1. General Principles & Basic Science MCQs

A randomized trial investigates a new drug to prevent deep vein thrombosis (DVT) after pelvic trauma. The incidence of DVT in the control group is 15%, while the incidence in the treatment group is 5%. What is the number needed to treat (NNT) to prevent one DVT?

A new diagnostic joint aspirate test for periprosthetic joint infection is implemented in a region where the prevalence of the disease recently doubled. Assuming the intrinsic sensitivity and specificity of the test remain unchanged, which of the following statistical parameters will increase?

A patient experiences a profound motor deficit in the extremity without significant sensory loss after the use of a pneumatic tourniquet for 140 minutes during upper limb reconstructive surgery. What is the primary pathophysiological mechanism responsible for this nerve injury?

A 35-year-old male sustains a multifragmentary diaphyseal femur fracture. The surgeon opts for a bridge plating technique to provide relative stability. According to Perren's strain theory, what range of gap strain is optimal for promoting secondary bone healing (callus formation)?

During a biomechanical testing study, a solid cylindrical titanium rod with a radius of 2 cm is compared to another solid titanium rod with a radius of 4 cm. Assuming identical length and loading conditions, how much stiffer in bending is the larger rod compared to the smaller one?

A randomized controlled trial evaluating a new nonsteroidal anti-inflammatory drug for knee osteoarthritis reports a p-value of 0.03, leading researchers to conclude it is superior to placebo. If the drug is actually no more effective than placebo in reality, what type of statistical error has occurred?

During anterior cruciate ligament reconstruction, the graft is tensioned and secured. Over time, the surgeon notes that the tension required to hold the graft at a constant length decreases. Which viscoelastic property does this phenomenon represent?

A 45-year-old man requires an urgent open reduction and internal fixation for a closed tibia plateau fracture. He has a documented history of severe anaphylaxis to penicillin. Which of the following is the most appropriate perioperative prophylactic antibiotic regimen?

A 28-year-old male sustains a massive segmental bone defect of the radius and receives a structural cortical allograft. During the physiological process of creeping substitution, what is the initial cellular phase that the cortical graft undergoes?

An infection control committee reviews a new silver-impregnated surgical dressing designed to prevent deep surgical site infections. A robust trial shows the absolute risk reduction (ARR) of infection using this dressing is 4% (0.04). What is the Number Needed to Treat (NNT) to prevent one additional infection?

During a complex revision total hip arthroplasty, a surgeon utilizes a 316L stainless steel screw to secure a titanium alloy acetabular component. Which of the following complications is most likely to occur at the interface of these two metals?

A researcher is studying the mechanical properties of cortical bone. On a standard stress-strain curve representing the tensile testing of a bone specimen, what term defines the exact point where the material transitions from elastic deformation to permanent plastic deformation?

A 72-year-old man on chronic warfarin therapy for atrial fibrillation presents with a closed, displaced femoral neck fracture. His admission INR is 3.8. He requires urgent surgical fixation within 24 to 48 hours. What is the most effective and rapid pharmacological method to reverse his coagulopathy?

To appropriately minimize the risk of surgical site infection in a primary total hip arthroplasty, standard prophylactic intravenous antibiotics (e.g., Cefazolin) should ideally be completely infused within what timeframe?

During bone graft incorporation, creeping substitution describes the process by which a graft is resorbed and replaced by host bone. Which of the following graft types relies entirely on creeping substitution and osteoconduction, completely lacking live osteogenic cells?

A 40-year-old woman undergoes prolonged pelvic surgery in the lithotomy position. Post-operatively, she complains of numbness over the anterolateral aspect of her leg and the dorsum of her foot, accompanied by a foot drop. Which nerve was most likely injured due to poor positioning?

A new clinical test for detecting meniscal tears is evaluated in a population of 1000 patients. MRI confirms that 100 patients truly have a meniscal tear. The new test is positive in 90 of the patients with a tear, and positive in 90 of the patients without a tear. What is the Positive Predictive Value (PPV) of this new test?