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Infection, Pharmacology & VTE MCQs

Practice Set 27 of 68

This practice set contains high-yield board review questions covering key concepts in Infection, Pharmacology & VTE. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 521

Topic: Infection, Pharmacology & VTE

A 21-year-old football player sustains a valgus blow to the knee. MRI confirms an isolated, acute grade III injury to the medial collateral ligament (MCL) at the femoral attachment. What is the recommended treatment?

. Immediate primary surgical repair of the MCL
. Surgical reconstruction using hamstring autograft
. Hinged knee bracing and early functional rehabilitation
. Cylinder cast immobilization in 30 degrees of flexion for 6 weeks
. Isolated pes anserinus transfer

Correct Answer & Explanation

. Immediate primary surgical repair of the MCL

Explanation

Isolated grade III MCL injuries, particularly those at the femoral insertion, have excellent healing potential. They are typically treated successfully nonoperatively with a hinged knee brace to protect against valgus stress and early functional rehabilitation.

Question 522

Topic: Infection, Pharmacology & VTE

A 4-year-old boy presents with a 2-day history of right hip pain and refusing to bear weight. His temperature is 38.8 Celsius (101.8 F). Laboratory studies show a WBC count of 13,000/mm3, ESR of 45 mm/hr, and CRP of 3.0 mg/dL. Radiographs of the hip are normal. Based on these findings, what is the most appropriate next step?

. Discharge home with oral NSAIDs and follow-up in 48 hours
. Order an MRI of the pelvis with IV contrast
. Perform an ultrasound-guided hip aspiration
. Initiate empiric IV antibiotics and observe
. Schedule an urgent bone scan

Correct Answer & Explanation

. Discharge home with oral NSAIDs and follow-up in 48 hours

Explanation

This patient meets all four Kocher criteria for septic arthritis (non-weight-bearing, temp >38.5 C, ESR >40, WBC >12,000), giving a 99% probability of the diagnosis. Urgent hip aspiration is required for definitive diagnosis and to guide treatment before considering surgical irrigation.

Question 523

Topic: Infection, Pharmacology & VTE
A 3-year-old boy presents with a temperature of 38.8°C, an ESR of 45 mm/hr, a WBC count of 14,000/mm³, and refusal to bear weight on his left leg. According to the Kocher criteria, what is the approximate probability that this child has septic arthritis of the hip?
. 40%
. 71%
. 83%
. 93%
. 99%

Correct Answer & Explanation

. 99%

Explanation

The patient meets all 4 of the classic Kocher criteria (fever >38.5°C, ESR >40, WBC >12,000, and non-weight-bearing). The presence of all 4 criteria correlates with a 99% predictive probability for septic arthritis of the hip.

Question 524

Topic: Infection, Pharmacology & VTE

A 5-year-old boy presents with a limp, a temperature of 38.9°C (102°F), and an inability to bear weight on his right leg. Laboratory tests show an ESR of 55 mm/hr and a WBC count of 14,000/mm3. According to the modified Kocher criteria, what is the predictive probability that this child has septic arthritis of the hip?

. 10%
. 40%
. 71%
. 93%
. 99%

Correct Answer & Explanation

. 10%

Explanation

The modified Kocher criteria include fever >38.5°C, inability to bear weight, ESR >40 mm/hr, and WBC >12,000/mm3. The presence of all four criteria yields a 99% probability of septic arthritis.

Question 525

Topic: Infection, Pharmacology & VTE
A 4-year-old boy presents with a 2-day history of right hip pain, a temperature of 38.8°C, and refusal to bear weight. Laboratory tests show an ESR of 50 mm/hr and a WBC of 14,000/mm³. Radiographs are unremarkable. What is the most appropriate next step?
. Observation and NSAIDs
. Outpatient oral antibiotics
. MRI of the right hip
. Ultrasound-guided aspiration of the hip
. Intravenous antibiotics without aspiration

Correct Answer & Explanation

. Ultrasound-guided aspiration of the hip

Explanation

The patient meets 4 of 4 Kocher criteria for septic arthritis (fever, non-weight bearing, ESR >40, WBC >12,000). Ultrasound-guided aspiration is required to confirm the diagnosis and decompress the joint.

Question 526

Topic: Infection, Pharmacology & VTE

According to the AAOS clinical practice guidelines on venous thromboembolic disease prophylaxis after elective total hip arthroplasty, which of the following regimens is recommended for patients with standard risk profiles?

. Aspirin alone
. Low molecular weight heparin (LMWH) for 14 days
. Warfarin with an INR goal of 2.5 to 3.5
. Aspirin combined with mechanical compression devices
. Unfractionated heparin for 5 days

Correct Answer & Explanation

. Aspirin alone

Explanation

Current AAOS guidelines support the use of pharmacologic agents, such as aspirin, combined with mechanical compressive devices for VTE prophylaxis in standard-risk patients undergoing elective THA. This balances efficacy in preventing DVT/PE with a lower risk of bleeding complications.

Question 527

Topic: Infection, Pharmacology & VTE

A 65-year-old man is scheduled for primary total hip arthroplasty. He is healthy with no history of prior DVT, pulmonary embolism, or bleeding disorders. According to the latest AAOS guidelines, what is the most appropriate routine venous thromboembolism (VTE) prophylaxis postoperatively?

. Aspirin
. Warfarin
. Low-molecular-weight heparin (LMWH)
. Unfractionated heparin
. Mechanical compression alone

Correct Answer & Explanation

. Aspirin

Explanation

Recent AAOS guidelines and consensus statements support the use of Aspirin for routine VTE prophylaxis in standard-risk patients undergoing elective total joint arthroplasty. It is highly effective and significantly reduces the risk of major bleeding compared to stronger anticoagulants.

Question 528

Topic: Infection, Pharmacology & VTE

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to delay fracture healing. This effect is primarily mediated through the inhibition of which enzyme crucial for early inflammatory signaling?

. Lipoxygenase
. Phospholipase A2
. Cyclooxygenase-2
. Matrix metalloproteinase-9
. Cathepsin K

Correct Answer & Explanation

. Lipoxygenase

Explanation

NSAIDs inhibit cyclooxygenase-2 (COX-2), an enzyme essential for synthesizing prostaglandins during the initial inflammatory phase of fracture healing. This inhibition impairs early angiogenesis, mesenchymal stem cell differentiation, and endochondral ossification.

Question 529

Topic: Infection, Pharmacology & VTE

The superficial medial collateral ligament (sMCL) is a primary static stabilizer of the knee. What is the precise location of its distal attachment?

. Medial epicondyle of the femur
. Adductor tubercle
. Medial tibial condyle just below the joint line
. Tibial metaphysis deep to the pes anserinus
. Fibular head

Correct Answer & Explanation

. Medial epicondyle of the femur

Explanation

The sMCL originates on the medial femoral epicondyle and inserts distally on the medial tibial metaphysis, approximately 4.5 cm distal to the joint line, lying deep to the pes anserinus tendons.

Question 530

Topic: Infection, Pharmacology & VTE

Which type of medial collateral ligament (MCL) tear has the lowest intrinsic healing potential and most frequently requires surgical repair if conservative management fails?

. Proximal femoral avulsion
. Mid-substance tear
. Distal tibial avulsion
. Deep medial capsular tear
. Posterior oblique ligament avulsion

Correct Answer & Explanation

. Proximal femoral avulsion

Explanation

Distal tibial MCL avulsions have a poor intrinsic healing potential because the torn end often displaces superficial to the pes anserinus tendons, creating a Stener-like lesion. These injuries frequently require surgical repair, whereas proximal and mid-substance tears generally heal well nonoperatively.

Question 531

Topic: Infection, Pharmacology & VTE

A 30-year-old skier sustains an acute grade III medial collateral ligament (MCL) tear at its tibial insertion. Which of the following factors is most strongly associated with failure of non-operative management for this specific injury pattern?

. Entrapment of the torn MCL superficial to the pes anserinus tendons
. Concomitant grade I lateral collateral ligament (LCL) sprain
. Proximal avulsion from the medial epicondyle
. Associated longitudinal tear of the medial meniscus
. Increased valgus laxity at 0 degrees of flexion

Correct Answer & Explanation

. Entrapment of the torn MCL superficial to the pes anserinus tendons

Explanation

Distal (tibial-sided) MCL tears can flip superficial to the pes anserinus tendons, creating a "Stener-like" lesion that prevents spontaneous healing. Proximal MCL tears typically heal well with non-operative bracing.

Question 532

Topic: Infection, Pharmacology & VTE

A 28-year-old skier sustains an isolated grade III medial collateral ligament (MCL) tear. MRI demonstrates an avulsion of the MCL from its distal tibial attachment with the torn end retracted superficial to the pes anserinus. What is the most appropriate treatment?

. Hinged knee brace for 6 weeks
. Primary operative repair
. Acute MCL reconstruction with allograft
. Injection of platelet-rich plasma
. Cast immobilization in 30 degrees of flexion

Correct Answer & Explanation

. Hinged knee brace for 6 weeks

Explanation

Distal MCL avulsions with retraction over the pes anserinus create a "Stener-like" lesion of the knee that prevents anatomic healing. Unlike proximal MCL tears which often heal nonoperatively, these specific distal lesions require primary surgical repair.

Question 533

Topic: Infection, Pharmacology & VTE

A 24-year-old skier sustains an isolated Grade III injury to the medial collateral ligament (MCL). Magnetic resonance imaging reveals an avulsion of the MCL from its tibial insertion with the distal end flipped superficial to the pes anserinus. What is the most appropriate management?

. Nonoperative management with a hinged knee brace
. Immediate primary surgical repair of the MCL
. MCL reconstruction with autograft
. Immobilization in a cast for 6 weeks
. Corticosteroid injection and physical therapy

Correct Answer & Explanation

. Nonoperative management with a hinged knee brace

Explanation

Distal MCL avulsions with the ligament displaced superficial to the pes anserinus (Stener-like lesion of the knee) lack the ability to heal properly due to soft tissue interposition. Unlike proximal tears which typically heal nonoperatively, these specific distal avulsions require primary surgical repair.

Question 534

Topic: Infection, Pharmacology & VTE

A surgeon is planning a posteromedial approach to address a displaced posteromedial shear fragment in a bicondylar tibial plateau fracture. Which surgical interval is typically utilized for this approach?

. Between the medial head of the gastrocnemius and the pes anserinus
. Between the lateral head of the gastrocnemius and the soleus
. Between the tibialis anterior and extensor hallucis longus
. Between the semimembranosus and semitendinosus
. Between the peroneus longus and brevis

Correct Answer & Explanation

. Between the medial head of the gastrocnemius and the pes anserinus

Explanation

The standard posteromedial approach to the proximal tibia exploits the interval between the pes anserinus anteriorly and the medial head of the gastrocnemius posteriorly. This safely exposes the posteromedial cortex for anti-glide plating.

Question 535

Topic: Infection, Pharmacology & VTE

A 42-year-old farmer sustains an open grade IIIB tibia fracture after his leg is caught in a tractor mechanism. Visible soil and organic debris contaminate the wound. What is the most appropriate initial intravenous antibiotic regimen?

. Cefazolin alone
. Cefazolin and gentamicin
. Cefazolin and penicillin
. Cefazolin, gentamicin, and penicillin
. Ceftriaxone alone

Correct Answer & Explanation

. Cefazolin alone

Explanation

For severe open fractures with heavy farm or soil contamination, the standard recommendation is triple antibiotic coverage. This includes a first-generation cephalosporin, an aminoglycoside for Gram-negative coverage, and high-dose penicillin to cover Clostridium species.

Question 536

Topic: Infection, Pharmacology & VTE

In the treatment of osteoporotic vertebral compression fractures, which of the following is a known absolute contraindication for balloon kyphoplasty?

. Fracture age greater than 4 weeks
. Complete loss of vertebral body height (vertebra plana)
. Presence of a vacuum cleft
. Fracture with posterior vertebral wall involvement and intact neurologic exam
. Active systemic infection or osteomyelitis

Correct Answer & Explanation

. Fracture age greater than 4 weeks

Explanation

Active systemic infection or local osteomyelitis at the fracture site is an absolute contraindication for kyphoplasty or vertebroplasty due to the risk of seeding the infection or exacerbating osteomyelitis.

Question 537

Topic: Infection, Pharmacology & VTE

A 2-year-old boy has been referred for musculoskeletal evaluation. Examination reveals shortened proximal limbs, hip and knee flexion contractures, an abducted thumb, and ear abnormalities. His parents are concerned about his deformed feet. What is the most common foot deformity associated with this patient's diagnosis?

. Pes calcaneovalgus
. Fixed pes planovalgus
. Rigid equinovarus
. Metatarsus adductus
. Skewfoot (forefoot adduction and heel valgus)

Correct Answer & Explanation

. Pes calcaneovalgus

Explanation

The patient has diastrophic dysplasia. Affected individuals have rhizomelic short stature, cauliflower ears, severe joint contractures (especially knees and hips), hitchhiker's thumb, and a cleft palate. The most common foot abnormality is a rigid equinovarus deformity. Surgical results are poorer than those for idiopathic clubfeet and often require bony procedures or talectomy. Ryoppy S, Poussa M, Merikanto J, Marttinen E, Kaitila I: Foot deformities in diastrophic dysplasia: An analysis of 102 patients. J Bone Joint Surg Br 1992;74:441-444.

Question 538

Topic: Infection, Pharmacology & VTE

A 62-year-old diabetic patient presents with a deep plantar neuropathic ulcer under the first metatarsal head. On examination, a sterile metal probe smoothly passes through the ulcer base and strikes hard, gritty bone. Which of the following is true regarding this clinical finding?

. It has a high false-positive rate in the presence of surrounding cellulitis.
. It has a high positive predictive value for underlying osteomyelitis.
. It is diagnostic of a Wagner Grade 1 ulcer.
. It mandates immediate primary below-knee amputation.
. It requires confirmation with an urgent MRI before initiating any antibiotics.

Correct Answer & Explanation

. It has a high false-positive rate in the presence of surrounding cellulitis.

Explanation

The probe-to-bone test is highly predictive of osteomyelitis in the presence of an infected diabetic foot ulcer. It has a high positive predictive value, often negating the absolute need for advanced imaging like MRI before starting tailored therapy.

Question 539

Topic: Infection, Pharmacology & VTE

A 60-year-old diabetic woman with a history of recurrent forefoot ulcers and osteomyelitis presents for preoperative evaluation for a planned Syme amputation. Which of the following noninvasive vascular parameters is the most reliable predictor of successful wound healing at this specific amputation level?

. Absolute ankle systolic pressure > 70 mm Hg
. Transcutaneous oxygen tension (TcPO2) > 20 mm Hg
. Ankle-Brachial Index (ABI) > 0.30
. Serum albumin > 2.5 g/dL
. Total lymphocyte count > 1000/mm3

Correct Answer & Explanation

. Absolute ankle systolic pressure > 70 mm Hg

Explanation

Healing of a Syme or hindfoot amputation typically requires an absolute ankle systolic pressure greater than 70 mm Hg. Toe pressures > 40 mm Hg are used to predict forefoot healing, while a minimum serum albumin of 3.0 g/dL is generally required for reliable soft tissue healing.

Question 540

Topic: Infection, Pharmacology & VTE

Which of the following clinical tests has the highest positive predictive value for diagnosing osteomyelitis beneath a diabetic foot ulcer?

. Erythrocyte sedimentation rate (ESR) > 30 mm/hr
. Positive probe-to-bone test
. Leukocytosis > 15,000
. Positive plain radiographs
. C-reactive protein (CRP) > 10 mg/L

Correct Answer & Explanation

. Erythrocyte sedimentation rate (ESR) > 30 mm/hr

Explanation

A positive probe-to-bone test is highly predictive of underlying osteomyelitis in a diabetic foot ulcer. While MRI is the most sensitive imaging modality, the clinical probe-to-bone test remains a critical diagnostic tool.

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