Introduction
Trigger finger or thumb (also known as stenosing tenosynovitis) is a painful condition often causing catching / locking of the tendon as you move the finger / thumb.
Tendons are responsible for bending of the finger / thumb. They are surrounded by a tunnel called the tendon sheath and held close to bone by pulleys.
Inflammation at the interface between the tendons and pulleys can cause scarring and thickening of pulleys and the tendon itself which can form a nodule. The A1 pulley is most commonly involved. The nodule gets caught in the pulley when the tendon moves hence causing trigger / locking / snapping sensation.
Trigger finger / thumb affects 2-3% of the population. The ring finger is most commonly affected. It commonly affects people in 50-60 years age group. It is more common in women. The incidence is closer to 10% in diabetics.
Causes
In MOST cases, the cause of trigger finger / thumb is unknown. There are however certain populations with increased predisposition:
- Repeated strong gripping – e.g.: occupation related.
- Diabetes.
- Rheumatoid Arthritis.
Signs and symptoms
Diagnosis is based on patient symptoms and examination findings. Scans are only required when diagnosis is uncertain.
Pain
Pain in the palm can occur when you bend or straighten the finger.
Tender Nodule
This is usually located in the palm.
Locking
This occurs when you bend the finger and have to forcefully straighten it.
Snapping / Popping / Clicking
This may occur as you move the finger.
Tests
Ultrasound / MRI
These can show thickening and inflammation of the tendon as well as nodule which catches on the pulley.
Non-surgical treatment
Night splint
This can be worn to minimize tendon movement and irritation. It is usually a temporary measure in mild early forms.
Activity Modification
Avoiding activities which cause the symptoms. This may involve changing jobs or changing roles at work.
Pain Killers / Anti-inflammatory Medications
These assist with pain only.
Injection
Corticosteroid / Cortisone is a powerful anti-inflammatory medication that may be injected into the tendon sheath. This may resolve symptoms up to one year. Up to two in lifetime may be given per tendon.
Diabetics usually have less successful results with injection.