1. General Principles & Basic Science MCQs

Which of the following bone morphogenetic proteins (BMPs) is an osteoinductive agent that signals primarily through the SMAD intracellular pathway and is FDA-approved for use in acute, open tibial shaft fractures?

In articular cartilage, which structural zone contains the highest concentration of water and has collagen fibers oriented parallel to the joint surface?

The use of a stainless steel screw through a titanium plate in an internal fixation construct is generally avoided in orthopedic surgery due to the risk of which type of corrosion?

Osteoclasts resorb bone by creating an acidic microenvironment at the ruffled border. Which specific enzyme is primarily responsible for the generation of protons (H+) necessary to maintain this acidic environment?

When analyzing the biomechanical properties of a hollow intramedullary nail, its torsional rigidity (polar moment of inertia) depends most heavily on which geometric parameter?

During the remodeling phase of secondary fracture healing, woven bone is gradually replaced by lamellar bone oriented along lines of stress. This biological response to mechanical loading is governed by which of the following principles?

Under high-load and low-speed conditions, articular cartilage relies primarily on a boundary lubrication mechanism to reduce friction. Which of the following molecules is most critical for providing this boundary lubrication at the outermost joint surface?

Healing of a ruptured medial collateral ligament (MCL) proceeds through distinct phases. During the early cellular repair phase, which type of collagen is synthesized in the highest proportion by invading fibroblasts before being eventually replaced during remodeling?

An 18-year-old man sustains an injury to the right brachial plexus after falling off his bicycle. Examination reveals no rhomboideus major or minor muscle function. This finding most likely indicates a preganglionic injury to which of the following nerve roots?

During an anterior intrapelvic (modified Stoppa) approach to the acetabulum, brisk arterial bleeding is encountered near the superior pubic ramus. This bleeding most likely originates from an anomalous anastomosis between the obturator vessels and which of the following?

During the classic ilioinguinal approach to the pelvis, the middle window is accessed to treat anterior column fractures. Which structures define the medial and lateral borders of this middle window?

A surgeon is performing a posterior approach to the humerus. To identify the radial nerve, she explores the triangular interval. This interval is bounded by the long head of the triceps, the teres major, and which of the following structures?

A rock climber presents with a "bowstringing" deformity of the right ring finger following a sudden pop. Rupture of which pair of flexor tendon pulleys is most commonly responsible for clinically significant bowstringing?

When planning repair of a torn abductor tendon of the hip, the surgeon must identify the distinct insertion footprints. The gluteus medius inserts primarily on which aspect of the greater trochanter?

During a volar approach to the proximal radius (Henry approach), the radial nerve is at risk when exposing the proximal third of the shaft. To safely mobilize the supinator muscle and protect the posterior interosseous nerve, the forearm should be placed in what position?

A patient suffers a traction injury to the upper trunk of the brachial plexus (Erb's palsy). Which of the following nerves branches directly from the roots of the brachial plexus and may remain intact depending on the exact level of the lesion?

A traumatic laceration to the mid-palm involves the superficial palmar arch. This structure is formed primarily by the continuation of the ulnar artery and is typically completed by a branch from which of the following?

A 35-year-old man undergoes a deltopectoral approach for open reduction and internal fixation of a proximal humerus fracture. During the procedure, a vessel passing through the quadrangular space with the axillary nerve is inadvertently injured. Which of the following arteries is most likely affected?

During an anterior (Smith-Petersen) approach to the hip for an open reduction of a developmental dysplasia of the hip, the surgeon utilizes a true internervous plane. This superficial plane is developed between muscles innervated by which two nerves?

During an ilioinguinal approach to the pelvis for an anterior column acetabular fracture, massive hemorrhage occurs from a torn vessel lying over the superior pubic ramus, approximately 5 cm from the symphysis. This bleeding is most likely originating from the 'corona mortis', which is an anastomosis between the external iliac system and which of the following?