1. General Principles & Basic Science MCQs

A patient with chronic kidney disease presents with profound hypocalcemia and secondary hyperparathyroidism. The patient's bone disease is primarily exacerbated by a deficiency in which of the following enzymes?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized to enhance bone healing. BMP-2 initiates the osteoinductive cascade by binding to a cell surface receptor, which directly activates which of the following intracellular signaling molecules?

Staphylococcus aureus is the most common organism isolated in orthopedic implant infections. Which of the following bacterial structures is primarily responsible for initial adhesion to host proteins (such as fibronectin and fibrinogen) that coat the implant surface?

When a constant tensile load is applied to a ligament over time, the ligament will gradually elongate. This time-dependent mechanical property is known as:

A massive segmental bone defect is reconstructed using a freshly harvested autogenous cancellous bone graft from the iliac crest. This graft provides which of the following biologic properties for bone regeneration?

Articular cartilage is divided into four structural zones. In which zone are the collagen fibers oriented parallel to the articular surface, primarily functioning to resist shear forces?

Osteoclasts are multinucleated cells responsible for bone resorption. They create a sealed microenvironment beneath their ruffled border. Following acidification of the resorption pit to dissolve the inorganic mineral, which of the following enzymes is primarily secreted to degrade the organic collagenous matrix?

A basic science researcher is evaluating the viscoelastic properties of a human anterior cruciate ligament. When the ligament is subjected to a constant physiological load over time, it continues to deform slowly. Which of the following terms best describes this phenomenon?

Which of the following describes the primary mechanism by which intermittent, low-dose administration of parathyroid hormone (PTH) increases bone mass?

Romosozumab is a monoclonal antibody recently developed for the treatment of osteoporosis. It functions by inhibiting sclerostin. Sclerostin primarily exerts its effect on bone metabolism by inhibiting which of the following pathways?

During an experimental study of articular cartilage mechanics, the collagen fibrils in a specific zone are noted to be oriented parallel to the joint surface to resist shear stress. Which zone is being described?

A massive structural allograft is used to reconstruct a diaphyseal defect following tumor resection. By which of the following mechanisms does the host incorporate the structural cortical allograft?

Bone morphogenetic protein-2 (BMP-2) is utilized clinically to enhance spinal fusion. Upon binding to its cell surface receptor, BMP-2 initiates intracellular signaling primarily through which of the following protein families?

A surgeon revises a fractured stainless steel plate by placing a new titanium screw into one of the remaining empty holes of the stainless steel plate. Over time, significant corrosion occurs at the screw-plate interface. This is an example of which type of corrosion?

A 4-year-old boy presents with multiple fractures and is diagnosed with malignant infantile osteopetrosis. The defect involves a failure of osteoclasts to create an acidic environment in the resorption pit. A mutation in the gene encoding which of the following enzymes is most likely responsible?

A patient with severe scurvy is found to have significantly weakened bones and bleeding gums. The primary defect in collagen synthesis caused by vitamin C deficiency occurs during which step?

Aggrecan is the most abundant proteoglycan in articular cartilage. Its ability to provide compressive stiffness to the tissue is heavily dependent on its binding to which of the following molecules via a link protein?

A diaphyseal radius fracture is rigidly fixated with a compression plate, achieving absolute stability and less than 2% interfragmentary strain. The fracture will heal primarily via which of the following mechanisms?