1. General Principles & Basic Science MCQs

Among the following synthetic bone graft substitutes, which has the slowest in vivo resorption rate, providing the longest-lasting structural scaffold?

Histologic examination of articular cartilage demonstrates distinct structural zones. In the superficial zone (lamina splendens), how are the collagen fibrils predominantly oriented relative to the articular surface?

A patient with severe osteoporosis is started on denosumab. This monoclonal antibody exerts its therapeutic effect by directly binding to which of the following targets?

A 45-year-old male with a history of severe alcohol use disorder presents with perifollicular petechiae, gingival bleeding, and poor wound healing. The underlying enzymatic defect in this patient most directly impairs which step in collagen synthesis?

Following a traumatic nerve transection, Wallerian degeneration occurs. If an electromyogram (EMG) is performed on the denervated muscle, what is the earliest expected abnormal finding, and when does it typically appear?

In periprosthetic joint infections, bacteria adhere to the implant and form a biofilm. The bacteria within this biofilm coordinate their behavior and gene expression based on population density through a communication mechanism known as:

A resident applies a Ponseti cast to an infant with idiopathic clubfoot. Initially, there is significant resistance from the tight Achilles tendon and posteromedial structures. Over the next several minutes, while the resident holds the foot in the corrected position, the resident notes that less force is required to maintain the exact same degree of dorsiflexion and abduction. Which biomechanical property of viscoelastic materials does this clinical scenario represent?

A patient undergoes revision open reduction and internal fixation of a femoral nonunion. Due to a shortage of hardware sets, a stainless steel screw is inadvertently placed into a titanium plate. Which of the following modes of corrosion is most likely to be significantly accelerated at the screw-plate interface?

During bone remodeling, the osteoclast creates a highly acidic microenvironment within the extracellular resorption pit to solubilize hydroxyapatite. Which enzyme is primarily responsible for generating the intracellular protons required to sustain this process?

In the cross-sectional histology of healthy adult articular cartilage, which zone is defined by possessing the highest concentration of water, the lowest concentration of proteoglycans, and collagen fibrils oriented parallel to the articular surface?

During a normal walking gait cycle, what is the primary kinematic function of the hip abductors (gluteus medius and minimus) during the single-leg stance phase?

During skeletal muscle contraction, rigor mortis characteristically occurs after death due to the total depletion of intracellular ATP. In a living, normally functioning skeletal muscle, what specific critical role does ATP binding to the myosin head serve in the sliding filament cross-bridge cycle?

When utilizing a large structural cortical bone autograft instead of a cancellous autograft for a massive osseous defect, which of the following best describes the cortical graft's biological and biomechanical incorporation profile?

According to Perren's strain theory regarding fracture healing, the specific type of tissue that forms within a fracture gap is ultimately dictated by the local mechanical strain. What is the maximum threshold of tissue strain tolerated that still allows for the direct formation of solid lamellar bone?

Aggrecan is the most abundant proteoglycan found within articular cartilage and is essential for maintaining its compressive biomechanical properties. Individual aggrecan monomers assemble into massive aggregates by binding to a long, unbranched central backbone molecule. What specific molecule constitutes this critical central backbone?