Hamate Fracture

The next of the five major wrist or hand injuries to consider in patients after a FOOSH is the hook-of-hamate fracture. Traditional teaching of the mechanism of the hook-of-hamate fracture is a direct blow from an elongated implement gripped in the hand such as a ski pole, golf club, or baseball bat. It is under-recognized that hook-of-hamate fractures can result from a FOOSH and occur concomitantly with a scaphoid fracture.⁷ Knowing the surface anatomy of the carpal bones is essential. The hook of the hamate lies 2 cm distal and 1 cm radial to the pisiform and can be felt on deep palpation; it should be palpated routinely in patients after a FOOSH. Picking these injuries up in the ED is important because if missed and not immobilized, non-union may ensue and the patient may require surgical intervention.⁸ If the hamate is tender on physical exam, it is important to order an additional X-ray view with the standard hand X-ray views: the hook of the hamate or carpal tunnel view is more sensitive than the standard wrist X-ray views for hook-of-hamate fractures. An important pitfall is assuming no fracture if a hook-of-hamate fracture is suspected clinically and the standard wrist views as well as the hook-of-hamate or carpal tunnel view are negative. The sensitivity of the hook-of-hamate view is only 40 percent for fracture.9 Similar to scaphoid fracture occult to X-ray, if clinically suspected, immobilize and arrange orthopedic follow-up regardless of the X-ray findings.

Lunate Ligamentous Injury

Another overlooked injury is the lunate ligamentous injury including the scapholunate injury. Age-related prevalence of wrist or hand injuries is again important here. Children with open growth plates are more likely to sustain fractures involving growth plates or diaphyseal-metaphyseal junction of the distal radius, while those older than years are more prone to classic long-bone fractures. For people between 15 and 60 years old, carpal 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. Lunate ligamentous injuries lie on a morbidity spectrum ranging from scapholunate sprains to dissociation and dislocation. Again, knowledge of surface anatomy is essential for accurate physical exam testing: the divot distal to Lister’s tubercle and a few millimeters ulnar is the scapholunate space. This space can also be identified by palpating 2 cm ulnar to the snuffbox. If a patient has point tenderness here, assume a scapholunate injury until proven otherwise.