Carpal injuries
The most commonly injured carpal bone is the scaphoid. Scaphoid fractures are common, especially in young. They occur due to fall on outstretched hand, and are classified according to Herbert. Symptoms include swelling, pain, and tenderness of the anatomical snuffbox. These fractures are not always visible on x-ray acutely, and so conservative treatment is usually performed despite x-ray evidence if the clinical suspicion is high, to prevent the high risk of complications.
Perilunate dislocation refers to dislocation of the carpus relative to the lunate. It’s a rare but serious injury which is often overseen initially. Treatment is surgical.
Etiology
Scaphoid fracture and perilunate dislocation occur due to fall on an outstretched dorsiflexed hand.
Classification
Scaphoid fractures are classified by the Herbert classification:
| Type | Description |
|---|---|
| Type A | Acute, stable |
| Type B | Acute, unstable |
| Type C | Delayed union |
| Type D | Nonunion |
Clinical features
Scaphoid fracture involves localised swelling and tenderness of the anatomical snuff box. There’s also pain when axially compressing the thumb.
Perilunate dislocation causes swelling, pain, and loss of function of the wrist. The dislocation can be palpated.
Diagnosis and evaluation
Scaphoid fractures may not always be visible acutely on x-ray. However, an untreated scaphoid fracture may cause complications. As such, if there is a clinical suspicion for scaphoid fracture, we should either treat conservatively and make another x-ray two weeks later (at which point the fracture will be visible) or make a CT/MRI to completely rule out fracture.
Diagnosis of perilunate dislocation is visible on x-ray as an empty lunate fossa, a triangularly shaped lunate bone, and misplacement of all carpal bones.
Treatment
Treatment of scaphoid fractures is mostly conservative, with thumb fixation with a cast. In case of dislocated fractures, ORIF with screw is performed.
Treatment of perilunate dislocation is surgical with ORIF.
Complications
Untreated scaphoid fracture has high risk of pseudoarthrosis due to avascular necrosis, nonunion, etc.