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8. Foot and Ankle MCQs

Practice Set 338 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 6741

Topic: 8. Foot and Ankle

A 70-year-old poorly controlled diabetic patient presents with a non-healing hallux ulcer. Vascular assessment reveals an Ankle-Brachial Index (ABI) of 1.4. What is the most appropriate next step in the non-invasive vascular evaluation of this patient?

. Reassure the patient as an ABI > 1.0 indicates excellent perfusion.
. Perform a Toe-Brachial Index (TBI) measurement.
. Proceed directly to below-knee amputation.
. Order a venous duplex ultrasound.
. Apply a compression wrap to improve venous return.

Correct Answer & Explanation

. Perform a Toe-Brachial Index (TBI) measurement.

Explanation

An ABI > 1.3 is falsely elevated due to medial arterial calcification (Monckeberg's sclerosis), which is common in diabetic patients. A Toe-Brachial Index (TBI) is required as the digital arteries are less susceptible to calcification, providing a more accurate assessment of perfusion.

Question 6742

Topic: 8. Foot and Ankle

A diabetic patient with sensory neuropathy presents with a recalcitrant Wagner Grade 1 ulcer under the first metatarsal head. He has an associated severe equinus contracture. Non-operative offloading has failed. What is the most appropriate surgical intervention to promote healing of the ulcer?

. First metatarsophalangeal joint fusion
. First metatarsal head resection
. Achilles tendon lengthening
. Flexor hallucis longus transfer
. Below-knee amputation

Correct Answer & Explanation

. Achilles tendon lengthening

Explanation

An equinus contracture increases forefoot plantar pressures during the gait cycle, contributing to forefoot ulceration. Achilles tendon lengthening (ATL) or gastrocnemius recession effectively reduces forefoot pressure and promotes ulcer healing in this scenario.

Question 6743

Topic: 8. Foot and Ankle

A 65-year-old diabetic male undergoes a Chopart (midtarsal) amputation for a severe midfoot infection. Post-operatively, he develops a prominent progressive deformity of the residual foot. Which of the following deformities is most common after this specific level of amputation, and what is its primary cause?

. Equinovarus due to unopposed pull of the Achilles and tibialis posterior tendons
. Calcaneocavus due to loss of the Achilles tendon
. Planovalgus due to rupture of the posterior tibial tendon
. Dorsiflexion contracture due to unopposed tibialis anterior
. Supination deformity due to intact peroneus brevis

Correct Answer & Explanation

. Equinovarus due to unopposed pull of the Achilles and tibialis posterior tendons

Explanation

A Chopart amputation often leads to a severe equinovarus deformity because the anterior tibial and peroneal tendon insertions are lost, leaving the Achilles and tibialis posterior tendons unopposed. Prophylactic Achilles lengthening and anterior tendon transfers are often required.

Question 6744

Topic: 8. Foot and Ankle

A 65-year-old diabetic male with a non-healing, ischemic forefoot wound is being evaluated for a transmalleolar (Syme) amputation. The surgical team is assessing his preoperative parameters to predict wound healing. Which of the following laboratory or physiologic values is the most reliable predictor of successful amputation healing in this patient?

. Ankle-Brachial Index (ABI) greater than 1.2
. Transcutaneous oxygen tension (TcPO2) greater than 40 mmHg
. Serum albumin less than 2.5 g/dL
. Total lymphocyte count less than 1000/mm3
. Hemoglobin A1c less than 9.0%

Correct Answer & Explanation

. Transcutaneous oxygen tension (TcPO2) greater than 40 mmHg

Explanation

Transcutaneous oxygen tension (TcPO2) > 30-40 mmHg, serum albumin > 3.0 g/dL, and total lymphocyte count > 1500/mm3 are reliable positive predictors of amputation wound healing. Ankle-Brachial Index (ABI) can be falsely elevated (>1.3) in diabetics due to medial arterial calcification, making it unreliable.

Question 6745

Topic: Midfoot & Hindfoot

A 60-year-old female with profound diabetic neuropathy presents with a red, swollen foot and a plantar ulcer that probes to the cuboid bone. Differentiating between acute Charcot arthropathy and osteomyelitis is critical. Which of the following MRI findings most strongly favors a diagnosis of osteomyelitis rather than Charcot arthropathy?

. Subchondral bone marrow edema in multiple contiguous bones
. Presence of intra-articular loose bodies and debris
. Diffuse midfoot joint subluxation
. Replacement of normal marrow fat on T1 with enhancement on T2 in a single bone contiguous with the ulcer
. Periarticular soft tissue edema without sinus tract formation

Correct Answer & Explanation

. Replacement of normal marrow fat on T1 with enhancement on T2 in a single bone contiguous with the ulcer

Explanation

The 'ghost sign' and contiguous spread from a soft tissue ulcer (showing low T1 and high T2 signals) in a single bone are classic for osteomyelitis. Conversely, Charcot arthropathy typically involves multiple periarticular bones, subchondral edema, and intra-articular debris.

Question 6746

Topic: 8. Foot and Ankle

Total contact casting (TCC) is considered the gold standard for offloading plantar diabetic foot ulcers. However, strict patient selection is required. In which of the following clinical scenarios is the use of a total contact cast absolutely contraindicated?

. Superficial Wagner grade 1 ulcer on the plantar first metatarsal head
. Wagner grade 2 ulcer without clinical signs of infection
. Eichenholtz stage 1 Charcot arthropathy without a skin ulceration
. Plantar ulcer presenting with active deep space infection and fluctuance
. Neuropathic patient with palpable pedal pulses and mild forefoot edema

Correct Answer & Explanation

. Plantar ulcer presenting with active deep space infection and fluctuance

Explanation

Total contact casting is absolutely contraindicated in the presence of an active deep infection, untreated osteomyelitis, or severe arterial ischemia. Applying a closed cast over a deep space infection or abscess can lead to disastrous complications, including gangrene.

Question 6747

Topic: 8. Foot and Ankle

A 50-year-old male with diabetes presents with a recurrent, non-infected plantar ulcer under the 3rd metatarsal head. Clinical examination reveals a fixed equinus contracture. Which of the following is the most appropriate adjunctive surgical procedure to offload the forefoot and decrease ulcer recurrence rates?

. Tibialis anterior tendon transfer
. Achilles tendon lengthening
. First metatarsophalangeal joint arthrodesis
. Isolated Weil osteotomy of the 3rd metatarsal without soft tissue balancing
. Split-thickness skin grafting of the ulcer base

Correct Answer & Explanation

. Achilles tendon lengthening

Explanation

A fixed equinus contracture significantly increases forefoot peak plantar pressures during the stance phase of gait, leading to recurrent metatarsal head ulcers. Achilles tendon lengthening effectively reduces these peak pressures and significantly lowers the ulcer recurrence rate.

Question 6748

Topic: Midfoot & Hindfoot

A 68-year-old female presents with Charcot arthropathy isolated to the tarsometatarsal (Lisfranc) joints, resulting in a fixed 'rocker-bottom' foot deformity. According to the Brodsky classification of Charcot arthropathy, which anatomic pattern does this represent?

. Type 1
. Type 2
. Type 3A
. Type 3B
. Type 4

Correct Answer & Explanation

. Type 1

Explanation

Brodsky Type 1 involves the tarsometatarsal (Lisfranc) and naviculocuneiform joints and is the most common pattern, typically causing a rocker-bottom deformity. Type 2 involves the Chopart joint, Type 3A the ankle, and Type 3B the posterior calcaneal tuberosity.

Question 6749

Topic: 8. Foot and Ankle

A 70-year-old poorly controlled diabetic male is evaluated for a non-healing hallux ulcer. Non-invasive vascular studies reveal an Ankle-Brachial Index (ABI) of 1.45. What is the most appropriate next step to accurately assess his arterial perfusion?

. Proceed with standard wound care as ABI > 1.0 indicates excellent flow
. Obtain a Toe-Brachial Index (TBI)
. Perform an immediate lower extremity CT angiogram
. Schedule a primary below-knee amputation
. Initiate aggressive hyperbaric oxygen therapy

Correct Answer & Explanation

. Obtain a Toe-Brachial Index (TBI)

Explanation

An ABI > 1.3 is considered falsely elevated and non-diagnostic due to Monckeberg's medial calcific sclerosis of the tibial vessels, rendering them non-compressible. A Toe-Brachial Index (TBI) should be obtained because digital vessels are typically spared from this calcification process.

Question 6750

Topic: Midfoot & Hindfoot

A 54-year-old male presents with a red, hot, swollen foot. Radiographs demonstrate acute fragmentation, subluxation of the midfoot, and intra-articular debris (Eichenholtz Stage I Charcot arthropathy). The plantar skin is intact without ulceration. What is the most appropriate initial management?

. Immediate open reduction and internal fixation with rigid plating
. Midfoot arthrodesis using large intramedullary beaming techniques
. Strict non-weight-bearing in a total contact cast
. Below-knee amputation
. Exostectomy of the medial cuneiform

Correct Answer & Explanation

. Strict non-weight-bearing in a total contact cast

Explanation

Acute Eichenholtz Stage I (fragmentation phase) Charcot arthropathy is treated non-operatively with strict immobilization and offloading via a total contact cast to arrest progression. Surgical reconstruction during the acute inflammatory phase carries a high risk of hardware failure and infection.

Question 6751

Topic: 8. Foot and Ankle
A 62-year-old female with a remote history of Charcot arthropathy now presents with a stable, consolidated midfoot (Eichenholtz Stage III). She suffers from a recurrent plantar midfoot ulcer directly overlying a prominent cuboid exostosis. The ulcer heals with casting but rapidly recurs in custom orthotics. There are no signs of active infection. What is the best surgical intervention?
. Primary below-knee amputation
. Midfoot ostectomy (exostectomy) of the prominent bone
. Complex midfoot realignment arthrodesis
. Achilles tendon lengthening alone
. Application of a circular external fixator

Correct Answer & Explanation

. Midfoot ostectomy (exostectomy) of the prominent bone

Explanation

For a stable, consolidated Charcot foot (Stage III) with a localized bony prominence causing recurrent ulceration despite proper accommodation, a simple exostectomy is highly effective. Major realignment arthrodesis is unnecessary in a stable foot and carries significantly higher complication rates.

Question 6752

Topic: 8. Foot and Ankle

A 48-year-old diabetic male presents with acute unilateral foot swelling, erythema, and a local temperature increase of 4 degrees Celsius compared to the contralateral foot. Plain radiographs are entirely normal. MRI reveals diffuse bone marrow edema in the cuboid without cortical destruction. What is the most likely diagnosis and appropriate management?

. Osteomyelitis; treat with 6 weeks of intravenous antibiotics
. Eichenholtz Stage 0 Charcot; treat with immediate immobilization and offloading
. Eichenholtz Stage 1 Charcot; treat with early primary arthrodesis
. Cellulitis; treat with elevation and oral antibiotics
. Gouty arthropathy; treat with colchicine and NSAIDs

Correct Answer & Explanation

. Eichenholtz Stage 0 Charcot; treat with immediate immobilization and offloading

Explanation

Eichenholtz Stage 0 (pre-radiographic) Charcot presents with acute clinical inflammation and MRI findings of bone marrow edema, but completely normal plain radiographs. Prompt offloading and immobilization are critical to prevent progression to the structural destruction seen in Stage 1.

Question 6753

Topic: 8. Foot and Ankle

The pathogenesis of Charcot neuropathic osteoarthropathy is traditionally described by two prevailing theories. Which of the following statements best describes the neurotraumatic theory?

. Autonomic dysfunction leads to arteriovenous shunting and active bone resorption
. Loss of protective sensation allows unperceived repetitive microtrauma to cause progressive joint destruction
. Increased sympathetic tone causes persistent vasoconstriction resulting in ischemic bone necrosis
. Motor neuropathy selectively atrophies intrinsic foot muscles leading to spontaneous midfoot dislocations
. Glycosylation of collagen in the capsuloligamentous structures causes spontaneous ligamentous rupture

Correct Answer & Explanation

. Loss of protective sensation allows unperceived repetitive microtrauma to cause progressive joint destruction

Explanation

The neurotraumatic theory posits that sensory neuropathy leads to an inability to perceive pain, allowing repetitive microtrauma to go unnoticed, eventually causing ligamentous failure and joint destruction. This contrasts with the neurovascular theory, which involves autonomic neuropathy leading to hyperemic bone resorption.

Question 6754

Topic: 8. Foot and Ankle

A 28-year-old female presents with a deep-seated, 4 cm mass bound to the Achilles tendon. Histology reveals nests of plump spindle cells with clear cytoplasm separated by fibrous septa. Immunohistochemistry is positive for HMB-45 and S-100. Which chromosomal translocation is pathognomonic for this tumor?

. t(X;18)(p11;q11)
. t(11;22)(q24;q12)
. t(12;22)(q13;q12)
. t(2;13)(q35;q14)
. t(9;22)(q22;q12)

Correct Answer & Explanation

. t(12;22)(q13;q12)

Explanation

Clear cell sarcoma, also known as melanoma of soft parts, typically involves tendons or aponeuroses of the foot and ankle in young adults. It is driven by the t(12;22) translocation resulting in the EWSR1-ATF1 fusion.

Question 6755

Topic: Midfoot & Hindfoot

The pathogenesis of Charcot arthropathy is debated between the neurotraumatic and neurovascular theories. Which of the following best describes the fundamental mechanism proposed by the neurovascular theory?

. Repeated microtrauma due to loss of protective pain sensation causes mechanical joint destruction.
. Autonomic neuropathy leads to loss of sympathetic tone, resulting in local hyperemia and increased osteoclastic resorption.
. Chronic low-grade infection leads to silent ischemic necrosis of the articular surfaces.
. Advanced glycation end-products selectively degrade articular cartilage matrix.
. Loss of motor innervation causes unopposed muscle pull, leading to chronic subluxation.

Correct Answer & Explanation

. Autonomic neuropathy leads to loss of sympathetic tone, resulting in local hyperemia and increased osteoclastic resorption.

Explanation

The neurovascular theory postulates that autonomic neuropathy abolishes sympathetic vasoconstriction, causing profound local hyperemia. This increased blood flow triggers active bone resorption, weakening the bone and predisposing the joint to collapse.

Question 6756

Topic: Midfoot & Hindfoot

A diabetic patient presents with a warm, erythematous, and swollen midfoot. Radiographs demonstrate periarticular fragmentation, bony debris, and subluxation at the tarsometatarsal joints, but no signs of coalescence. According to the Eichenholtz classification, what is the stage and best initial management?

. Stage 0; Surgical arthrodesis
. Stage 1; Total contact casting and strict non-weight bearing
. Stage 2; Custom orthotic shoe wear
. Stage 3; Exostectomy
. Stage 4; Below-knee amputation

Correct Answer & Explanation

. Stage 1; Total contact casting and strict non-weight bearing

Explanation

The patient is in Eichenholtz Stage 1 (Developmental/Fragmentation), defined by profound swelling, erythema, bony debris, and subluxation. The standard of care is rigid immobilization with a total contact cast to arrest progression and prevent further deformity.

Question 6757

Topic: Midfoot & Hindfoot

According to the Eichenholtz classification of Charcot arthropathy, which of the following radiographic findings is hallmark for the Coalescence stage (Stage 2)?

. Joint effusion and soft tissue edema without bone changes
. Subchondral fragmentation, debris formation, and joint subluxation
. Absorption of fine debris, early fusion of large fragments, and sclerosis
. Remodeling of bone ends, decreased sclerosis, and stable joint formation
. Frank dislocation without associated fracture or debris

Correct Answer & Explanation

. Absorption of fine debris, early fusion of large fragments, and sclerosis

Explanation

Eichenholtz Stage 2 (Coalescence) is marked by the absorption of fine intra-articular debris, early fusion of larger bone fragments, and increased sclerosis. Stage 1 is characterized by fragmentation, while Stage 3 involves reconstruction and remodeling.

Question 6758

Topic: Midfoot & Hindfoot

A diabetic patient presents with a hot, swollen, erythematous foot without an open ulceration. X-rays show acute periarticular fragmentation at the midfoot. What is the most appropriate initial management?

. Immediate surgical arthrodesis of the midfoot
. Intravenous broad-spectrum antibiotics and I&D
. Total contact casting and strict non-weight bearing
. Below-knee amputation
. Custom orthotic shoe wear and protected weight bearing

Correct Answer & Explanation

. Total contact casting and strict non-weight bearing

Explanation

The patient is in the acute fragmentation stage (Eichenholtz Stage 1) of Charcot arthropathy. The gold standard initial treatment is immediate immobilization with a total contact cast (TCC) and non-weight bearing to prevent further structural collapse.

Question 6759

Topic: 8. Foot and Ankle

In a patient with established Charcot arthropathy of the foot and ankle, which of the following is the most widely accepted indication for surgical reconstruction or arthrodesis?

. Eichenholtz Stage 1 (Acute fragmentation) with significant soft tissue swelling
. A painless, stable, and plantigrade foot
. An unbraceable deformity with recurrent ulceration in Eichenholtz Stage 3
. Prophylaxis in a diabetic patient with severe neuropathy but normal alignment
. First presentation of early midfoot collapse without skin compromise

Correct Answer & Explanation

. An unbraceable deformity with recurrent ulceration in Eichenholtz Stage 3

Explanation

Surgery for Charcot arthropathy is primarily indicated for patients with severe, unstable, or unbraceable deformities that lead to recurrent ulceration. It is typically deferred until the chronic or coalescent stages (Stage 2 or 3) to minimize failure rates.

Question 6760

Topic: 8. Foot and Ankle
A 55-year-old diabetic male presents with a swollen, erythematous, and warm foot without skin ulceration. Radiographs show extensive bone fragmentation, periarticular debris, and joint subluxation. Which stage of the Eichenholtz classification does this represent, and what is the primary initial treatment?
. Stage 0 (Pre-fragmentation); Immediate arthrodesis
. Stage I (Developmental/Fragmentation); Total contact casting and non-weight bearing
. Stage II (Coalescence); Custom orthosis alone
. Stage III (Reconstruction); Charcot restraint orthotic walker (CROW)
. Stage IV; Below-knee amputation

Correct Answer & Explanation

. Stage I (Developmental/Fragmentation); Total contact casting and non-weight bearing

Explanation

Eichenholtz Stage I (Developmental/Fragmentation) is characterized by acute inflammation, osteopenia, bone fragmentation, and subluxation. The mainstay of initial treatment is immobilization and offloading, typically utilizing a total contact cast (TCC).

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