Table 2.

Differential diagnosis table for acute onset ulnar-sided wrist pain in the setting of trauma.

Diagnosis	Etiology, Mechanism	Imaging
Ulnar styloid fracture	50–65% of cases associated with concurrent distal radius fracture. Can be isolated as well.	X-ray: Standard PA and lateral radiographs are diagnostic.
Hook of hamate fracture	2–4% of carpal bone fractures Associated with racket sports	X-ray: Standard radiographs of the wrist are not helpful. Needs special views of the wrist like semi supinated, oblique or carpal tunnel view of the wrist CT: diagnostic
Base of fifth metacarpal fracture	16–34% of fractures of the metacarpal bone fractures.	X-ray: Routine PA and lateral radiographs of the wrist are diagnostic.
Pisiform fracture	Rare- 0.2% of carpal fractures.	X-ray: Difficult to detect on Standard radiographs of the wrist. Best demonstrated on carpal tunnel or semi supinated oblique views of the wrist. CT: diagnostic.
Triquetral fracture	2nd most common carpal fracture 20–30% of carpal bone fractures.	X-ray: Lateral radiographs of the wrist are diagnostic.
Triquetral dislocation	Rare	X-ray: Can be overlooked on routine radiographs of the wrist. CT: diagnostic
TFCC injury	Commonly seen with fractures of ulnar styloid process and distal radius.	MRI: Sensitive to detect tears of TFCC.
Lunotriquetral ligament injury	Seen with traumatic injuries resulting from fall onto outstretched hand	MRI: can detect tears of lunotriquetral ligament.
ECU tendon injury	Seen in sports related injury.	US: Dynamic ultrasound can demonstrate subluxation of the tendon. MRI: Sensitive to detect ECU subsheath tear.