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Dr. Yeshwanth NandimandalamTrigger finger

Introduction Trigger finger or Stenosing tenosynovitis of finger is caused by a nodule or thickening of flexor tendon which catches on the proximal edge of A1 pulley when the finger is actively flexed.

Trigger fingers are characterized by the inability to flex or extend the digit smoothly.

All digits can be affected, but the ring finger is most often involved, followed by the thumb and the long, index, and small fingers, in that order.

More than one trigger digit can be present on the same hand.

Triggering of digits in both hands is also common

Anatomy From the metacarpal heads to the distal phalanges all five digits are provided with a strong unyielding fibrous sheath in which the flexor tendons lie .

Synovial sheath is reinforced by a system of fibrous pulleys

It include 5 annular pulleys and 3 cruciform pulleys

A1, A3, and A5 overlie the MP, PIP and DIP joints respectively A2 and A4 over proximal and middle phalanx respectivelyA2 and A4 are considered most important. Their disruption leads to bowstringing, reduced mechanical efficiency and decreased flexion.

Cruciate pulleys function to prevent sheath collapse and expansion during digital motionThey facilitates approximation of annular pulleys during flexionC1 -Near head of proximal phalanxC2 - Base of middle phalanxC3 - Distal end of middle phalanx

Flexor synovial sheath for thumb starts proximal to carpal canal and its retinacular portion has 2 annular pulleys and an oblique pulley

A1 At MCP jointA2 At IP jointOblique Middle of proximal phalanx

Function of this system is to increase the mechanical efficiency by preventing bowstringing

Etiology Congenital

Repetitive trauma such as may occur in gardening, sewing, cutting with scissors, typing etc

Associated with conditions like Rheumatoid arthritis, Gout, Diabetes, Hypothyroidisism, Amyloidosis

Other rare causes are: -- Abnormal collateral ligament that may catch on a bony prominence on the side of metacarpal head.Abnormal seasmoid bone on the metacarpal head.Interposed capsule due to trauma.

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Pathophysiology The flexor digitorum profundus, flexor digitorum sublimis, and flexor pollicis longus should glide through the annular pulley system unobtrusively in flexion and extension of the digits.

Normally, there is a double synovial sheath that facilitates smooth gliding.

This synovial membrane is intimately involved with the tendons and the pulley system.

Stenosing tenosynovitis is a pathologic disproportion between the volume of the retinacular sheath and its contents

This disproportion inhibits gliding as the tendon moves through the A1 pulley

Inflammation manifests itself as a spindle shaped thickening in a localized area of the flexor tendon

There are two types of pathologic involvement of the tendon that occur with clinically triggering digits nodular and diffuse.

In nodular stenosing tenosynovitis, this occurs just distal to the A1 pulley, where tendon friction deforms the tendon and causes a nodule to form.

In diffuse stenosing tenosynovitis, the inflammation will not be as localized and may well extend beyond the A1 pulley

Signs and symptomsPain at the root of finger

Swelling

Tenderness

Palpable nodule

Abnormal crepitus

Locking of the digit either correctable or fixed

EAST WOOD CLASSIFICATIONGrade 0 : mild crepitus in a non triggering digit

Grade 1 : uneven movement of the digit

Grade 2 : clicking without locking

Grade 3 : locking of the digit that is either actively or passively correctable

Grade 4 : locked digit.

Medical management

Nonsteroidal anti-inflammatory drugs should be the initial form of treatment unless inadvisable because of the patients age or the presence of a peptic ulcer diathesis.

Use of NSAIDs can be combined with massage, ice therapy, splinting, and corticosteroid injections.

Splinting Affected finger should be kept in an extended position. The splint helps to rest the joint and prevents from curling of fingers into a fist while sleeping

Grade 4 (locked) digits will not respond to splinting

For the splints to be successful, they may have to be worn for as long as 4 months

In early nodular tenosynovitis, the combination of finger splinting, and NSAIDs has been successful

Coticosteroid injectionAll grades of tenosynovitis have been treated with injections, and all have been reported to respond.

Nodular trigger digit can be treated with an injection into the tendon sheath. An NSAID should accompany the injection if there is no history of ulcer disease.

Diffuse stenosing tenosynovitis should be treated with only one steroid injection and only if symptoms have been present for less than 4 months.

If symptoms have been present for longer than 4 months or persist after the initial injection, surgical release is appropriate without further nonoperative treatment.

Steroid injection into the tendon sheath can be done from either a lateral or a palmar approach.

The lateral approach is less painful because the neurovascular bundle lies palmar to the area of injection.

From the radial border of the finger, the needle is inserted into the midlateral area of the proximal phalanx over the first cruciate pulley.

The skin and subcutaneous area are anesthetized with 1% xylocaine without epinephrine

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The needle is inserted only until slight resistance is felt. The patient is asked to wiggle the finger.

Slight grating can be felt at the end of the needle.

If the needle is in the tendon proper, there is paradoxical motion of the needle and syringe

The rest of the anesthetic is then injected into the tendon sheath.

The needle is disconnected from the syringe but left in place, and the syringe is reloaded with 0.75 mL of corticosteroid and 0.25 mL of 1% xylocaine which is reconnected to the needle.

The patient is again asked to wiggle the finger to ascertain the correct position of the needle. The injection is given, and the needle is withdrawn

It is preferable to use the midlateral approach for patients who present with grade 1 or grade 2 disease and a small nodule and for patients with diffuse tenosynovitis of the fingers.

The treated digit should remain anesthetized for 3 to 4 hours.

Benefits from the steroid injection should persist for 2 to 5 days after the procedure

The palmar approach is equally effective, but it can be more painful because the palmar aspect of the hand has more sensory endings than the lateral and medial aspects of the fingers.

The palmar approach is preferred for grade 3 or grade 4 disease and for the second injection.

Surgical treatmentSurgical release of the A1 pulley can be done through either a transverse or a longitudinal incision in the palm.

Local anesthesia is preferable because it allows active flexion and extension on the operating table, and the completeness of the release can be confirmed.

The A1 pulley release is performed, and the patient is asked to flex and extend the digit intraoperatively.

If triggering is still occurring, the release should be checked for completeness; further release of the A1 pulley may be warranted.

If no further triggering occurs, the tourniquet is released, bleeding is checked, and the patient is asked to make a fist

Percutaneous techniqueAfter the finger or thumb has been well anesthetized, the patient is asked to actively trigger the affected digit.

A 20-gauge, 1-inch needle is then inserted with the sharp bevel parallel to the tendon.

The needle is inserted one third the distance from the distal palmar crease to the base of the long, ring, or small finger.

In the case of the index finger, the needle is inserted one third the distance from the distal thenar crease and the base of the finger.

These locations have been found to consistently correlate with the middle of the A1 pulley and to allow cutting both proximally and distally to completely transect it24

In the thumb, the needle is inserted at the intersection of the proximal thumb crease and a line perpendicular to it. Insertion at this point avoids the radial digital nerve of the thumb.

The A1 pulley is cut with a swiping movement of the needle. A definite grating should be felt.

Bevel of the needle should be oriented longitudinal with the needle

Once the pulley is thought to have been transected, the needle is withdrawn, and the patient is asked to flex the digit.

If triggering persists, the nodule is gently palpated to feel where it is catching on the A1 pulley. The needle is then reinserted so as to cut more proximally or distally

Drawbacks of percutaneous release include -incomplete release of the A1 pulley and -potential injury to adjacent neurovascular structures, to the tendons themselves, or to the volar plate.

The proximity of the radial sensory nerve to the A1 pulleys of the thumb and the index finger has prompted that these digits not be treated with percutaneous release.

Complications Injection of steroid into the neurovascular bundle can cause permanent damage of the digital nerve or artery

Complications of surgical release include -digital nerve transection, -A2 pulley injury with subsequent bowstringing of the tendons,- bothersome scars,- recurrent symptoms, - stiffness, and - sympathetic dystrophy.

Complications of percutaneous release include -incomplete release of the A1 pulley and -potential injury to adjacent neurovascular structures and to tendons themselves.

Paediatric Trigger thumb Pediatric trigger thumb and trigger finger represent distinct clinical entities and should not be managed like their adult counterparts.

Trigger thumb is 10 times more common than trigger finger among infants and children.

Approximately 25% of patients with trigger thumb experience bilateral involvement.

EtiologyThe etiology of acquired pediatric trigger thumb remains unknown.

It is postulated that constant flexed position of the thumb during the prenatal and neonatal periods results in collagen degeneration and synovial proliferation, which produces a FPL nodule and thickening of the tendon sheath.

This nodule was first recognized by Alphonse Henri Notta in 1850 and is now commonly referred to as a Notta nodule

Pediatric triggering secondary to intratendinous calcification, granulation tissue, and cysts also has been reported.

In addition, pediatric trigger finger has been linked with mucopolysaccharide storage disorders such as Hurler syndrome and Hunter syndrome

Clinical featuresPatients most commonly present at approximately 2 years of age.

Parents may give a history of triggering of finger assosciated with a palpable nodule

In most patients, a fixed flexion deformity of the IP joint, rather than triggering is noted.

Management Nonsurgical management of pediatric trigger thumb includes passive extension exercises and splinting.

The splints were applied continuously for 6 to 12 weeks before transition to night time splinting

Currently, the role of nonsurgical management remains unclear with the late presentation of patients with fixed contractures.

Surgical managementTrigger thumb release is typically performed under general anesthesia.

A 1-cm transverse incision is created at the thumb palmodigital (MCP flexion) crease

The flexor tendon sheath is then exposed with blunt dissection

The A1 pulley is sharply incised under direct visualization

The proximal edge of the oblique pulley should be identified and preserved to confirm complete division of the A1 pulley and to prevent inadvertent bowstringing and loss of motion

Upon inspection of the unroofed FPL, the Notta nodule is easily identified but does not require excision

The IP joint is hyperextended to stretch the contracted volar plate

The Notta nodule should be visualized during passive IP joint extension to ensure that the FPL glides distally without further entrapment or triggering

In trigger fingers, in addition to A1 pulley release, additional measures such as resection of one or both slips of the FDS tendon are done.

An extensile Brunner-type incision is created over the A1 pulley

After division of the A1 pulley, flexor tendon gliding is evaluated with passive digital range of motion.

Proximal decussation of the FDS is a common source of triggering and should be checked for

Single slip or multiple slips of the flexor digitorum superficialis tendon should be resected and checked for finger movement.

Once an adequate release is achieved, skin closure is completed and a bulky soft dressing is applied

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