Trigger finger and trigger thumb
What is it?
Trigger finger is a painful condition in which a finger or thumb clicks or locks as it is bent towards the palm.
What is the cause?
The forearm muscles bend (flex) the fingers of the hand by pulling up the cords called tendons, which are attached to the bases of the small bones of the fingers. These tendons are guided through a tunnel with a series of thick bands called pulleys, which prevents them bow stringing as well glide with no friction! These pulley bands can become less elastic and leathery with ageing and cause some friction. This then leads to mild tendon fraying, inflammation and pain at the site. Later a nodule develops in the tendon. When this nodule passes up and down the pulley, it clicks and is painful. Later, the strong bending muscles can pull the nodule up to bend the finger fully, but the weaker straightening (extensor) muscles can’t pull it back down to straighten the finger. When you force it or give it a help with the other hand it straightens suddenly with a click –the typical trigger finger. Later when the pulley is too tight the finger remains in permanent flexion or extension..
What are the symptoms?
- Pain at the site of triggering in the palm (fingers) or on the palm surface of the thumb at the base joint, usually in a person over the age of 40.
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Tenderness if you press on the site of pain
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Clicking of the digit during movement, or locking in a bent position, often worse on waking in the morning. The digit may need to be straightened with pressure from the opposite hand.
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Stiffness, especially in trigger thumb where movement at the end joint is reduced.
What is the treatment?
Trigger finger and trigger thumb are not harmful, but can be a really painful nuisance.
Some mild cases recover over a few weeks without treatment. The options for treatment are:
- Avoiding activities that cause pain, if possible
- Using a small splint to hold the finger or thumb straight at night. A splint can be fitted by a hand therapist, but even a lollipop stick held on with tape can be used as a temporary splint.
- Steroid injection relieves the pain and triggering in about 70% of cases, but the success rate is lower in people with diabetes. The risks of injection are small, but it very occasionally causes some thinning or colour change in the skin at the site of injection. Improvement may occur within a few days of injection, but may take several weeks. A second injection is sometimes helpful, but surgery may be needed if triggering persists.
- Percutaneous trigger finger release with a needle. Some surgeons prefer to release the tight mouth of the tunnel using a needle inserted under a local anaesthetic injection, but others feel that open surgery is more effective. The needle method is not suitable for all cases and all digits.
Surgical decompression of the tendon tunnel is usually performed under local anaethesia. Through a small incision, and protecting the nerves that lie near the tunnel, the surgeon widens the mouth of the tendon tunnel by slitting its roof. The wound will require a small dressing for 10-14 days, but light use of the hand is possible from the day of surgery and active use of the digit will aid the recovery of movement. Pain relief is usually rapid. Although the scar may be red and tender for several weeks, it is seldom troublesome in the longer term. Recurrence of triggering after surgery is uncommon.
Complications are rare. Major complications occur in about 1in a 1000 operations. CRPS occurs 1 in 3000 hand surgeries.
Minor Complications
Scar tenderness, dysesthesia
Swelling, pain, discomfort
Limited range of motion
Wound (infection, dehiscence)
Major Complications
Infection, leading to many months of pain and ending up with stiff finger
Incomplete release needing re operation
Over release leading to inability straighten finger fully – dropped finger.
Nerve damage leading to numbness, troublesome sensitive nerve
Complex regional pain syndrome causing many months of painful stiff hand.
Tendon rupture
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