1. General Principles & Basic Science MCQs

Following a peripheral nerve transection, Wallerian degeneration occurs distal to the injury site. Which cell type is primarily responsible for orchestrating the clearance of myelin debris to allow for subsequent nerve regeneration?

During a prolonged endurance event, such as a marathon, an athlete relies heavily on specific skeletal muscle fibers. Which of the following accurately describes the primary muscle fiber type recruited and its dominant metabolic pathway?

Bone morphogenetic protein-2 (BMP-2) is utilized clinically to enhance spinal fusion and fracture healing. Upon binding to its cell surface receptor, which of the following intracellular molecules translocates to the nucleus to regulate target gene transcription?

A 6-year-old child presents with gingival bleeding, petechiae, and metaphyseal radiolucencies on radiographs. The child is diagnosed with scurvy due to severe Vitamin C deficiency. The defective biochemical process in collagen synthesis primarily occurs in which cellular compartment?

A patient presents with a painful total hip arthroplasty 5 years post-operation. Aspiration yields sterile, thick, metal-stained fluid. The biological process occurring at the modular head-neck taper (trunnionosis) is primarily driven by a combination of which two forms of corrosion?

Osteocytes act as mechanosensors in bone, coordinating remodeling responses to mechanical loads.

Which type of cell junction allows for the direct intercellular exchange of signaling molecules, such as calcium and prostaglandins, between the dendritic processes of adjacent osteocytes?

Secondary fracture healing relies on the formation of a soft and hard callus. Which specific local mechanical and physiological environment most strongly favors endochondral ossification (cartilage intermediate) over intramembranous ossification during this process?

A 45-year-old active male undergoes a total hip arthroplasty with a ceramic-on-ceramic bearing surface. Two years later, he complains of a new, audible sound coming from his hip during ambulation. What is the most likely specific cause of this phenomenon?

When performing a direct anterior approach to the hip for a total hip arthroplasty, the surgeon exploits an internervous plane. Which of the following accurately describes the muscles and their respective innervations that define this plane superficially?

Corrosion at modular junctions in total joint arthroplasty can lead to early implant failure. Which type of corrosion is defined as the mechanical destruction of the passivating oxide layer on the metal surface due to micromotion, followed by rapid electrochemical dissolution of the underlying exposed metal?

A 55-year-old female undergoes a direct anterior approach for a total hip arthroplasty. Post-operatively, she complains of numbness over the anterolateral aspect of her thigh. Which nerve is most likely affected, and what is its anatomic relationship to the surgical interval?

Tranexamic acid (TXA) is routinely used in total joint arthroplasty to reduce blood loss. What is the specific mechanism of action of this pharmacological agent?

In the process of aseptic loosening of a total joint arthroplasty, particulate wear debris initiates a biologic cascade leading to osteolysis. Which of the following cells is the primary initiator of this inflammatory cascade by phagocytosing the debris?

A 75-year-old female taking alendronate for 10 years presents with insidious onset thigh pain. Radiographs reveal a transverse radiolucent line with lateral cortical thickening in the subtrochanteric femur. What is the primary mechanism leading to this injury?

During an ilioinguinal approach for an anterior column acetabular fracture, significant hemorrhage occurs while dissecting the posterior aspect of the superior pubic ramus. Which of the following vascular anastomoses is most likely injured?

An 80-year-old male on warfarin for atrial fibrillation sustains a displaced femoral neck fracture. His admission INR is 3.5. To minimize mortality and morbidity, what is the most appropriate sequence of management?

A 40-year-old female presents with a posteromedial shear fracture of the tibial plateau. What surgical approach provides the most direct and optimal access for buttress plating of this specific fragment?

When evaluating a severely injured lower extremity to determine the appropriateness of amputation versus salvage, the Mangled Extremity Severity Score (MESS) is often referenced. Which of the following is NOT a variable included in the MESS?

A 28-year-old woman presents with knee pain. Radiographs demonstrate an eccentrically located lytic lesion in the distal femoral epiphysis that extends to the subchondral bone. Histology reveals mononuclear cells and multinucleated giant cells. Which of the following best describes the true neoplastic cells in this lesion?