7. Hand and Wrist MCQs

What is the primary arterial supply to the scaphoid that makes fractures of its proximal pole particularly susceptible to delayed union and avascular necrosis?

A 60-year-old female undergoes open reduction and internal fixation of a distal radius fracture with a volar locking plate. Six months postoperatively, she presents with an inability to actively flex the interphalangeal joint of her thumb. This complication is most directly related to plate placement in relation to which anatomical landmark?

A new diagnostic imaging modality is being tested to detect scaphoid fractures. In a study of 200 patients (100 with true scaphoid fractures and 100 normal wrists), the test correctly identifies a fracture in 80 patients and correctly rules out a fracture in 90 patients. What is the sensitivity of this new imaging modality?

A 32-year-old male sustains a severe laceration to the volar wrist, completely transecting the ulnar nerve proximal to the Guyon's canal. Several months later, he presents with significant clawing of the ring and small fingers. Which of the following explains why a more distal injury would have resulted in even more severe clawing?

A 28-year-old carpenter sustains a laceration to the volar aspect of his index finger at the level of the proximal phalanx, transecting both the FDS and FDP tendons. He undergoes primary flexor tendon repair. To permit a safe early active motion protocol postoperatively, the repair must rely primarily on which mechanical parameter?

A 40-year-old mechanic presents with a swollen, erythematous right index finger after sustaining a puncture wound 3 days ago. Which of Kanavel's four cardinal signs of flexor tenosynovitis is typically considered the earliest and most sensitive indicator of the infection?

A 6-year-old boy sustains a completely displaced supracondylar humerus fracture. Radiographs reveal the distal fragment is displaced posterolaterally. Based on this displacement pattern, which nerve is at the highest risk of injury?

A 65-year-old female sustains an undisplaced distal radius fracture and is treated non-operatively in a cast. Six weeks later, she complains of a sudden, painless inability to actively extend her thumb at the interphalangeal joint. What is the primary pathomechanism of this complication?

A 32-year-old tennis player presents with ulnar-sided wrist pain. An MRI arthrogram reveals a tear of the triangular fibrocartilage complex (TFCC) at its ulnar peripheral attachment without bony avulsion. According to the Palmer classification, what is this tear type, and is it generally amenable to direct primary repair?

During an open carpal tunnel release, the surgeon notes a highly branched recurrent motor branch of the median nerve that directly pierces the transverse carpal ligament. According to the Lanz classification of median nerve variations, which anatomic group does this represent?

In the digital flexor tendon sheath, which of the following annular pulleys are biomechanically the most critical to prevent tendon bowstringing and must be preserved or reconstructed during flexor tendon surgery?

A skier presents with a traumatic abduction injury to the thumb metacarpophalangeal (MCP) joint. MRI confirms a complete rupture of the ulnar collateral ligament (UCL) with a Stener lesion. Which anatomic structure is interposed between the torn UCL ends in a Stener lesion?

During surgical fasciectomy for Dupuytren's contracture, the surgeon dissects out the spiral cord. The spiral cord characteristically displaces the neurovascular bundle in which direction, placing it at increased risk of iatrogenic injury?

A patient is evaluated in the clinic for an inability to make an 'OK' sign with the thumb and index finger. Neurological examination reveals normal sensation throughout the entire hand and digits. Which of the following muscles is primarily affected by this specific nerve palsy?