Review Question - QID 213669

This patient with persistent pain and tenderness in the anatomical snuffbox following a fall on an outstretched hand has an occult scaphoid fracture and is, therefore, at risk of osteonecrosis (i.e., avascular necrosis or bone infarction).

The scaphoid is the most commonly fractured carpal bone. A scaphoid fracture classically occurs after a fall on an outstretched hand and causes pain and tenderness in the "anatomical snuffbox" (area at the dorsal base of the thumb, between the tendons of the extensor pollicis longus and extensor pollicis brevis). Such a fracture may be visible on initial radiograph, but often, radiographs are initially normal, and a fracture is only seen on repeat radiograph at least 1 week later. For this reason, if a scaphoid fracture is clinically suspected (based on classic history and exam findings, as seen in this case), it should be treated empirically with thumb spica cast, even if radiographs are negative. Since the scaphoid has a tenuous retrograde blood supply (from branches of the radial artery), an untreated fracture can interrupt this supply, leading to bone infarction (also known as osteonecrosis or avascular necrosis).

Incorrect Answers:
Answer 1: Carpal tunnel syndrome (compression of the median nerve within the carpal tunnel) can occur as a complication of lunate dislocation, not scaphoid fracture.

Answer 2: "Claw hand" deformity is a manifestation of ulnar nerve injury, which is a possible complication of hook of the hamate fracture.

Answer 4: Septic arthritis occurs when bacteria from the blood or an open wound seed a joint but is not likely to occur after a closed fracture.

Answer 5: Thenar atrophy occurs with damage to or compression of the median nerve (i.e., carpal tunnel syndrome), a possible complication of lunate dislocation.

Bullet Summary:
Due to its tenuous, retrograde blood supply, fracture of the scaphoid bone can result in osteonecrosis.