A 23-year-old male reports that during a game of basketball, he tripped while driving the ball to the basket, and fell on his outstretched right hand with the palm down. Two days later, he phoned his anatomist father and related that his right wrist was painful. Later that day, he visited his father, who noted that the wrist was slightly swollen and tender but without deformity. He instructed his son to extend the right thumb, thereby accentuating the anatomical “snuffbox,” which is extremely tender to deep palpation. His father advised him to get his hand and wrist x-rayed.
Discussion:
Most likely diagnosis: Wrist fracture
Most likely anatomical defect: Fracture of the narrow middle portion of the scaphoid carpal bone
CLINICAL CORRELATION
This young man tripped while playing basketball and stretched out his right hand to protect himself. His hand, with the palm down and probably deviated to the side of the radius, took the brunt of the fall, resulting in significant impact force to the wrist. This resulted in pain and swelling of the wrist, especially on the radial side, with point tenderness deep in the anatomical snuffbox. This is the common mechanism for a fracture of the scaphoid carpal bone, the most commonly fractured carpal bone. Point tenderness over a bone or bony process is a hallmark of a fracture at that site. Radiologic confirmation of a fracture is important. The scaphoid bone has a unique blood supply, and proper reduction and alignment of the segments is necessary to decrease the risk of avascular necrosis. A fall on an outstretched hand such that it produces hyperextension of the wrist may result in dislocation of the lunate bone. The lunate is usually displaced anteriorly into the carpal tunnel and may impinge on the median nerve. The lunate is the most commonly dislocated carpal bone. A fall on an outstretched palm may also result in a transverse fracture of the distal radius or a Colles fracture, which produces a dorsal displacement of the distal fragment, resulting in the characteristic “dinner fork” (also termed “bayonet”) deformity. A Smith fracture of the radius in the same region of younger individuals is less common. In a Smith fracture, there is trauma to the dorsal aspect of a flexed wrist, and the wrist is deformed with the distal radial fragment displaced ventrally in a “spade” deformity.
