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Trigger finger

Description

Stenosing tenosynovitis, also known as “trigger finger,” is a condition in which the flexor tendons of the fingers may get caught within their sheaths thereby limiting movement and causing pain. When the tendons are caught, the finger can get stuck temporarily in a flexed position. When the finger is then forced into full extension, a painful snap or click is felt, hence the name trigger finger. This condition is sometimes known as "stenosing tenosynovitis," as the common lesion seen in all forms of triggering is a relative narrowing (stenosis) of the space for the tendon relative to the size of the tendon itself.

Structure and function

Finger flexion is powered by the flexor digitorum profundus (for the distal interphalangeal, or DIP, joint) and the flexor digitorum superficialis for the proximal interphalangeal (PIP) joint. These tendons travel together in the palm and ascend the fingers through a fibro-osseous canal along each digit. This canal is formed by the metacarpals/phalanges, and by a pulley system and tendon sheath. The pulley system keeps the flexor tendons snug to the bone, preventing “bowstringing” during active flexion and converting a linear force into rotation and torque at the finger joints.

  

When this canal is abnormally tight (that is, "stenotic") the tendons may get stuck. Stenosis may result from either thickening of the tendon (with or without nodule formation) or by thickening of the tendon sheath, thereby reducing the relative volume of the canal.



Figure: Drawing of the flexor tendons in profile. The tendons are held close to the bone by a system of pulleys (only one of which is shown here in green). If there is a nodule (shown here in red) within the flexor tendon, it might be unable to pass through the pulley. Thus, the finger can get stuck in flexion.

 

Flexion of the proximal phalanx, particularly with power grip, results in high loads at the distal edge of the most proximal (A1) pulley.  The pulleys respond to this load with growth and become hypertrophic. A nodule may develop on the flexor tendon, likely in response to abrasion with the tendon sheath.  Hypertrophy or module formation may cause a mismatch between the size of the tendon and the tendon sheath through which the tendon must slide.  The mechanical impingement of the flexor tendons as they pass through a narrowed A1 pulley results in the phenomenon of trigger finger.  The flexor mechanism in the hand is usually strong enough to overcome the narrowed tendon sheath, but the extensor mechanism generally is not as strong. Hence, the affected finger may become locked in flexion rather than extension.  

The term "stenosing tenosynovitis," in particular the -itis suffix, may not accurately reflect the pathophysiology of the condition. There is stenosis, but stenosing tenosynovitis is not an inflammatory condition per se. Inflammation, when seen, is part of the body's correct (but perhaps too exuberant) response to a stimulus.

The most common etiology of trigger finger is idiopathic - that is, for no known reason.  Secondary trigger finger can be seen in patients with collagen vascular disorders and inflammatory disorders including rheumatoid arthritis, amyloidosis, gout, diabetes, hypothyroidism, and sarcoidosis. Secondary trigger finger is associated with a worse prognosis.  

Patient presentation

Trigger finger can present as an acquired condition in adulthood or as a congenital condition in children.

In children (<2 years of age), triggering most commonly occurs in the thumb and is then known as “trigger thumb.” Congenital trigger thumb typically presents with the thumb interphalangeal joint locked in some flexion and a palpable nodule at the metacarpophalangeal (MCP) flexion crease. 

In adults, mild cases of trigger finger can present with a sense of finger stiffness, particularly in the morning. With more advanced cases, patients will commonly present with an initial complaint of painless clicking with finger movement.  This can progress to painful locking of the finger in flexion and may require passive manipulation of the digit into extension.  Often a painful nodule can be palpated in the palmar MCP area.  

          

Clinical evidence

Patients with stenosing flexor tenosynovitis without a history of injury or inflammatory arthritis do not need routine radiographs.  

Similarly, no laboratory tests are needed to make the diagnosis, but such tests may be helpful for detecting an underlying cause. Test for diabetes, thyroid disorders, and rheumatoid arthritis may be clinically indicated. 

Epidemiology

This condition occurs most commonly in the fifth and sixth decades of life and has been reported to be up to six times more common in women than in men.   Lifetime risk of trigger finger has been shown to be 2-3% but increases up to 10% in diabetics. The ring finger and thumb are the most commonly affected digits followed by the long, index, and then small. The dominant hand is most commonly affected.  

 

Differential diagnosis

The classic presentation of a painful click with forced extension of the fingers, with a palpable nodule probably does not have a true "differential diagnosis". That is, when a tender nodule impeding passive extension is palpated by the examiner, there is no mistaking this condition for something else.  

If the presentation is not classic, other conditions may be considered. Dupuytren disease can present with fixed contracture of the finger, as can a contracture of the joint capsule itself. A loose body in the MCP joint or an articular irregularity may cause a mechanical blockage. Failure of the extensor mechanism will also cause the finger to be held in flexion (as the flexors are unopposed). Extensor failure is distinguished from trigger finger, as in that case gentle passive correction is unimpeded. Irritation of the sesamoid bones (e.g., sesamoiditis) can mimic the painful sensation of trigger thumb.

It is also possible that reported triggering is a manifestation of psychiatric disease.

Red flags

Secondary trigger finger can be seen in patients with collagen vascular disorders and inflammatory disorders including rheumatoid arthritis, amyloidosis, gout, diabetes, hypothyroidism, and sarcoidosis and is associated with a worse prognosis after treatment.  

Treatment options and outcomes

Non-operative treatment modalities include activity modification, NSAIDs, PIP joint immobilization and corticosteroid injections.  NSAIDS and corticosteroid injections both work to reduce inflammation. 


Figure: Trigger finger injection.

Corticosteroid injections are  placed into the tendon sheath at the level of the A1 pulley.  If an injection does not cure the problem, a second or even third injection may be tried before deeming this approach a failure.  Possible side effects include fat necrosis, skin hypopigmentation and, rarely, tendon rupture. 

Most patients do well with non-operative measures. For those who do not, surgery can be performed to release the A1 pulley. An alternative, and less invasive, method is percutaneous release of the pulley with the use of a needle. This needle method, though, has a higher risk of digital nerve injury in the thumb and is thought to have a higher risk of incomplete release of the pulley. 

The success rates of open surgical release has been shown to be greater than 90%. The complication rates are low (3% in some studies). Possible complications include nerve injury, bowstringing, scar formation, and continued pain. 

 

In children less than 6 months old, 30% of trigger thumbs will resolve spontaneously.  After 6 months of age, spontaneous resolution is decreased to nearly 10% and surgical intervention with release of the A1 pulley may be indicated. 

 

 

Risk factors and prevention

There is a higher risk of development of trigger finger in patients with diabetes, hypothyroidism, gout, sarcoidosis, rheumatoid arthritis, and amyloidosis. There are no data on prevention methods in general, or those steps that could prevent a nascent case from worsening. (The latter, especially, would be particularly helpful.)

Miscellany

A cross-sectional study of 665 workers at a meat-packing plant found that the person-year incidence rate of trigger finger was more than five-fold higher among those workers with repetitive tool use compared to non-tool use workers. This suggests that trigger finger may indeed be a work related condition.

In guitar players, standard release of the A1 pulley for trigger finger may interfere with the fine control of the fingertip when the finger is held in extreme flexion.

Key terms

stenosing tenosynovitis, trigger finger, trigger thumb

Skills  

Recognize the clinical features of trigger finger and the treatment options.

Content

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  1. Mar 09, 2014

    a comment to make sure it works

  2. Mar 12, 2014

    COMMENTS:

    1. Structure and function: page 3

    “flexor digitorum profundus (for the DIP)” NOTE: I don’t know how basic this is or where in the book this chapter will be, but consider spelling out “distal interphalangeal joint”

    “flexor digitorum superficialis for the PIP” NOTE: for consistency, put “for the PIP” in parenthesis, and, as above, consider spelling out “proximal interphalangeal joint”

     “This canal is formed by the metacarpals/phalanges, and by the pulley system and tendon sheath.”à take out the comma after phalanges, consider “by a pulley system” rather than “the pulley system”       

    NOTE: For the graphic, consider having a key spelling out “DP, MP, PP, MC”

    Paragraph under graphic: “When this canal is tight (ie "stenotic")”-->periods between “i.e.”

     

    1. Structure and function: page 4

    “The pulleys can respond to this load with growth become hypertrophic.” NOTE: The pulley responds to this load with growth and becomes hypertrophic. (take out “can”, add an “s" to "pulley” and "hypertrophic" and add in “and”)

    “This causes a mismatch between the size of the tendons and the tendon sheaths through which the tendons slide.” NOTE: Hypertrophy and/or nodule development can cause a mismatch....

    “Hence, the affected finger may become locked in flexion rather than extension.” NOTE: "For this reason, the affected finger may become…. ” QUESTION: perhaps add: “and is sometimes referred to as stenosing flexor tenosynovitis”(question)

    “The term "stenosing tenosynovitis" may not accurately reflect the pathophysiology of the condition, as it is not an inflammatory condition per se; inflammation, when seen, is part of the body's correct (but perhaps too exuberant) response to a stimulus.” NOTE: The term “stenosing tenosynovitis,” therefore, does not accurately reflect the pathophysiology of the condition. It is not an inflammatory condition. Inflammation, when seen….”

    “Secondary trigger finger can be seen in patients with collagen vascular disorders and inflammatory disorders including rheumatoid arthritis, amyloidosis, gout, diabetes, hypothyroidism, and sarcoidosis and is associated with a worse prognosis after conservative or surgical treatment.” NOTE: no need for comma after hypothyroidism. also add in word "both" to the following:worse prognosis after both conservative and surgical treatment.” QUESTION? would it make sense to include something along the lines of, "perhaps the condition was named as a result of the association with these inflammatory conditions"

     

    2.       Patient presentation: p. 5

    NOTE: I would have the explanatory paragraphs mirror the order of the first sentence–i.e. either reverse the order of the first sentence to have congenital condition in children first and then have the paragraph describing it as the first one, or reverse the second and third paragraphs to mirror the order of the first sentence as it stands now.

    In children (<2 years of age), this most commonly occurs in the thumb and is then known as “trigger thumb.” Congenital trigger thumb typically presents with the thumb interphalangeal joint locked in some flexion and a palpable nodule at the metacarpophalangeal (MCP) flexion crease.” NOTE: In children (<2 years of age), the thumb is most commonly affected by this condition, and is therefore named “trigger thumb…. locked in flexion (to a variable degree)….

    QUESTION: is this node painful in children?

    Mild cases of adult trigger finger can present with a sense of finger stiffness, particularly in the morning. With more advanced cases, patients will commonly present with an initial complaint of painless clicking with finger movement. This can progress to painful locking of the finger in flexion and may require passive manipulation of the digit into extension. Often a painful nodule can be palpated in the palmar MCP area.” NOTE: In adults, mild cases of trigger finger….

    QUESTION FOR CLARIFICATION: is the palmar MCP area in adults the same as the MCP flexion crease in children? If so, I would use same language for both. If not, perhaps go into slightly more detail? 

     

    3. Clinical evidence p. 6

    NOTE: this is the first time the term “flexor tenosynovitis” is used, not sure that this is confusing, but perhaps insert  the term on page 4—noted above.

    “total of 110 involved fingers found that radiographs not once influenced management." NOTE: radiographs did not influence management even once

    “such as diabetes, thyroid disorders, and rheumatoid arthritis if clinically indicated.”àno need for comma after thyroid disorders

     

    QUESTION: What about for patients with a history of injury or inflammatory arthritis? Is practice are they actually treated the same?


    4. Epidemiology p.7

    NOTE: No need to capitalize “Trigger Finger” here—everywhere else it is both with lower case letters. (or always capitalize both letters). No need for comma after “index.”

    QUESTION: lifetime risk for all comers? Women ? men? 

    NOTE: Last sentence a bit awkward–change to: the dominant hand of the patient is more commonly affected.


    5. Differential Diagnosis p. 8

    NOTE: Colon should go inside the quotation marks of “differential diagnosis”

    NOTE: Periods should go between the “i.e.” first line second paragraph.

    “A loose body in MCP joint or articular irregularity may cause a mechanical blockage.” NOTE: A loose body in the MCP joint or an articular irregularity ….

    “Failure of the extensor mechanism will obviously cause the finger to fall into flexion, though this is easily corrected passively” NOTE: ...flexion, though contrary to trigger finger, this condition is easily corrected passively and ?painlessly.

    NOTE: periods should go between e.g. in parenthesis (e.g. sesamoiditis).

    “It is also possible that reported triggering is manifestation of psychiatric disease.” NOTE: triggering is a manifestation….

     NOTE: perhaps include a table or chart with the 6 DDx?


    6.Red flags p.9

    NOTE:  no need for comma after hypothyroidism


    7. Treatment options and outcomes p. 10

    NOTE: no need for comma after immobilization in second line first paragraph

    NOTE: no need for the word “also” in second line, SHOULD BE: NSAIDS and corticosteroid injections both work to reduce inflammation

    “An alternative less invasive method is percutaneous release of the pulley with the use a needle,though this method has a higher risk of digital nerve injury in the thumb and is thought to have a higher risk of incomplete release of the pulley.”  NOTE: An alternative, less invasive, method is percutaneous release of the pulley with the use of a needlePercutaneous release has a higher risk of digital nerve injury …. [insert commas around “less invasive, add the word “of” and end sentence after needle].

    QUESTION: is the risk of digital nerve injury only when the thumb is what is being released? Or it is a risk the thumb with release of all digits? Or are all digital nerves at risk?

    NOTE:  There is no “photo for eye candy of surgical release of trigger” yet

    “Possible side effects include fat necrosis, skin hypopigmentation and rarely tendon rupture.” NOTE: insert comma after “rarely”

    NOTE: should you move the fourth paragraph (The success rate of corticosteroid injection has been found to be as high as 92% after 3 injections. Possible side effects include fat necrosis, skin hypopigmentation and rarely tendon rupture.) to be the second paragraph before discussing surgical intervention?

    “The complication rates are low (3% in some studies), but possible complications include nerve injury, bowstringing, scar formation, and continued pain.” NOTE: no need for comma after scar formation

    QUESTIONS: Is the order of treatment always a trial of 3 corticosteroid injections? Are there data about success of surgical release after trial of noninvasive measures? Are there different treatments/approaches to treatment for those with inflammatory diseases? Are there data of how much less successful treatment is for them? What is most often practiced given what seems to be the fairly equivalent treatment modalities and low complication risk across all modalities?

    8. Risk factors and prevention p. 11

    Hypothyroid change to: hypothyroidism, no need for comma after rheumatoid arthritis.

    QUESTION: anything to be done for prevention? Does early attention and immobilization limit progression?


    9. Miscellany p. 12

    QUESTION: should repetitive tool use be listed as a risk factor in previous chapter? No need for the word “ indeed” in last line of first paragraph.


    10. Key terms p. 13

    NOTE: the term “stenosing tenovaginitis” was not mentioned in the chapter until this point.

    NOTE: no need for comma after trigger finger

     

     

     

     

     

  3. Apr 13, 2014

    thanks for the close read!