfer), hindfoot valgus correction (medial displacement calcaneal osteotomy), forefoot abduction correction (lateral column lengthening such as an Evans osteotomy), and addressing equinus (gastrocnemius recession). Rigid deformities (Stage III) require arthrodesis.

Question 5245

Topic: 8. Foot and Ankle

Which deep tendon reflex is MOST likely to be diminished or absent in a patient with a symptomatic S1 radiculopathy?

. Patellar reflex
. Achilles reflex
. Biceps reflex
. Brachioradialis reflex
. Triceps reflex

Correct Answer & Explanation

. Achilles reflex

Explanation

The Achilles reflex (ankle jerk) primarily tests the S1 nerve root. The patellar reflex (knee jerk) tests L3-L4. The biceps (C5-C6), brachioradialis (C5-C6), and triceps (C7) reflexes are upper extremity reflexes.

Question 5246

Topic: 8. Foot and Ankle

A patient undergoes microdiscectomy for L5 radiculopathy. Postoperatively, they develop a new, profound foot drop (0/5 strength in ankle dorsiflexion). What is the MOST likely cause?

. Anesthetic complications
. Postoperative epidural hematoma
. Dural tear
. Wrong level surgery
. Nerve root contusion or transaction

Correct Answer & Explanation

. Nerve root contusion or transaction

Explanation

A new, profound neurological deficit immediately post-discectomy, such as a 0/5 foot drop, strongly suggests direct nerve root injury (contusion, stretch, or rare transaction) during the surgery. While epidural hematoma can cause neurological deficits, a profound, isolated deficit like this points more directly to intraoperative nerve root insult. Wrong level surgery is also a possibility but nerve root injury is more common for this immediate post-op presentation. Dural tear typically causes headache, not profound motor weakness.

Question 5247

Topic: 8. Foot and Ankle

When utilizing a circular external fixator to correct a severe rigid ankle equinus deformity, the axis of rotation of the frame's hinges should ideally be collinear with:

. The center of the body of the talus
. The tip of the medial malleolus
. The subtalar joint axis
. The anatomical center of rotation of the ankle joint
. The calcaneocuboid joint

Correct Answer & Explanation

. The anatomical center of rotation of the ankle joint

Explanation

To correct an ankle deformity without creating joint compression or distraction, the hinges must be collinear with the anatomic center of rotation of the ankle joint. This is typically located within the body of the talus, but precise alignment with the joint's true axis is required.

Question 5248

Topic: 8. Foot and Ankle

In a cavus foot deformity, the apex of the deformity (CORA) is typically at the midfoot. If a closing wedge osteotomy is planned with the hinge placed at the plantar aspect (concave side) directly at the CORA, which Paley rule is being applied?

. Rule 1
. Rule 2
. Rule 3
. Rule 4
. Rule 5

Correct Answer & Explanation

. Rule 1

Explanation

If the osteotomy passes through the CORA and the hinge is also placed at the CORA, this strictly follows Paley's Rule 1. Placing the hinge on the concave side specifically results in a closing wedge correction without axis translation.

Question 5249

Topic: 8. Foot and Ankle

During Ilizarov frame correction of a severe rigid varus foot, attempting to rapidly correct the deformity is most likely to precipitate which of the following complications?

. Tarsal tunnel syndrome
. Anterior tibial artery aneurysm
. Subtalar joint ankylosis
. Tarsometatarsal dislocation
. Superficial peroneal nerve palsy

Correct Answer & Explanation

. Tarsal tunnel syndrome

Explanation

Rapid correction of a rigid varus or equinovarus foot aggressively stretches the medial soft tissue structures. This can precipitate tarsal tunnel syndrome due to acute traction on the posterior tibial nerve.

Question 5250

Topic: 8. Foot and Ankle

When utilizing a Taylor Spatial Frame (TSF) for correcting a complex ankle deformity, what does the 'reference fragment' defined in the software represent?

. The bone segment that moves dynamically during the correction phase
. The stable bone segment to which the origin of the coordinate system is attached
. The soft tissue envelope surrounding the planned osteotomy site
. The specific level of the osteotomy relative to the joint line
. The magnitude of the mechanical axis deviation in millimeters

Correct Answer & Explanation

. The stable bone segment to which the origin of the coordinate system is attached

Explanation

In TSF planning, the reference fragment is defined as the stationary bone segment (usually proximal or closest to the joint). The moving fragment's trajectory is calculated relative to this stable coordinate system.

Question 5251

Topic: 8. Foot and Ankle

The normal mechanical lateral distal tibial angle (mLDTA) on an AP radiograph, which is critical for planning supramalleolar osteotomies, is approximately:

. 80 degrees
. 84 degrees
. 89 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 89 degrees

Explanation

The normal mechanical lateral distal tibial angle (mLDTA) averages 89 degrees, with a typical range of 86 to 92 degrees. Restoring this angle is essential to achieving a horizontal ankle joint line during deformity correction.

Question 5252

Topic: 8. Foot and Ankle

In ankle distraction arthroplasty for osteoarthritis, what is the primary mechanical purpose of adding hinges to the circular fixator construct instead of using a static rigid frame?

. To allow for continuous passive motion promoting cartilage regeneration
. To prevent pin tract infections by decreasing skin tension
. To facilitate immediate full weight-bearing on the forefoot
. To allow independent medial and lateral translation of the talus
. To maintain distraction only during axial loading

Correct Answer & Explanation

. To allow for continuous passive motion promoting cartilage regeneration

Explanation

Hinged ankle distraction permits continuous passive motion (CPM) while maintaining joint separation. The intermittent variations in intra-articular fluid pressure help nourish the cartilage and stimulate fibrocartilage repair.

Question 5253

Topic: Midfoot & Hindfoot

In a patient presenting with a Charcot 'rocker-bottom' foot deformity undergoing planning for circular frame correction, the sagittal plane CORA is most frequently located at:

. The talonavicular and calcaneocuboid (Chopart's) joints
. The tarsometatarsal (Lisfranc) joints
. The subtalar joint
. The tibiotalar joint
. The metatarsophalangeal joints

Correct Answer & Explanation

. The tarsometatarsal (Lisfranc) joints

Explanation

In the classic Charcot rocker-bottom foot, the midfoot collapse and primary apex of the sagittal plane deformity (CORA) typically occur at the tarsometatarsal (Lisfranc) joint complex.

Question 5254

Topic: 8. Foot and Ankle

During Taylor Spatial Frame (TSF) correction of an equinovarus foot, postoperative radiographs show progressive anterior translation of the talus relative to the tibia. This indicates the virtual hinge was likely placed:

. Anterior to the true anatomic axis of the ankle joint
. Exactly on the true anatomic axis of the ankle joint
. Posterior to the true anatomic axis of the ankle joint
. Proximal to the tibial plafond
. Distal to the subtalar joint

Correct Answer & Explanation

. Anterior to the true anatomic axis of the ankle joint

Explanation

According to Paley's Rule 3, placing the hinge eccentric to the true joint axis causes translation during angular correction. A hinge placed anterior to the ankle axis results in unintended anterior translation of the talus during dorsiflexion correction.

Question 5255

Topic: 8. Foot and Ankle

You are correcting a severe rigid equinus deformity using a circular external fixator. To avoid compressive forces across the talar dome during gradual dorsiflexion, where should the hinge axis of the frame be placed relative to the anatomical axis of the ankle joint?

. Exactly collinear with the anatomical axis of the ankle joint
. Proximal and anterior to the anatomical axis of the ankle joint
. Proximal and posterior to the anatomical axis of the ankle joint
. Distal and inferior to the anatomical axis of the ankle joint
. Directly anterior to the anatomical axis on the talar neck

Correct Answer & Explanation

. Distal and inferior to the anatomical axis of the ankle joint

Explanation

To prevent joint compression and provide a necessary distraction effect (arthrodiastasis) during equinus correction, the hinge should be placed distal (inferior) to the true anatomical axis of the ankle joint. This causes the joint to pull apart slightly as it rotates into dorsiflexion.

Question 5256

Topic: 8. Foot and Ankle

When analyzing the mechanical axis of the lower extremity for an ankle deformity, what is the accepted normal range for the Lateral Distal Tibial Angle (LDTA)?

. 80 to 84 degrees
. 85 to 87 degrees
. 86 to 92 degrees
. 93 to 96 degrees
. 97 to 100 degrees

Correct Answer & Explanation

. 86 to 92 degrees

Explanation

The normal Mechanical Lateral Distal Tibial Angle (mLDTA) is 89 degrees, with a widely accepted normal range of 86 to 92 degrees. Deviation outside this range typically indicates a varus or valgus ankle deformity requiring correction.

Question 5257

Topic: 8. Foot and Ankle

A 50-year-old male presents with asymmetric medial ankle arthritis and a valgus distal tibial deformity (LDTA = 80 degrees). A medial opening-wedge supramalleolar osteotomy is planned. What is a key biomechanical advantage of this specific technique over a lateral closing wedge?

. It decompresses the lateral joint space directly
. It maintains or increases leg length and tightens medial soft-tissue structures
. It significantly shortens the fibula
. It avoids the need for a bone graft completely
. It permits immediate full weight-bearing without hardware

Correct Answer & Explanation

. It maintains or increases leg length and tightens medial soft-tissue structures

Explanation

A medial opening-wedge supramalleolar osteotomy corrects the valgus deformity while maintaining or slightly increasing leg length. It also increases tension on the deltoid ligament complex, which is often stretched in chronic valgus.

Question 5258

Topic: 8. Foot and Ankle

During the correction of a rigid equinocavovarus foot deformity using an Ilizarov frame, a midfoot osteotomy (e.g., Paley's V-osteotomy or U-osteotomy) is often required. What is the primary purpose of this specific midfoot osteotomy?

. To arthrodese the subtalar joint directly
. To correct the multi-planar deformity of the midfoot independent of the ankle joint
. To lengthen the Achilles tendon without soft tissue surgery
. To bypass a fixed forefoot supination
. To correct a pure hindfoot varus

Correct Answer & Explanation

. To correct the multi-planar deformity of the midfoot independent of the ankle joint

Explanation

Paley's midfoot osteotomies (like the V or U osteotomy) are designed to correct complex multi-planar deformities (cavus, adduction, supination) located primarily at the midfoot apex, sparing the ankle and hindfoot joints if they are unaffected or addressed separately.

Question 5259

Topic: 8. Foot and Ankle

A patient is undergoing metatarsal lengthening via distraction osteogenesis for a severely hypoplastic 4th metatarsal (brachymetatarsia). What is the most common and significant complication associated with this specific procedure?

. Nonunion of the metatarsal regenerate
. Metatarsophalangeal (MTP) joint subluxation and stiffness
. Avascular necrosis of the metatarsal head
. Rupture of the extensor digitorum longus
. Tarsometatarsal joint dislocation

Correct Answer & Explanation

. Metatarsophalangeal (MTP) joint subluxation and stiffness

Explanation

The most common complication of metatarsal lengthening is stiffness and subluxation (usually dorsal) of the MTP joint due to the increased tension on the soft tissues, particularly the extensor tendons, crossing the joint.

Question 5260

Topic: 8. Foot and Ankle

In the context of deformity correction, which of the following best defines the 'Mechanical Axis Deviation' (MAD) of the lower extremity?

. The distance from the center of the knee joint to the mechanical axis line drawn from the center of the femoral head to the center of the ankle.
. The angle formed between the anatomical axis of the femur and the anatomical axis of the tibia.
. The angle of the joint line relative to the horizontal plane during single-leg stance.
. The distance between the anatomical axis and the mechanical axis at the level of the lesser trochanter.
. The measure of tibial torsion relative to the transmalleolar axis.

Correct Answer & Explanation

. The distance from the center of the knee joint to the mechanical axis line drawn from the center of the femoral head to the center of the ankle.

Explanation

Mechanical Axis Deviation (MAD) is measured in millimeters as the perpendicular distance from the center of the knee joint to the true mechanical axis line (Mikulicz line), which connects the center of the femoral head to the center of the ankle.

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