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Musculoskeletal Medicine for Medical Students

Trigger Finger (stenosing flexor tenosynovitis)

 

  Trigger Finger

References :

Description

Trigger finger is when the tendon of the finger gets stuck during straightening or flexing the finger and instead of smoothly straightening or flexing the finger, it pops or doesn't straighten at all.

American Academy of Orthopaedic Surgeons website

Pathology (organ, cell, system)

There is noninfectious inflammation of the flexor tendon sheath of the finger. Also, the tendon may thicken and nodules may form, makings passage through the tunnel more difficult. This inflammation/thickening is secondary to another process (usually idiopathic) and causes the symptoms.

UpToDate

Pathophysiology

The flexor tendons for each digit travel in flexor tendon sheath/tunnel. There are also multiple pulleys over which the tendon glides. Swelling or nodules forming on the flexor tendon or within the tunnel(particularly the A1 pulley) prevent smooth gliding of the tendon over the pulleys, leading to 'popping' or 'locking' which can cause the finger to lock in flexion.

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Differential Diagnosis

Differential diagnosis includes:

1. gamekeeper's thumb: see pain at MP joint

2. sprain of MP joint(often trauma): see tenderness on either side of MP joint associated with loss of full flexion.

3. de Quervain's tenosynovitis: see pain near anatomic snuff box combined with radial styloid tenderness and pain aggravated by isometrically resisting thumb extension.

4. If after human or animal bite of hand: consider infectious flexor tenosynovitis

Trigger thumb is often seen in diabetics. Therefore, a patient with trigger thumb may warrant checking for previously undiagnosed diabetes.

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Epidemiology

Primary trigger finger occurs most commonly in the middle

fifth to sixth decades of life and up to 6 times more frequently

in women. The lifetime risk of trigger finger development

is between 2 and 3%, but increases to up to 10% in diabetics

The incidence in diabetics is associated

with actual duration of the disease, not glycemic control

Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6. Trigger finger: etiology, evaluation, and treatment. Makkouk AH, Oetgen ME, Swigart CR, Dodds SD.

Etiology

The cause is usually unknown. Several causes of trigger finger have been proposed including: repetitive finger movements and local trauma. The real answer is nobody knows. However, considering that it is 6x more common in women than men, I am inclined to believe (although I have no data to support this), that autoimmune  or hormonal issues may play a role.

 

Diabetes is very common in these patients and diabetes interferes with healing, so perhaps the microdamage/trauma that occurs from overuse or repetitive injury leads to damage that is never healed properly, leading to scar formation.

 

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Clinical manifestations

Symptoms can include a tender nodule in the palm (corresponding to the scar nodule that forms along the tenosynovium sheath. Swelling can be present (which corresponds to the inflammatory nature of the disease). Pain can be present when bending or straightening the finger. Most notably this is worse after inactivity. With use, throughout the day, the tendon 'loosens up'. The most prominent symptom is the catching or popping sensation in the digit or thumb joints. Although depending on when in the day the patient is examined this sign may not be elicited on exam.

AAOS website

Late presentation, complications

Trigger finger is NOT a dangerous condition.  Over time the joint stiffness can worsen which becomes compounded by less attempted mobility leading to further stiffening (vicious cycle). Eventually the finger can become stuck in the trigger position. The disability of this condition varies among patients.

AAOS website

Nutritional factors

Not applicable directly. Although indirectly applicable because diabetes duration is associated with increased incidence of trigger finger. Therefore, better glucose and diet control would delay onset of diabetes therefore indirectly delaying onset of trigger finger. (This is my own conjecture)

none

Radiographic evidence

Play xrays are NOT necessary in suspected  cases of trigger finger.

UpToDate

Laboratory evidence

No lab values are relevant here, other than checking for an diabetes (random glucose, A1c, etc)

 

Psychosocial impact of disease

It all depends on what you use your hands for. If you are a pianist, then you are screwed. If you are a couch potato who obsesses over fantasy sports but never leaves the couch and is not concerned about aesthetics, then you're fine. If it were, me, I would be very concerned, I don't like asymmetry… it would weird me out to see one finger stuck in a fixed position even if it had no impact on my day to day life.

none

Risk factors

Obesity (increases risk for DM), occupations involving repetitive hand use or trauma (although this is controversial), female, 5th or 6th decade of life

Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6. Trigger finger: etiology, evaluation, and treatment. Makkouk AH, Oetgen ME, Swigart CR, Dodds SD.

Prevention

none

AAOS, UpToDate, Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6. Trigger finger: etiology, evaluation, and treatment. Makkouk AH, Oetgen ME, Swigart CR, Dodds SD.

Treatment options

1. Rest: resting the finger with or without a splint, may be enough to resolve the problem. This provides sufficient relief of symptoms in approximately 50%  of patients.

2. Medications to relieve pain: NSAIDS, acetaminophen

3. Steroid injections. Is effective in up to 93% of patients.

4. Surgery (cutting the tendon sheath tunnel to loosen up the tendon and give it more room to move through it) is the definitive treatment for patients who fail conservative therapy. Surgery  is reported as 90-100% effective depending on the series. 

 

Rodgers JA, McCarthy JA, Tiedeman JJ. Functional distal

interphalangeal joint splinting for trigger finger in laborers: a

review and cadaver investigation. Orthopedics 1998;21:305–9,

discussion 309–10.

Freiberg A, Mulholland RS, Levine R. Nonoperative treatment of

trigger fingers and thumbs. J Hand Surg [Am] 1989;14:553–8.

Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6. Trigger finger: etiology, evaluation, and treatment. Makkouk AH, Oetgen ME, Swigart CR, Dodds SD.

 

Outcomes  of treatment

Most patients find relief from conservative management (splinting/steroid injections) and those who fail generally do well with surgery.  With most having full recovery within 6 months of surgery. Physical therapy can help to loosen the joint after surgery.

Curr Rev Musculoskelet Med. 2008 Jun;1(2):92-6. Trigger finger: etiology, evaluation, and treatment. Makkouk AH, Oetgen ME, Swigart CR, Dodds SD.

 

AAOS website

Potential
Complications of treatment

Incomplete extension: due to persistent tightness of the tendon sheath beyond the part that was released. Persistent triggering: due to incomplete release of the first part of the sheath. Bowstringing: due to excessive release of the sheath. Infection. Nerve damage

Akhtar S, Bradley MJ, Quinton DN et al. Management and

referral for trigger finger/thumb. BMJ 2005;331:30–3.

Misc

Trigger finger is one big question mark (and the finger stuck in the flexed position kind of looks like a question mark). Nobody seems to agree or know why patients get it. Although diabetes seems to play a role or unknown degree.

none

 

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