1. General Principles & Basic Science MCQs

During the process of secondary bone healing, which phase is characterized by the highest level of osteoclastic activity to restore the medullary canal and original bone contours?

When a stainless steel screw is placed through a titanium plate in an orthopedic construct, the resulting corrosion at the interface is best described as:

Parathyroid hormone (PTH) plays a key role in calcium homeostasis. By which of the following mechanisms does continuous high-level exposure to PTH induce bone resorption?

A 3-year-old boy presents with progressive bowing of his legs and short stature. Labs show normal serum calcium, normal PTH, low serum phosphorus, and elevated alkaline phosphatase. Which of the following is the most likely pathophysiologic mechanism for his disease?

A 6-year-old boy presents with progressive bowing of the legs and short stature. Laboratory tests show normal serum calcium, profoundly low serum phosphate, normal PTH, and normal 25-hydroxyvitamin D levels. A mutation in the PHEX gene is identified. The primary pathophysiology of his bone disease is driven by the overproduction of:

Ligaments and tendons exhibit distinct viscoelastic properties. When a constant length (deformation) is maintained on a ligament over a period of time, the load or force required to maintain that specific deformation progressively decreases. This biomechanical phenomenon is termed:

During the establishment of an orthopedic implant-associated infection, bacteria within a biofilm begin to communicate and coordinate group behaviors (such as altering gene expression and increasing virulence) once a critical population density is reached. What is this communication process called?

A 72-year-old patient undergoes an aspiration of a swollen, painful knee. Synovial fluid analysis under polarized light microscopy reveals rhomboid-shaped crystals demonstrating weak positive birefringence. These crystals are primarily composed of:

A 32-year-old female is diagnosed with an expansile, lytic Giant Cell Tumor (GCT) in the distal femur. Because the lesion is large and abuts the subchondral bone, she is placed on neoadjuvant denosumab therapy to facilitate joint-salvage surgery. Denosumab functions by binding directly to which of the following?

Tranexamic acid (TXA) has become a standard of care in total joint arthroplasty for reducing perioperative blood loss. Which of the following accurately describes its pharmacological mechanism of action?

In the structural organization of articular cartilage, which zone contains the largest diameter collagen fibrils oriented perpendicular to the articular surface and chondrocytes arranged in vertical columns?

A 65-year-old man with progressive cranial enlargement and anterior bowing of his tibiae is diagnosed with Paget's disease of bone. The underlying cellular abnormality involves hyperactive osteoclasts. Familial forms of this condition are most strongly associated with a mutation in which of the following genes?

An orthopedic surgeon utilizes a stainless steel screw through a titanium alloy fracture plate. Postoperatively, there is an increased risk of accelerated implant degradation due to the transfer of electrons between the two dissimilar metals in the presence of the body's saline environment. This specific type of corrosion is termed:

A 68-year-old woman is diagnosed with multiple myeloma after presenting with diffuse bone pain and 'punched-out' lytic lesions on radiographs. The profound osteolysis seen in multiple myeloma is predominantly driven by myeloma cell-induced upregulation of which of the following combinations of factors?

During the excitation-contraction coupling process in skeletal muscle, the action potential triggers the release of calcium ions from the sarcoplasmic reticulum. To expose the myosin-binding sites on the actin filament and initiate the power stroke, these calcium ions must bind directly to:

To maximally decrease the joint reaction force across an osteoarthritic hip during the stance phase of gait, a patient should be instructed to hold a cane in the contralateral hand. Biomechanically, this intervention reduces the hip joint reaction force primarily by:

A 22-year-old patient presents with recurrent fractures, anemia, and cranial nerve palsies. Radiographs demonstrate diffusely dense bones and a "rugger jersey" spine. The underlying pathophysiology of this condition is most commonly due to a primary defect in which of the following?

A 55-year-old female presents with diffuse, dull bone pain and proximal muscle weakness. Laboratory studies reveal low serum calcium, low serum phosphate, elevated alkaline phosphatase, and elevated parathyroid hormone (PTH). Radiographs show bilateral pseudofractures in the femoral neck. What is the most likely diagnosis?