Trigger Thumb Basics

TRIGGER THUMB

Many conditions of the thumb can cause pain.
Flexor Tendon Pulley System of the Thumb

• A1 pulley
• Oblique
• A2 pulley

 

• Trigger thumb is often called stenosing tenosynovitis and it can be bilateral.
• Trigger thumb can be associated with painful triggering or locking.
• Focal degenerative thickening of the flexor tendon (flexor pollicis longus) creates what looks like a nodule (localized swelling) at the level of the meta – carpal phalangeal joint of the thumb.
• This limits the tensor excursion with tendon stretch.
• The nodule gets jammed beneath the A1 pulley
• This occurs with a painful snap or click, similar to a trigger getting pulled or released with either flexion or extension of the thumb.
• A small change in the size between the flexor tendon diameter and the A1 pulley will effect the thumb in flexion and extension.
• When the nodule gets jammed, the thumb becomes locked.
• Idiopathic trigger thumb occurs more in women.
• It occurs during the 5th or 6th decade of life and is often bilateral.

Causes

• Idiopathic
• Diabetes
• Osteoarthritis
• Inflammatory arthritis
• Gout

 

• Patients with trigger thumb most likely will develop carpal tunnel syndrome or De Quervain’s syndrome
• Patients with trigger thumb may develop the condition from playing too much video games.

TREATMENT

• anti – inflammatory medication.
• injection into the sheath not the tendon.
• ultrasound is a great modality for precise injection.

Consider surgery in difficult cases.

• release of the pulley.
• avoid injury to the radial digital nerve.
• the radial digital nerve crosses obliquely over the the sheath proximal to the A1 pulley.

Courtesy : Prof Nabile Ebraheim, Chairman, Department of Orthopaedics and Trauma, University of Toledo, Ohio, United States