1. General Principles & Basic Science MCQs

A new diagnostic test for diagnosing prosthetic joint infection has a sensitivity of 90% and a specificity of 95%. If the prevalence of the disease in the tested population increases from 2% to 10%, which of the following statistical parameters will also increase?

A 12-year-old boy presents with multiple fractures and a history of anemia and cranial nerve palsies. Radiographs reveal generalized osteosclerosis and a 'bone-within-bone' appearance. Which of the following is the most likely cellular defect responsible for this condition?

In the pathogenesis of periprosthetic joint infections, bacteria form a biofilm to evade host defenses and antibiotics. Which of the following terms describes the intercellular communication mechanism used by bacteria to coordinate gene expression and initiate biofilm formation?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized in orthopedic and spine surgery to augment bone healing. BMP-2 initiates the osteoinductive signaling cascade by binding to serine-threonine kinase receptors. Which intracellular signaling molecules are directly phosphorylated by this activated receptor complex?

Which of the following modifications to a cortical bone screw design would most significantly increase its pullout strength?

According to Perren's strain theory, what is the maximum gap strain environment that will allow for primary (direct) bone healing without the formation of a visible fracture callus?

A 4-year-old boy presents with progressive bowing of his legs. Laboratory testing reveals normal serum calcium, markedly decreased serum phosphate, normal PTH, and elevated alkaline phosphatase. A genetic defect is identified on the X chromosome. Which of the following circulating factors is primarily responsible for the renal phosphate wasting in this patient?

Tranexamic acid (TXA) has become a standard pharmacological agent to reduce perioperative blood loss in total joint arthroplasty. What is the precise mechanism of action of this drug?

During a revision open reduction internal fixation of a distal femur fracture, a surgeon applies a titanium locking plate and secures it using stainless steel screws. What type of corrosion is most likely to occur at the interface between the plate and the screws?

Following a closed humerus fracture, a patient develops a radial nerve palsy. An EMG at 4 weeks shows fibrillation potentials, but the nerve remains anatomically continuous with disruption of axons and their myelin sheath, while the endoneurium, perineurium, and epineurium remain intact. This injury corresponds to which Sunderland grade?

When a massive structural cortical allograft is utilized in reconstructive surgery, the process of 'creeping substitution' dictates its incorporation. During the initial 6 to 12 months of this process, what happens to the mechanical strength of the allograft?

Articular cartilage provides a nearly frictionless surface for joint articulation. Which zone of articular cartilage contains the highest concentration of water and collagen fibers oriented parallel to the joint surface, providing the highest resistance to tensile and shear forces?

During the normal human gait cycle, at what point does the maximum compressive force occur across the hip joint?

A 68-year-old woman is prescribed alendronate for the treatment of severe osteoporosis. By which of the following intracellular mechanisms does this drug primarily inhibit osteoclast-mediated bone resorption?

Which type of corrosion is most likely to occur in the restricted, oxygen-depleted space between the head and neck taper of a modular total hip arthroplasty implant?

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is FDA-approved for use in acute, open tibial shaft fractures. Which intracellular signaling pathway is primarily activated by BMP-2 binding to its receptor?

A patient with malignant infantile osteopetrosis is found to have defective osteoclasts. The loss of function of which of the following enzymes is a well-known genetic cause of the failure of osteoclasts to acidify the bone surface?

On a stress-strain curve representing the mechanical properties of a bone plate, what does the area under the curve up to the yield point represent?

During a regional block, a patient inadvertently receives an intravascular injection of bupivacaine and subsequently develops refractory cardiac arrest. What is the recommended first-line antidote for this specific toxicity?