1. General Principles & Basic Science MCQs

During a standard deltopectoral approach to the shoulder for open reduction internal fixation of a proximal humerus fracture, the surgeon attempts to identify the axillary nerve to protect it. At the inferior border of the subscapularis muscle, the axillary nerve passes posteriorly through the quadrangular space. Which of the following structures forms the superior border of this anatomic space?

A 19-year-old male presents to the emergency department after a rugby tackle with severe pain at the base of his neck, difficulty swallowing, and a sensation of shortness of breath. Physical examination reveals an asymmetric chest wall with a depression at the right sternoclavicular joint. A CT scan confirms a posterior sternoclavicular dislocation. Which of the following statements regarding the management of this injury is most accurate?

A 40-year-old man undergoes a single-incision anterior approach for a distal biceps tendon repair using cortical button fixation. Postoperatively, he notes numbness and tingling over the lateral aspect of his forearm but demonstrates normal strength in wrist and finger extension. Which structure was most likely injured during the procedure, and during which step of the surgery does this typically occur?

A 42-year-old right-hand-dominant male undergoes a single-incision anterior repair of an acute complete distal biceps tendon rupture using cortical button fixation. Two weeks postoperatively, he complains of profound numbness over the lateral aspect of his forearm. His motor examination is completely intact. Which of the following nerves was most likely injured or compressed during the surgical exposure?

A 32-year-old male bodybuilder feels a sudden pop in his anterior axilla while performing a heavy bench press. Examination reveals loss of the anterior axillary fold and weakness in internal rotation. In a complete rupture of the pectoralis major, which anatomical segment is most commonly torn from its humeral insertion?

A 31-year-old competitive weightlifter feels a tearing sensation in his anterior chest while performing a heavy bench press. Examination reveals extensive ecchymosis and loss of the anterior axillary fold. MRI confirms a complete rupture of the pectoralis major. Which portion of the musculotendinous unit is most commonly injured in this mechanism?

A 25-year-old chef lacerates his index finger flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in Zone II. He undergoes an uncomplicated primary repair using a 4-strand core suture and an epitendinous repair. What is the most appropriate postoperative rehabilitation protocol?

A patient presents with an inability to extend their fingers at the metacarpophalangeal (MCP) joints following a penetrating injury to the proximal forearm. When asked to extend the wrist, it strongly deviates radially. This clinical presentation is most consistent with an injury to which nerve?

A 32-year-old bodybuilder feels a pop in his anterior chest while performing a heavy bench press. Examination reveals bruising and a loss of the anterior axillary fold contour. MRI confirms a complete pectoralis major rupture. Which portion of the muscle is most commonly injured in this classic mechanism?

A 19-year-old football player presents to the emergency department after a high-impact collision. He complains of severe pain at the base of his neck, difficulty swallowing, and a feeling of fullness in his throat. What is the most appropriate initial imaging modality to confirm the suspected diagnosis?

When performing a primary repair of a severed flexor tendon in Zone II, which biomechanical factor contributes most significantly to the ultimate tensile strength of the repair during the early postoperative rehabilitation phase?

A 35-year-old woman is diagnosed with a large, destructive, recurrent giant cell tumor of the sacrum with impending neurologic compromise. Surgical resection would result in significant morbidity, so her multidisciplinary oncology team initiates targeted medical therapy. What is the mechanism of action of the most appropriate pharmacological agent?

A 32-year-old woman presents with persistent knee pain. Radiographs show an eccentric, lytic epiphyseal lesion in the distal femur. A biopsy demonstrates mononuclear cells and multinucleated giant cells. Which of the following is the specific molecular target of the monoclonal antibody denosumab, which may be used in the medical management of this condition?

A 35-year-old woman is diagnosed with a giant cell tumor of the distal femur. Due to the proximity of the lesion to the articular surface, she is started on a course of denosumab therapy prior to intralesional curettage. Which of the following best describes the specific mechanism of action of this medication?

A 65-year-old man presents with new-onset severe lower back pain and generalized fatigue. Laboratory studies reveal a normocytic anemia, elevated serum creatinine, and hypercalcemia. A skeletal survey shows multiple 'punched-out' lytic lesions in the skull and pelvis with no surrounding reactive sclerosis. Which of the following factors is most directly responsible for the uncoupled bone remodeling that leads to these purely lytic lesions?

A 32-year-old woman presents with worsening knee pain. Radiographs reveal an eccentric, purely lytic lesion in the distal femur that extends directly to the subchondral bone without a sclerotic margin. Biopsy demonstrates numerous multinucleated giant cells in a background of mononuclear stromal cells. Due to the proximity of the lesion to the joint surface and its size, she is treated with a targeted monoclonal antibody to downstage the tumor prior to surgery. What is the precise mechanism of action of this medication?

During fracture healing, a complex molecular cascade dictates the differentiation of multipotent mesenchymal stem cells into the specific cell lineages necessary for bone repair. Which of the following transcription factors serves as the critical 'master regulator' for committing mesenchymal stem cells to the osteoblastic lineage?

A 70-year-old woman with a history of postmenopausal osteoporosis sustains a fragility fracture of her distal radius. She has been on oral alendronate therapy for the past three years. Nitrogen-containing bisphosphonates, such as alendronate, inhibit osteoclast-mediated bone resorption primarily through which of the following molecular mechanisms?

A 12-year-old boy presents with multiple palpable, painless, bony prominences around his knees, ankles, and shoulders. Radiographs confirm multiple pedunculated and sessile bony outgrowths projecting away from the adjacent joints in the metaphyses of the long bones, continuous with the medullary cavity of the native bone. He is diagnosed with Multiple Hereditary Exostoses (MHE). What is the primary underlying biochemical defect associated with the genetic mutations in this disorder?