Carpal bone most commonly dislocated?

Carpal bone most commonly dislocated?

• A. Capitate
• B. Scaphoid
• C. Lunate
• D. Trapezium

Answer: (C)

Lunate is the carpal bone most commonly dislocated. Its central position in the proximal row makes it particularly vulnerable when the wrist is forced into hyperextension, such as in a fall on an outstretched hand. In this mechanism the lunate can lose its normal alignment with the radius and capitate and be driven palmarly into the carpal tunnel, leading to possible median nerve symptoms. A lateral X-ray classicly shows the “spilled teacup” sign, reflecting the lunate’s volar displacement. The other carpal bones are far less likely to dislocate, and the scaphoid is more commonly fractured than dislocated, with capitate or trapezium dislocations being relatively rare.

Lunate is the carpal bone most commonly dislocated. Its central position in the proximal row makes it particularly vulnerable when the wrist is forced into hyperextension, such as in a fall on an outstretched hand. In this mechanism the lunate can lose its normal alignment with the radius and capitate and be driven palmarly into the carpal tunnel, leading to possible median nerve symptoms. A lateral X-ray classicly shows the “spilled teacup” sign, reflecting the lunate’s volar displacement. The other carpal bones are far less likely to dislocate, and the scaphoid is more commonly fractured than dislocated, with capitate or trapezium dislocations being relatively rare.