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8. Foot and Ankle MCQs

Practice Set 336 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 6701

Topic: 8. Foot and Ankle

A 70-year-old diabetic patient presents with bilateral claw toe deformities and prominent metatarsal heads. The patient has a history of recurrent plantar ulcerations. These deformities are primarily a result of diabetic motor neuropathy affecting which of the following nerve/muscle groups?

. Loss of innervation to the tibialis anterior
. Loss of innervation to the intrinsic foot musculature
. Hyperactivity of the gastrocnemius-soleus complex
. Loss of innervation to the extensor digitorum longus
. Spasticity of the flexor digitorum longus

Correct Answer & Explanation

. Loss of innervation to the intrinsic foot musculature

Explanation

Correct Answer: BDiabetic motor neuropathy frequently affects the distal nerves first, leading to denervation and atrophy of the intrinsic foot musculature (lumbricals and interossei). The intrinsic muscles normally function to flex the metatarsophalangeal (MTP) joints and extend the interphalangeal (IP) joints. When they are weakened, the extrinsic muscles (extensor digitorum longus and flexor digitorum longus) overpower them, resulting in an 'intrinsic minus' foot. This manifests as claw toe deformities (hyperextension of the MTP joints and flexion of the IP joints). The hyperextension of the MTP joints drives the metatarsal heads plantarward, making them prominent and highly susceptible to high peak pressures and subsequent neuropathic ulceration.

Question 6702

Topic: 8. Foot and Ankle

A 60-year-old male with diabetes is diagnosed with Eichenholtz stage I Charcot arthropathy of the midfoot. The decision is made to treat the patient with a total contact cast (TCC). Which of the following best describes the primary biomechanical mechanism by which a TCC promotes healing and prevents further deformity?

. It rigidly immobilizes the ankle to prevent any weight-bearing on the affected extremity.
. It transfers weight-bearing forces from the foot to the proximal lower leg.
. It increases the surface area of contact, thereby reducing peak plantar pressures.
. It applies continuous compression to reduce autonomic hyperemia.
. It holds the foot in maximum dorsiflexion to stretch the Achilles tendon.

Correct Answer & Explanation

. It increases the surface area of contact, thereby reducing peak plantar pressures.

Explanation

Correct Answer: CThe total contact cast (TCC) is the gold standard for the non-operative management of acute Charcot arthropathy and plantar neuropathic ulcers. The primary biomechanical mechanism of the TCC is to distribute weight-bearing forces over the largest possible surface area of the foot and lower leg. By increasing the contact area, the TCC significantly reduces peak plantar pressures at specific high-risk sites (such as prominent metatarsal heads or the midfoot). While it does transfer some load to the lower leg (approximately 30%), its main efficacy comes from pressure offloading via increased surface area contact. It also enforces patient compliance by being non-removable.

Question 6703

Topic: 8. Foot and Ankle
A 62-year-old male with diabetic neuropathy presents with a deformed, painless right foot. She states the foot was swollen and red several months ago but has since resolved. Radiographs demonstrate sclerosis, fusion of the tarsometatarsal joints, and absence of acute fragmentation or joint subluxation. According to the Eichenholtz classification, what stage of Charcot arthropathy does this represent?
. Stage 0
. Stage I
. Stage II
. Stage III
. Stage IV

Correct Answer & Explanation

. Stage III

Explanation

The Eichenholtz classification describes the natural history of Charcot arthropathy. Stage 0 (added later by Shibata et al.) is the prodromal stage with erythema and edema but normal radiographs. Stage I (Development/Fragmentation) is characterized by acute inflammation, joint subluxation, debris formation, and bone fragmentation. Stage II (Coalescence) shows decreased inflammation, absorption of fine debris, and early healing/fusion of fragments. Stage III (Consolidation/Reconstruction) is the chronic phase where inflammation has resolved, and radiographs show osteosclerosis, remodeling, and solid bony fusion (arthrodesis) of the involved joints. This patient's presentation of a painless, non-inflamed foot with radiographic sclerosis and fusion is classic for Stage III.

Question 6704

Topic: 8. Foot and Ankle

A 68-year-old male with a 20-year history of diabetes mellitus and documented loss of protective sensation presents for evaluation. He is found to have a full-thickness neuropathic ulcer. Based on the altered biomechanics and typical foot deformities associated with diabetic neuropathy, what is the most common anatomical location for this type of ulceration?

. Plantar aspect of the heel
. Dorsum of the proximal interphalangeal joints
. Plantar aspect of the metatarsal heads
. Medial aspect of the first metatarsal head
. Lateral aspect of the fifth metatarsal base

Correct Answer & Explanation

. Plantar aspect of the metatarsal heads

Explanation

Correct Answer: CNeuropathic ulcers in diabetic patients most commonly occur on the plantar aspect of the metatarsal heads, particularly the first and third metatarsal heads. This is due to a combination of factors: motor neuropathy leading to intrinsic muscle wasting and claw toe deformities (which drive the metatarsal heads plantarward), and equinus contractures (which increase forefoot loading during the stance phase of gait). The loss of protective sensation (sensory neuropathy) allows repetitive microtrauma at these high-pressure areas to go unnoticed, eventually leading to skin breakdown and ulceration.

Question 6705

Topic: 8. Foot and Ankle

A 59-year-old male with poorly controlled diabetes mellitus presents with a swollen, warm right foot. He has bounding pedal pulses and dry, cracked skin on the plantar aspect of his feet. Which of the following best explains the presence of dry, cracked skin and bounding pulses in this patient?

. Somatic sensory neuropathy
. Somatic motor neuropathy
. Autonomic neuropathy
. Peripheral arterial disease
. Venous insufficiency

Correct Answer & Explanation

. Autonomic neuropathy

Explanation

Correct Answer: CDiabetic neuropathy affects sensory, motor, and autonomic nerves. Autonomic neuropathy leads to a loss of sympathetic tone in the lower extremities. This causes two primary clinical findings: 1) Decreased function of sweat and sebaceous glands, resulting in dry, scaly, and cracked skin (anhidrosis), which can serve as a portal of entry for infection. 2) Arteriovenous shunting and loss of vascular autoregulation, leading to a hyperemic state characterized by a warm foot and bounding pedal pulses. Somatic sensory neuropathy causes loss of protective sensation, while somatic motor neuropathy causes intrinsic muscle wasting and deformities.

Question 6706

Topic: 8. Foot and Ankle

A 62-year-old male with a 15-year history of poorly controlled type 2 diabetes presents for a routine foot examination. The physician uses a 5.07 Semmes-Weinstein monofilament to assess protective sensation. What is the specific bending force exerted by this monofilament when applied correctly?

. 1 gram
. 4 grams
. 10 grams
. 75 grams
. 100 grams

Correct Answer & Explanation

. 10 grams

Explanation

Correct Answer: C (10 grams)The 5.07 Semmes-Weinstein monofilament is the gold standard screening tool for assessing the loss of protective sensation in diabetic patients. When applied perpendicular to the skin until it buckles, the 5.07 monofilament delivers exactly 10 grams of linear pressure. The inability of a patient to perceive this 10-gram force indicates a loss of protective sensation, which places them at a significantly increased risk for developing neuropathic ulcerations and Charcot arthropathy. For reference, a 4.56 monofilament exerts 4 grams of force and is used to test for normal sensation.

Question 6707

Topic: Midfoot & Hindfoot

A 58-year-old female with diabetes mellitus is found to have absent sensation to the 5.07 Semmes-Weinstein monofilament on the plantar aspect of her feet. She is currently asymptomatic with intact skin. Based on this specific sensory deficit, which of the following conditions is she at the highest immediate risk of developing?

. Ischemic rest pain
. Neuropathic ulceration
. Deep vein thrombosis
. Plantar fasciitis
. Tarsal tunnel syndrome

Correct Answer & Explanation

. Neuropathic ulceration

Explanation

Correct Answer: B (Neuropathic ulceration)The primary clinical consequence of losing protective sensation (indicated by the inability to feel the 5.07 monofilament) is the inability to perceive repetitive microtrauma or excessive pressure. This sensory deficit is the most critical risk factor for the development of neuropathic ulcerations. Without the feedback of pain, patients continue to walk on areas of high pressure, leading to tissue breakdown. While diabetic patients are also at risk for vascular disease (ischemic rest pain), the specific finding of an absent 5.07 monofilament test directly correlates with neuropathic complications, including ulcers and Charcot arthropathy.

Question 6708

Topic: 8. Foot and Ankle

A 65-year-old diabetic patient with loss of protective sensation presents with new-onset foot deformities characterized by hyperextension at the metatarsophalangeal (MTP) joints and flexion at the interphalangeal (IP) joints. This deformity increases plantar pressure under the metatarsal heads. Which of the following is the primary pathophysiologic cause of this specific deformity?

. Autonomic neuropathy causing arteriovenous shunting
. Motor neuropathy leading to intrinsic muscle wasting
. Sensory neuropathy causing unrecognized microtrauma
. Ischemic necrosis of the plantar fascia
. Contracture of the Achilles tendon

Correct Answer & Explanation

. Motor neuropathy leading to intrinsic muscle wasting

Explanation

Correct Answer: B (Motor neuropathy leading to intrinsic muscle wasting)Diabetic peripheral neuropathy affects sensory, motor, and autonomic nerve fibers. Motor neuropathy specifically leads to denervation and wasting of the intrinsic muscles of the foot (the lumbricals and interossei). Because the intrinsic muscles normally flex the MTP joints and extend the IP joints, their weakness creates a severe muscle imbalance. The strong, unopposed extrinsic muscles (extensor digitorum longus and flexor digitorum longus) take over, resulting in a "claw toe" deformity (MTP hyperextension and IP flexion). This intrinsic-minus posture drives the metatarsal heads plantarward, drastically increasing local peak plantar pressures and predisposing the patient to ulceration.

Question 6709

Topic: 8. Foot and Ankle

During a diabetic foot evaluation, a patient is noted to have warm, dry, and scaly skin with bounding pedal pulses, despite a history of peripheral neuropathy. Loss of protective sensation is confirmed with a 5.07 monofilament. The skin changes and bounding pulses are most directly attributed to which of the following?

. Somatic motor neuropathy
. Large fiber sensory neuropathy
. Small fiber sensory neuropathy
. Autonomic neuropathy
. Peripheral arterial disease

Correct Answer & Explanation

. Autonomic neuropathy

Explanation

Correct Answer: D (Autonomic neuropathy)Autonomic neuropathy in diabetic patients results in a loss of sympathetic nervous system tone. This has two major effects on the foot. First, it causes sudomotor dysfunction (loss of sweating), which leads to dry, scaly, and cracked skin that can serve as a portal of entry for bacteria. Second, the loss of sympathetic vascular tone causes arteriovenous (AV) shunting. Blood bypasses the capillary beds, leading to a warm foot with bounding pulses, even though there may be tissue-level ischemia. This hyperemic state is also a key component of the neurovascular theory of Charcot arthropathy.

Question 6710

Topic: 8. Foot and Ankle

A 55-year-old male with long-standing diabetes and absent protective sensation presents with a swollen, erythematous, and warm right foot. Radiographs reveal periarticular fragmentation and subluxation at the tarsometatarsal joints. The "neurovascular theory" for the pathogenesis of this condition suggests that bone destruction is primarily driven by:

. Repeated unrecognized mechanical trauma
. Autonomic neuropathy leading to hyperemia and active bone resorption
. Ischemic necrosis from microvascular disease
. Direct bacterial invasion of the joint space
. Glycosylation of type I collagen in the ligaments

Correct Answer & Explanation

. Autonomic neuropathy leading to hyperemia and active bone resorption

Explanation

Correct Answer: B (Autonomic neuropathy leading to hyperemia and active bone resorption)The pathogenesis of Charcot arthropathy (neuropathic arthropathy) is classically described by two complementary theories. The neurotraumatic theory posits that a loss of protective sensation allows for repetitive, unrecognized microtrauma that mechanically destroys the joint. The neurovascular theory, on the other hand, suggests that autonomic neuropathy leads to a loss of sympathetic tone, resulting in arteriovenous shunting and localized hyperemia. This increased, bounding blood flow stimulates osteoclastic activity, leading to active bone resorption, osteopenia, and subsequent structural failure of the bones and joints.

Question 6711

Topic: 8. Foot and Ankle

A 60-year-old female with diabetes mellitus and loss of protective sensation presents with a unilateral, warm, swollen, and erythematous foot. There are no open wounds or ulcers. Radiographs show early fragmentation of the navicular and medial cuneiform. Laboratory markers (WBC, ESR, CRP) are within normal limits. What is the most appropriate initial management?

. Intravenous antibiotics and bone biopsy
. Open reduction and internal fixation of the midfoot
. Total contact casting and non-weight bearing
. Custom orthotic shoe wear and weight-bearing as tolerated
. Below-knee amputation

Correct Answer & Explanation

. Total contact casting and non-weight bearing

Explanation

Correct Answer: C (Total contact casting and non-weight bearing)This patient is presenting with acute Charcot arthropathy (Eichenholtz stage 0 or I), characterized by a red, hot, swollen foot with early radiographic changes but no signs of systemic infection or open wounds. The gold standard for the initial management of acute Charcot foot is immediate immobilization and offloading, which is most effectively achieved with a total contact cast (TCC). TCC helps to reduce edema, distribute plantar pressures evenly, and prevent further mechanical destruction of the osteopenic bone. Surgical intervention (ORIF) is generally contraindicated in the acute, inflammatory phase due to the poor quality of the hyperemic bone and the high risk of hardware failure and infection.

Question 6712

Topic: 8. Foot and Ankle

A 68-year-old diabetic patient with a history of a recently healed plantar ulcer presents with a swollen, red, and warm foot. The 5.07 monofilament test is negative. Plain radiographs show osteopenia and cortical irregularity of the first metatarsal head. Which of the following imaging modalities is most sensitive and specific for differentiating acute neuropathic arthropathy from osteomyelitis in this setting?

. Three-phase technetium-99m bone scan
. Indium-111 labeled leukocyte scan combined with technetium-99m sulfur colloid marrow scan
. Computed tomography (CT) scan
. Ultrasound of the foot
. Plain radiography with weight-bearing views

Correct Answer & Explanation

. Indium-111 labeled leukocyte scan combined with technetium-99m sulfur colloid marrow scan

Explanation

Correct Answer: B (Indium-111 labeled leukocyte scan combined with technetium-99m sulfur colloid marrow scan)Differentiating acute Charcot arthropathy from osteomyelitis is a common clinical challenge, as both present with a red, hot, swollen foot and similar plain radiographic findings (osteopenia, bone destruction). While MRI is frequently used as a first-line advanced imaging modality, the most specific test to differentiate the two is a combined labeled leukocyte (WBC) scan and a bone marrow scan. In osteomyelitis, the WBC scan is positive (indicating infection) while the marrow scan is negative (as normal marrow is replaced by infection). In Charcot arthropathy, the rapid bone turnover and marrow proliferation cause both the WBC scan and the marrow scan to be positive in the exact same spatial distribution.

Question 6713

Topic: 8. Foot and Ankle
A 50-year-old diabetic male with a history of recurrent plantar ulcerations under the 3rd metatarsal head is evaluated. He has absent protective sensation. Physical examination reveals an inability to dorsiflex the ankle past neutral with the knee extended, but dorsiflexion improves to 10 degrees with the knee flexed. Which of the following surgical interventions is most appropriate to reduce forefoot plantar pressures and aid in ulcer healing?
. Tibialis anterior tendon transfer
. Gastrocnemius recession
. Metatarsal head resection
. First metatarsophalangeal joint arthrodesis
. Plantar fascia release

Correct Answer & Explanation

. Gastrocnemius recession

Explanation

The patient's physical exam demonstrates a positive Silfverskiรถld test, indicating an isolated gastrocnemius contracture (equinus contracture). Equinus contracture is a major biomechanical deforming force in the diabetic foot; it prevents normal ankle dorsiflexion during the stance phase of gait, thereby drastically increasing peak plantar pressures under the forefoot (metatarsal heads). Performing a gastrocnemius recession (e.g., Strayer or Baumann procedure) effectively restores ankle dorsiflexion, unloads the forefoot, and is highly successful in promoting the healing of recalcitrant forefoot ulcers and preventing their recurrence.

Question 6714

Topic: 8. Foot and Ankle

A 59-year-old male with a 20-year history of diabetes mellitus lacks protective sensation to the 5.07 monofilament. He presents with a chronic, non-healing ulcer on his foot. Given his neuropathy and typical altered foot biomechanics, what is the most common anatomical location for a neuropathic ulcer to develop in this patient population?

. Plantar aspect of the heel
. Dorsum of the proximal interphalangeal joints
. Plantar aspect of the metatarsal heads
. Medial malleolus
. Lateral border of the fifth metatarsal

Correct Answer & Explanation

. Plantar aspect of the metatarsal heads

Explanation

Correct Answer: C (Plantar aspect of the metatarsal heads)The most common location for neuropathic ulcers in the diabetic foot is the plantar aspect of the metatarsal heads. This predilection is due to a combination of factors: sensory neuropathy (loss of protective sensation), motor neuropathy (leading to intrinsic muscle wasting, claw toe deformity, and plantarflexion of the metatarsal heads), and biomechanical abnormalities (such as equinus contracture). Together, these factors concentrate peak plantar pressures directly under the metatarsal heads during the propulsive phase of gait, leading to repetitive microtrauma, callus formation, and eventual tissue breakdown and ulceration.

Question 6715

Topic: 8. Foot and Ankle

A 62-year-old male with a 15-year history of poorly controlled type 2 diabetes mellitus presents for a routine foot examination. The physician uses a 5.07 Semmes-Weinstein monofilament to test for loss of protective sensation. What is the specific buckling force of this monofilament?

. 1 gram
. 5 grams
. 10 grams
. 25 grams
. 75 grams

Correct Answer & Explanation

. 10 grams

Explanation

Correct Answer: CThe 5.07 Semmes-Weinstein monofilament is the gold standard screening tool for detecting loss of protective sensation (LOPS) in diabetic patients. It is precisely calibrated to buckle when exactly 10 grams of linear pressure is applied. Inability to perceive this 10-gram force indicates that the patient has lost protective sensation, placing them at a significantly increased risk for unrecognized microtrauma, neuropathic ulceration, and subsequent Charcot arthropathy. The other gram forces listed do not correspond to the 5.07 monofilament used for this specific clinical threshold.

Question 6716

Topic: 8. Foot and Ankle

A 58-year-old female with long-standing diabetes mellitus presents with recurrent plantar ulcerations under the first metatarsal head. Examination reveals clawing of the lesser toes and a plantarflexed first ray. Which of the following best explains the biomechanical cause of her toe deformities?

. Loss of protective sensation from sensory neuropathy
. Intrinsic muscle wasting due to motor neuropathy
. Arteriovenous shunting from autonomic neuropathy
. Ischemic contracture of the flexor digitorum longus
. Rupture of the plantar plate

Correct Answer & Explanation

. Intrinsic muscle wasting due to motor neuropathy

Explanation

Correct Answer: BDiabetic neuropathy affects sensory, motor, and autonomic nerves. Motor neuropathy preferentially affects the intrinsic muscles of the foot (lumbricals and interossei). This leads to an 'intrinsic-minus' foot, creating a severe muscle imbalance where the extrinsic muscles (long flexors and extensors) overpower the weakened intrinsics. This results in claw toe deformities characterized by metatarsophalangeal (MTP) joint hyperextension and interphalangeal (IP) joint flexion. This deformity drives the metatarsal heads plantarward, increasing focal plantar pressure and leading to ulceration. Sensory neuropathy causes the lack of pain, but motor neuropathy causes the structural deformity.

Question 6717

Topic: 8. Foot and Ankle

A 65-year-old diabetic patient presents with a swollen, warm, and erythematous right foot. He denies any trauma. Pedal pulses are bounding, and the skin is dry and scaly. Radiographs show early fragmentation of the tarsometatarsal joints. The dry, scaly skin and bounding pulses are primarily a result of which of the following?

. Sensory neuropathy
. Motor neuropathy
. Autonomic neuropathy
. Peripheral arterial disease
. Venous insufficiency

Correct Answer & Explanation

. Autonomic neuropathy

Explanation

Correct Answer: CAutonomic neuropathy in diabetes leads to a loss of sympathetic tone in the lower extremities. This has two major consequences: 1) Anhidrosis (decreased sweating), which leads to dry, scaly skin that is prone to cracking and secondary infection. 2) Arteriovenous shunting, which leads to bounding pulses and increased local blood flow (hyperemia). This hyperemia increases osteoclastic activity, contributing to the osteopenia and bone resorption seen in the early stages of Charcot arthropathy. Sensory neuropathy leads to loss of protective sensation, while motor neuropathy leads to structural deformities.

Question 6718

Topic: Midfoot & Hindfoot
A 55-year-old male with diabetes mellitus and loss of protective sensation presents with a unilateral, warm, swollen, and erythematous foot. Radiographs demonstrate periarticular osteopenia and early subluxation at the Lisfranc joint without an open ulcer. What is the most appropriate initial management?
. Intravenous antibiotics and surgical debridement
. Total contact casting and non-weight bearing
. Arthrodesis of the tarsometatarsal joints
. Custom orthotic shoe wear
. Open reduction and internal fixation

Correct Answer & Explanation

. Total contact casting and non-weight bearing

Explanation

The patient is presenting with acute Eichenholtz stage I (developmental/fragmentation) Charcot arthropathy. The clinical presentation of a red, hot, swollen foot in a diabetic patient without an ulcer is Charcot arthropathy until proven otherwise. The mainstay of treatment for the acute inflammatory phase is strict immobilization and offloading, which is most effectively achieved with a total contact cast (TCC). Surgery (arthrodesis or ORIF) is generally contraindicated in the acute inflammatory phase due to severe osteopenia, poor bone quality, and a high risk of hardware failure and infection. Custom orthotics are used for maintenance after the acute phase has resolved (Stage III).

Question 6719

Topic: Midfoot & Hindfoot

A 60-year-old male with diabetes mellitus is evaluated in the clinic. He is found to have an inability to perceive the 5.07 Semmes-Weinstein monofilament on the plantar aspect of his foot. According to the literature, this specific physical examination finding most directly predicts an increased risk for which of the following?

. Peripheral arterial disease
. Deep vein thrombosis
. Neuropathic ulceration
. Squamous cell carcinoma
. Plantar fasciitis

Correct Answer & Explanation

. Neuropathic ulceration

Explanation

Correct Answer: CThe inability to feel the 5.07 (10-gram) Semmes-Weinstein monofilament indicates a loss of protective sensation (LOPS). Patients with LOPS are at a significantly increased risk for developing neuropathic ulcerations and Charcot arthropathy. Because they cannot perceive repetitive microtrauma, excessive pressure from tight shoes, or foreign bodies, they sustain continuous damage to the skin and soft tissues, eventually leading to breakdown and ulceration. It does not directly predict peripheral arterial disease, DVT, or malignancy.

Question 6720

Topic: Midfoot & Hindfoot
A 59-year-old female with diabetic neuropathy presents with a deformed midfoot. She states her foot was swollen and red several months ago but is now painless and no longer swollen. Radiographs reveal sclerosis, osteophyte formation, and fusion of the tarsometatarsal joints. Which Eichenholtz stage does this represent?
. Stage 0
. Stage I
. Stage II
. Stage III
. Stage IV

Correct Answer & Explanation

. Stage III

Explanation

The Eichenholtz classification describes the natural history of Charcot arthropathy. Stage 0 is the prodromal phase (warm, swollen foot with normal radiographs). Stage I is the developmental/fragmentation phase (joint subluxation, bony debris, fragmentation). Stage II is the coalescence phase (absorption of fine debris, early fusion). Stage III is the reconstruction/consolidation phase, characterized by the resolution of osteopenia, sclerosis, osteophyte formation, and a stable (though often deformed) joint. This patient's clinical and radiographic findings are classic for Stage III.

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