1. General Principles & Basic Science MCQs

Perren's strain theory postulates that the specific type of tissue forming within a fracture gap is dependent on local mechanical strain. According to this theory, which of the following tissues tolerates the highest percentage of strain before failure?

Tranexamic acid (TXA) is frequently utilized in orthopedic surgery to minimize perioperative blood loss. Which of the following accurately describes its primary mechanism of action?

Following a closed humerus fracture, a patient demonstrates a complete radial nerve palsy. An electromyogram (EMG) at 4 weeks shows fibrillation potentials in the brachioradialis, but imaging confirms preserved continuity of the endoneurial tubes. According to the Seddon classification, this is best classified as:

During an eccentric muscle contraction, the muscle length actively increases while generating tension. Compared to concentric contractions, eccentric contractions are biomechanically characterized by:

The diaphyseal blood supply of an adult long bone is primarily provided by the nutrient artery system. In a normal, uninjured adult long bone, the physiologic flow of blood through the diaphyseal cortex is typically:

A 30-year-old woman has an expansile, eccentric lytic lesion in the distal femur extending to the subchondral bone. Histology confirms a giant cell tumor of bone. If medical therapy is considered for an unresectable lesion, what is the exact molecular target of the preferred pharmacological agent?

You are reviewing the basic science of articular cartilage.

In which zone of articular cartilage are the collagen fibers oriented parallel to the joint surface, providing the greatest tensile strength?

During skeletal muscle contraction, calcium ions are released from the sarcoplasmic reticulum. To initiate the cross-bridge cycle and expose the myosin-binding sites on actin, calcium must directly bind to which of the following proteins?

A patient who underwent a revision total hip arthroplasty using a cobalt-chromium femoral head and a titanium alloy stem presents with groin pain. Radiographs are unremarkable, but blood tests show elevated metal ions. What is the primary mechanism of corrosion expected at the modular head-neck junction?

A 70-year-old man presents with increasing hat size and dull, aching pain in his right thigh.

Radiographs show cortical thickening and trabecular coarsening of the femur. Laboratory tests reveal markedly elevated alkaline phosphatase but normal calcium and phosphorus. The primary cellular defect in this condition involves an abnormality in which cell type?

A transverse radial shaft fracture is treated with absolute stability using open reduction and rigid internal fixation with a dynamic compression plate. How will this fracture primarily heal?

An infant presents with multiple fractures and is found to have uniformly dense "marble-like" bones on radiographs. A bone marrow biopsy reveals a lack of marrow space. This condition is most commonly caused by a defect in which osteoclast enzyme?

A 32-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic lesion in the distal femoral epiphysis extending to the subchondral bone. Biopsy shows mononuclear cells and multinucleated giant cells. If she is treated with denosumab prior to surgery, what is the specific target of this medication?

Which of the following Bone Morphogenetic Proteins (BMPs) is most strongly osteoinductive and has been FDA-approved for use in acute, open tibial shaft fractures?

In normal adult articular cartilage, which structural zone possesses the highest concentration of water and collagen, but the lowest concentration of proteoglycans?

A 28-year-old pitcher presents with vague posterior shoulder pain and isolated atrophy of the teres minor. An MRI demonstrates a paralabral cyst in the quadrilateral space. Which of the following borders the quadrilateral space superiorly?

A 35-year-old man sustains a spiral fracture of the distal third of the humeral shaft. On presentation, he is unable to extend his wrist or fingers. Which structure is at highest risk of entrapment or injury in this specific fracture pattern?

A surgeon is utilizing the volar (Henry) approach to the proximal radius for open reduction and internal fixation of a radius fracture. Supination of the forearm during this approach protects which nerve by moving it radially and away from the surgical field?

During a volar (Henry) approach to the proximal radius, what structure marks the proximal edge of the superficial layer of the supinator muscle where the posterior interosseous nerve enters?