Trigger finger is a condition affecting the gliding movement of the tendon as you bend or straighten the finger.
Tendons of the fingers or thumb extend from the forearm to the end of the digit. Within the finger, they are held close to the bones by fibrous tissue called pulleys. These pulleys form a tunnel for the tendon passage. The tendons are covered by a slippery coating called tenosynovium that reduces the friction during tendon gliding as the finger bends and extends. The pulley at the entrance of the tunnel located at the base of the finger is called the A1 pulley.
What is the cause of trigger finger?
It is the result of thickening of the tenosynovium or narrowing of the pulley. Constant irritation from the tendon sliding repeatedly through the pulley causes the tendon to swell and creates a nodule near the A1 pulley.
Who gets trigger finger?
Anyone can get trigger finger. But it is commonly seen in women between the ages of 40-60.
Certain conditions such as rheumatoid arthritis and diabetes mellitus predispose the patients to trigger finger. Partial tendon laceration, repeated trauma or occupation requiring long hours of grasping can lead to trigger finger too.
Triggering is also observed in infants and young children. It commonly affects the thumb but other fingers can be affected too.
How to make a diagnosis?
Diagnosis is made from symptom and physical examination. It started with clicking and pain at the palmar side of the base of finger as the finger is straightened from bent position. In later stage, there is more difficulty in straightening the bent finger. It is relieved by a forceful straightening, usually followed by a click and pain. In severe cases, the finger is locked in a bent position and cannot be straightened even with force.
No X-ray is required to make diagnosis. But X-ray may be taken to rule out arthritis of the joint when the joint is deformed.
How can the trigger finger be treated?
Treatment depends on the severity of triggering and how much it affects your daily function.
You can leave it alone in mild early cases with finger exercise and stretching. You may need to change your activities to prevent triggering and give the inflamed tendon time to heal.
Steroid injection adjacent to the A1 pulley area can decrease the inflammation and swelling. It helps to relieve the triggering. It is very effective but may be short lived. There is a risk of injuring the finger nerve and blood vessel.
Surgery is required if the triggering is troublesome and interferes with your work and activity or when the finger is difficult to straighten or locked. In this surgery, the A1 pulley which forms the entrance of the tunnel is released. If the tenosynovium is thickened, this may be excised too. In general, this surgery is safe and very successful with over 98% of patients have satisfactory result. There will be scar tenderness for few weeks. Nerve and blood vessels injury is uncommon with the use of loupe magnification. Recurrent is rare.