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8. Foot and Ankle MCQs

Practice Set 335 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 6681

Topic: 8. Foot and Ankle

A 58-year-old male with diabetic neuropathy presents with a deformed, painless left foot. He states the foot was swollen and red several months ago but has since cooled down. Current radiographs demonstrate sclerosis, fusion of fragments, and remodeling of the midfoot without active fragmentation. According to the Eichenholtz classification, what stage of Charcot arthropathy does this represent, and what is the appropriate management?

. Stage 0; immediate open reduction and internal fixation
. Stage 1; total contact casting
. Stage 2; custom orthotic shoe wear
. Stage 3; custom orthotic shoe wear or accommodative bracing
. Stage 4; below-knee amputation

Correct Answer & Explanation

. Stage 3; custom orthotic shoe wear or accommodative bracing

Explanation

Correct Answer: DThe Eichenholtz classification of Charcot arthropathy includes Stage 0 (clinical signs of inflammation, normal radiographs), Stage 1 (development/fragmentation: debris, periarticular fragmentation, subluxation), Stage 2 (coalescence: absorption of debris, fusion of fragments, sclerosis), and Stage 3 (reconstruction/consolidation: remodeling, rounded bone ends, decreased sclerosis). The patient's foot is no longer inflamed and shows remodeling and fusion, consistent with Stage 3. Management for Stage 3 typically involves accommodative bracing or custom orthotic shoe wear to prevent ulceration over deformities.

Question 6682

Topic: 8. Foot and Ankle

A 60-year-old diabetic patient presents with a red, hot, swollen foot and a plantar ulcer under the first metatarsal head. Radiographs show osteopenia and periosteal reaction. Which of the following MRI findings is most specific for differentiating osteomyelitis from acute Charcot arthropathy?

. Bone marrow edema in the subchondral bone
. Joint effusion and soft tissue edema
. Diffuse marrow enhancement post-gadolinium
. Replacement of marrow fat with fluid signal on T1-weighted images extending away from the joint
. Subchondral cysts and periarticular fragmentation

Correct Answer & Explanation

. Replacement of marrow fat with fluid signal on T1-weighted images extending away from the joint

Explanation

Correct Answer: DDifferentiating acute Charcot arthropathy from osteomyelitis can be challenging as both present with a red, hot, swollen foot. On MRI, Charcot arthropathy typically shows bone marrow edema that is periarticular (subchondral). Osteomyelitis is characterized by diffuse marrow edema that extends away from the joint, often contiguous with a skin ulcer or sinus tract. A key finding in osteomyelitis is the replacement of normal marrow fat with fluid signal on T1-weighted images (confluent decreased T1 signal) in areas not restricted to the subchondral bone.

Question 6683

Topic: 8. Foot and Ankle
A 55-year-old male with diabetic neuropathy develops a recurrent plantar ulcer under the third metatarsal head despite appropriate offloading with custom orthotics. Physical examination reveals a rigid equinus contracture with inability to dorsiflex the ankle past neutral with the knee extended or flexed. Which of the following surgical interventions is most appropriate to address the underlying biomechanical cause of the recurrent ulcer?
. Flexor tenotomy
. Gastrocnemius recession
. Tendo-Achilles lengthening
. Metatarsal head resection
. Tibialis anterior tendon transfer

Correct Answer & Explanation

. Tendo-Achilles lengthening

Explanation

The patient has a rigid equinus contracture that is present with both knee extension and flexion, indicating tightness of the entire triceps surae complex (both gastrocnemius and soleus). A tendo-Achilles lengthening (TAL) is indicated to correct this. If the equinus were only present with the knee extended (positive Silfverskiöld test), a gastrocnemius recession would be appropriate. Equinus contracture increases forefoot plantar pressures, leading to recurrent ulcers under the metatarsal heads. Correcting the equinus reduces these pressures and aids in ulcer healing.

Question 6684

Topic: 8. Foot and Ankle

A 50-year-old female with diabetes mellitus and loss of protective sensation presents with a non-infected, non-ischemic plantar ulcer under the first metatarsal head. The physician recommends a total contact cast (TCC). What is the primary biomechanical mechanism by which a TCC promotes ulcer healing?

. It increases arterial inflow to the foot by providing a warm environment.
. It transfers weight-bearing forces from the plantar aspect of the foot to the lower leg.
. It immobilizes the ankle to prevent the windlass mechanism and reduces plantar pressures by increasing the weight-bearing surface area.
. It applies direct pressure to the ulcer bed to stimulate granulation tissue formation.
. It corrects underlying bony deformities through continuous dynamic traction.

Correct Answer & Explanation

. It immobilizes the ankle to prevent the windlass mechanism and reduces plantar pressures by increasing the weight-bearing surface area.

Explanation

Correct Answer: CTotal contact casting (TCC) is the gold standard for offloading diabetic plantar foot ulcers. It works by immobilizing the ankle and foot joints, which limits the propulsive phase of gait and prevents the windlass mechanism, thereby reducing forefoot pressures. Additionally, the cast is molded to the contours of the foot, which increases the total weight-bearing surface area, distributing forces more evenly and reducing peak plantar pressures over the ulcer site. It does not transfer significant weight to the lower leg (unlike a patellar tendon-bearing cast).

Question 6685

Topic: Midfoot & Hindfoot

A 59-year-old female with a history of Charcot arthropathy presents with a stable, rigid rocker-bottom deformity of her left foot. She has a recurrent ulcer on the plantar aspect of the midfoot over a bony prominence, despite compliant use of a CROW (Charcot Restraint Orthotic Walker) boot. There are no signs of acute infection. What is the most appropriate surgical management?

. Below-knee amputation
. Exostectomy of the bony prominence
. Arthrodesis of the midfoot
. Application of a circular external fixator
. Split-thickness skin grafting of the ulcer

Correct Answer & Explanation

. Exostectomy of the bony prominence

Explanation

Correct Answer: BIn a patient with a stable, rigid Charcot deformity (Eichenholtz Stage 3) who develops a recurrent ulcer over a bony prominence despite maximal conservative offloading (like a CROW boot), an exostectomy (shaving down the bony prominence) is the most appropriate surgical intervention. Arthrodesis or osteotomy is generally reserved for unstable deformities or when exostectomy is insufficient. Amputation is a last resort for uncontrollable infection or non-reconstructable, non-braceable limbs.

Question 6686

Topic: Midfoot & Hindfoot

A 54-year-old male with a 20-year history of diabetes mellitus is diagnosed with Charcot arthropathy. Which of the following anatomic locations is most frequently affected by Charcot arthropathy in diabetic patients?

. Ankle joint (tibiotalar)
. Hindfoot (subtalar joint)
. Midfoot (tarsometatarsal / Lisfranc joint)
. Forefoot (metatarsophalangeal joints)
. Knee joint

Correct Answer & Explanation

. Midfoot (tarsometatarsal / Lisfranc joint)

Explanation

Correct Answer: CIn diabetic patients, Charcot arthropathy most commonly affects the midfoot, specifically the tarsometatarsal (Lisfranc) and transverse tarsal (Chopart) joints. This often leads to the classic "rocker-bottom" deformity due to collapse of the medial longitudinal arch. While the hindfoot and ankle can also be involved, the midfoot is the most frequent site (up to 60% of cases). The knee is more commonly affected in patients with neurosyphilis (tabes dorsalis), and the shoulder/elbow in patients with syringomyelia.

Question 6687

Topic: 8. Foot and Ankle

A 55-year-old male with a 15-year history of poorly controlled type 2 diabetes mellitus presents for a routine foot examination. The orthopedic surgeon uses a Semmes-Weinstein monofilament to assess for loss of protective sensation. The 5.07 monofilament is utilized. What is the equivalent buckling force of this specific monofilament?

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

Correct Answer & Explanation

. 10 grams

Explanation

Correct Answer: 10 gramsThe 5.07 Semmes-Weinstein monofilament requires exactly 10 grams of linear force to buckle. Inability to perceive this 10g force indicates a loss of protective sensation (LOPS), placing the patient at a significantly increased risk for neuropathic ulceration and Charcot arthropathy. The 4.17 monofilament, which exerts 1 gram of force, is considered the threshold for normal sensation.

Question 6688

Topic: 8. Foot and Ankle

A 62-year-old female with long-standing diabetes mellitus presents with a swollen, warm, and erythematous right foot. She denies any trauma. Pulses are bounding, and the skin is dry and cracked. Radiographs reveal early fragmentation of the tarsometatarsal joints. Which of the following pathophysiologic mechanisms best explains the bounding pulses and warm extremity in this patient?

. Somatic motor neuropathy leading to intrinsic muscle wasting
. Autonomic neuropathy causing loss of sympathetic tone and arteriovenous shunting
. Peripheral arterial disease causing compensatory vasodilation
. Somatic sensory neuropathy leading to repetitive unrecognized microtrauma
. Hyperglycemia-induced endothelial dysfunction and capillary basement membrane thickening

Correct Answer & Explanation

. Autonomic neuropathy causing loss of sympathetic tone and arteriovenous shunting

Explanation

Correct Answer: Autonomic neuropathy causing loss of sympathetic tone and arteriovenous shuntingThe neurovascular theory of Charcot arthropathy suggests that autonomic neuropathy leads to a loss of sympathetic tone. This results in an autosympathectomy, causing vasodilation, arteriovenous shunting, and increased blood flow to the bone. This hyperemic state leads to active bone resorption, osteopenia, and susceptibility to periarticular fracture. The bounding pulses and warm, dry skin are classic clinical signs of autonomic neuropathy in the diabetic foot.

Question 6689

Topic: Midfoot & Hindfoot

A 58-year-old diabetic male presents with a painless, swollen left foot. Radiographs demonstrate extensive periarticular debris, fragmentation of the navicular and cuboid, and subluxation of the midtarsal joint. According to the Eichenholtz classification, what is the most appropriate initial management for this stage of the disease?

. Immediate open reduction and internal fixation
. Total contact casting and non-weight bearing
. Custom orthotic shoe wear
. Midfoot arthrodesis with rigid fixation
. Below-knee amputation

Correct Answer & Explanation

. Total contact casting and non-weight bearing

Explanation

Correct Answer: Total contact casting and non-weight bearingThe patient is in Eichenholtz Stage I (Developmental/Fragmentation stage) of Charcot arthropathy, characterized by joint edema, erythema, periarticular debris, fragmentation, and subluxation. The gold standard for initial management of acute (Stage I) Charcot arthropathy is immobilization and offloading, typically achieved with a total contact cast (TCC). Surgery is generally contraindicated in the acute inflammatory phase due to poor bone quality, active hyperemia, and a high risk of hardware failure, unless there is an impending skin breakdown that cannot be managed conservatively.

Question 6690

Topic: 8. Foot and Ankle

A 60-year-old male with diabetes mellitus and peripheral neuropathy presents with a chronic, non-healing ulcer under the first metatarsal head. He has a loss of protective sensation to the 5.07 Semmes-Weinstein monofilament. Examination reveals a rigid equinus contracture of the ankle. Which of the following interventions is most likely to decrease the plantar forefoot pressures and aid in ulcer healing?

. Flexor tenotomy
. Tibialis anterior tendon transfer
. Tendo-Achilles lengthening
. First metatarsophalangeal joint arthrodesis
. Plantar fascia release

Correct Answer & Explanation

. Tendo-Achilles lengthening

Explanation

Correct Answer: Tendo-Achilles lengtheningAnkle equinus contracture, often due to glycosylation of the Achilles tendon and gastrocnemius-soleus complex in diabetic patients, significantly increases plantar pressures in the forefoot during the stance phase of gait. Tendo-Achilles lengthening (TAL) or gastrocnemius recession is highly effective in reducing forefoot plantar pressures and is frequently utilized as an adjunct to aid in the healing of recalcitrant forefoot neuropathic ulcers.

Question 6691

Topic: 8. Foot and Ankle

A 65-year-old diabetic patient presents with claw toe deformities and prominent metatarsal heads. He has a history of recurrent plantar ulcerations. The claw toe deformity in diabetic patients is primarily driven by which of the following mechanisms?

. Spasticity of the extensor digitorum longus
. Motor neuropathy leading to intrinsic muscle wasting and imbalance
. Contracture of the plantar fascia
. Autonomic neuropathy causing joint capsular laxity
. Ischemic necrosis of the lumbrical muscles

Correct Answer & Explanation

. Motor neuropathy leading to intrinsic muscle wasting and imbalance

Explanation

Correct Answer: Motor neuropathy leading to intrinsic muscle wasting and imbalanceMotor neuropathy in diabetes affects the intrinsic muscles of the foot (lumbricals and interossei) before the extrinsic muscles. The intrinsic muscles normally flex the metatarsophalangeal (MTP) joints and extend the interphalangeal (IP) joints. Their weakness leads to a dynamic imbalance where the extrinsic extensors hyperextend the MTP joints and extrinsic flexors flex the IP joints, resulting in claw toe deformities. This exposes the metatarsal heads to increased plantar pressures, leading to ulceration.

Question 6692

Topic: 8. Foot and Ankle

A 50-year-old male with poorly controlled diabetes presents with a red, hot, swollen left foot. He has a small, superficial ulceration on the plantar aspect of the midfoot. It is difficult to distinguish clinically between an acute Charcot event and osteomyelitis. Which of the following imaging modalities is most specific for differentiating osteomyelitis from acute Charcot arthropathy in the diabetic foot?

. Three-phase technetium-99m bone scan
. Plain radiography
. Indium-111 labeled leukocyte scan combined with technetium-99m sulfur colloid marrow scan
. Computed tomography (CT) scan
. Magnetic resonance imaging (MRI) without contrast

Correct Answer & Explanation

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

Explanation

Correct Answer: Indium-111 labeled leukocyte scan combined with technetium-99m sulfur colloid marrow scanDifferentiating acute Charcot arthropathy from osteomyelitis is challenging because both present with a red, hot, swollen foot and can have similar MRI findings (such as extensive bone marrow edema). The most specific imaging modality for this distinction is a combined Indium-111 labeled white blood cell (WBC) scan and a Technetium-99m sulfur colloid bone marrow scan. In osteomyelitis, the WBC scan is positive, but the marrow scan is negative (discordant). In Charcot arthropathy, both scans show increased uptake (concordant) due to marrow proliferation.

Question 6693

Topic: Midfoot & Hindfoot
A 68-year-old female with a history of Charcot arthropathy presents for a follow-up. Her foot is no longer swollen or erythematous. Radiographs show rounding of bone fragments, sclerosis, and fusion of the tarsometatarsal joints with a stable rocker-bottom deformity. She has no ulcerations. What Eichenholtz stage does this represent, and what is the appropriate management?
. Stage 0; Total contact casting
. Stage I; Surgical reconstruction
. Stage II; Charcot Restraint Orthotic Walker (CROW)
. Stage III; Custom accommodative footwear
. Stage III; Midfoot osteotomy and arthrodesis

Correct Answer & Explanation

. Stage III; Custom accommodative footwear

Explanation

The patient is in Eichenholtz Stage III (Consolidation/Reconstruction). This stage is characterized clinically by the resolution of inflammation and radiographically by bone remodeling, rounding of fragments, sclerosis, and spontaneous arthrodesis. Since she has a stable deformity without ulceration, the appropriate management is accommodation with custom footwear (e.g., extra-depth shoes with custom molded inserts) to prevent future ulceration. Surgery is reserved for unstable deformities or recurrent ulcerations that cannot be managed conservatively.

Question 6694

Topic: 8. Foot and Ankle

A 45-year-old male with newly diagnosed type 2 diabetes presents for a baseline foot evaluation. The physician uses a set of Semmes-Weinstein monofilaments. Which of the following monofilament values represents the threshold for normal 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, which exerts 1 gram of force, is considered the threshold for normal sensation. The 5.07 monofilament (10 grams of force) is the threshold for protective sensation. Inability to feel the 5.07 monofilament indicates a loss of protective sensation (LOPS), which is a critical predictor for the development of diabetic foot ulcers.

Question 6695

Topic: 8. Foot and Ankle

A 55-year-old diabetic female develops acute Charcot arthropathy. According to the Brodsky classification, which of the following anatomic locations is the most common site for Charcot neuroarthropathy in the foot and ankle?

. Ankle joint (Tibiotalar)
. Hindfoot (Subtalar joint)
. Midfoot (Tarsometatarsal and naviculocuneiform joints)
. Forefoot (Metatarsophalangeal joints)
. Calcaneus

Correct Answer & Explanation

. Midfoot (Tarsometatarsal and naviculocuneiform joints)

Explanation

Correct Answer: Midfoot (Tarsometatarsal and naviculocuneiform joints)The midfoot (tarsometatarsal/Lisfranc and naviculocuneiform joints) is the most common site of Charcot arthropathy, accounting for approximately 60% of cases (Brodsky Type 1). The hindfoot (subtalar, talonavicular, calcaneocuboid) accounts for about 30% (Brodsky Type 2). The ankle joint accounts for about 10% (Brodsky Type 3).

Question 6696

Topic: 8. Foot and Ankle
A 60-year-old male with a history of midfoot Charcot arthropathy presents with a recurrent plantar midfoot ulceration. He has been compliant with custom orthotic footwear and total contact casting, but the ulcer recurs shortly after healing due to a severe, rigid rocker-bottom deformity with a prominent cuboid. He is currently in Eichenholtz Stage III. What is the most appropriate definitive management?
. Continued total contact casting indefinitely
. Exostectomy of the prominent cuboid
. Below-knee amputation
. Achilles tendon lengthening alone
. Split-thickness skin grafting of the ulcer

Correct Answer & Explanation

. Exostectomy of the prominent cuboid

Explanation

In a patient with a stable, consolidated Charcot deformity (Eichenholtz Stage III) who develops recurrent ulcerations due to a focal bony prominence (such as the cuboid in a rocker-bottom foot) despite appropriate accommodative footwear, an exostectomy (removal of the bony prominence) is indicated. This directly addresses the mechanical cause of the ulceration without destabilizing the foot, which could occur with more extensive reconstructive procedures. Amputation is reserved for severe, life-threatening infections or unsalvageable limbs.

Question 6697

Topic: 8. Foot and Ankle

A 65-year-old male with a 15-year history of poorly controlled type 2 diabetes mellitus presents for a routine foot examination. The orthopedic surgeon uses a 5.07 Semmes-Weinstein monofilament to assess for loss of protective sensation. Which of the following best describes the physical property of the 5.07 monofilament when applied correctly?

. It delivers exactly 1 gram of linear pressure before buckling.
. It delivers exactly 10 grams of linear pressure before buckling.
. It delivers exactly 5.07 grams of linear pressure before buckling.
. It measures vibratory sensation at 128 Hz.
. It assesses two-point discrimination at 5 mm.

Correct Answer & Explanation

. It delivers exactly 10 grams of linear pressure before buckling.

Explanation

Correct Answer: BThe 5.07 Semmes-Weinstein monofilament is the most reliable screening tool for detecting the loss of protective sensation in diabetic patients. The number '5.07' represents the logarithm of the force (in tenths of a milligram) required to buckle the filament. In practical terms, the 5.07 monofilament is calibrated to deliver exactly 10 grams of linear pressure when applied perpendicular to the skin until it bows. Inability to feel this 10-gram force correlates strongly with a loss of protective sensation, placing the patient at a significantly increased risk for neuropathic ulcerations and Charcot arthropathy.

Question 6698

Topic: 8. Foot and Ankle
A 62-year-old male with diabetic neuropathy presents with a recurrent plantar ulcer under the first metatarsal head despite appropriate offloading footwear. Physical examination reveals a lack of protective sensation. Ankle dorsiflexion is limited to -5 degrees with the knee extended, but improves to 15 degrees of dorsiflexion with the knee flexed. Which of the following surgical interventions is most appropriate to reduce forefoot plantar pressures and aid in ulcer healing?
. First metatarsophalangeal joint arthrodesis
. Tendo-Achilles lengthening
. Gastrocnemius recession
. First metatarsal osteotomy
. Tibialis anterior tendon transfer

Correct Answer & Explanation

. Gastrocnemius recession

Explanation

The patient has a recurrent plantar ulcer associated with an equinus contracture. The Silfverskiöld test is used to differentiate between isolated gastrocnemius tightness and combined gastrocnemius-soleus tightness. In this patient, ankle dorsiflexion improves significantly when the knee is flexed (relaxing the gastrocnemius, which crosses the knee joint), indicating an isolated gastrocnemius contracture. A gastrocnemius recession is the most appropriate surgical intervention. Equinus contractures increase peak plantar pressures in the forefoot, contributing to ulcer formation. Correcting the equinus deformity reduces these pressures and promotes ulcer healing. Tendo-Achilles lengthening would be indicated if dorsiflexion remained restricted with the knee flexed (combined gastroc-soleus contracture).

Question 6699

Topic: 8. Foot and Ankle

A 55-year-old male with diabetes presents with a red, hot, swollen left foot and a plantar ulcer probing to bone. Radiographs show destruction of the cuboid and fourth metatarsal base. Which of the following is considered the gold standard for differentiating acute Charcot arthropathy from osteomyelitis in this patient?

. Three-phase technetium-99m bone scan
. Indium-111 labeled white blood cell scan
. Magnetic resonance imaging (MRI)
. Bone biopsy for histopathology and culture
. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

Correct Answer & Explanation

. Bone biopsy for histopathology and culture

Explanation

Correct Answer: DDifferentiating acute Charcot arthropathy from osteomyelitis can be clinically and radiographically challenging, as both present with a red, hot, swollen foot and bone destruction on plain films. While MRI is highly sensitive and often the advanced imaging modality of choice, the definitive gold standard for diagnosis is a bone biopsy for histopathological examination and microbiological culture. Histopathology in osteomyelitis will show acute/chronic inflammatory cells and necrosis, while Charcot will show bone remodeling, fibrosis, and shards of dead bone without active infection. A positive culture from the bone biopsy confirms osteomyelitis.

Question 6700

Topic: 8. Foot and Ankle

A medical student is instructed to perform a diabetic foot screening using a 5.07 Semmes-Weinstein monofilament. Which of the following describes the correct technique for applying the monofilament to test for protective sensation?

. Stroke the monofilament lightly across the plantar surface from heel to toe.
. Apply the monofilament perpendicular to the skin and apply pressure until it bends, holding for 1-2 seconds.
. Tap the monofilament rapidly against the metatarsal heads to assess for vibratory response.
. Apply the monofilament parallel to the skin surface until the patient reports a sharp sensation.
. Press the monofilament into the skin until the patient reports pain, then immediately release.

Correct Answer & Explanation

. Apply the monofilament perpendicular to the skin and apply pressure until it bends, holding for 1-2 seconds.

Explanation

Correct Answer: BThe correct technique for using the Semmes-Weinstein monofilament involves applying the filament perpendicular to the skin surface. Pressure is applied smoothly until the filament buckles or bends, and this position is held for approximately 1 to 2 seconds before releasing. The patient, whose eyes should be closed, is asked to respond when they feel the touch. The test should be performed at multiple specific sites on the plantar aspect of the foot (e.g., plantar aspects of the 1st, 3rd, and 5th metatarsal heads, and the plantar surfaces of the toes). Stroking or tapping the monofilament does not accurately deliver the calibrated 10 grams of force.

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