A 27-Year-Old Male with Pain After a Fall

Differential Diagnosis

• Dorsal intercalated segmental instability
• Scapholunate advanced collapse
• Scapholunate dissociation
• Volar intercalated segmental instability

Diagnosis

This patient was diagnosed with scapholunate dissociation (disruption of the ligament between the scaphoid and lunate carpel bones), denoted by a widening of the scapholunate interval.  The patient also has rotation of the lunate and scaphoid.

Learnings/What to Look for

• In adults, a scapholunate gap of >3 mm with clenched fist view (Terry Thomas sign) on AP radiographs is considered diagnostic of scapholunate dissociation
• In children, the scapholunate interval is normally wider due to unossified portions of each of the carpal bones. Females have a shorter distance due to earlier skeletal maturity and reach adult values at ~11 years, whereas males reach adult values at ~12 years
• The most common mechanism of injury is a fall on outstretched hand (FOOSH)

Pearls for Initial Management

• Acute, nondisplaced and chronic asymptomatic scapholunate interosseous ligament injuries may be treated conservatively with nonsteroidal anti-inflammatories and immobilization
• Surgical repair or reconstruction of the scapholunate interosseous ligament may be required to prevent long-term complications (eg, proximal migration of the capitate between the scaphoid and lunate, possibly resulting in scapholunate advanced collapse)

Acknowledgment: Image and case presented by Experity Teleradiology (www.experityhealth.com/teleradiology).