Terry-Thomas sign

Radiographic sign of wrist instability

The Terry-Thomas sign is a radiographic finding indicative of wrist instability, specifically involving the scapholunate ligament. It is named after the British comedian Terry-Thomas, who was known for his distinctive gap between his front teeth, which the sign resembles.

Pathophysiology

The Terry-Thomas sign is associated with a disruption of the scapholunate ligament, which is a critical stabilizer of the carpal bones in the wrist. This ligament connects the scaphoid and lunate bones, and its injury can lead to a gap between these bones, visible on an X-ray.

Radiographic Appearance

Scapholunate dissociation marked on X-ray

On a standard posteroanterior view of the wrist, the Terry-Thomas sign is identified by an increased gap between the scaphoid and lunate bones. Normally, this gap is less than 3 mm, but in the presence of a scapholunate ligament injury, the gap can widen to more than 3 mm, often measuring between 4 to 5 mm or more.

Clinical Significance

The presence of the Terry-Thomas sign is indicative of scapholunate dissociation, which can lead to wrist instability and arthritis if left untreated. Patients may present with wrist pain, weakness, and decreased range of motion. Early diagnosis and management are crucial to prevent long-term complications.

Management

Treatment of scapholunate dissociation may involve conservative measures such as splinting and physical therapy, or surgical intervention to repair or reconstruct the scapholunate ligament. The choice of treatment depends on the severity of the injury and the patient's symptoms.

Related Pages

• Scapholunate ligament injury
• Wrist joint
• Carpal bones
• Arthritis