What is trigger finger?

A trigger finger is a finger that becomes 'locked' after it has been bent (flexed). It is difficult to straighten out without pulling on it by the other hand. You may hear a 'click' when it is pulled straight. One or more fingers may be affected. Sometimes there is mild pain and/or a small swelling at the base of the affected finger.

What causes trigger finger?

The cause is often not clear. It is thought to be due to some inflammation which causes swelling of a tendon or tendon sheath.

• • A tendon is a strong tissue that attaches a muscle to a bone. In this case the tendon comes from a muscle in the forearm. It passes through the palm and attaches to the finger bone. The muscle pulling on this tendon bends (flexes) the finger towards the palm.

  • A tendon sheath is like a tunnel that covers and protects parts of a tendon. Normally, the tendon slides easily in and out of the sheath as you bend and straighten the finger. In trigger finger the tendon can slide out of the sheath when you bend your finger. However, it cannot easily slide back in due to the swelling. The finger then remains bent (flexed) unless you pull it straight with your other hand.

Most cases occur for no apparent reason in healthy people. In some cases it occurs after you have used your palm a lot. For example, after jobs which involved a lot of screwdriving, or using tools that press on the palm. These may cause some inflammation in the palm.

Sometimes trigger finger occurs as feature of another disease. For example, trigger finger is more common in people with rheumatoid arthritis, amyloidosis, diabetes, carpal tunnel syndrome, and in people on dialysis. In these situations you will have other symptoms of the condition and the trigger finger is just one feature. And it has to be stressed that, most people with trigger finger do not have any of these conditions.

What is the treatment for trigger finger?

Not treating is an option at first

Simply resting the hand and allowing any inflammation to settle may resolve the problem without the need for treatment.

A steroid injection

A steroid injection into the tendon sheath is the usual treatment if the condition does not settle. The steroid is combined with a local anaesthetic to make the injection painless. Steroids work by reducing inflammation. A finger splint may be advised for a few days after the injection to rest the finger. This treatment works in about 9 in 10 cases. A second injection may be needed if the first does not work.

Surgery

An operation done under local anaesthetic may be advised if the above does not work. A small cut is made at the base of the finger and the tendon sheath is widened. The operation is usually successful. However, with this operation there is a small risk of damaging the tiny finger nerve, and causing some numbness to the finger. Also, as with any operation, there is a small risk of the wound becoming infected.

Injection of the tendon sheath with a corticosteroid is effective over weeks to months in more than half of patients.^[4]

When corticosteroid injection fails, the problem is predictably resolved by a relatively simple surgical procedure (usually outpatient, under local anesthesia). The surgeon will cut the sheath that is restricting the tendon. Anecdotally, patients who respond at least transiently to corticosteroid injection are more likely to respond to surgical treatment.

One recent study in the Journal of Hand Surgery suggests that the most cost-effective treatment is two trials of corticosteroid injection, followed by open release of the first annular pulley.^[5] Choosing surgery immediately is the most expensive option and is often not necessary for resolution of symptoms.^[5]

Congenital Trigger Thumb

- Discussion:

- stenosing tenosynovitis of the flexor pollicis longus in childhood is relatively uncommon condition which causes triggering, IP joint flexion contracture, and a flexor tendon nodule over the metacarpal head level (Notta's nodule);

- although present at birth, dx often not made until 4-6 months of age

- often bilateral, with fixed flexion contractures at presentation;

- in some cases, there will be an associated anomaly;

- diff dx:

- may be mistaken for a fracture or dislocation of the thumb;

- congenital loss of the extensor tendon;

- in some cases, the diagnosis will be confused with arthrogryposis or CP;

- prognosis:

- if trigger thumb is present at birth, approximately 30 % of children will recover spontaneously in one year;

- 12 % of the trigger thumbs that develop at the age of six to 30 months recover in six months;

- if trigger thumb develops in a child over three years of age, however, it almost never improves spontaneously;

- therefore, it is wise to operate as soon as acceptable at this age

- a child not seen until after the age of four has a 50 per cent chance of developing a permanent flexion contracture;

- in the report by Moon, et al, 7,700 newborn children were examined prospectively to determine the congenital incidence of trigger thumb and finger - no cases were found;

- case histories of 43 trigger digit cases (35 trigger thumbs and 8 trigger fingers) noted in 40 children diagnosed were reviewed;

- of 35 thumb cases, 23 underwent surgical release and all responded satisfactorily to surgical treatment;

- spontaneous recovery was noted in 12 trigger thumb cases and in all eight trigger finger cases;

- trigger finger developed earlier in life than trigger thumb and the spontaneous recovery rate was higher in trigger finger than trigger thumb;

- ref: Trigger Digits in Children.

- Exam:

- most often involves the thumb but may involve any digit;

- thumb is often held in fixed, flexed position;

- characteristically, a palpable nodule called Notta's node is present on tendon in the region of the metacarpal head;

- Non Operative Treatment:

- Comparison of Splinting Versus Nonsplinting in the Treatment of Pediatric Trigger Finger

- Treatment:

- surgery should be considered if not resolved by 12 months of age;

- most surgical procedures should not be delayed beyond 3 years because of possible flexion contractures;

- general anesthesia;

- only potential surgical complication of significance in this anomaly is the severing of one of the digital nerves;

- radial digital nerve is esp at risk;

- both nerves hug the flexor tendon, and one or both can be easily cut by slight deviation of a knife or scissors in either direction as the pulley is opened;

- avoid making incisions directly over MP flexion crease, since there is little or no subQ fat underneath the crease, which leaves nerves unprotected during incision;

- generally only excision of the A1 pulley is required (since Notta's flexion tendon nodule will disapate with time);

- outcomes:

- in the report by McAdams TR, et al (2002), the authors reexamined 21 patients (30 thumbs) who underwent a release procedure, with an average follow-up of 181.3 months (15.1 years).

- 23 % of patients had a loss of IP motion and 17.6% had metacarpal phalangeal hyperextension, and this was unrelated to age at the time of surgery;

- there were no recurrence of triggering or nodules and no functional deficit;

- all seven patients who had a longitudinal incision had concerns about their scar appearance;

- it is the authors' belief that a transverse skin incision and surgical release of the A1 pulley for trigger thumb in children is a successful procedure even when done after age 3, but IP motion loss and metacarpal phalangeal hyperextension may occur in the long term

- Long-Term Follow-Up of Surgical Release of the A(1) Pulley in Childhood Trigger Thumb

Congenital trigger digit.

Congenital trigger digit.

Trigger thumbs in children. A review of the natural history and indications for treatment in 105 patients.

Incidence and Development of Trigger Thumb in Children.

Surgical Treatment of the Pediatric Trigger Finger

The Natural History of Pediatric Trigger Thumb

The treatment outcome of trigger thumb in children.

Acquired thumb flexion contracture in children: Congenital trigger thumb.

Pediatric Trigger Thumb in Identical Twins: Congenital or Acquired?

Pediatric trigger thumb with locked interphalangeal joint: can observation or splinting be a treatment option?

http://www.wheelessonline.com/ortho/congenital_trigger_thumb

https://en.wikipedia.org/wiki/Congenital_trigger_thumb

Original Text by Clifford R. Wheeless, III, MD.

References

• 1. ^ ^{a b c} Makkouk et al. (2008). "Trigger finger: etiology, evaluation, and treatment". Curr Rev Musculoskelet Med 1 (2): 92–6.

  2. ^ Gorsche R, Wiley JP, Renger R, Brant R, Gemer TY, Sasyniuk TM (1998 Jun). "Prevalence and incidence of stenosing flexor tenosynovitis (trigger finger) in a meat-packing plant". J Occup Environ Med 40 (6): 556–60. PMID 9636936.

  3. ^ Kasdan ML, Leis VM, Lewis K, Kasdan AS (1996 Nov). "Trigger finger: not always work related". J Ky Med Assoc 94 (11): 498–9.PMID 8973080.

  4. ^ ^{a b} Baumgarten KM, Gerlach D, Boyer MI (2007 Dec). "Corticosteroid injection in diabetic patients with trigger finger. A prospective, randomized, controlled double-blinded study". Journal of Bone and Joint Surgery (American) 89 (12): 2604–2611. PMID 18056491.

  5. ^ ^{a b} Kerrigan CL, Stanwix MG (2009 Jul–Aug). "Using evidence to minimize the cost of trigger finger care". J Hand Surg Am 34 (6): 997–1005.PMID 19643287.