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 261
Topic: Infection, Pharmacology & VTE
Which of the following is the most common immediate complication following lumbar decompression for spinal stenosis?
Correct Answer & Explanation
. Dural tear.
Explanation
Correct Answer: CIncidental durotomy (dural tear) is the most common immediate complication during or after lumbar decompression surgery, with reported rates ranging from 3% to 17%. While other complications listed can occur, dural tears are particularly frequent due to the close proximity of the dura to the compressed structures being removed (e.g., hypertrophied ligamentum flavum, osteophytes). DVT/PE (Options A, D) are less common with appropriate prophylaxis. Surgical site infection (Option B) is a serious but less frequent immediate complication. New-onset foot drop (Option E) could occur due to nerve root injury, but dural tear is generally more common.
Question 262
Topic: Infection, Pharmacology & VTE
A 50-year-old IV drug user presents with fever, severe T12 back pain, and new-onset paraparesis. Pending blood cultures and biopsy results, what is the most appropriate empiric intravenous antibiotic regimen?
Correct Answer & Explanation
. Vancomycin and Ceftriaxone
Explanation
Correct Answer: AIn a patient with risk factors for both MRSA (IV drug user) and Gram-negative bacteria (potentially via hematogenous spread or urinary source), empiric broad-spectrum coverage is essential. Vancomycin provides excellent coverage against MRSA, while a third-generation cephalosporin like Ceftriaxone provides good coverage against Gram-negative organisms, making this a common and appropriate empiric combination. Ciprofloxacin and Rifampin would be used for specific organisms (e.g., Cipro for Pseudomonas, Rifampin in combo for S. aureus after susceptibility). Penicillin G is too narrow. Doxycycline/Metronidazole targets anaerobic and atypical bacteria. Fluconazole/Amphotericin B are for fungal infections.
Question 263
Topic: Infection, Pharmacology & VTE
A 4-year-old boy presents with acute right hip pain, fever of 39.0°C, and absolute refusal to bear weight. His ESR is 50 mm/hr and WBC is 14,000/mm³. According to the Kocher criteria, what is the approximate statistical probability that this child has septic arthritis?
Correct Answer & Explanation
. 99%
Explanation
The patient meets all four classic Kocher criteria: fever > 38.5°C, non-weight-bearing status, ESR > 40 mm/hr, and WBC > 12,000/mm³. The presence of all four criteria predicts a 99% probability of septic arthritis.
Question 264
Topic: Infection, Pharmacology & VTE
A 3-year-old boy presents with a 2-day history of refusal to bear weight on his right leg. He is febrile to 39.0 degrees C. His ESR is 50 mm/hr, CRP is 4.5 mg/dL, and WBC is 14,000/mm^3. Based on the classic Kocher criteria, what is the predictive probability that this child has a septic hip?
Correct Answer & Explanation
. 99%
Explanation
The classic Kocher criteria for a septic hip include non-weight-bearing, temperature > 38.5 C, ESR > 40 mm/hr, and WBC > 12,000/mm^3. The presence of all four criteria predicts a 99% probability of septic arthritis.
Question 265
Topic: Infection, Pharmacology & VTE
A 55-year-old intravenous drug user presents with severe back pain. MRI reveals L3-L4 discitis and adjacent osteomyelitis without epidural compression. He is hemodynamically stable and neurologically intact. Blood cultures have been drawn but are pending. What is the next best step in management?
Correct Answer & Explanation
. CT-guided needle biopsy of the disc space
Explanation
In a hemodynamically stable, neurologically intact patient with suspected vertebral osteomyelitis/discitis, an image-guided biopsy should be performed to direct antibiotic therapy before empiric antibiotics are started.
Question 266
Topic: Infection, Pharmacology & VTE
A 45-year-old intravenous drug user presents with swelling, erythema, and severe pain over the sternoclavicular joint. Aspiration yields purulent fluid. What is the most common organism responsible for septic arthritis of the SC joint in this patient population?
Correct Answer & Explanation
. Staphylococcus aureus
Explanation
While Pseudomonas aeruginosa is classically taught as being associated with IV drug use, Staphylococcus aureus is still the most common overall pathogen responsible for septic arthritis of the sternoclavicular joint in all patient demographics.
Question 267
Topic: Infection, Pharmacology & VTE
A 67-year-old female sustains a posteromedial shear fracture of the tibial plateau.
What is the optimal surgical interval to address this specific fracture fragment with buttress plating?
Correct Answer & Explanation
. Between the medial head of the gastrocnemius and the pes anserinus.
Explanation
Posteromedial plateau fragments require buttress plating applied from the posteromedial side to effectively counteract shear forces. The classic posteromedial approach utilizes the interval between the medial head of the gastrocnemius (retracted posteriorly) and the pes anserinus (retracted anteriorly).
Question 268
Topic: Infection, Pharmacology & VTE
A patient is considering ankle fusion and asks about potential complications.
Which of the following is NOT listed in the case as a potential complication of ankle fusion?
Correct Answer & Explanation
. Exacerbating or developing arthritis in other joints
Explanation
Correct Answer: DThe candidate lists the following complications for ankle fusion: 'Non-union, malunion, delayed union, infection, wound-healing problems, nerve or vessel damage, DVT/PE, risk of exacerbating or developing arthritis in other joints.' Stress fracture of the ipsilateral tibia is not mentioned in this list.Options A, B, C, and E are all explicitly listed as potential complications of ankle fusion in the case.
Question 269
Topic: Infection, Pharmacology & VTE
When discussing consent for the proposed Scarf osteotomy, the candidate outlines potential complications.
Which of the following complications is explicitly mentioned by the candidate as a possibility following a Scarf osteotomy?
Correct Answer & Explanation
. Significant stiffness of the MTP joint and sensory loss due to dorsomedial sensory nerve injury.
Explanation
Correct Answer: CThe candidate explicitly states: 'A minority of patients will have significant stiffness of the MTP joint afterwards and there can be sensory loss if the dorsomedial sensory nerve is injured.' While DVT/PE and CRPS are general surgical risks, they are not specifically highlighted by the candidate in this discussion. Avascular necrosis is a known complication of some distal osteotomies (e.g., Chevron) but not specifically emphasized for Scarf in this context. The recurrence risk is mentioned as 'greatest in adolescent cases' and not given a specific high percentage like 50% for this patient.
Question 270
Topic: Infection, Pharmacology & VTE
According to the AAOS Clinical Practice Guidelines on the management of osteoarthritis of the knee, which of the following non-operative modalities has a strong recommendation against its use?
The AAOS guidelines provide a strong recommendation against the use of intra-articular hyaluronic acid for symptomatic knee osteoarthritis, citing a lack of clinically significant efficacy over placebo. NSAIDs, weight loss, and physical therapy all have strong recommendations for use.
Question 271
Topic: Infection, Pharmacology & VTE
According to the American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines for the management of osteoarthritis of the knee, which of the following non-operative treatments is strongly recommended based on high-quality evidence?
Correct Answer & Explanation
. Weight loss and oral nonsteroidal anti-inflammatory drugs (NSAIDs)
Explanation
The AAOS strongly recommends weight loss, physical therapy, and oral NSAIDs for the symptomatic treatment of knee osteoarthritis. High-quality evidence has consistently demonstrated a lack of efficacy for oral glucosamine/chondroitin, lateral wedge insoles, and intra-articular hyaluronic acid in the routine management of primary knee OA.
Question 272
Topic: Infection, Pharmacology & VTE
Aspirin is often used for deep vein thrombosis (DVT) prophylaxis following total joint arthroplasty. What is the primary mechanism of action of aspirin in this clinical context?
Correct Answer & Explanation
. Irreversible inhibition of cyclooxygenase-1 (COX-1)
Explanation
Aspirin acts by irreversibly inhibiting the cyclooxygenase-1 (COX-1) enzyme, which prevents the production of thromboxane A2 and inhibits platelet aggregation for the lifespan of the platelet. This provides effective and cost-efficient DVT prophylaxis in appropriate orthopedic patients.
Question 273
Topic: Infection, Pharmacology & VTE
A 15-year-old non-ambulatory patient with Duchenne Muscular Dystrophy is recovering from a posterior spinal fusion. On postoperative day 2, the patient develops increasing shortness of breath, decreased oxygen saturation, and a weak cough. Which of the following is the most likely early postoperative complication in this patient, and what is the immediate management strategy?
Correct Answer & Explanation
. Respiratory insufficiency/failure; Prolonged mechanical ventilation and aggressive pulmonary hygiene.
Explanation
Correct Answer: CThe case identifies respiratory insufficiency/failure as a moderate-to-high incidence early postoperative complication in DMD patients, especially after major surgery like spinal fusion. Symptoms like increasing shortness of breath, decreased oxygen saturation, and a weak cough are classic signs. The recommended management strategy includes prolonged mechanical ventilation (invasive/non-invasive), aggressive pulmonary hygiene, early mobilization, and respiratory consult.Option A (Deep Vein Thrombosis (DVT); Initiate immediate systemic anticoagulation):DVT is a possible complication, but the symptoms described (shortness of breath, decreased O2 sat, weak cough) are more indicative of primary respiratory compromise rather than a DVT/PE as the initial event. While DVT prophylaxis is important, this is not the most likely immediate cause of these specific symptoms.Option B (Wound infection; Administer broad-spectrum antibiotics and consider wound debridement):Wound infection is a possibility, but it typically presents with local signs (redness, warmth, drainage, fever) and usually manifests a few days later. The described symptoms are not typical for an early wound infection.Option D (Cardiac decompensation; Optimize cardiac medications and transfer to ICU):Cardiac decompensation is a risk, but the symptoms (shortness of breath, decreased O2 sat, weak cough) are more directly related to pulmonary mechanics and respiratory muscle weakness, which are profoundly affected in DMD, especially post-spinal surgery. While cardiac monitoring is crucial, respiratory issues are often the more immediate and direct concern in this scenario.Option E (Pseudarthrosis; Plan for revision surgery with additional bone graft):Pseudarthrosis (non-union) is a late postoperative complication, occurring months to years after surgery, not on postoperative day 2.
Question 274
Topic: Infection, Pharmacology & VTE
The 33-year-old patient's current symptom of intermittent painful locking is directly caused by the loose body. What is the most appropriate definitive treatment for this patient's current symptoms and to prevent future locking episodes?
Correct Answer & Explanation
. Arthroscopic removal of the loose body
Explanation
Correct Answer: CExplanation:The patient's primary symptom is intermittent painful locking caused by a loose body. The most appropriate definitive treatment for a symptomatic intra-articular loose body in the elbow isarthroscopic removal of the loose body. This procedure directly addresses the mechanical obstruction causing the locking and pain. Physical therapy and activity modification (A) and NSAIDs and observation (B) are conservative measures that may temporarily alleviate symptoms but will not remove the mechanical block or prevent future locking episodes. Open reduction and internal fixation (D) would be considered if the loose body was a large, viable osteochondral fragment that could be reattached to its bed, but for a free, symptomatic loose body causing locking, simple removal is typically preferred. Corticosteroid injections (E) may reduce inflammation but will not resolve the mechanical issue of a loose body.
Question 275
Topic: Infection, Pharmacology & VTE
A 72-year-old diabetic female undergoes a two-stage revision for chronic PJI due to MRSA. The first stage involves implant removal, extensive debridement, and placement of an articulating antibiotic-loaded cement spacer. After 6 weeks of targeted intravenous antibiotics, her ESR is 25 mm/hr (down from 80), CRP is 3 mg/L (down from 55), and repeat knee aspirations are negative for growth on multiple cultures. What is the most critical next step before proceeding to the second stage of reimplantation?
Correct Answer & Explanation
. Confirm absence of infection with at least two consecutive negative synovial fluid cultures, ideally off antibiotics for a period.
Explanation
Correct Answer: CThe most critical step to confirm infection eradication before proceeding to the second stage of reimplantation is obtaining at least two, preferably three, consecutive negative synovial fluid cultures from the knee, ideally after a period off antibiotics (e.g., 2 weeks) to reduce false negatives. While inflammatory markers (ESR, CRP) can guide treatment, they are not definitive for eradication. Imaging (MRI, CT) may be useful for assessing bone stock or identifying occult infection but does not replace microbiological confirmation. Serum alpha-defensin is a diagnostic marker for PJI, not typically used for confirming eradication post-treatment. Empirically continuing antibiotics without microbiological clearance increases the risk of resistance and does not confirm eradication.
Question 276
Topic: Infection, Pharmacology & VTE
The examiner asks about removing the acetabular component. The candidate states the safest way is to disrupt the PE cup from the cement using curved gouges. After removal of the cup, the cement is removed piecemeal. What is the primary reason for this specific initial approach to acetabular component removal?
Correct Answer & Explanation
. B. To prevent inadvertent damage to the bone of the acetabulum bed
Explanation
Correct Answer: BExplanation:The case describes the acetabular component removal: 'The safest way is to disrupt the PE cup from the cement using curved gouges. This prevents inadvertent damage to the bone of the acetabulum bed. After removal of the cup the cement is removed piecemeal.'A. To allow for easier visualization of anchoring holes for burring:While visualization is important, the primary reason stated for this initial step is bone protection, not specifically visualization for burring. Burring comes later for debulking cement.B. To prevent inadvertent damage to the bone of the acetabulum bed:This is the explicit reason given in the case for disrupting the PE cup from the cement first with curved gouges. Protecting the host bone is paramount in revision surgery.C. To facilitate the use of a threaded extractor through a drill hole:A threaded extractor is mentioned as analternativemethod ('Sometimes a threaded extractor through a drill hole in the PE can be used'), not the primary reason for the initial gouge technique.D. To reduce operating time and blood loss:While efficient removal can contribute to this, the primary stated reason for this specific technique is safety and bone preservation, not necessarily a reduction in time or blood loss.E. To ensure complete removal of all polyethylene debris:While removing the PE cup is part of the process, the stated reason forthis specific initial techniqueis bone protection, not debris removal.
Question 277
Topic: Infection, Pharmacology & VTE
Which of the following is the most critical factor determining the success of a debridement, antibiotics, and implant retention (DAIR) procedure for an acute periprosthetic knee infection?
Correct Answer & Explanation
. Duration of symptoms prior to intervention
Explanation
The duration of symptoms is the most critical determinant of DAIR success, with significantly higher failure rates if symptoms have been present for more than 3 to 4 weeks. Early intervention is paramount before a mature biofilm can fully establish on the implant surfaces.
Question 278
Topic: Infection, Pharmacology & VTE
Which of the following describes the primary mechanism by which adding Rifampin enhances the efficacy of antibiotic regimens in the treatment of staphylococcal periprosthetic joint infections?
Correct Answer & Explanation
. It penetrates bacterial biofilms and kills stationary-phase organisms on the implant surface.
Explanation
Rifampin is uniquely highly effective against staphylococcal species residing within biofilms on orthopedic implants. It penetrates the biofilm matrix and kills slow-growing, stationary-phase bacteria by inhibiting DNA-dependent RNA polymerase.
Question 279
Topic: Infection, Pharmacology & VTE
According to the American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines for the non-operative management of knee osteoarthritis, which of the following treatments has a "Strong" recommendation FOR its use?
Oral NSAIDs, topical NSAIDs, and supervised exercise/weight loss have "Strong" recommendations for treating symptomatic knee OA. Intra-articular hyaluronic acid and glucosamine/chondroitin are explicitly not recommended by current AAOS guidelines.
Question 280
Topic: Infection, Pharmacology & VTE
According to the American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines for the non-operative management of knee osteoarthritis, which of the following treatments is strongly recommended against?
Correct Answer & Explanation
. Intra-articular hyaluronic acid injections
Explanation
The AAOS strongly recommends against the use of intra-articular hyaluronic acid (viscosupplementation) for symptomatic osteoarthritis of the knee due to a lack of clinically significant efficacy in high-quality studies.
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