Trigger finger is also called as stenosing tenosynovitis of the finger. The muscles of the forearms are connected through the tendons along with the finger bones. The tendons in every single finger are covered by a protective sheath, which is lined with synovium(1) producing a fluid which helps the tendons to slide easily while bending and straightening the finger. Trigger finger is a condition that affects the tendon sheaths and tendons in the finger. Trigger finger is caused in the flexor tendon of the finger. When the tendons become thick they restrict or lock the finger forcing it to stay in a bent position creating difficulty in straightening the finger. Trigger finger occurs due to formation of a nodule in the tendon which gets jammed while passing through the tendon sheath resulting in the condition of the trigger finger.
Generally a trigger finger begins with inflammation of tendons situated within a protective shield known as the tendon sheath. When the tendon becomes inflamed, nodular and swollen, this leads to catching of either of the pulleys by the swollen tendon creating difficulty for the tendon to slide inside the sheath and hence flexing the finger towards the palm.
Causes of Trigger Finger or Stenosing Tenosynovitis
The main cause of trigger finger is still not known, however there are few reasons suspected to cause them:
- Trigger finger could frequently occur in people participating in strenuous activities(2) of the hand like meat cutting or gymnastics.
- In few cases if previous injury of the finger again gets reinjured this leads to formation of the trigger finger.
- Irritation or inflammation of the synovium and tendons may be caused by repeatedly using tools like wrench or drill.
- A severe injury in the palm of the hand may also cause a trigger finger.
- Women above 40 years can suffer with the condition of trigger finger.
- Gripping an object for a long time may also result in triggering of the finger.
- People having medical history of diabetes or rheumatoid arthritis could be at a risk for developing the condition of trigger finger.
- Conditions like carpal tunnel syndrome, de Quervains tenosynovitis, underactive thyroid, gout and Dupuytren’s contracture may also lead to trigger finger.
Signs and Symptoms of Trigger Finger or Stenosing Tenosynovitis
- Painful snapping or clicking while trying to extend or flex the finger.
- Pain at the base of the finger could also be experienced.
- Feeling of stiffness in the finger especially in the morning.
- The affected finger getting locked in a flexed position.
- Pain on firmly touching the base of the finger.
- Formation of a nodule at the base of the finger may also be noticed.
- Difficulty in straightening the finger back after bending.
- Generally symptoms get exacerbated during the day.
Treatment for Trigger Finger or Stenosing Tenosynovitis
First step towards treatment is a conservative or nonoperative approach, which generally helps overcome the problem. Conservative treatment includes:
- Restricting activities aggravating the condition.
- Using a splint or guard for protection of the affected finger.
- Anti-inflammatory medications either oral or injections into the tendon sheath to reduce pain, inflammation, clicking and locking.
Surgery may be required only when conservative treatment such as mentioned above fails to yield any results. Surgery is performed under local anesthesia to release the pulley from constriction and restore full movement of the tendon. Surgery is usually performed as an outpatient.
Exercises for Trigger Finger or Stenosing Tenosynovitis
Stretching Exercises for Trigger Finger or Stenosing Tenosynovitis
- Finger Abduction 1: This exercise is performed by placing the hand with affected finger on a flat table and joining the affected finger with the adjoining finger side by side. With the help of the thumb and the index finger of the other hand press them slightly. Apply slight resistance to the two fingers moving them apart using thumb and index finger with adequate resistance to separate the two fingers. Performing this exercise regularly not only helps in enhancing the blood circulation of the injured finger, but also straightens its small ligaments.
- Finger Abduction 2: This exercise is performed by separating the injured finger as far as possible from the adjacent normal finger in order to make a V shape. With the help of the index finger and the thumb of the other hand, push the two fingers against other fingers. Slightly press the two fingers joining them closer together. Performing this exercise regularly not only helps in enhancing the blood circulation of the injured finger, but also straightens its small ligaments.
- Extensor Stretch: This exercise is performed by placing the hand with affected finger on a flat table and holding the affected finger with the help of other hand. Slowly raise the affected finger upwards leaving other fingers flat on a table surface. Hold this position for few seconds until the affected finger stretches slightly. Performing this exercise regularly helps in activating the injured finger after the surgery.
- Finger Stretch: Start this exercise by straightening the fingers and joining them all together. Stretch the fingers apart as far as possible until a pain-free stretch is felt. Hold this position for few seconds then return back to the starting position.
- Other exercises could also be performed by bending the finger backwards and forwards holding this position for few seconds in order to stretch the joint. Perform the exercises till the hand gets completely relaxed.
- Stretching exercises not only helps in conditioning the muscles, but also reduce swelling modifying the position of the fingers.
Strengthening Exercises for Trigger Finger or Stenosing Tenosynovitis(3)
- Tennis Ball Squeeze: This exercise involves holding a tennis ball in the hand and squeezing it as hard as possible ensuring comfort without pain. Hold for 5 seconds and release. Repeat 5 to 10 times ensuring there is no exacerbation of symptoms.
- Towel Grab: This exercise is performed by folding the towel in half and putting it flat on a table. Place the injured hand on the towel with palm facing downwards. By grabbing the towel scrunch it as far as possible applying pressure towards the fist until a mild to moderate pain free stretch is felt. Gradually straighten the fingers releasing the towel back on the table. Perform this exercise for about 8 to 12 times.
- Finger Spring: This exercise is performed by wearing a rubber band around the outer surface of fingers including thumb. Stretch the rubber band by stretching the fingers. Perform 2 sets of 15.
- Apart from this there are also some tendon glide exercises that can be performed to improve range of motion of the affected finger.
Investigations for Trigger Finger or Stenosing Tenosynovitis
Generally a complete subjective and physical examination is performed to diagnose a trigger finger and to find out the possible affected structures. An MRI may be used in the rare cases.