What is "trigger finger"?
"Trigger finger" is a common condition affecting the tendons that flex the fingers or thumb, as they pass into the tunnel system, or "tendon sheath" in the hand. The tendon sheath becomes thickened, and the tendon itself may develop a swelling, or "nodule". This causes the finger to "stick" in a flexed, bent position, and there may be a click as the finger extends again. Sometimes, the finger has to be manually straightened using the other hand. Eventually, secondary stiffness or contractures may result. Some patients complain primarily of pain with use.
The problem occurs most often in middle-aged ladies, and may affect multiple digits. This is more common in certain patient groups, notably with diabetes or rheumatoid arthritis, who also tend to have a worse outcome after treatment.
Why does it occur?
The pathology i.e. the abnormality is a thickening of the near end of the flexor sheath. Why this occurs is unclear but it is primarily a degenerative i.e. a wear and tear type process. It is probably related to overuse in some patients either at work or just as commonly at home e.g. pruning with secateurs. In most people it comes on for no good reason.
What happens if nothing is done?
(This is referred to as the natural history i.e. what happens if Nature runs its own course.) Some people's symptoms resolve spontaneously especially in the thumb although it may take up to 18 months. Most people have sufficient symptoms that persist so they seek medical help.
Making the diagnosis
The Hand specialist who sees the patient will ask questions about their symptoms, when they started, how they progressed, what treatment (if any) they have had and other questions relevant to the problems. They will then examine the patient looking at the wrists and hands. Stressing i.e. pushing on the affected finger is usually uncomfortable. It is necessary to demonstrate some tenderness to confirm the site of the symptoms but this should not be too painful.
What test(s) might be performed?
Tests (also known medically as Investigations) include X-rays, scans, blood tests and particularly in the hand electrical tests (known as EMGs or Neurophysiology). These may be used to help make or confirm a diagnosis after a patient has described their symptoms and been examined.
In cases of trigger finger the diagnosis is usually obvious so tests are not required.
What are the non-operative treatments?
Treatment should start with non-operative options. These include activity modification (which usually does not give much benefit or has already been tried by the patient) and a steroid injection which is typically very effective. We inject a long-acting steroid, such as Depomedrone or Triamcinolone, with some local anaesthetic into the joint at the bottom of the thumb. The body naturally produces steroids to help dampen down inflammation. This appears to be one of the actions at this site. Success cannot be guaranteed but in 70-80% of patients there is some significant benefit. How long this lasts is unpredictable. Some people only have a few weeks or months of benefit. Others may have years or even life-long benefit such that they do not require further treatment, although may still have some mild on-going symptoms. If one injection provides only short term benefit then it is typically repeated. Patients often ask how many injections can be given. There is no set rule about this. Typically, however, a second injection will work a little less well than the first (although this is not inevitable). By the time three injections have been given a further injection will be successful and most specialists would recommend an alternative approach. There are risks. The biggest risk is of failure. There are risks of some pain for a few days, although that is usually minimised by taking pain-killers, starting while the area is still numb from the local anaesthetic. In theory there is a risk of infection, but this seems very rare and has not occurred in our Practice in over 10 years. The main other risk is some thinning of the skin. This can present with some pallor and a little less bulk at the site and occasionally an increased tendency to bleeding if the area is knocked. This is not common with this injection but is common with some other injections. If it does occur then that is a relative contra-indication to further injections, i.e. the patient's surgeon would probably decide not to go ahead with further injections because of the risks of further local damage. Overall about 90% of our patients are resolved with steroid injections.
What does the operation involve?
Historically this was always performed opening the operating theatre. Increasingly we are performing it closed i.e. not opening the finger but performing the procedure with a needle passed through the skin.
This is performed under local anaesthetic in the clinic. 1-2 ml of long-acting local anaesthetic is injected at the site of surgery. A large needle is passed through the skin and the near end of the tendon sheath is divided over about 1cm to relieve the triggering. The patient should be able to bend the finger without triggering at the end of the procedure. No stitches are needed. A light dressing is applied.
This is usually performed under a local anaesthetic in the operating theatre. A tight band, like a blood pressure cuff, is placed around the top of the arm, during the operation to reduce bleeding, which makes the operation easier and safer. The surgeon makes a small (1-2 cm) incision in the palm of the hand, just at the base of the affected finger. The constricted first portion of the tunnel system is released, so that the tendon has more space in its tunnel, and can run freely. This is checked by asking the patient to bend their finger. The skin is then stitched up with absorbable sutures.
The total time in hospital is usually a 1-2 hours.
What happens in the next few weeks?
The care of the hand in the post-operative period is very important in helping to ensure a good result. Initially the aims are comfort and elevation. These are met by keeping the hand up (elevated) especially in the first few days and by use of a long acting local anaesthetic (Bupivicaine). The local anaesthtic lasts at least 12 hours and sometimes 48 hours. Patients should start taking painkillers before the pain starts i.e. on return home and for at least 24 hours from there. This way most of our patients report little or any pain.
The bandage can be removed after 2-7 days, leaving a sticky dressing beneath. The patient or GP practice nurse can do this. If well healed at that stage then the wound can be left open (exposed). If in doubt it can be covered with a light dressing for a few more days. The patient is reviewed in clinic between 2-4 weeks following the operation. Typically dissolvable stitches are used so they should not require to be removed.
The hand can be used for normal activity after the first few days. Most patients can drive after a 2-3 days. Most patients return to work in 2-5 weeks, but this varies with occupation; heavy manual work usually takes about 4 weeks. The wound should be massaged by the patient 3 times a day with a bland soft cream for 3 months once the wound is well healed (typically after 2 weeks). This reduces the scar sensitivity which can be a nuisance. If this is marked a Physio may be organised to help reduce the scar tenderness but this is rarely required. Patients should avoid pressing heavily on the scar for 3 months following the operation as this will be quite painful. Examples of activities to avoid are using the palm to grip/twist a heavy or tight object or use the palm to help get out of a chair.
What are the results of the operation?
At least 85-90% of patients say they have a good result following this operation, with relief of the pain and triggering. If there is already severe stiffness of the finger, then this may not improve. Recurrent symptoms do occur but in our experience in only a 2-3% mainly in patient with more severe symptoms and particularly patients with Diabetes.
Are there any risks?
All interventions in medicine have risks. In general the larger the operation the greater the risks. For trigger finger or thumb release the risks include:
- The scar may be tender, in about 20% of patients. This usually improves with scar massage, over 3 months.
- Aching, in the are may occur for a few weeks but usually settles fully.
- Grip strength can also take some months to return to normal.
- Stiffness may occur in particular in the fingers. This is usually short-term and only infrequently requires physiotherapy. But it is very important that it is resolved quickly to avoid permanent stiffness. This occurs rarely but can do associated with CRPS (see below)
- Numbness can occur around the scar but this rarely causes any functional problems.
- Wound infections occur in about 1% of cases. These usually quickly resolve with antibiotics.
- Chronic Regional Pain Syndrome "CRPS". This is a rare but serious complication, with no known cause or proven treatment. The nerves in the hand "over-react", causing swelling, pain, discolouration and stiffness, which very slowly improve.
- Any operation can have unforeseen consequences and leave a patient worse than before surgery.