Trigger Finger and Thumb

 The tendons that move the fingers are held in place on the bones by a series of ligaments called pulleys. These ligaments form an arch on the surface of the bone that creates a tunnel for the tendon to run in along. To keep the tendons moving smoothly under the ligaments, the tendons are wrapped in a slippery coating called tenosynovium. The tenosynovium reduces the friction and allows the tendons to glide through the tunnel as the hand is used to grasp objects.

Triggering usually results from of a thickening in the tendon that forms a nodule. The pulley may thicken as well. The constant irritation from the tendon repeatedly sliding through the pulley causes the tendon to swell in this area and create the nodule. Rheumatoid arthritis or partial tendon lacerations can also cause triggering. Diabetics are more prone to the problem in whom it is likely to affect multiple fingers. Triggering can also be caused by a congenital defect that forms a nodule in the tendon. The condition is not usually noticeable until infants begin to use their hands.

Symptoms

The symptoms of trigger finger or thumb include pain and a funny clicking sensation when the finger or thumb is bent and straightened. Tenderness usually occurs over the area of the nodule, in the palm at the bottom of the finger or thumb. The clicking sensation occurs when the nodule moves through the tunnel. With the finger straight, the nodule is under the pulley. When the finger is bent, the nodule passes out from under the pulley and causes the clicking sensation. If the nodule becomes too large it may not be able to pass back under the pulley and gets stuck at the near edge and the finger becomes locked in the bent position.

Treatments provided by an occupational therapist may be effective when triggering has been present for less than a few months. Therapists often build a splint to hold and rest the inflamed area. You might be shown ways to change your activities to prevent triggering and to give the inflamed area a chance to heal. Therapy sessions sometimes include iontophoresis, which uses a mild electrical current to push anti-inflammatory medicine to the sore area. This treatment is especially helpful for patients who can't tolerate injections.

A cortisone injection into the tendon sheath acts to decrease the inflammation and shrink the nodule. This can help relieve the triggering in 70-80% of patients. In some patients there is a permanent cure, whilst in about 20% some recurrence of the symptoms may develop a few months later. A splint may be used after the injection to rest the tendon and help decrease the inflammation and shrink the nodule. Side effects from the injection are usually minimal. Patients may notice some mild aching in the area for 1-2 days, on occasion requiring a Panadol. Diabetic patients may have some elevation of their blood sugars for 1-2 days and must therefore monitor their blood sugar levels and contact their physician if they become significantly raised.  

Other local reactions are uncommon and include infection, abscess formation, increase or decrease in skin pigmentation, skin or fat atrophy, tendon or nerve damage. More serious generalized complications are rare and include fluid retention, heart irregularities, hip bone necrosis, muscle weakness, peptic ulceration or convulsions.  A maximum of 2 injections is given as the cortisone may weaken the tendon and cause it to snap if repeated treatments are given.

The surgical solution for treating a trigger digit is to split open the pulley that is obstructing the nodule and keeping the tendon from sliding smoothly. This surgery can usually be done as a daycase procedure. The surgery can be done using a general anesthetic or a local anesthetic with some sedation. A 2 cm incision will be made in the skin along the natural palmar crease line in the hand. The skin and fascia are separated so the tendon pulley is identified. Special care is taken not to damage the nearby nerves and blood vessels. The tendon pulley is then divided longitudinally along its roof and movement checked to make sure it is no longer catching. The skin is sewn together with fine stitches.

After the surgery you will probably have a large padded bandage on your hand, which will need to be kept dry. This is to provide gentle compression and reduce the bleeding and swelling that occurs immediately after surgery. We will change this dressing after a week to a small dressing pad that you can shower with. You'll begin a gentle range-of-motion exercises straight after surgery. It is essential that you keep your fingers moving post operatively so that they do not swell and stiffen. i.e. make a fist and then straighten out the fingers several times every half hour during the day.

Most patients won't need to participate in a formal rehabilitation program unless the finger or thumb was locked for a while before surgery. In these cases, the finger or thumb may not straighten out right away after the surgery. An occupational therapist may apply a special brace to get the finger or thumb to straighten. The therapist may also apply ultrasound, soft-tissue massage, and hands-on stretching to help with the range of motion.

The scar may be thick, lumpy, tender and tight for 2-3 months after surgery. If it is a problem then the occupational therapist can treat the area and help the scar tissue to resolve. This may involve ultrasound, soft-tissue massage, silicone gel sheeting or iontophoresis with dexamethasone.

Some of the exercises you'll begin to do are to help strengthen and stabilize the muscles and joints in the hand. Other exercises are used to improve fine motor control and dexterity. You'll be given tips on ways to do your activities while avoiding extra strain on the healing tendon. You may need to return to therapy one or two sessions each week for up to six weeks.

POSSIBLE COMPLICATIONS OF THE OPERATION

1. Bleeding and haematoma (bleeding into the tissues).  This rarely requires return to the operating theatre.  Aspirin and other non-steroidal anti-inflammatory agents taken up to two weeks prior to surgery, even as a singe small dose, can increase the risk of bleeding.  Patients on anti-coagulants need specific peri-operative management.
2. Wound separation and delayed healing.
3. Inflammation and infection.
4. Pain – the severity and duration of post-operative pain varies.
5. Anaesthetic complications e.g. Sore throat when a tube is used to administer general anaesthetic, painful or infected intravenous site, nausea and vomiting, stroke, heart attacks, cardiac arrhythmias, deep venous thrombosis (DVT) leading to pulmonary embolism, allergic reaction.
6. Sensitivity to dressings and tape.
7. Thick, lumpy and tender scars.
8. Unsatisfactory result and the need for revisional surgery. The cure rate for this type of surgery is approximately 98%
9. Damage to other structures – Nerves, blood vessels, bone and soft tissues may be damaged during surgery.
10. Reflex sympathetic dystrophy – Chronic pain, swelling and limited movement in the hand