1. General Principles & Basic Science MCQs

A ligament subjected to a constant, sustained load elongates progressively over time. This viscoelastic property is best described as:

Osteoclasts resorb bone matrix by creating an acidic microenvironment at the ruffled border. Which intracellular enzyme is primarily responsible for generating the protons required for this acidification process?

Which of the following components of the extracellular matrix is primarily responsible for the compressive stiffness of articular cartilage?

Sclerostin (SOST) regulates bone mass by inhibiting a specific cellular signaling pathway. Which of the following pathways is directly antagonized by sclerostin?

On a stress-strain curve for an orthopedic biomaterial, the area under the curve strictly within the elastic region represents the material's:

In the epiphyseal growth plate, which zone is primarily responsible for longitudinal bone growth through rapid cellular division and column formation?

According to Perren's strain theory of bone healing, what is the maximum interfragmentary strain that allows for the formation of primary lamellar bone without intermediate soft callus formation?

Parathyroid hormone (PTH) stimulates bone resorption primarily by binding to receptors located directly on which of the following cell types?

During prolonged standing, resulting in static high loads across the knee joint, which mechanism of articular cartilage lubrication is primarily responsible for minimizing friction between the joint surfaces?

An orthopedic implant undergoes cyclical loading well below its ultimate yield strength but eventually fails. On an S-N (Stress-Number of cycles) curve, what does the endurance limit represent?

During the remodeling phase of cortical bone healing, cutting cones progress longitudinally through the haversian systems. What is the leading cell type at the forefront of a functioning cutting cone?

In comparing orthopedic implant materials, which of the following accurately describes the relationship between the Young's modulus of elasticity of titanium, stainless steel, and cortical bone?

Bone morphogenetic proteins (BMPs) initiate intracellular signaling primarily through which of the following pathways to promote osteoblastic differentiation?

Cortical bone exhibits viscoelastic properties, meaning its biomechanical behavior depends on the rate of loading. Which of the following best describes the response of cortical bone to high-rate loading compared to low-rate loading?

The pullout strength of a cortical screw is most significantly increased by maximizing which of the following geometric parameters?

A surgeon considers using a titanium locking plate with stainless steel screws for fracture fixation. Why is this combination traditionally contraindicated in orthopedic surgery?

A patient presents with a pseudotumor around a modular total hip arthroplasty secondary to adverse local tissue reaction. The primary mechanism generating metal ions at the modular head-neck taper interface is:

A clubfoot is treated with serial Ponseti casting. The gradual stretching and elongation of the tightened medial ligaments and tendons under a constant applied load over time demonstrates which viscoelastic property?