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1. General Principles & Basic Science MCQs

Practice Set 466 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 9301

Topic: 1. General Principles & Basic Science

To accurately assess protective sensation using the 5.07 Semmes-Weinstein monofilament in a diabetic patient, what is the correct technique for application?

. Dragging the monofilament across the plantar skin
. Applying the monofilament perpendicular to the skin until it buckles
. Tapping the monofilament rapidly against the medial malleolus
. Pressing the monofilament parallel to the skin
. Puncturing the epidermis slightly

Correct Answer & Explanation

. Applying the monofilament perpendicular to the skin until it buckles

Explanation

Correct Answer: Applying the monofilament perpendicular to the skin until it bucklesThe proper technique for using the Semmes-Weinstein monofilament involves applying it perpendicular to the skin surface and applying just enough pressure to cause the filament to buckle or bend. This ensures that exactly 10 grams of force (for the 5.07 monofilament) is applied to test for protective sensation.

Question 9302

Topic: Biology, Genetics & Bone Healing

During a clinical examination of a diabetic foot, a physician utilizes a 5.07 Semmes-Weinstein monofilament. The patient's inability to perceive this monofilament indicates a loss of protective sensation. Which of the following pathophysiologic mechanisms is most directly responsible for the subsequent development of plantar neuropathic ulcerations in these patients?

. Macrovascular arterial insufficiency
. Venous valvular incompetence
. Repetitive unrecognized mechanical stress
. Autoimmune destruction of the dermal-epidermal junction
. Hyperproliferation of the stratum corneum due to advanced glycation end-products

Correct Answer & Explanation

. Repetitive unrecognized mechanical stress

Explanation

Correct Answer: Repetitive unrecognized mechanical stressNeuropathic ulcerations in diabetic patients primarily occur due to repetitive unrecognized mechanical stress (shear and pressure forces) during ambulation. Because the patient lacks protective sensation (indicated by failing the 5.07 monofilament test), they do not alter their gait or relieve pressure in response to tissue damage. This repetitive microtrauma leads to callus formation, subcutaneous hemorrhage, and eventual skin breakdown. While macrovascular disease impairs healing, the initial ulceration in a purely neuropathic foot is mechanically driven.

Question 9303

Topic: 1. General Principles & Basic Science

When performing the 5.07 Semmes-Weinstein monofilament test to screen for protective sensation, what is the correct technique for application?

. Drag the monofilament lightly across the plantar skin
. Apply perpendicular to the skin until the filament buckles and hold for 1-2 seconds
. Tap the skin rapidly with the tip of the monofilament
. Apply parallel to the skin until the patient reports pain
. Apply perpendicular to the skin until the skin blanches without buckling the filament

Correct Answer & Explanation

. Apply perpendicular to the skin until the filament buckles and hold for 1-2 seconds

Explanation

Correct Answer: Apply perpendicular to the skin until the filament buckles and hold for 1-2 secondsThe correct technique for using a Semmes-Weinstein monofilament is to apply it perpendicular to the skin surface. Pressure is applied until the filament just buckles (bends), and it is held in place for 1 to 2 seconds. The patient, whose eyes should be closed, is asked to indicate when and where they feel the pressure.

Question 9304

Topic: 1. General Principles & Basic Science

Which of the following physical examination modalities is considered the most reliable screening tool for evaluating the loss of protective sensation in a patient with diabetes mellitus?

. Sharp two-point discrimination
. 128-Hz tuning fork vibratory sensation
. Hot and cold temperature discrimination
. 5.07 Semmes-Weinstein monofilament
. Deep tendon reflex testing

Correct Answer & Explanation

. 5.07 Semmes-Weinstein monofilament

Explanation

Correct Answer: 5.07 Semmes-Weinstein monofilamentWhile vibratory sensation, light touch, and temperature discrimination can all be altered in diabetic neuropathy, the most reliable and clinically useful screening tool specifically for the presence of 'protective sensation' is the ability to feel the 5.07 Semmes-Weinstein monofilament. This has been validated extensively in the literature as the primary predictor for ulceration risk.

Question 9305

Topic: 1. General Principles & Basic Science

A 62-year-old patient with type 2 diabetes presents with dry, cracked, and fissured skin on the bilateral feet. The feet are warm with bounding pedal pulses. This presentation is primarily a manifestation of which of the following pathophysiologic processes?

. Motor neuropathy causing intrinsic muscle wasting
. Sensory neuropathy leading to loss of protective sensation
. Autonomic neuropathy causing arteriovenous shunting and anhidrosis
. Peripheral arterial disease causing ischemic changes
. Venous insufficiency leading to stasis dermatitis

Correct Answer & Explanation

. Autonomic neuropathy causing arteriovenous shunting and anhidrosis

Explanation

Autonomic neuropathy in diabetes results in loss of sympathetic tone, causing anhidrosis (dry, cracked skin) and sympathetic autosympathectomy leading to arteriovenous shunting (warm feet, bounding pulses). This impairs the normal skin barrier and increases ulceration risk.

Question 9306

Topic: 1. General Principles & Basic Science

According to the University of Texas Wound Classification system, a diabetic ulcer that penetrates to the tendon or capsule, and is accompanied by both infection and ischemia, is classified as:

. Grade 1, Stage B
. Grade 2, Stage D
. Grade 3, Stage C
. Grade 3, Stage D
. Grade 2, Stage B

Correct Answer & Explanation

. Grade 2, Stage D

Explanation

The University of Texas classification uses Grades (0=pre-ulcerative, 1=superficial, 2=tendon/capsule, 3=bone/joint) and Stages (A=clean, B=infected, C=ischemic, D=infected and ischemic). Thus, a wound to the tendon/capsule with infection and ischemia is Grade 2, Stage D.

Question 9307

Topic: Infection, Pharmacology & VTE

Differentiating acute Charcot neuroarthropathy from osteomyelitis can be challenging on MRI. Which of the following MRI findings is most specific for osteomyelitis rather than acute Charcot changes?

. Bone marrow edema involving multiple contiguous bones
. Periarticular subchondral cysts
. Bone marrow edema confined to a single bone adjacent to a skin ulcer
. Joint effusion and synovial enhancement
. Soft tissue edema without an overlying skin defect

Correct Answer & Explanation

. Bone marrow edema involving multiple contiguous bones

Explanation

In acute Charcot, MRI typically shows diffuse bone marrow edema involving multiple periarticular bones. In contrast, osteomyelitis usually presents with bone marrow edema localized to a single bone that is directly contiguous with an overlying ulcer or sinus tract.

Question 9308

Topic: 1. General Principles & Basic Science

The neurovascular theory (French theory) of Charcot neuroarthropathy pathogenesis postulates that destruction is primarily driven by:

. Repeated unperceived microtrauma due to sensory neuropathy
. Autonomic neuropathy leading to increased blood flow and osteoclastic bone resorption
. Ischemic necrosis secondary to macrovascular disease
. Direct bacterial invasion of the periosteum
. Autoimmune targeting of articular cartilage

Correct Answer & Explanation

. Autonomic neuropathy leading to increased blood flow and osteoclastic bone resorption

Explanation

The neurovascular theory suggests that autonomic neuropathy leads to loss of sympathetic tone, causing arteriovenous shunting and hyperemia. This increased blood flow stimulates localized osteoclastic activity, leading to osteopenia and mechanical failure of the bone.

Question 9309

Topic: Infection, Pharmacology & VTE

Which of the following is considered the gold standard for the definitive diagnosis of osteomyelitis in the setting of a chronic diabetic foot ulcer?

. Three-phase Technetium-99m bone scan
. Magnetic Resonance Imaging (MRI) with contrast
. Positive probe-to-bone test
. Bone biopsy for histopathology and microbiology
. Erythrocyte sedimentation rate (ESR) > 70 mm/hr

Correct Answer & Explanation

. Bone biopsy for histopathology and microbiology

Explanation

While MRI is the most sensitive and specific advanced imaging modality, the definitive gold standard for diagnosing osteomyelitis is a bone biopsy. It provides both histopathologic confirmation and targeted microbiological data for precise antibiotic therapy.

Question 9310

Topic: Infection, Pharmacology & VTE

According to the Wagner classification system for diabetic foot ulcers, how is a Grade 3 lesion defined?

. Superficial ulcer not involving subcutaneous tissue
. Deep ulcer involving tendon or bone without infection
. Deep ulcer complicated by osteomyelitis, abscess, or joint sepsis
. Localized gangrene of a toe
. Extensive gangrene of the entire foot

Correct Answer & Explanation

. Deep ulcer complicated by osteomyelitis, abscess, or joint sepsis

Explanation

The Wagner classification grades ulcers from 0 to 5. Grade 3 is defined as a deep ulcer with deep abscess, osteomyelitis, or joint sepsis. Grade 4 is localized gangrene, and Grade 5 is gangrene of the whole foot.

Question 9311

Topic: 1. General Principles & Basic Science

A diabetic patient presents for routine screening with warm, profoundly dry, and cracked skin on the feet, alongside bounding pedal pulses. These clinical findings are most directly attributed to which pathophysiologic mechanism?

. Peripheral somatic motor denervation
. Loss of sympathetic autonomic vasomotor control
. Advanced glycation end-product deposition in the dermis
. Small-vessel microangiopathy causing ischemia
. Hyperactivity of the parasympathetic nervous system

Correct Answer & Explanation

. Loss of sympathetic autonomic vasomotor control

Explanation

Autonomic neuropathy leads to a loss of sympathetic tone, which normally innervates sweat glands and regulates capillary blood flow. This loss results in anhidrosis (dry, cracked skin) and arteriovenous shunting, creating warm feet with bounding pulses despite potential tissue ischemia.

Question 9312

Topic: Infection, Pharmacology & VTE

A diabetic foot wound extends entirely through the subcutaneous tissue, exposing the underlying flexor tendon and joint capsule. There is no clinical or radiographic evidence of osteomyelitis or deep abscess. According to the Wagner Classification system, what grade is this ulcer?

. Grade 1
. Grade 2
. Grade 3
. Grade 4
. Grade 5

Correct Answer & Explanation

. Grade 2

Explanation

A Wagner Grade 2 ulcer is defined as a deep ulcer penetrating to the tendon, ligament, or joint capsule, but without frank bone involvement or abscess formation. Grade 3 introduces deep infection such as osteomyelitis or deep fascial abscess.

Question 9313

Topic: Infection, Pharmacology & VTE

During the clinical evaluation of a diabetic plantar foot ulcer, the examiner uses a sterile blunt probe. The probe easily reaches a hard, gritty surface at the base of the wound. What is the clinical significance of a positive 'probe-to-bone' test in this setting?

. It has a high negative predictive value for ruling out soft tissue infection
. It reliably differentiates between Charcot neuroarthropathy and gout
. It has a high positive predictive value for underlying osteomyelitis
. It indicates the absolute necessity for a major limb amputation
. It confirms the presence of an anaerobic necrotizing fascial infection

Correct Answer & Explanation

. It has a high positive predictive value for underlying osteomyelitis

Explanation

A positive probe-to-bone test in the presence of a clinically infected diabetic foot ulcer has a high positive predictive value (often >85%) for osteomyelitis. It is a simple, cost-effective clinical screening maneuver.

Question 9314

Topic: Infection, Pharmacology & VTE

While Total Contact Casting (TCC) is considered the gold standard for offloading non-infected neuropathic plantar foot ulcers, it is contraindicated in certain scenarios. Which of the following is considered an absolute contraindication to the application of a TCC?

. A superficial Wagner Grade 1 ulcer
. A history of previous toe amputation
. Active, untreated deep infection or osteomyelitis
. Concomitant mild sensory neuropathy
. Charcot neuroarthropathy in the consolidation phase

Correct Answer & Explanation

. Active, untreated deep infection or osteomyelitis

Explanation

Total contact casting should not be used in the presence of active deep infection, untreated osteomyelitis, severe ischemia, or unmanageable excessive wound drainage. Enclosing an active deep infection in a cast risks rapid progression to sepsis or limb loss.

Question 9315

Topic: Physiology & Rehabilitation

Which metabolic pathway is primarily implicated in the development of diabetic peripheral neuropathy through the accumulation of intracellular osmoles and subsequent cellular edema?

. Hexose monophosphate shunt
. Krebs cycle disruption
. Polyol pathway
. Gluconeogenesis
. Anaerobic glycolysis

Correct Answer & Explanation

. Polyol pathway

Explanation

Hyperglycemia activates the polyol pathway, where aldose reductase converts excess glucose into sorbitol. Sorbitol cannot easily cross cell membranes, leading to osmotic stress, cellular edema, and eventual neuronal damage.

Question 9316

Topic: Infection, Pharmacology & VTE

Differentiating acute Charcot neuroarthropathy from pedal osteomyelitis on MRI can be challenging. Which of the following MRI findings most strongly favors a diagnosis of osteomyelitis over Charcot changes?

. Subchondral bone marrow edema in the midfoot
. Joint subluxation and capsular distension
. Intra-articular loose bodies and periarticular debris
. Replacement of normal marrow fat on T1 with a contiguous skin defect or sinus tract
. Diffuse subcutaneous soft tissue edema without localized collections

Correct Answer & Explanation

. Replacement of normal marrow fat on T1 with a contiguous skin defect or sinus tract

Explanation

Osteomyelitis on MRI is characterized by low T1 signal (marrow fat replacement) and high T2/STIR signal directly contiguous with an overlying ulcer or sinus tract. Charcot typically presents with periarticular marrow edema that affects multiple joints without necessarily having an overlying skin defect.

Question 9317

Topic: 1. General Principles & Basic Science

A diabetic patient with a chronic plantar foot ulcer is suspected of having underlying osteomyelitis. Radiographs show periosteal reaction but are inconclusive. Which imaging modality has the highest sensitivity and specificity for diagnosing osteomyelitis in the setting of a neuropathic diabetic foot without prior surgery?

. Triple-phase Technetium-99m bone scan
. Indium-111 labeled leukocyte scan
. Magnetic Resonance Imaging (MRI) with and without contrast
. Computed Tomography (CT) scan
. Positron Emission Tomography (PET) scan

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI) with and without contrast

Explanation

MRI is the most sensitive and specific imaging modality for diagnosing osteomyelitis in the diabetic foot. It excellently differentiates soft tissue infection from bone marrow edema and cortical destruction, guiding appropriate surgical or medical management.

Question 9318

Topic: Infection, Pharmacology & VTE

A 65-year-old poorly controlled diabetic presents with a deep, foul-smelling, necrotic foot ulcer accompanied by systemic inflammatory signs. He has a history of recent hospitalization and prior antibiotic use. Which of the following best represents the most appropriate empiric intravenous antibiotic coverage pending deep tissue cultures?

. Cefazolin and clindamycin
. Vancomycin and piperacillin-tazobactam
. Oral cephalexin and metronidazole
. Intravenous penicillin G
. Ciprofloxacin monotherapy

Correct Answer & Explanation

. Vancomycin and piperacillin-tazobactam

Explanation

Severe or limb-threatening diabetic foot infections, particularly in patients with recent healthcare exposure, are typically polymicrobial. Empiric therapy must include broad-spectrum coverage for MRSA, Gram-negative bacilli (including Pseudomonas), and anaerobes.

Question 9319

Topic: 1. General Principles & Basic Science

The phenomenon of Limited Joint Mobility (LJM) syndrome in long-standing diabetic patients, often leading to increased plantar pressures and ulceration, is primarily caused by which biochemical process?

. Accumulation of advanced glycation end products (AGEs) in collagen
. Progressive loss of articular cartilage secondary to sensory deprivation
. Denervation-induced muscle fibrosis
. Endoneurial microvascular thrombosis
. Autoimmune destruction of synovial tissue

Correct Answer & Explanation

. Accumulation of advanced glycation end products (AGEs) in collagen

Explanation

Chronic hyperglycemia causes non-enzymatic glycosylation of proteins, leading to the accumulation of advanced glycation end products (AGEs). This cross-links periarticular collagen, resulting in stiff, rigid joints and abnormally high plantar pressures during weight-bearing.

Question 9320

Topic: 1. General Principles & Basic Science
A 4-year-old girl with Osteogenesis Imperfecta Type III is admitted for her first cycle of intravenous pamidronate. Approximately 24 hours after the infusion, she develops a temperature of 38.8°C (101.8°F), myalgias, and irritability. Laboratory studies show a normal white blood cell count and slightly elevated CRP. What is the most appropriate next step in management?
. Immediately discontinue the pamidronate and start broad-spectrum intravenous antibiotics.
. Obtain blood cultures and perform a joint aspiration of the most painful limb.
. Administer antipyretics and provide supportive care, as this is a self-limiting reaction.
. Administer intravenous calcium gluconate to treat acute hypocalcemia.
. Order an urgent MRI to rule out an acute osteomyelitis.

Correct Answer & Explanation

. Administer antipyretics and provide supportive care, as this is a self-limiting reaction.

Explanation

An acute phase reaction is a very common, well-documented side effect following the first intravenous infusion of nitrogen-containing bisphosphonates (such as pamidronate or zoledronic acid). It is characterized by fever, flu-like symptoms, myalgias, and bone pain, typically occurring within 24 to 48 hours of the infusion. It is caused by the release of pro-inflammatory cytokines (like IL-6 and TNF-alpha) from gamma-delta T cells. The reaction is self-limiting, usually resolving within 24-48 hours, and is managed supportively with antipyretics (e.g., acetaminophen or ibuprofen). It is significantly less common and less severe with subsequent infusions. Sepsis workups or antibiotics are not indicated unless there is a specific clinical suspicion beyond the expected post-infusion window.

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