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Question 921

Topic: Infection, Pharmacology & VTE



During harvest of a hamstring autograft, the pes anserinus is exposed via an anteromedial tibial incision. From anterior to posterior, what is the correct order of the tendinous insertions?

. Sartorius, Gracilis, Semitendinosus
. Gracilis, Sartorius, Semitendinosus
. Semitendinosus, Gracilis, Sartorius
. Sartorius, Semitendinosus, Gracilis
. Gracilis, Semitendinosus, Sartorius

Correct Answer & Explanation

. Sartorius, Gracilis, Semitendinosus


Explanation

The mnemonic 'Say Grace before Tea' dictates the anterior-to-posterior orientation of the pes anserinus: Sartorius, Gracilis, and Semitendinosus.

Question 922

Topic: Infection, Pharmacology & VTE
The recent PREVENT CLOT trial compared low-molecular-weight heparin (LMWH) and aspirin for venous thromboembolism (VTE) prophylaxis in patients with extremity fractures. What was the primary finding regarding the use of aspirin compared to LMWH in this patient population?
. Aspirin was associated with a higher rate of fatal pulmonary embolism.
. Aspirin was non-inferior to LMWH in preventing fatal and non-fatal pulmonary embolisms.
. Aspirin demonstrated a significantly higher rate of deep surgical site infections.
. LMWH provided superior protection against deep vein thrombosis but with a lower bleeding risk.
. Aspirin was inferior to LMWH in preventing overall mortality.

Correct Answer & Explanation

. Aspirin was non-inferior to LMWH in preventing fatal and non-fatal pulmonary embolisms.


Explanation

The PREVENT CLOT trial (2023) demonstrated that in patients treated operatively for extremity fractures, thromboprophylaxis with aspirin was non-inferior to low-molecular-weight heparin (LMWH) in preventing death and pulmonary embolism, supporting the safety and efficacy of aspirin in this population.

Question 923

Topic: Infection, Pharmacology & VTE

In the original Kocher criteria for differentiating pediatric septic arthritis from transient synovitis of the hip, which of the following laboratory/clinical parameters was NOT one of the four factors used?

. White blood cell count > 12,000 cells/mm3
. Erythrocyte sedimentation rate (ESR) > 40 mm/hr
. Temperature > 38.5 degrees Celsius
. Serum C-reactive protein (CRP) > 2.0 mg/dL
. Inability to bear weight

Correct Answer & Explanation

. White blood cell count > 12,000 cells/mm3


Explanation

The original four Kocher criteria are: non-weight bearing, temperature > 38.5 C, ESR > 40 mm/hr, and WBC > 12,000 cells/mm3. CRP > 2.0 mg/dL was later validated and added by Caird et al., creating a 5-factor model, but it was not part of the original 4 criteria.

Question 924

Topic: Infection, Pharmacology & VTE
A 2-year-old child presents with a limp, fever of 38.5°C, and refusal to bear weight on the left leg. Aspiration of the hip yields purulent fluid. Which of the following organisms is the most common cause of joint infections in this specific age group and often requires specialized culture techniques (e.g., BACTEC blood culture bottles) for detection?
. Staphylococcus aureus
. Kingella kingae
. Streptococcus pneumoniae
. Haemophilus influenzae type b
. Neisseria gonorrhoeae

Correct Answer & Explanation

. Kingella kingae


Explanation

Kingella kingae is a fastidious Gram-negative coccobacillus that has surpassed S. aureus as the most common cause of septic arthritis and osteomyelitis in children under the age of 4. It is notoriously difficult to grow on standard solid media, and its detection rate increases significantly when synovial fluid is inoculated directly into blood culture vials.

Question 925

Topic: Infection, Pharmacology & VTE
A 5-year-old boy presents with acute right hip pain, inability to bear weight, a temperature of 38.8°C (101.8°F), a WBC count of 14,000/mm³, and an ESR of 55 mm/hr. According to the Kocher criteria, what is the most appropriate next step in management?
. Observation and administration of NSAIDs
. MRI of the bilateral hips with contrast
. Immediate open arthrotomy without aspiration
. Ultrasound-guided hip aspiration
. Bone scan of the lower extremities

Correct Answer & Explanation

. Ultrasound-guided hip aspiration


Explanation

This patient meets all four Kocher criteria (non-weight bearing, fever, ESR > 40, WBC > 12k), predicting a 99% probability of septic arthritis. The next best step is an ultrasound-guided aspiration of the hip to confirm the diagnosis and identify the organism before surgical washout.

Question 926

Topic: Infection, Pharmacology & VTE
A 4-year-old child presents with an acute onset of an inability to bear weight on the right leg, a temperature of 38.8°C, an ESR of 50 mm/hr, and a WBC count of 13,000/mm³. According to the Kocher criteria, what is the probability that this child has septic arthritis of the hip?
. < 10%
. 25-35%
. 50-60%
. 70-80%
. > 90%

Correct Answer & Explanation

. > 90%


Explanation

This patient meets all four Kocher criteria: non-weight bearing, temperature >38.5°C, ESR >40 mm/hr, and WBC >12,000/mm³. The presence of all four criteria correlates with a 99% predictive probability of septic arthritis.

Question 927

Topic: Infection, Pharmacology & VTE

A surgeon is exposing the medial tibia to harvest hamstring tendons for ACL reconstruction. From anterior to posterior, what is the correct anatomic order of the pes anserinus tendon insertions?

. Gracilis, Sartorius, Semitendinosus
. Semitendinosus, Gracilis, Sartorius
. Sartorius, Gracilis, Semitendinosus
. Sartorius, Semitendinosus, Gracilis
. Gracilis, Semitendinosus, Sartorius

Correct Answer & Explanation

. Gracilis, Sartorius, Semitendinosus


Explanation

The tendons of the pes anserinus insert on the proximal medial tibia. From anterior to posterior, they are the Sartorius, Gracilis, and Semitendinosus (SGS).

Question 928

Topic: Infection, Pharmacology & VTE

A 19-year-old football player sustains a severe blunt trauma to his anterior thigh from a helmet collision. Three weeks later, he presents with significantly restricted knee flexion and a firm, painful mass in his quadriceps. Radiographs demonstrate peripheral calcification within the muscle belly. What is the most appropriate initial management for this condition?

. Immediate surgical excision of the mass to restore motion
. Aggressive passive stretching under regional anesthesia
. Extracorporeal shockwave therapy and deep tissue massage
. Rest, gentle active range of motion, and NSAIDs
. Intralesional corticosteroid injection followed by casting

Correct Answer & Explanation

. Immediate surgical excision of the mass to restore motion


Explanation

The patient has developed myositis ossificans traumatica following a severe quadriceps contusion. The hallmark radiographic finding at 3-4 weeks is peripheral maturation/calcification with a radiolucent center. Initial management is strict nonoperative care, including rest, gentle active (not passive) range of motion, and NSAIDs (like Indomethacin) to help halt further heterotopic bone formation. Aggressive passive stretching or massage can exacerbate the condition. Surgical excision is absolutely contraindicated in the acute/immature phase due to an extremely high risk of recurrence; it is only considered if the mass remains symptomatic after full maturation (typically 6-12 months).

Question 929

Topic: Infection, Pharmacology & VTE

A 78-year-old female on chronic warfarin therapy sustains a displaced femoral neck fracture. Her admission INR is 3.5. To facilitate urgent surgical intervention within 24 hours, what is the best agent for rapid reversal of her anticoagulation?

. Intravenous Vitamin K
. Fresh Frozen Plasma (FFP)
. Prothrombin Complex Concentrate (PCC)
. Cryoprecipitate
. Protamine sulfate

Correct Answer & Explanation

. Intravenous Vitamin K


Explanation

Prothrombin Complex Concentrate (PCC) is the preferred agent for rapid, reliable reversal of vitamin K antagonists like warfarin in urgent surgical scenarios. It works faster and has lower volume overload risks compared to FFP.

Question 930

Topic: Infection, Pharmacology & VTE

An 82-year-old female sustains a non-displaced femoral neck fracture. To minimize mortality and morbidity, national guidelines recommend that surgical intervention should ideally be performed within what timeframe from admission?

. Within 6 hours
. Within 72 hours
. Within 24-48 hours
. Within 5 days
. Once all medical comorbidities are completely resolved

Correct Answer & Explanation

. Within 6 hours


Explanation

There is a strong consensus among major orthopedic societies (e.g., AAOS) that surgical intervention for geriatric hip fractures should ideally be performed within 24 to 48 hours of admission. Delays beyond this timeframe significantly increase mortality, pneumonia, DVT, and pressure ulcers.

Question 931

Topic: Infection, Pharmacology & VTE

An 82-year-old female with a history of atrial fibrillation presents with a displaced femoral neck fracture. She is taking Apixaban (a direct factor Xa inhibitor). What is the optimal timing for surgery to minimize mortality and bleeding risk?

. Delay surgery for 5 days to allow complete washout of Apixaban
. Proceed with surgery within 48 hours; consider holding Apixaban for 24-48 hours depending on renal function
. Administer Vitamin K and Fresh Frozen Plasma, then proceed to surgery immediately
. Administer Protamine sulfate and proceed to surgery immediately
. Perform non-operative management only

Correct Answer & Explanation

. Delay surgery for 5 days to allow complete washout of Apixaban


Explanation

Current guidelines advocate surgery within 48 hours for geriatric hip fractures. For patients on direct oral anticoagulants like Apixaban, surgery can typically be safely performed after holding the medication for 24-48 hours. Vitamin K and FFP do not reverse DOACs.

Question 932

Topic: Infection, Pharmacology & VTE

An 82-year-old female sustains an open distal femur fracture. Her medical history includes atrial fibrillation, for which she takes rivaroxaban (a direct Factor Xa inhibitor). She requires urgent surgical debridement and stabilization. If she experiences severe, life-threatening hemorrhage during surgery, what is the most specific and appropriate reversal agent?

. Idarucizumab
. Andexanet alfa
. Protamine sulfate
. Vitamin K and Fresh Frozen Plasma
. Desmopressin (DDAVP)

Correct Answer & Explanation

. Idarucizumab


Explanation

Rivaroxaban (Xarelto) and apixaban (Eliquis) are direct Factor Xa inhibitors. The specific reversal agent for life-threatening bleeding in patients taking these medications is Andexanet alfa, a recombinant modified human Factor Xa decoy protein. Idarucizumab is the specific reversal agent for dabigatran (a direct thrombin inhibitor). Protamine sulfate reverses heparin, and Vitamin K/FFP (or Prothrombin Complex Concentrate) is used for warfarin reversal.

Question 933

Topic: Infection, Pharmacology & VTE

During a total knee arthroplasty for a severe varus deformity, the medial compartment remains tight in both flexion and extension after initial bone resections. Which of the following is the most appropriate sequence of soft tissue release?

. Deep medial collateral ligament (MCL), posterior medial corner, semimembranosus, superficial MCL
. Superficial MCL, pes anserinus, deep MCL, posterior oblique ligament
. Deep MCL, superficial MCL (anterior aspect), pes anserinus, posterior medial corner
. Deep MCL, posteromedial capsule, semimembranosus, superficial MCL
. Iliotibial band, popliteus, lateral collateral ligament

Correct Answer & Explanation

. Deep medial collateral ligament (MCL), posterior medial corner, semimembranosus, superficial MCL


Explanation

For a tight medial compartment (varus knee) in both flexion and extension, standard releases proceed sequentially: 1. Osteophyte removal; 2. Deep MCL release; 3. Posteromedial capsule and semimembranosus (to address extension tightness); 4. Superficial MCL subperiosteal stripping; 5. Pes anserinus.

Question 934

Topic: Infection, Pharmacology & VTE
A 4-year-old child presents with a limp, fever of 39.0°C, and inability to bear weight. Laboratory tests show a WBC of 14,000/mm³ and an ESR of 55 mm/hr. According to the Kocher criteria, what is the probability that this child has septic arthritis of the hip?
. Less than 10%
. Approximately 40%
. Approximately 70%
. Greater than 90%
. 100%

Correct Answer & Explanation

. Greater than 90%


Explanation

The Kocher criteria to differentiate septic arthritis from transient synovitis include: non-weight-bearing on the affected side, temperature > 38.5°C, ESR > 40 mm/hr, and WBC > 12,000/mm³. Having all 4 predictors yields a 99% probability (greater than 90%) of septic arthritis.

Question 935

Topic: Infection, Pharmacology & VTE
A patient is prescribed rivaroxaban for deep vein thrombosis (DVT) prophylaxis following total hip arthroplasty. Rivaroxaban exerts its anticoagulant effect through the direct inhibition of which component of the coagulation cascade?
. Thrombin (Factor IIa)
. Factor Xa
. Antithrombin III
. Vitamin K epoxide reductase
. Plasminogen

Correct Answer & Explanation

. Factor Xa


Explanation

Rivaroxaban and Apixaban are direct oral anticoagulants (DOACs) that specifically and reversibly inhibit free and clot-bound Factor Xa (hence the suffix '-xaban'). This interrupts both the intrinsic and extrinsic pathways of the coagulation cascade. Dabigatran (Option A) is a direct thrombin (IIa) inhibitor. Warfarin inhibits Vitamin K epoxide reductase (Option D).

Question 936

Topic: Infection, Pharmacology & VTE

During a regional block for an orthopaedic procedure, a patient develops sudden perioral numbness, tinnitus, and subsequent cardiovascular collapse. Which of the following agents is the primary targeted rescue treatment for this acute condition?

. Flumazenil
. Naloxone
. 20% Lipid emulsion
. Intravenous calcium gluconate
. Protamine sulfate

Correct Answer & Explanation

. Flumazenil


Explanation

The patient is exhibiting signs of Local Anesthetic Systemic Toxicity (LAST), most commonly associated with highly lipid-soluble agents like bupivacaine. The primary targeted rescue therapy is the rapid intravenous administration of a 20% lipid emulsion (Intralipid), which creates a 'lipid sink' in the intravascular space, drawing the lipophilic anesthetic away from susceptible cardiac and neural tissues.

Question 937

Topic: Infection, Pharmacology & VTE
A 65-year-old male is prescribed rivaroxaban for deep vein thrombosis prophylaxis following a total hip arthroplasty. What is the specific molecular target of this medication?
. Thrombin (Factor IIa)
. Factor Xa
. Vitamin K epoxide reductase
. Antithrombin III
. Platelet P2Y12 receptor

Correct Answer & Explanation

. Factor Xa


Explanation

Rivaroxaban is a Direct Oral Anticoagulant (DOAC) that exerts its effect by directly and reversibly inhibiting Factor Xa, halting the conversion of prothrombin to thrombin in the coagulation cascade. Dabigatran, another DOAC, acts via direct thrombin (Factor IIa) inhibition. Warfarin targets Vitamin K epoxide reductase, and clopidogrel targets the P2Y12 receptor.

Question 938

Topic: Infection, Pharmacology & VTE

During the pathogenesis of orthopedic implant infections, Staphylococcus aureus forms a biofilm. Which of the following host-pathogen interactions mediates the initial irreversible adhesion phase to the implant surface?

. Planktonic dispersion driven by physical forces
. Exopolysaccharide matrix secretion
. Microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) binding to host proteins
. Quorum-sensing molecule diffusion
. Teichoic acid degradation

Correct Answer & Explanation

. Planktonic dispersion driven by physical forces


Explanation

MSCRAMMs mediate the initial irreversible adhesion of bacteria to the host-protein coated implant surface. Following this attachment, the bacteria multiply and secrete an exopolysaccharide matrix to develop a mature biofilm.

Question 939

Topic: Infection, Pharmacology & VTE

In correcting a severe varus deformity during a primary total knee arthroplasty, after resection of osteophytes, the medial side remains tight in both flexion and extension. According to standard medial release algorithms, which structure is typically released first?

. Superficial medial collateral ligament
. Pes anserinus tendons
. Deep medial collateral ligament
. Semimembranosus tendon
. Posterior cruciate ligament

Correct Answer & Explanation

. Superficial medial collateral ligament


Explanation

In a varus knee, the deep MCL and medial capsule are typically released first along with comprehensive osteophyte removal. If further balancing is needed, the superficial MCL and pes anserinus can be sequentially addressed.

Question 940

Topic: Infection, Pharmacology & VTE
A 16-month-old male presents with a refusal to bear weight on his left leg and a low-grade fever (38.1°C). His WBC count is normal, but CRP is elevated (35 mg/L). Joint aspiration of the knee yields synovial fluid with 65,000 WBCs/mm³. Standard Gram stain and routine cultures are negative at 48 hours. A specialized PCR of the synovial fluid returns positive for a Gram-negative coccobacillus. Which of the following organisms is the most likely pathogen?
. Staphylococcus aureus
. Streptococcus pyogenes
. Kingella kingae
. Haemophilus influenzae type b
. Neisseria gonorrhoeae

Correct Answer & Explanation

. Kingella kingae


Explanation

Kingella kingae is now recognized as the most common cause of septic arthritis in children between the ages of 6 months and 4 years. It is a slow-growing, Gram-negative coccobacillus that frequently colonizes the oropharynx. It is notoriously difficult to grow on solid routine culture media but grows better when inoculated directly into blood culture vials (BACTEC) or detected via specific PCR assays. Standard Gram stains are often negative.