Terry-Thomas sign

Terry-Thomas sign refers to an increased gap between the scaphoid and lunate bones of the wrist, visible on an X-ray. This condition is indicative of a scapholunate dissociation, a type of wrist injury that disrupts the scapholunate ligament and can lead to instability and pain in the wrist. The sign is named after the British actor Terry-Thomas, who was known for his distinctive gap-toothed smile, metaphorically likening the gap between the teeth to the gap between the wrist bones.

Causes

The Terry-Thomas sign is most commonly caused by trauma to the wrist, such as a fall on an outstretched hand, leading to a tear in the scapholunate ligament. This ligament plays a crucial role in stabilizing the scaphoid and lunate bones, allowing them to move together smoothly. When it is damaged, the bones can move apart, creating a gap that is visible on an X-ray.

Symptoms

Symptoms of a scapholunate dissociation may include:

• Pain in the wrist, especially when bearing weight or moving the wrist in certain ways
• Swelling and tenderness around the wrist
• A feeling of instability or weakness in the wrist
• Decreased range of motion in the wrist

Diagnosis

Diagnosis of a scapholunate dissociation involves a physical examination of the wrist, assessment of the patient's medical history, and imaging tests. An X-ray is typically the first imaging test performed, where the Terry-Thomas sign can be observed. In some cases, more advanced imaging techniques such as MRI or CT scan may be used to assess the extent of the injury and the condition of the ligament.

Treatment

Treatment for a scapholunate dissociation varies depending on the severity of the injury and the patient's overall health. Options may include:

• Non-surgical treatments, such as splinting or casting to immobilize the wrist and allow the ligament to heal
• Physical therapy to strengthen the wrist and improve its range of motion
• Surgical intervention to repair or reconstruct the damaged ligament and stabilize the bones

Prognosis

The prognosis for patients with a scapholunate dissociation depends on the severity of the injury and the treatment approach. Early diagnosis and treatment can improve outcomes, but some patients may experience ongoing symptoms such as pain, weakness, or reduced range of motion in the wrist.