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8. Foot and Ankle MCQs

Practice Set 258 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 5141

Topic: 8. Foot and Ankle

A 62-year-old female with diabetes mellitus undergoes routine foot screening. She is unable to feel the 5.07 Semmes-Weinstein monofilament on her bilateral plantar metatarsal heads. She currently has no open ulcerations, erythema, or structural deformities. What is the most appropriate next step in management?

. Total contact casting
. Prescription of custom accommodative footwear and daily foot inspection
. Prophylactic metatarsal head resections
. Achilles tendon lengthening
. Referral for lower extremity arterial bypass

Correct Answer & Explanation

. Prescription of custom accommodative footwear and daily foot inspection

Explanation

Correct Answer: Prescription of custom accommodative footwear and daily foot inspectionIn a patient who has lost protective sensation but has no active ulceration or severe structural deformity (Wagner Grade 0), the standard of care is preventative. This includes patient education, daily foot inspections, and the use of custom accommodative footwear to distribute plantar pressures and prevent the initial breakdown of skin.

Question 5142

Topic: 8. Foot and Ankle

A patient with long-standing diabetes mellitus presents with a swollen, erythematous, and warm foot without any open wounds. Radiographs reveal periarticular debris, fragmentation, and subluxation at the tarsometatarsal joints. Which of the following screening tests would have most likely been abnormal prior to the onset of this condition?

. Ankle-brachial index (ABI)
. 5.07 Semmes-Weinstein monofilament test
. Venous duplex ultrasound
. Electromyography (EMG) of the anterior compartment
. Serum uric acid levels

Correct Answer & Explanation

. 5.07 Semmes-Weinstein monofilament test

Explanation

Correct Answer: 5.07 Semmes-Weinstein monofilament testThe clinical presentation and radiographic findings are classic for acute Charcot arthropathy (neuropathic arthropathy). A prerequisite for the development of Charcot arthropathy is profound peripheral neuropathy with a loss of protective sensation. Therefore, the 5.07 Semmes-Weinstein monofilament test would have been abnormal prior to the onset of the joint destruction.

Question 5143

Topic: 8. Foot and Ankle

The Semmes-Weinstein monofilament test uses different filament thicknesses to evaluate varying degrees of neuropathy. While the 5.07 monofilament tests for protective sensation, which monofilament value is generally accepted as the threshold for normal light touch sensation in the foot?

. 2.83
. 3.61
. 4.17
. 5.07
. 6.10

Correct Answer & Explanation

. 4.17

Explanation

Correct Answer: 4.17The 4.17 Semmes-Weinstein monofilament requires 1 gram of force to buckle and is considered the threshold for normal light touch sensation in the foot. The 5.07 monofilament requires 10 grams of force and represents the threshold for protective sensation. The 6.10 monofilament requires 75 grams of force and indicates a profound loss of sensation.

Question 5144

Topic: 8. Foot and Ankle

While the 5.07 Semmes-Weinstein monofilament evaluates sensory neuropathy, diabetic patients also suffer from motor neuropathy. Which of the following foot deformities is most directly caused by diabetic intrinsic motor neuropathy?

. Hallux valgus
. Pes planovalgus
. Claw toes
. Tailor's bunion
. Plantar fibromatosis

Correct Answer & Explanation

. Claw toes

Explanation

Correct Answer: Claw toesDiabetic motor neuropathy preferentially affects the intrinsic muscles of the foot (lumbricals and interossei) before the extrinsics. This creates an 'intrinsic minus' foot, leading to a muscle imbalance where the long extensors hyperextend the MTP joints and the long flexors flex the IP joints, resulting in claw toe deformities. This deformity increases plantar pressure under the metatarsal heads, further increasing ulcer risk.

Question 5145

Topic: 8. Foot and Ankle

According to the literature regarding current practice patterns in the treatment of the diabetic foot, what is the primary clinical utility of identifying a patient who cannot feel the 5.07 Semmes-Weinstein monofilament?

. It dictates the need for immediate surgical debridement of the foot.
. It identifies patients who require immediate vascular bypass surgery.
. It identifies patients at high risk for developing neuropathic ulcerations and Charcot arthropathy.
. It determines the exact anatomic level of a peripheral nerve compression.
. It confirms the diagnosis of chronic osteomyelitis.

Correct Answer & Explanation

. It identifies patients at high risk for developing neuropathic ulcerations and Charcot arthropathy.

Explanation

Correct Answer: It identifies patients at high risk for developing neuropathic ulcerations and Charcot arthropathy.The primary utility of the 5.07 Semmes-Weinstein monofilament test is risk stratification. As noted by Pinzur et al., the absence of protective foot sensation identifies patients who are at a significantly increased risk for developing neuropathic ulcerations and Charcot arthropathy, allowing clinicians to implement preventative measures such as specialized footwear and rigorous foot care education.

Question 5146

Topic: 8. Foot and Ankle
A 58-year-old diabetic male has a non-healing plantar ulcer. Noninvasive vascular studies show an Ankle-Brachial Index (ABI) of 1.45. Which of the following is the most appropriate next step to assess the vascular supply of the foot?
. Venous duplex ultrasound
. Toe-Brachial Index (TBI)
. Exercise treadmill testing
. Reassurance as an ABI > 1.4 indicates excellent perfusion
. Lower extremity CT angiography

Correct Answer & Explanation

. Toe-Brachial Index (TBI)

Explanation

An ABI > 1.3 is falsely elevated due to medial arterial calcification (Mönckeberg's sclerosis), which is common in diabetics. A Toe-Brachial Index (TBI) or transcutaneous oxygen measurement (TcPO2) is required because digital vessels are typically spared from calcification.

Question 5147

Topic: 8. Foot and Ankle

A diabetic patient presents with bilateral claw toe deformities, characterized by hyperextension at the MTP joints and flexion at the PIP and DIP joints. This deformity most directly results from the neuropathy-induced dysfunction of which of the following?

. Tibialis anterior
. Extensor digitorum longus
. Flexor hallucis longus
. Lumbricals and interossei
. Gastrocnemius-soleus complex

Correct Answer & Explanation

. Lumbricals and interossei

Explanation

Motor neuropathy in diabetes leads to denervation and atrophy of the intrinsic muscles (lumbricals and interossei). This results in an imbalance where the unopposed extrinsic extensors and flexors create claw toe deformities, increasing plantar pressure under the metatarsal heads.

Question 5148

Topic: 8. Foot and Ankle

When evaluating a diabetic foot ulcer for healing potential, transcutaneous oxygen tension (TcPO2) is measured. Which of the following TcPO2 values is generally considered the minimum threshold required to support spontaneous wound healing or amputation site healing?

. 10 mmHg
. 30 mmHg
. 50 mmHg
. 70 mmHg
. 90 mmHg

Correct Answer & Explanation

. 30 mmHg

Explanation

A TcPO2 of >30 mmHg is widely considered the minimum threshold indicative of adequate tissue perfusion for spontaneous wound healing. Values <20-30 mmHg suggest severe ischemia where healing is unlikely without revascularization.

Question 5149

Topic: 8. Foot and Ankle

A 55-year-old poorly controlled diabetic presents with a unilaterally swollen, red, and warm foot. He denies trauma. Radiographs are normal. Infection has been ruled out. What is the most appropriate initial management for this patient?

. Intravenous antibiotics and observation
. Immediate MRI of the foot with contrast
. Total contact casting and non-weight-bearing
. Corticosteroid injection into the midfoot
. Surgical arthrodesis of the midfoot

Correct Answer & Explanation

. Total contact casting and non-weight-bearing

Explanation

The patient is presenting with Eichenholtz stage 0 (acute) Charcot arthropathy. The mainstay of initial treatment is immediate immobilization and offloading, typically with a total contact cast (TCC), to prevent progressive bone destruction and deformity.

Question 5150

Topic: Midfoot & Hindfoot

In patients developing Charcot neuroarthropathy of the foot, which of the following anatomic locations is the most commonly affected (Brodsky Type 1)?

. Ankle joint
. Subtalar joint
. Tarsometatarsal (Lisfranc) joint
. Metatarsophalangeal joints
. Talonavicular joint

Correct Answer & Explanation

. Tarsometatarsal (Lisfranc) joint

Explanation

Brodsky Type 1 Charcot arthropathy involves the tarsometatarsal (Lisfranc) and naviculocuneiform joints and is the most common anatomic pattern, occurring in approximately 60% of cases. It typically leads to midfoot collapse and a rocker-bottom deformity.

Question 5151

Topic: 8. Foot and Ankle

A 48-year-old patient with type 1 diabetes is found to have profound peripheral neuropathy on examination but has no history of foot ulcers or noticeable foot deformities. According to standard diabetic foot guidelines (e.g., IWGDF), how often should this patient undergo comprehensive foot screening?

. Every 1-3 months
. Every 3-6 months
. Every 6-12 months
. Every 2 years
. Every 5 years

Correct Answer & Explanation

. Every 6-12 months

Explanation

According to the International Working Group on the Diabetic Foot (IWGDF), a patient with loss of protective sensation (neuropathy) but no peripheral arterial disease, deformity, or prior ulcer is classified as Risk Category 1. They should undergo screening every 6-12 months.

Question 5152

Topic: 8. Foot and Ankle
A 50-year-old diabetic patient presents with a swollen, deformed foot. Radiographs reveal prominent periarticular fragmentation, subluxation of the midfoot joints, and significant bony debris. According to the Eichenholtz classification, what stage of Charcot neuroarthropathy does this represent?
. Stage 0 (Acute/Inflammatory)
. Stage I (Developmental/Fragmentation)
. Stage II (Coalescence)
. Stage III (Reconstruction/Consolidation)
. Stage IV (Ulceration)

Correct Answer & Explanation

. Stage I (Developmental/Fragmentation)

Explanation

Eichenholtz Stage I is the developmental or fragmentation stage, characterized radiographically by osteopenia, periarticular fragmentation, subluxation/dislocation, and bony debris. Stage II involves early healing/sclerosis, and Stage III shows mature consolidation.

Question 5153

Topic: Midfoot & Hindfoot

Total Contact Casting (TCC) is a highly effective method for offloading plantar diabetic neuropathic ulcers. Which of the following is considered an absolute contraindication to the use of a TCC?

. Wagner Grade 1 ulcer
. Deep infection or active osteomyelitis
. History of a previous successfully treated ulcer
. Charcot arthropathy in Eichenholtz Stage I
. Bilateral sensory neuropathy

Correct Answer & Explanation

. Deep infection or active osteomyelitis

Explanation

Total Contact Casting is contraindicated in the presence of active deep infection, abscess, untreated osteomyelitis, or severe peripheral arterial disease. Casting an infected foot can lead to rapid, undetected progression of the infection and potential limb loss.

Question 5154

Topic: 8. Foot and Ankle
A diabetic patient has a recurrent, recalcitrant neuropathic ulcer located plantar to the first metatarsal head. Clinical examination reveals significant limitation in ankle dorsiflexion with the knee extended, which improves when the knee is flexed. What surgical intervention is most likely to reduce the recurrence of this forefoot ulcer?
. Anterior tibial tendon transfer
. First metatarsophalangeal joint arthrodesis
. Percutaneous Achilles tendon lengthening
. Plantar fascia release
. Amputation of the first ray

Correct Answer & Explanation

. Percutaneous Achilles tendon lengthening

Explanation

The clinical exam indicates a gastrocnemius contracture (positive Silfverskiöld test), leading to equinus and increased forefoot pressures during the stance phase of gait. Percutaneous Achilles tendon lengthening decreases forefoot loading and significantly reduces ulcer recurrence.

Question 5155

Topic: 8. Foot and Ankle

A 65-year-old male with long-standing type 2 diabetes presents with progressive bilateral claw toe deformities and thick calluses under the metatarsal heads. Which specific neurologic deficit is the primary driver of this structural deformity?

. Loss of protective sensation via large myelinated fibers
. Loss of sympathetic vasomotor control
. Motor neuropathy causing intrinsic muscle wasting
. Small-fiber neuropathy affecting pain and temperature
. Proximal demyelination of the posterior tibial nerve

Correct Answer & Explanation

. Motor neuropathy causing intrinsic muscle wasting

Explanation

Motor neuropathy in diabetes selectively affects the intrinsic muscles of the foot, leading to an intrinsic-minus foot. This imbalance causes claw toe deformities, distal migration of the plantar fat pad, and increased peak plantar pressures under the metatarsal heads.

Question 5156

Topic: 8. Foot and Ankle

A 70-year-old diabetic female presents with a non-healing neuropathic ulcer on her right hallux. Her initial ankle-brachial index (ABI) is measured at 1.45. What is the most appropriate next step to accurately assess the arterial perfusion of her foot?

. Initiate immediate hyperbaric oxygen therapy
. Measure the toe-brachial index (TBI)
. Perform a transfemoral diagnostic angiogram
. Proceed with a primary Syme amputation
. Repeat the ABI measurement with a higher pressure cuff

Correct Answer & Explanation

. Measure the toe-brachial index (TBI)

Explanation

An ABI greater than 1.3 is falsely elevated due to medial arterial calcification (Monckeberg sclerosis), which is highly prevalent in the diabetic population. Digital arteries are typically spared from this calcification, making the toe-brachial index (TBI) a much more reliable measure of distal perfusion.

Question 5157

Topic: 8. Foot and Ankle

When evaluating a diabetic patient for a transmetatarsal amputation due to a chronic ulcer, transcutaneous oxygen tension (TcPO2) mapping is utilized. What minimum TcPO2 level is generally required to predict successful primary wound healing?

. 10 mmHg
. 20 mmHg
. 30 mmHg
. 60 mmHg
. 90 mmHg

Correct Answer & Explanation

. 30 mmHg

Explanation

A TcPO2 level of at least 30 to 40 mmHg is necessary for normal wound healing in a diabetic foot amputation or ulcer. Levels below 20 mmHg are strongly associated with wound failure and indicate a need for revascularization or a higher amputation level.

Question 5158

Topic: 8. Foot and Ankle

A biothesiometer is often used to quantitatively assess large-fiber sensory neuropathy. A vibration perception threshold (VPT) greater than what value is an independent predictor of high risk for diabetic foot ulceration?

. 10 Volts
. 15 Volts
. 25 Volts
. 40 Volts
. 50 Volts

Correct Answer & Explanation

. 25 Volts

Explanation

A Vibration Perception Threshold (VPT) greater than 25 Volts measured with a biothesiometer indicates a severe loss of large-fiber nerve function. It is a well-established, highly predictive threshold for the development of future neuropathic foot ulcers.

Question 5159

Topic: 8. Foot and Ankle

According to the International Working Group on the Diabetic Foot (IWGDF) risk stratification, a patient exhibiting a loss of protective sensation (LOPS) and a clinically significant foot deformity, but no history of ulceration or amputation, falls into which risk category?

. Risk Category 0
. Risk Category 1
. Risk Category 2
. Risk Category 3
. Risk Category 4

Correct Answer & Explanation

. Risk Category 2

Explanation

The IWGDF classifies LOPS with foot deformity (or peripheral arterial disease) but no previous ulcer as Risk Category 2. These patients require prophylactic orthotic footwear and clinical screening every 3 to 6 months.

Question 5160

Topic: 8. Foot and Ankle

A 55-year-old diabetic male presents with an erythematous, warm, and swollen left foot without skin ulceration. Radiographs show periarticular fragmentation, debris, and subluxation at the tarsometatarsal joints. What is the most appropriate immediate management?

. Intravenous antibiotics and surgical debridement
. Total contact casting and strict non-weight-bearing
. Immediate open reduction and internal fixation of the midfoot
. Prescription of a custom-molded accommodative shoe
. Below-knee amputation

Correct Answer & Explanation

. Total contact casting and strict non-weight-bearing

Explanation

This presentation is classic for Eichenholtz Stage I (Developmental) acute Charcot neuroarthropathy. The gold standard for initial treatment is strict offloading and immobilization, typically via a total contact cast (TCC), to halt disease progression and prevent further severe deformity.

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