1. General Principles & Basic Science MCQs

A 45-year-old male presents with acute knee pain. Aspiration yields 40 mL of cloudy fluid. Cell count reveals 65,000 WBCs/mm3 with 85% polymorphonuclear leukocytes. Crystals are negatively birefringent under polarized light. What is the most likely composition of these crystals?

Ligaments and tendons exhibit viscoelastic properties. Which of the following best describes the phenomenon where a tissue subjected to a constant deformation experiences a gradual decrease in stress over time?

A 65-year-old man presents with progressive bowing of his right femur and increasing hat size. Laboratory studies show normal calcium and phosphorus, but markedly elevated alkaline phosphatase. Which of the following is the primary cellular defect in this disease?

During a deltopectoral approach to the shoulder, the cephalic vein is identified. Which interval is being utilized, and which nerve is at greatest risk if dissection proceeds excessively inferior to the subscapularis?

Articular cartilage is highly specialized to resist compressive forces. Which component of the extracellular matrix is primarily responsible for its compressive stiffness due to its ability to retain water?

A 25-year-old female presents with knee pain. Radiographs reveal an eccentric, lytic, epiphyseal lesion in the distal femur extending to the subchondral bone. A biopsy confirms Giant Cell Tumor of Bone (GCT). Which medication works by inhibiting RANKL to reduce recurrence in surgically difficult GCTs?

A 4-week-old neonate presents with pseudo-paralysis of the right leg and fever. An ultrasound reveals a significant hip effusion. Joint aspiration confirms septic arthritis. Which of the following is the most appropriate empiric antibiotic regimen?

A 72-year-old woman sustains a distal radius fracture. A DEXA scan reveals a T-score of -3.1 in the lumbar spine. She is prescribed teriparatide. What is the mechanism of action of this medication?

A 12-year-old boy presents with a history of recurrent fractures, cranial nerve palsies, and diffuse sclerosis of the skeletal system on radiographs, including a "rugger jersey" spine appearance. Which of the following is the primary pathophysiological defect in this condition?

A 65-year-old man presents with progressive hearing loss, increasing hat size, and deep, aching bone pain in his right thigh. Radiographs show cortical thickening and trabecular coarsening. What is the characteristic histological finding of the bone in the mixed phase of this disease?

A 7-year-old boy with a highly restricted diet presents with bleeding gums, petechiae, and bone pain. Radiographs reveal a periosteal reaction and a dense zone of provisional calcification. The underlying biochemical defect involves the impaired function of which process?

A 72-year-old woman presents with acute swelling, pain, and erythema of her right knee. Joint aspiration yields a cloudy fluid. Microscopic analysis of the fluid is most likely to reveal which of the following if she has pseudogout?

A surgeon plans to use demineralized bone matrix (DBM) to augment a posterolateral spinal fusion. Which of the following best describes the biological properties of DBM?

Articular cartilage relies on its distinct zones for unique biomechanical properties. The high tensile strength and ability to resist shear stress in the superficial zone are primarily due to which structural feature?

During the process of secondary fracture healing, the transition from a soft cartilaginous callus to a hard bony callus is critically dependent on which of the following microenvironmental changes?

During skeletal muscle contraction, the release of calcium ions from the sarcoplasmic reticulum directly triggers the exposure of myosin-binding sites on actin. Calcium achieves this by binding to which specific protein?

A 40-year-old hiker from the northeastern United States presents with monoarticular arthritis of the knee. Joint fluid analysis is negative for crystals but demonstrates a high leukocyte count. Serology is positive for Borrelia burgdorferi. What is the first-line treatment for this stage of the disease?

A 5-year-old boy presents with proximal muscle weakness, pseudohypertrophy of the calves, and a positive Gowers sign. Genetic testing confirms a deletion in the dystrophin gene. What is the pattern of inheritance for this disorder?

During bone graft incorporation, creeping substitution occurs. Which of the following bone graft options undergoes the most rapid creeping substitution?