When evaluating a patient in the emergency department after a high-energy fall onto an outstretched hand, a true lateral radiograph of the wrist reveals a classic ‘spilled teacup’ sign. This radiographic finding is highly pathognomonic for which specific, severe carpal injury?

Explanation:
The correct option is c. Carpal dislocations follow a progressive pattern of perilunar instability (Mayfield stages). In a standard perilunate dislocation, the lunate remains perfectly seated within the distal radial fossa, while the capitate and the rest of the carpus dislocate dorsally. However, in the final and most severe stage (Stage IV), the dorsal radiocarpal ligaments tear completely. The capitate forcefully snaps back into the radial fossa, violently ejecting the lunate volarward out of the joint. On a lateral x-ray, the dislocated lunate tilts forward, closely resembling a 'spilled teacup'. This is a surgical emergency to prevent acute median nerve compression. Reference: Mayfield JK et al. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg Am. High-yield Ortho mcq.