1. General Principles & Basic Science MCQs

Tranexamic acid (TXA) is widely used in orthopedic surgery to reduce perioperative blood loss. Which of the following best describes its primary mechanism of action?

A 30-year-old male presents with recurrent fractures and a radiograph showing generalized osteosclerosis with a rugger jersey spine appearance. A defect in the osteoclast ruffled border is suspected. A mutation in which of the following is the most likely cause?

Articular cartilage is highly specialized to withstand complex mechanical environments. Which zone of articular cartilage is primarily responsible for resisting shear stress and contains collagen fibers oriented parallel to the joint surface?

A 65-year-old female with a modular unipolar hemiarthroplasty presents with new-onset groin pain and a large sterile effusion 5 years postoperatively. Revision surgery reveals black debris and corrosion at the head-neck junction. Which of the following best describes the underlying tribological mechanism?

Which of the following best describes the viscoelastic property of cortical bone when subjected to a rapid rate of loading?

According to Perren's strain theory, what interfragmentary strain environment is required to allow for primary (direct) bone healing without callus formation?

Articular cartilage is composed of multiple zones with varying biochemical compositions. Which zone contains the highest concentration of water and the lowest concentration of proteoglycans?

A 45-year-old woman with a history of malabsorption syndrome presents with bone pain and a fragility fracture. Labs show low 25-hydroxyvitamin D. Which of the following laboratory profiles is most consistent with severe nutritional osteomalacia?

A 60-year-old man presents with back pain, anemia, and hypercalcemia. Radiographs show multiple punched-out lytic lesions in his skull and spine. In this condition, which cytokine is predominantly secreted by neoplastic plasma cells to activate osteoclasts?

During the lifecycle of a bacterial biofilm on an infected orthopedic implant, which phase represents the systemic shedding of bacteria to colonize new sites?

A 19-year-old male presents with night pain in his proximal femur that is dramatically relieved by ibuprofen. Radiographs show a 1 cm radiolucent nidus surrounded by reactive sclerosis. The intense pain associated with this lesion is primarily mediated by local production of:

A 70-year-old woman with severe osteoporosis and a recent vertebral compression fracture is started on teriparatide. What is the mechanism of action of this medication?

A 65-year-old osteoporotic woman is prescribed alendronate. By which of the following intracellular mechanisms does this nitrogen-containing bisphosphonate inhibit osteoclast-mediated bone resorption?

A 30-year-old female presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion in the distal femur. Biopsy reveals multinucleated giant cells interspersed among mononuclear cells. Which cell population in this lesion harbors the primary neoplastic defect and what factor do they secrete?

Articular cartilage relies on its distinct zonal architecture for unique biomechanical properties. Which of the following best describes the structural composition of the superficial (tangential) zone?

A 22-year-old patient presents with a subtrochanteric fracture after a minor fall. Radiographs demonstrate uniformly dense bones with an "Erlenmeyer flask" deformity of the distal femurs. A defect in which of the following is most likely responsible for this condition?

Teriparatide is utilized in the management of severe osteoporosis. What is the fundamental mechanism by which intermittent, rather than continuous, administration of this parathyroid hormone analog results in an anabolic effect on bone?