With 8 carpal bones in each of our wrists, it's difficult to know which injuries to concentrate our energies on. Understanding the age-related prevalence and mechanism of carpal bone injuries is a prerequisite to familiarizing yourself with these injuries. Carpal bone injuries occur predominately in young adults, often after a high energy mechanism of injury. In this 2nd part of our 2-part podcast series on wrist injuries, with the expert insights of Dr. Arun Sayal and Dr. Matt Distefano, we highlight the "Big 4" most common carpal bone injuries - triquetrum chip fractures, scapholunate injuries, hook of the hamate fractures, and of course, scaphoid fractures. These can be easily missed in the ED with significant consequences for our patients...



Podcast production, sound design & editing by Anton Helman; voice editing by Braedon Paul

Written Summary and blog post by Kate Dillon, edited by Anton Helman. January, 2024

Cite this podcast as: Helman, A. Distefano, M. Sayal, A. Episode 190: Carpal Bone Injuries- The Big 4. Emergency Medicine Cases. January, 2024. https://emergencymedicinecases.com/carpal-bone-injuries-big-4. Accessed November 19, 2024

Résumés EM Cases 

Go to part 1 of this 2-part podcast on wrist and carpal bone injuries

Carpal bones mnemonic memory aid

So Long to Pinky, Here Comes The Thumb mnemonic - starting at proximal row, radial wrist



* Scaphoid

* Lunate

* Triquetrum

* Pisiform

* Hamate

* Capitate

* Trapezoid

* Trapezium



Source: wikipedia

The Big 4 carpal bone injuries

The following carpal bone injures are commonly missed with serious consequences for patients. Other carpal bone injuries are less common and may co-occur with the "Big 4" injuries:



* Triquetrum chip fractures

* Scapholunate sprains/dissociation/dislocation

* Hook of the hamate fracture

* Scaphoid fracture



Understanding carpal bone injuries: Age related prevalence of disease

Age plays a significant role in determining the prevalence of musculoskeletal injuries. Younger individuals with open growth plates are more likely to sustain fractures involving growth plates or diaphyseal/metaphyseal junction of the distal radius, while older individuals with low bone density are more prone to classic long-bone fractures. For individuals between 15 and 60 years old carpal non-long bone and inter-carpal ligament injuries occur more often. Hence, carpal bone injuries occur predominantly in young adults as a result of a high energy mechanism. 

1. Triquetrum chip fracture - the commonly missed ulnar wrist injury

We tend to concentrate on the radial aspect of the wrist for patients who have sustained a wrist injury. The 2nd most common carpal bone injury comprising 20% of carpal bone fractures, and the most common ulnar wrist injury is a triquetrum chip fracture, highlighting the need to scrutinize the ulnar aspect of the wrist on physical exam and x-ray.

Dorsal aspect of triquetrum avulsed or knocked off.

Mechanism: FOOSH (most common), also fall on back of the hand (volar injuries are more likely to lead to carpal instability and require orthopedic intervention)

Surface anatomy/physical exam: dorsal, ulnar side of hand, palpate the divot distal to the ulnar styloid and proximal to the 4th metacarpal

Surface Anatomy of the triquetrum bone.