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1. General Principles & Basic Science MCQs

Practice Set 495 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 9881

Topic: Infection, Pharmacology & VTE

A patient is admitted for septic arthritis of the third MCP joint following a fight bite. After 48 hours of IV antibiotics and surgical debridement, the patient's C-reactive protein (CRP) has slightly decreased, but the joint remains significantly swollen and painful. What is the most appropriate next step?

. A. Discontinue antibiotics due to inadequate response.
. B. Transition to oral antibiotics and discharge home.
. C. Perform a second look surgical irrigation and debridement.
. D. Order a CT scan of the hand to assess for osteomyelitis.
. E. Immediately apply negative pressure wound therapy.

Correct Answer & Explanation

. C. Perform a second look surgical irrigation and debridement.

Explanation

If a patient with septic arthritis does not show clear signs of improvement (e.g., significant reduction in pain, swelling, and inflammatory markers) within 24-48 hours after initial surgical debridement and appropriate intravenous antibiotics, a second-look surgical irrigation and debridement is indicated. This suggests residual infection, inadequate debridement, or an undiagnosed complication like osteomyelitis or an abscess. Discontinuing antibiotics (A) or discharging with oral antibiotics (B) would be dangerous. While a CT scan (D) can be helpful, it should not delay re-exploration if clinical signs point to persistent infection. Negative pressure wound therapy (E) is a wound management technique, not an intervention for persistent deep infection.

Question 9882

Topic: 1. General Principles & Basic Science

Which imaging modality is most sensitive for detecting early osteomyelitis in the setting of a complicated fight bite?

. A. Plain Radiographs
. B. Computed Tomography (CT) scan
. C. Magnetic Resonance Imaging (MRI)
. D. Ultrasound
. E. Bone Scan (Technetium-99m)

Correct Answer & Explanation

. C. Magnetic Resonance Imaging (MRI)

Explanation

Magnetic Resonance Imaging (MRI) is considered the most sensitive imaging modality for detecting early osteomyelitis, especially in the context of a hand infection where soft tissue and bone marrow edema are key early signs. It can identify changes in bone marrow signal before cortical changes become apparent on plain radiographs or even CT scans. Plain radiographs (A) are useful for initial screening but have low sensitivity for early osteomyelitis. CT scans (B) provide excellent bone detail but are less sensitive than MRI for early marrow changes. Ultrasound (D) is good for superficial fluid collections and tendon pathology, but not bone marrow. Bone scans (E) are sensitive but lack specificity for infection versus other inflammatory processes and have poor anatomical resolution.

Question 9883

Topic: 1. General Principles & Basic Science

What is the significance of Eikenella corrodens in human bite infections?

. A. It is resistant to all commonly used antibiotics.
. B. It is a Gram-positive obligate anaerobe that produces gas.
. C. It is a fastidious Gram-negative rod highly characteristic of human oral flora.
. D. It primarily causes necrotizing fasciitis.
. E. It is transmitted via mosquito bites.

Correct Answer & Explanation

. C. It is a fastidious Gram-negative rod highly characteristic of human oral flora.

Explanation

Eikenella corrodens is a fastidious (meaning it has complex nutritional requirements), Gram-negative, facultative anaerobic rod that is a key component of human oral flora. It is frequently isolated from human bite wounds and its presence is a strong indicator of human saliva inoculation. It is typically sensitive to penicillin-class antibiotics (like amoxicillin-clavulanate) and cephalosporins, but often resistant to macrolides and clindamycin (though some strains are sensitive to clinda, hence combination therapy often used). It is not resistant to all antibiotics (A), is not Gram-positive (B), and does not primarily cause necrotizing fasciitis (D) or transmit via mosquito bites (E).

Question 9884

Topic: Infection, Pharmacology & VTE

Which factor significantly increases the risk of osteomyelitis developing from a fight bite wound?

. A. Superficial skin laceration only.
. B. Early presentation and immediate antibiotic treatment.
. C. Direct inoculation of bacteria into the bone or adjacent joint with delayed treatment.
. D. History of mild hypertension.
. E. Patient is a non-smoker.

Correct Answer & Explanation

. C. Direct inoculation of bacteria into the bone or adjacent joint with delayed treatment.

Explanation

Direct inoculation of bacteria into the bone (e.g., from a tooth fragment) or into an adjacent joint leading to septic arthritis that spreads to the bone, especially with delayed or inadequate treatment, significantly increases the risk of osteomyelitis. Superficial wounds (A) and early treatment (B) reduce the risk. Mild hypertension (D) and being a non-smoker (E) are not direct risk factors for developing osteomyelitis from a bite wound, though comorbidities can affect overall healing.

Question 9885

Topic: Infection, Pharmacology & VTE

A patient presents 48 hours after a fight bite to the fourth MCP joint. The wound is small and appears benign on the surface, but the patient reports increasing throbbing pain and fever (38.5°C). What is the most appropriate management plan?

. A. Oral antibiotics and close outpatient follow-up.
. B. Admit for IV antibiotics, urgent surgical exploration and debridement.
. C. Rest, ice, compression, elevation (RICE) and monitor symptoms.
. D. Superficial wound cleaning and dressing change.
. E. Obtain a wound culture and await results before any definitive action.

Correct Answer & Explanation

. B. Admit for IV antibiotics, urgent surgical exploration and debridement.

Explanation

Despite a seemingly benign superficial wound, increasing throbbing pain and systemic signs of infection like fever after a fight bite are red flags for a deep-seated infection (e.g., septic arthritis, osteomyelitis, tenosynovitis). This warrants immediate admission for intravenous broad-spectrum antibiotics and urgent surgical exploration and debridement to identify and treat the source of the deep infection. Oral antibiotics (A) are insufficient. RICE (C) is for trauma, not infection. Superficial cleaning (D) is inadequate. Awaiting culture results (E) will delay critical treatment.

Question 9886

Topic: 1. General Principles & Basic Science

What is the maximum recommended duration for prophylactic antibiotic use in a superficial human bite wound where deep involvement is definitively ruled out?

. A. 1 dose
. B. 1-2 days
. C. 3-5 days
. D. 7-10 days
. E. 14 days

Correct Answer & Explanation

. C. 3-5 days

Explanation

For prophylactic antibiotic use in superficial human bite wounds where deep involvement has been definitively ruled out, a course of 3-5 days is generally considered sufficient. The goal is to prevent initial bacterial proliferation. Longer courses (D, E) are typically reserved for established infections, not prophylaxis. Shorter courses (A, B) may be inadequate given the polymicrobial nature and virulence of human bite flora.

Question 9887

Topic: 1. General Principles & Basic Science

Which condition is a direct contraindication for a digital nerve block using lidocaine with epinephrine in the finger?

. A. Penicillin allergy
. B. History of anxiety
. C. Compromised vascularity of the digit
. D. Diabetes mellitus
. E. Mild hypertension

Correct Answer & Explanation

. C. Compromised vascularity of the digit

Explanation

Compromised vascularity of the digit (e.g., severe peripheral vascular disease, Reynaud's phenomenon, or significant crush injury) is an absolute contraindication for using lidocaine with epinephrine for a digital block. Epinephrine causes vasoconstriction, which can further reduce blood flow to an already compromised digit, leading to ischemia and potentially necrosis. Penicillin allergy (A), anxiety (B), diabetes (D), and mild hypertension (E) are not contraindications for this specific procedure.

Question 9888

Topic: 1. General Principles & Basic Science

After surgical debridement of a fight bite wound with septic arthritis, the surgeon decides to use an antibiotic-impregnated polymethylmethacrylate (PMMA) spacer in the joint. What is the primary purpose of this spacer?

. A. To provide permanent joint replacement.
. B. To deliver high local concentrations of antibiotics and maintain joint space.
. C. To prevent soft tissue adherence to bone.
. D. To absorb wound exudates.
. E. To provide immediate weight-bearing stability.

Correct Answer & Explanation

. B. To deliver high local concentrations of antibiotics and maintain joint space.

Explanation

Antibiotic-impregnated PMMA spacers are commonly used in the management of septic joints, particularly when there is significant bone or cartilage loss, or in two-stage revision arthroplasty. Their primary purpose is to deliver high local concentrations of antibiotics directly to the infected area, while also helping to maintain the joint space, which facilitates a potential future definitive reconstruction. They are not permanent replacements (A) and do not provide immediate weight-bearing stability in the hand (E). While they can help prevent soft tissue adherence (C), this is secondary to antibiotic delivery and space maintenance. Absorbing exudates (D) is not their main function.

Question 9889

Topic: Surgical Anatomy & Approaches

Which approach is generally preferred for fixation of the distal radial shaft in a Galeazzi fracture due to superior exposure of the anterior radial surface and relative safety for the posterior interosseous nerve?

. Dorsal approach (Thompson approach)
. Ulnar approach
. Volar approach (Henry approach)
. Direct lateral approach
. Combined dorsal and volar approaches

Correct Answer & Explanation

. Volar approach (Henry approach)

Explanation

The volar approach (Henry approach) is generally preferred for fixation of distal radial shaft fractures, including Galeazzi fractures. It provides excellent exposure of the volar surface of the radius, where the plates are typically applied, and minimizes the risk to the posterior interosseous nerve (PIN), which is associated with the dorsal approach. The anterior interosseous nerve (AIN) is the primary structure at risk with the Henry approach, requiring careful identification and protection.

Question 9890

Topic: Biology, Genetics & Bone Healing

A 5-year-old boy presents with disproportionate short stature, a short trunk, and epiphyseal dysplasia of the femoral head. Genetic testing reveals a mutation in the COL2A1 gene. Which of the following proteins is primarily affected in this condition?

. Type I collagen
. Type II procollagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Type X collagen

Correct Answer & Explanation

. Type II procollagen

Explanation

Correct Answer: Type II procollagenCongenital spondyloepiphyseal dysplasia (SEDc) is an inherited chondrodysplasia caused by a mutation in the COL2A1 gene, which encodes type II procollagen. This leads to defective cartilage formation, resulting in short stature, a short trunk, and epiphyseal dysplasia.

Question 9891

Topic: 1. General Principles & Basic Science

A 10-year-old boy presents with a short neck, broad chest, and disproportionate short stature. Radiographs reveal characteristic vertebral anomalies. His mother is of normal stature and has no clinical symptoms, but her brother has a similar condition. What is the most likely inheritance pattern of this specific disorder?

. Autosomal dominant
. Autosomal recessive
. X-linked dominant
. X-linked recessive
. Mitochondrial

Correct Answer & Explanation

. X-linked recessive

Explanation

Correct Answer: X-linked recessiveSpondyloepiphyseal dysplasia tarda (SEDt) is an X-linked recessive progressive osteochondrodysplasia. It affects males only, while heterozygous carrier females are generally clinically and radiographically normal.

Question 9892

Topic: 1. General Principles & Basic Science

A family seeks genetic counseling regarding Spondyloepiphyseal Dysplasia Tarda. The father is unaffected, and the mother is a known heterozygous carrier. What is the probability that their daughter will exhibit the clinical and radiographic manifestations of the disease?

. 0%
. 25%
. 50%
. 75%
. 100%

Correct Answer & Explanation

. 0%

Explanation

Correct Answer: 0%Spondyloepiphyseal dysplasia tarda is an X-linked recessive disorder. Heterozygous carrier females are clinically and radiographically normal. The disease affects males only. Therefore, the probability of a daughter exhibiting clinical manifestations is 0% (though she has a 50% chance of being a carrier).

Question 9893

Topic: Biology, Genetics & Bone Healing

A 5-year-old boy presents with disproportionate short stature, a short trunk, and the spinal radiographic findings shown below. Genetic testing is most likely to reveal a mutation affecting which of the following?


. Type I collagen
. Type II procollagen
. Fibroblast growth factor receptor 3 (FGFR3)
. Cartilage oligomeric matrix protein (COMP)
. Core-binding factor alpha 1 (CBFA1)

Correct Answer & Explanation

. Type II procollagen

Explanation

Correct Answer: Type II procollagenSpondyloepiphyseal dysplasia congenita (SEDc) is an inherited chondrodysplasia characterized by a short trunk, platyspondyly, and epiphyseal dysplasia. It is caused by a mutation in the COL2A1 gene, which encodes type II procollagen.

Question 9894

Topic: 1. General Principles & Basic Science

A 10-year-old boy presents with a short neck, broad chest, and the characteristic vertebral shape seen in the radiograph below. His mother is clinically and radiographically normal. What is the inheritance pattern of this specific condition?


. Autosomal dominant
. Autosomal recessive
. X-linked dominant
. X-linked recessive
. Mitochondrial

Correct Answer & Explanation

. X-linked recessive

Explanation

Correct Answer: X-linked recessiveThe radiograph shows 'champagne-bottle' shaped vertebrae, characteristic of Spondyloepiphyseal dysplasia tarda (SEDt). SEDt is an X-linked recessive progressive osteochondrodysplasia. It affects males only, while heterozygous carrier females are clinically and radiographically normal.

Question 9895

Topic: 1. General Principles & Basic Science

A family presents for genetic counseling. The father has a history of spondyloepiphyseal dysplasia tarda (SEDt). Which of the following statements regarding the transmission and manifestation of this specific disorder is correct?

. It affects both males and females equally
. Heterozygous carrier females exhibit mild radiographic abnormalities
. The disease affects males only and manifests in childhood
. It is caused by a mutation in the COL1A1 gene
. It typically presents at birth with severe respiratory distress

Correct Answer & Explanation

. The disease affects males only and manifests in childhood

Explanation

Correct Answer: The disease affects males only and manifests in childhoodSpondyloepiphyseal dysplasia tarda is an X-linked recessive disorder. It manifests in childhood with disproportionate short stature. Heterozygous carrier females are generally clinically and radiographically normal, and the disease affects males only.

Question 9896

Topic: 1. General Principles & Basic Science

A 10-year-old boy presents with disproportionate short stature, a broad chest, and a short neck. Radiographs reveal 'champagne bottle' shaped vertebrae. His parents are unaffected, but his maternal uncle has a similar condition. What is the inheritance pattern of this specific disorder?

. Autosomal dominant
. Autosomal recessive
. X-linked dominant
. X-linked recessive
. Mitochondrial

Correct Answer & Explanation

. X-linked recessive

Explanation

Correct Answer: DSpondyloepiphyseal dysplasia tarda (SEDt) is an X-linked recessive progressive osteochondrodysplasia. It manifests in childhood with disproportionate short stature, a short neck and trunk, and a broad chest. Because it is X-linked recessive, heterozygous carrier females are generally clinically and radiographically normal, and the disease exclusively affects males.

Question 9897

Topic: Biology, Genetics & Bone Healing

A young female patient presents with the clinical and radiographic findings of the hands and feet shown below. In the context of spondyloepiphyseal dysplasia, what is the primary underlying defect causing these skeletal manifestations?




. Defective mineralization of osteoid
. Mutation in the gene encoding type I collagen
. Growth disorder of the spine and epiphysis of the limbs
. Premature closure of the physes due to hyperthyroidism
. Abnormal osteoclast function

Correct Answer & Explanation

. Growth disorder of the spine and epiphysis of the limbs

Explanation

Correct Answer: CThe images show short, small tubular bones and broad feet. Spondyloepiphyseal dysplasia is an inherited chondrodysplasia characterized by a growth disorder of the spine and the epiphyses of the limbs, leading to these characteristic changes in the hands and feet. It is not a defect of mineralization (rickets/osteomalacia) or osteoclast function (osteopetrosis).

Question 9898

Topic: 1. General Principles & Basic Science

A couple seeks genetic counseling. The father has spondyloepiphyseal dysplasia tarda, and the mother is unaffected and is not a carrier. What is the probability that their sons will be affected by the disease?

. 0%
. 25%
. 50%
. 75%
. 100%

Correct Answer & Explanation

. 0%

Explanation

Correct Answer: ASpondyloepiphyseal dysplasia tarda is an X-linked recessive disorder. An affected father will pass his Y chromosome to all of his sons, meaning none of his sons (0%) will inherit the defective X chromosome or the disease. He will pass his defective X chromosome to all of his daughters, making them obligate carriers, but they will be clinically normal.

Question 9899

Topic: Biology, Genetics & Bone Healing

Spondyloepiphyseal dysplasia congenita is primarily caused by a defect in which of the following structural components of cartilage?

. Type I collagen
. Type II procollagen
. Type X collagen
. Aggrecan
. Fibroblast growth factor receptor

Correct Answer & Explanation

. Type II procollagen

Explanation

Correct Answer: BSpondyloepiphyseal dysplasia congenita occurs through a mutation in the COL2A1 gene, which encodes type II procollagen. Type II collagen is the primary structural collagen found in articular and hyaline cartilage, explaining the epiphyseal and spinal growth disturbances seen in this condition.

Question 9900

Topic: 1. General Principles & Basic Science

A 10-year-old boy presents with progressive arthropathy, a short neck, and a broad chest. Radiographs show characteristic vertebral anomalies. His mother is clinically and radiographically normal, but his maternal uncle has a similar condition. What is the inheritance pattern of this disorder?

. Autosomal dominant
. Autosomal recessive
. X-linked dominant
. X-linked recessive
. Mitochondrial

Correct Answer & Explanation

. X-linked recessive

Explanation

Correct Answer: X-linked recessiveThe clinical picture describes Spondyloepiphyseal Dysplasia Tarda (SEDT). SEDT is an X-linked recessive progressive osteochondrodysplasia. It manifests in childhood and affects males only, while heterozygous carrier females are generally clinically and radiographically normal.

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