1. General Principles & Basic Science MCQs

A 24-year-old male sustains a closed femoral shaft fracture treated with an intramedullary nail. Postoperatively, he takes high-dose nonsteroidal anti-inflammatory drugs (NSAIDs) for six weeks. Which phase of bone healing is most likely directly impaired by this medication?

When analyzing the biochemical differences between normal aging articular cartilage and early osteoarthritic cartilage, which of the following characteristics is distinctly unique to the early stages of osteoarthritis?

An anterior cruciate ligament (ACL) graft undergoes gradual, progressive elongation over time when subjected to a constant physiological load. This viscoelastic phenomenon is best described as:

A 45-year-old male sustains a closed transverse midshaft humerus fracture. He is treated with open reduction and internal fixation using a dynamic compression plate, achieving absolute stability with an interfragmentary gap of less than 0.1 mm.

What is the primary mode of bone healing expected in this construct?

Which molecule is primarily responsible for boundary lubrication in a diarthrodial joint, providing a critical reduction in friction under high loads and low speeds?

Of the following orthopedic implant materials, which has a modulus of elasticity that is closest to that of human cortical bone, thereby potentially reducing stress shielding?

A massive structural cortical allograft is utilized for reconstruction after an intercalary tumor resection.

During the first two years of incorporation, what biomechanical vulnerability is most characteristic of this graft type?

Which of the following molecules acts as an antagonist of the Wnt/beta-catenin signaling pathway, thereby inhibiting osteoblastogenesis and bone formation?

Which of the following collagen types forms the primary structural fibrillar network of articular cartilage and represents 90-95% of its total collagen content?

Distraction osteogenesis fundamentally relies on the biological principle of the tension-stress effect. What is the predominant type of bone formation seen in the distraction gap under optimal conditions?

Due to the avascular nature of normal articular cartilage, mature chondrocytes reside in a relatively hypoxic environment. They generate ATP required for extracellular matrix synthesis primarily through:

Bone morphogenetic proteins (BMPs), such as BMP-2 and BMP-7, initiate osteoblast differentiation by binding to specific heterodimeric cell surface receptors. These receptors primarily function as:

Which family of zinc-dependent enzymes is considered the primary mediator of extracellular matrix degradation, specifically targeting type II collagen and aggrecan, in the pathogenesis of osteoarthritis?

According to Perren's strain theory, what level of local interfragmentary strain is required to allow for primary bone healing (osteonal remodeling without visible callus)?

Which zone of articular cartilage contains the highest concentration of water, the lowest concentration of proteoglycans, and chondrocytes aligned parallel to the articular surface?

Biochemical analysis of articular cartilage in early osteoarthritis typically reveals which of the following changes compared to normal aging cartilage?

Bone morphogenetic proteins (BMPs) initiate intracellular signaling upon binding to serine/threonine kinase receptors. Which of the following intracellular proteins are directly phosphorylated and translocate to the nucleus to regulate gene expression?

On a stress-strain curve for a given orthopedic alloy, the specific point at which the material transitions from elastic deformation to permanent plastic deformation is defined as the:

A surgeon inadvertently uses a stainless steel screw with a titanium alloy plate in a saline-rich physiologic environment, increasing the risk of galvanic corrosion. Which of the following statements is correct regarding this couple?

When a constant compressive load is applied to articular cartilage, the fluid is slowly extruded from the extracellular matrix, resulting in a time-dependent increase in deformation. This viscoelastic property is known as: