DEFINITION

Trigger finger is an entrapment of the digital flexor tendon(s) by the flexor tendon sheath.

Trigger finger progressively causes inflammation, pain, catching, locking, and reduced range of motion (ROM).

 

 

ANATOMY

 

The flexor digitorum profundus and superficialis (flexor pollicis longus in the thumb) pass under (dorsal to) the flexor sheath, which consists of annular and cruciate pulleys.

 

The A1 pulley, which is volar to the metacarpophalangeal (MCP) joint, is the most proximal pulley (except for a

thickening known as the palmar aponeurotic pulley7) and is almost always the primary site of entrapment (FIG 1).

 

PATHOGENESIS

 

High angular loads at the A1 pulley and often other causes of local inflammation result in a flexor tendon sheath whose inner diameter is too narrow to accommodate the flexor tendon(s).

 

 

 

FIG 1 • To understand trigger finger and its release, an appreciation of the flexor tendon pulley system of the finger (A) and thumb (B) is required.

 

 

This size mismatch causes hypertrophy (thickening) of the A1 pulley and tendinous swelling.

 

These changes exacerbate the size discrepancy, setting up a cycle in which entrapment causes hypertrophy and hypertrophy causes entrapment.

 

NATURAL HISTORY

 

Trigger digits may develop spontaneously or may occur after swelling, from either trauma or a period of heavy use.

 

Trigger digits may:

 

 

 

Resolve spontaneously (especially in mild cases) Persist with the same level of symptoms

 

Advance to passively correctable locking

 

Become indefinitely locked in either flexion or extension

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

The history may include any of the following:

 

 

 

Pain in the distal palm, often radiating proximally along the path of the flexor tendon(s) Pain occurring with use and difficulty grasping objects or flexing the digit

 

Clicking or locking with digital flexion and extension, which is often perceived by the patient to be at the proximal interphalangeal (PIP) joint

 

 

The finger being stuck in flexion, often in the morning, requiring the other hand to straighten it Being unable to flex or extend the digit fully or at all (FIG 2)

 

The history should elicit the following information:

 

 

Whether the patient has had a trigger finger before, in either the currently involved or any other digit

 

 

 

 

FIG 2 • Reduced flexion caused by ring finger triggering.

 

 

P.801

 

Previous treatments for trigger finger and the extent and duration of the result

 

Whether the condition began after a particular incident or period of increased hand use

 

The patient's medical history should be evaluated for conditions that may cause trigger fingers and alter treatment as well as commonly associated conditions, including the following:

 

 

Diabetes

 

Rheumatoid arthritis and other inflammatory arthropathies

 

 

Amyloidosis, most commonly secondary to renal disease requiring dialysis Lysosomal storage diseases

 

Carpal tunnel syndrome (often seen in patients with trigger finger but not causally related)

 

The history and physical examination should exclude other conditions that cause overlapping symptoms, including the following:

 

 

 

Nerve compression Muscle weakness

 

 

Tendon interruption from laceration (partial or complete) or rupture Pulley rupture and bowstringing

 

Joint or soft tissue contracture or swelling or both

 

 

Extensor tendon laceration or subluxation, especially at the MCP joint Joint dislocation

 

MCP joint collateral ligament injury

 

The physical examination should include the following:

 

 

ROM test, which is the most objective measure of severity. If the patient has absolutely no active motion at the PIP (or thumb interphalangeal [IP]), consider tendon interruption.

 

Palpation of the palm. If the A1 pulley is not tender, strongly consider other diagnoses. Examine for other causes of the patient's symptoms, including Dupuytren contracture, tendon sheath ganglion, PIP joint injury, and A3 pulley triggering.

 

Examination of the extensor apparatus. Rule out extensor mechanism abnormalities and stress test the collateral ligaments of the MCP joint (radially and ulnarly) to rule out conditions that may cause overlapping signs or symptoms, including a popping sensation with ROM.

 

Examination of the collateral ligaments at the MCP joint. Stress the collateral ligaments radially and ulnarly.

 

Perform a neurovascular examination. Carpal tunnel syndrome often is associated with trigger finger. Muscle weakness may cause similar findings. Any neurovascular deficit should be documented before treatment.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Radiographs can exclude some unusual causes of trigger finger symptoms and can assess for arthritis but are not required to make the diagnosis of trigger finger.

 

Ultrasound/dynamic ultrasound has been increasingly useful in confirmation of diagnosis and in guiding corticosteroid therapy for trigger finger.9

 

If other pathology is suspected, magnetic resonance imaging (MRI) can be useful.

 

Nerve conduction studies can evaluate for anterior interosseous nerve (AIN) compression, which may mimic a trigger thumb or concomitant carpal tunnel syndrome.

 

DIFFERENTIAL DIAGNOSIS

Extensor tendon subluxation at the MCP joint

Joint contracture or injury, including MCP locking due to collateral ligaments and a swollen PIP joint

 

Soft tissue swelling or contracture, including Dupuytren contracture Partial tendon laceration

Triggering at the A3 pulley (rare)

Muscle weakness, including flexor pollicis longus weakness secondary to AIN palsy Masses (especially tendon sheath ganglions), which may cause A1 pulley tenderness

 

 

NONOPERATIVE MANAGEMENT

 

Observation and splinting

 

 

Mild, early cases often resolve spontaneously or do not bother the patient significantly. Use of a night extension splint may help minimize morning locking.

 

Unless the PIP joint remains locked, in either flexion or extension, for several weeks, delayed treatment usually does not significantly change either the options available or their results.

 

Injection

 

 

Long-term relief in most affected digits with one to three injections2

 

Results in diabetic patients are not as good,1,4 but it still is worth trying. The patient should be warned that there glucose level may temporarily go up.

 

Injection technique (FIG 3)

 

One milliliter of 2% plain (no epinephrine) lidocaine and 1 mL of a soluble corticosteroid solution (eg, betamethasone or dexamethasone) in a single syringe with a 25-gauge needle is given.

 

 

The A1 pulley area is prepped with an antiseptic solution such as alcohol or Betadine. A topical spray may be used to reduce discomfort.

 

One to 2 mL is injected in the sheath or subcutaneously around the A1 pulley.13 Avoid injecting into the tendon itself; if increased resistance is encountered, this may be the cause.

 

Ultrasound guidance may provide increased accuracy and avoid possible complications especially in the thumb.9

SURGICAL MANAGEMENT

 

Indications for surgical treatment include the following:

 

 

Symptoms that persist despite conservative management

 

Inability to flex or extend the finger even passively: This is an indication for earlier release to prevent secondary joint contracture.

 

 

Open A1 pulley release is indicated for any routine trigger finger. Percutaneous trigger finger release:

 

 

Requires an actively triggering digit so the patient can flex to confirm needle placement and pulley release Is used primarily for the middle and ring fingers. Use in the other digits may place digital nerves in jeopardy.15

 

In patients with very extensive synovitis, such as that seen in rheumatoid arthritis, lysosomal storage diseases, or amyloidosis associated with end-stage renal disease, releasing the A1 pulley percutaneously or through a routine, small

 

P.802

incision is often not sufficient. A more extensive tenosynovectomy and sometimes ulnar slip of the flexor digitorum superficialis resection (USSR) is often required.

 

 

 

 

FIG 3 • Technique for trigger digit injection.

 

Preoperative Planning

 

Clinical notes and any studies obtained preoperatively should be reviewed.

 

If procedures beyond an A1 pulley release are considered likely to be necessary (eg, possible resection of the ulnar slip of the flexor digitorum superficialis [FDS]), they should be discussed with the patient preoperatively.

 

Positioning

 

The patient is supine.

 

The extremity is positioned so that the palm is facing up on a hand table.

 

For index, middle, ring, and small digits, a hand holder (eg, a “lead hand”) may be helpful.

 

For the thumb, it is more useful for the surgeon and assistant to position the hand and thumb throughout the procedure or to use a specialized thumb holder.

 

Place a padded tourniquet and inflate it just before making the incision.

 

Approach

 

Anesthesia is obtained by injecting 2% plain (no epinephrine) lidocaine subcutaneously around the incision and in the tendon sheath.

 

 

Sedation will mitigate the discomfort associated with the injection and the tourniquet. If sedation is used, the patient should be allowed to wake up in time to demonstrate complete active digital flexion and extension without locking, documenting successful pulley release.

 

A standard volar approach to the A1 pulley is made with either an oblique Bruner-type, transverse, or longitudinal incision.

 

For resection of the ulnar slip of the sublimis, a Bruner-type or midaxial longitudinal incision is used over the distal portion of the proximal phalanx.

 

TECHNIQUES

• Open A1 Pulley Release

Incision and Exposure

A 1-cm incision is placed over the A1 pulley.

Longitudinal (TECH FIG 1A)

If a transverse incision is used, it is placed in a palmar skin crease (TECH FIG 1B): Distal palmar crease for small and ring fingers

Proximal palmar crease for index finger

An incision between creases may be required for middle finger release.

Oblique or Bruner-type

Avoid crossing palmar skin creases at a right angle with any incision type. Incise only the skin and dermis with a no. 15 blade.

Bluntly spread subcutaneous tissue to avoid injury to the digital nerves.

 

 

 

 

TECH FIG 1 • A. A longitudinal incision for ring finger A1 release. Index finger demonstrates a well-healed longitudinal incision without any contracture. (continued)

 

 

P.803

 

 

 

TECH FIG 1 • (continued) B. Position of transverse incisions for trigger finger release in relation to the palmar skin creases and the A1 pulley. C. The digital neurovascular structures are right next to the A1 pulley and must be protected. The circle demonstrates the proximity of the digital nerves and arteries. Because the radial digital nerve of the thumb may cross at the level of the A1 pulley, it is particularly vulnerable.

 

 

The digital neurovascular structures adjacent to the A1 pulley must be retracted and protected.

 

Extensive dissection and exposure of these structures are not required.

 

The radial digital nerve of the thumb is at the greatest risk because it typically crosses the surgical field16 (TECH FIG 1C).

 

 

 

TECH FIG 2 • A. The digital neurovascular structures are retracted, and the A1 pulley has been cleared of all overlying soft tissue. B. The A1 pulley has been completely released. C. The palmar pulley remaining after A1 release. D. The flexor tendons are bluntly separated and pulled out of the wound, which then flexes the digit. (A-D: Top is proximal.)

 

Performing the Release

 

Clear off the A1 pulley with sponge dissection.

 

 

 

The A1 pulley is not incised until it is clearly visualized (TECH FIG 2A). Use of small right angle retractors helps provide needed visualization.

 

 

Begin the A1 pulley incision with a knife, taking care not to cut deep into the tendon.

 

P.804

 

Complete the release with scissors until the pulley leaflets can be spread completely apart (TECH FIG 2B).

 

Avoid cutting any significant portion of the A2 pulley (or the oblique pulley in the thumb).

 

The A2 pulley is separated from the A1 pulley either by a space (where there is no sheath) or a section of very thin sheath tissue.11

 

If the tendons appear constricted by the palmar aponeurotic pulley7 proximal to the A1 pulley, it should also be released (TECH FIG 2C).

 

Bluntly separate the tendons (in the fingers) and pull the tendon(s) out of the wound (TECH FIG 2D). Minimize any direct handling of the tendons.

 

 

 

TECH FIG 3 • A. Tenosynovium between the tendons can be gently removed. B. A tendon sheath mass. Pathologic analysis confirmed it was a tendon sheath ganglion. C,D. Full active extension and flexion after release.

Completion

 

A limited tenosynovectomy may be performed if required (TECH FIG 3A). Any unusual resected tissue or mass is sent to the pathology department for analysis (TECH FIG 3B).

 

Confirm that the patient can actively flex and extend the finger (TECH FIG 3C,D). If the active ROM is not full or significantly improved or if the tendons are not passing under the remaining pulleys, recheck for any portions of the A1 pulley or palmar aponeurotic pulley and consider USSR as well as etiologies other

than standard trigger finger.6,8,10,12

 

Release the tourniquet, and irrigate the wound.

 

Obtain hemostasis, usually with manual compression. Reinspect the wound, check for any arterial bleeding, and confirm the finger has brisk capillary refill.

 

Close the skin with interrupted sutures and place a mildly compressive dressing.

• Percutaneous A1 Pulley Release

   

  The patient must have active triggering.

   

   

   

  The procedure is performed with a sterile prep in either the office or operating room. Hyperextend the MCP joints over a towel to help displace the neurovascular structures dorsally. Palpate the A1 pulley.

   

  Inject the local anesthetic (with or without corticosteroid) as described for nonoperative treatment.

   

  An 18- or 19-gauge needle is placed through the A1 pulley, centered radial to ulnar, and into the tendon (TECH FIG 4).

   

  The patient actively flexes the finger which moves the needle, confirming location.

   

   

   

  The needle is pulled back slightly so that it remains in the A1 pulley but not the tendon. The needle is rotated so that the bevel is in line with the longitudinal axis of the pulley. Sweep the needle proximally and distally until grating is no longer felt.

   

  The patient should be able to actively flex and extend the finger without triggering, confirming release.

   

   

   

  TECH FIG 4 • Percutaneous A1 release.

   

   

  P.805

   

   

• Open A1 Pulley Release with Flexor Digitorum Superficialis Ulnar Slip Excision The initial steps are performed in the same manner as described for an open A1 pulley release. A Bruner-type or ulnar midaxial incision can be used.

 

Bruner-type incision (TECH FIG 5)

 

A zigzag skin incision is made with the points over the finger flexion creases.

 

The skin only is opened with a no. 15 blade, and blunt dissection is used to separate the

neurovascular bundles as a unit. Formal dissection of the nerve and artery, or separating them from each other, is not required.

 

Care should be taken to stay more centrally as the incision proceeds distally (over the PIP and distal interphalangeal joints) because the neurovascular bundles can become less radial and ulnar on the digit.

 

Ulnar midaxial incision (less invasive alternative)

 

A 1- to 1.5-cm incision is made beginning at the PIP flexion crease and proceeding proximally.

 

The dissection plane proceeds dorsal to the digital neurovascular bundle, isolating the ulnar aspect of the flexor sheath.

 

Inspect the tendon distal to the A2 pulley, confirming that there is no catching under the A3 pulley10 and that an enlarged, bulbous flexor digitorum profundus is not catching under the distal end of the A2

pulley.12 In either of these cases, USSR may or may not relieve the problem.

 

Ulnar slip excision is then performed in either distal to proximal fashion8 or with a proximal to distal technique.6

 

In extremely severe cases of recalcitrant trigger finger, both FDS slips can be removed.5 Although there is historical evidence to suggest the increased possibility of developing a swan-neck deformity, there is no consensus. It should probably be avoided in the rheumatoid population.

 

 

 

TECH FIG 5 • A Bruner-type incision. (Courtesy of Dominique Le Viet.)

 

Distal to Proximal Ulnar Slip Excision

 

Just distal to the A2 pulley, incise the tendon sheath, creating a radially based flap. This flap may be repaired later with 6-0 Prolene if desired.

 

With the PIP joint maximally flexed, isolate and cut the ulnar slip of the FDS distally, taking care to preserve the vinculum brevis.

 

 

 

Pull the tendon into the proximal wound and cut it as far proximal as can be reached safely. Confirm that the tendons now pass smoothly under the pulley system through a complete ROM. Release the tourniquet. Irrigate the wounds.

 

Obtain hemostasis, usually with manual compression. Reinspect the wound, check for any arterial bleeding, and confirm the finger has brisk capillary refill.

 

Close the skin with interrupted sutures and place a mildly compressive dressing.

Proximal to Distal Ulnar Slip Excision

 

Examine the part of the tendon meant to glide under the A1 and A2 pulleys for enlargement, degeneration, longitudinal splitting, or loss of its smooth surface (TECH FIG 6A).

 

Fully flex the finger, identify the ulnar and radial slips of the FDS distally, and split them longitudinally in a proximal direction (TECH FIG 6B).

 

With the finger and wrist flexed, cut the ulnar slip of the FDS as far proximal as possible. Pull the ulnar slip distally, carefully separating it through the chiasm, and, with the PIP joint flexed, cut it distally at the edge of the A3 pulley. The tendon slip is then removed from either direction; a loop of 3-0 wire can be used to separate adhesions if necessary (TECH FIG 6C).

 

Release the tourniquet. Irrigate the wound.

 

Obtain hemostasis, usually with manual compression. Reinspect the wound, check for any arterial bleeding, and confirm the finger has brisk capillary refill.

 

Close the skin with interrupted sutures and place a mildly compressive dressing.

 

 

P.806

 

 

 

 

TECH FIG 6 • Open A1 pulley release with FDS ulnar slip excision. A. Enlargement of tendon proximal to A2 pulley (after A1 release). B. Separating the FDS tendon slips. C. Use of a wire loop to separate tendon adhesions after cutting the FDS tendon proximally. (A,B: Modified from Le Viet D, Tsionos I, Boulouednine M, et al. Trigger finger treatment by ulnar superficialis slip resection [U.S.S.R.]. J Hand Surg Br 2004:29[4]:368-373.)

 

PEARLS AND PITFALLS
	Confirm that the tendon glides freely after release.

 

	Satisfactory ▪ If there was no joint contracture preoperatively, the patient should have release significantly improved active (or passive, if the patient is under general anesthesia) ROM. If not, assess the cause and correct.     Avoid injury ▪ Release of more than 25% of the A2 pulley may cause bowstringing, reducing to A2 flexion ROM, and require pulley reconstruction. pulley.

 

 

 

P.807

 

 

 

 

FIG 4 • A soft dressing is applied with all the digits free.

 

POSTOPERATIVE CARE

 

A soft dressing is applied with all of the digits free (FIG 4). Active ROM as tolerated is encouraged. Minimize dressing bulk to avoid inhibiting motion.

 

Formal therapy is required only if the patient has difficulty regaining ROM.

 

Patients whose digits were locked preoperatively are more likely to need therapy. This may be started within the first week.

 

Scar massage is encouraged after the wound is sealed.

OUTCOMES

Surgical release of trigger digits has a high success rate with a low complication and recurrence rate.3,14

 

 

COMPLICATIONS

 

Injury to digital nerve or artery Bowstringing

Wound infection or dehiscence resulting in a flexor sheath infection Postoperative stiffness

Incomplete release Recurrence Incisional tenderness

 

 

REFERENCES

1. Baumgarten KM, Gerlach D, Boyer MI. Corticosteroid injection in diabetic patients with trigger finger. A prospective, randomized, controlled double-blinded study. J Bone Joint Surg Am 2007;89(12):2604-2611.

    

    

2. Benson LS, Ptaszek AJ. Injection versus surgery in the treatment of trigger finger. J Hand Surg Am 1997;22:138-144.

    

    

3. Gilberts EC, Wereldsma JC. Long-term results of percutaneous and open surgery for trigger fingers and thumbs. Int Surg 2002;87:48-52.

    

    

4. Griggs SM, Weiss AC, Lane LB, et al. Treatment of trigger finger in patients with diabetes mellitus. J Hand Surg Am 1995;20:787-789.

    

    

5. Husain SN, Clarke SE, Buterbaugh GA, et al. Recalcitrant trigger finger managed with flexor digitorum superficialis resection. Am J Orthop 2011;40(12):620-624.

    

    

6. Le Viet D, Tsionos I, Boulouednine M, et al. Trigger finger treatment by ulnar superficialis slip resection (U.S.S.R.). J Hand Surg Br 2004; 29:368-373.

    

    

7. Manske PR, Lesker PA. Palmar aponeurosis pulley. J Hand Surg Am 1983;8:259-263.

    

    

8. Marcus AM, Culver JE Jr, Hunt TR III. Treating trigger finger in diabetics using excision of the ulnar slip of the flexor digitorum superficialis with or without A1 pulley release. Hand 2007;2: 227-231.

    

    

9. Mardani Kivi M, Lahiji FA, Jandaghi AB, et al. Efficacy of sonographically guided intra-flexoral sheath corticosteroid injection in the treatment of trigger thumb. Acta Orthop Traumatol Turc 2012;46(5):346-352.

    

    

10. Rayan GM. Distal stenosing tenosynovitis. J Hand Surg Am 1990; 15:973-975.

     

     

11. Ryzewicz M, Wolf JM. Trigger digits: principles, management, and complications. J Hand Surg Am 2006;31:135-146.

     

     

12. Seradge H, Kleinert HE. Reduction flexor tenoplasty. J Hand Surg Am 1981;6:543-544.

     

     

13. Taras JS, Raphael JS, Pan WT, et al. Corticosteroid injections for trigger digits: is intrasheath injection necessary? J Hand Surg Am 1998;23:717-722.

     

     

14. Turowski GA, Zdankiewicz PD, Thomson JG. The results of surgical treatment of trigger finger. J Hand Surg Am 1997;22:145-149.

     

     

15. Wilhelmi BJ, Mowlavi A, Neumeister MW, et al. Safe treatment of trigger finger with longitudinal and transverse landmarks: an anatomic study of the border finger for percutaneous release. Plast Reconstr Surg 2003;112:993-999.

     

     

16. Wolfe SW. Tenosynovitis. In: Green DP, Hotchkiss RN, Pederson WC, et al, eds. Green's Operative Hand Surgery, ed 5. Philadelphia: Elsevier, 2005:2137-2158.