Trigger Finger Treatment & Management

Early series recommended surgical treatment of trigger finger (TF) as straightforward and highly effective, while regarding prolonged conservative treatment as unreliable and expensive. Subsequent series documented poor results from surgical treatment in 7-9% of cases.

In 1972, Lapidus reversed his previous recommendation for operative treatment of TF after he and Guidotti reported uniformly good results following a single injection of prednisolone into the tendon sheath. ^[35] Rhoades et al subsequently reported a 72% success rate in a series of 53 digits following injection and immobilization. ^[36]

Injection therapy is now generally agreed to be the first line of management. Surgery is reserved for individuals in whom injection treatment has failed or in whom other pathology, particularly rheumatoid arthritis (RA), is suspected to be causing triggering that cannot be treated conservatively. ^[37] No absolute contraindications exist for surgical management.

In May 2014, the European HANDGUIDE Group published a guideline for multidisciplinary treatment of trigger finger. ^[38] By consensus, suitable treatment options were considered to include the following:

• Orthoses (splinting)
• Corticosteroid injections
• Corticosteroid injections plus use of orthoses
• Surgery

Severity and duration of disease and prior treatments received were judged to be the primary factors influencing choice of therapy. ^[38]

Conservative treatment

Most trigger digits in adults can be managed successfully with local steroid injections and splinting. ^[39] Oral or topical pharmacologic measures have not been demonstrated to be effective. A 2021 Cochrane review found that injection of nonsteroidal anti-inflammatory drugs offered little or no benefit as compared with steroids. ^[40]

The outcome of conservative treatment for pediatric trigger thumb is somewhat controversial. ^[41] A report by Baek et al on the natural history of this condition demonstrated that after a follow-up period of 5 years or more in patients who received no treatment for pediatric trigger thumb, complete resolution of flexion deformity occurred in 66 out of 87 thumbs (75.9%), and partial improvement occurred in the remaining 21 thumbs. ^{[30, 42]}

Another study, by Lee et al, reported that extension splinting for 12 weeks led to improvement in 71% of thumbs, compared with 23% improvement in patients not receiving any treatment. ^[43] See also the recommendations described by Ogino. ^[44]

Surgical release

The chief indications for surgical management of TF are as follows:

• Failure of splinting and/or injection treatment
• Irreducibly locked TF
• Trigger thumb in infants - Without surgical release, these infants are likely to develop a fixed flexion deformity of the interphalangeal (IP) joint

Although the results of percutaneous release are well established, the open technique is absolutely essential for the thumb or little finger or in the presence of proximal interphalangeal (PIP) contractures. Percutaneous release should be reserved for the index, middle, and ring fingers. ^{[6, 7, 8, 9]}

In a study from Oxford comparing percutaneous and open surgical methods, the two approaches displayed similar effectiveness, and both proved superior to conservative corticosteroid-injection treatment with regard to trigger cure and relapse rates. ^[45]

In children, triggering has varying causes. Release of the A1 pulley alone does not always correct the problem. Additional treatment (eg, resection of one or both limbs of the flexor digitorum superficialis [FDS] tendon, A3 pulley release) may be required and is recommended in RA tenosynovitis. ^{[9, 46, 47, 48]}

In infants, the nodule on the flexor pollicis longus (FPL) tendon can be resected with good results. Corticosteroid injections are generally not helpful in these cases of trigger thumb.

Pregnant patients

Splinting and local corticosteroid injection can be performed if the patient is pregnant. Surgical release of the A1 pulley is generally an elective procedure and is usually deferred until after delivery.

Elderly patients

In elderly patients with a history of gastrointestinal problems or other complications from nonsteroidal anti-inflammatory drugs (NSAIDs), consider cyclo-oxygenase-2 (COX-2) inhibitors if oral NSAIDs are needed.

Consultations

Surgical consultation for operative treatment may be required. Typically, such procedures are performed by an orthopedic hand surgeon or a plastic surgeon.

Corticosteroid injection in the area of tendon sheath thickening is considered to be the first-line treatment of choice for TF. ^{[49, 50, 51, 52, 10]} Research in 2009 concluded that the most successful and cost-effective management strategy for TF is the algorithm of two steroid injections prior to surgical intervention, if needed. ^[53]

A variety of preparations have been used—most commonly prednisolone, dexamethasone, and triamcinolone—in the steroid injection treatment of TF, and most are uniformly successful in relieving symptoms. ^{[54, 49, 55, 56]}

A highly satisfactory rate of success can be predicted in female patients and in patients with single digit involvement, short duration of symptoms (ie, < 4 months), no associated conditions (eg, RA, diabetes mellitus [DM]), or a discrete, palpable nodule. (Patients with RA or DM seem to be more resistant to injection treatment.) ^{[26, 27, 57]}

Procedure

The author's technique for steroid injection is as follows. A mixture of triamcinolone, 1% lidocaine, and 0.5% bupivacaine is used, in a ratio of 2:1:1, respectively; adrenaline is not used. The nodule in the palm is well localized and circled out using an indelible skin marker. The procedure is performed in an office setting, using strict aseptic precautions, with alcoholic povidone-iodine used for injection-site preparation. Ethyl chloride is used only if requested; frequently, it is unnecessary, and most patients tolerate this procedure quite well

A 26-gauge needle is introduced in a proximal-to-distal direction in the nodule, making an angle of 45° with the palm (see the first image below). The needle enters the nodule with a distinct grating sensation; positioning of the needle is verified by asking the patient to move the digit when it is possible to clearly observe the needle moving with the digit (see the second image below)

The syringe with the steroid preparation then is attached to the needle. Attempting to inject the drug with light pressure confirms the intratendinous location of the needle. Do not inject the solution if significant resistance to injection flow is noted, because this may indicate that the needle tip is in the tendon rather than just within the tendon sheath. The needle is withdrawn very carefully until a give-way sensation is felt, indicating that the tip of the needle is out of the tendon and in the sheath. The preparation is then injected.

A small water-impermeable dressing is applied. The patient is actively encouraged to move the digit; in most cases, the triggering is relieved

(Carlson and Curtis prefer a midaxial injection at the level of the midproximal phalanx as a simple and painless way to access the flexor sheath for the purpose of injection. ^[58] )

A follow-up appointment is made for 3-4 weeks after the treatment. Splinting is not used routinely for these cases, though a hand-based MP-block Orthoplast splint has been described as useful.

Although injection treatment has long been administered by "feel" and experience, research suggests that using ultrasonographically guided steroid injection may maximize the injection's accuracy and, consequently, its beneficial effects in the treatment of trigger digits. ^{[59, 60]}

No major complications from injection treatment are noted. A transient rise in blood and urine sugar levels is common in patients with diabetes. Advise these patients that this is likely to occur. Theoretically, repeated steroid injections could cause attrition and/or rupture of tendons, but only 1 such case has been reported to date. ^[61]

Pain relief

While corticosteroid injections into the palm are considered highly effective in treating TF, the injection itself may be significantly painful. A study that compared conventional injection with injection preceded by median and ulnar nerve blocks performed at the wrist found that of the study’s 19 patients, who were treated with 47 total injections, 88% preferred to have the median and ulnar nerve block prior to the injection. ^[62]

Both study groups, however, had excellent resolution of TF, with excellent resolution being defined in the study as an asymptomatic hand (without triggering) and a pain score on the 0-10 cm Visual Analog Scale of less than 2 cm. ^[62]

Repeat injections

A second corticosteroid injection may be performed 3-4 weeks after the first one. If two or perhaps three injections fail to provide adequate resolution, consider referring the patient for surgical release. Repetitive injections theoretically increase the likelihood of tendon rupture, although such a risk was not found in Anderson's study of repeated injections for TF. ^[63]

Alternative injection techniques

Proximal phalanx technique

Another injection method, the proximal phalanx technique, allows for injection directly into the tendon sheath through the palmar surface of the midproximal phalanx. Injections performed this way were found to be less painful than injecting the flexor tendon sheath directly over the metacarpal head. There was no statistically significant difference in the rate of recurrent pain between the two injection methods. ^[64]

Subcutaneous injection

Although corticosteroid injection has traditionally been administered into the tendon sheath (but not into the tendon itself), ^[61] studies seem to indicate that subcutaneous injection may be as effective as the intrasheath approach. ^{[65, 66, 67]} Additionally, in some cases, steroid injection into the subcutaneous tissue seems to result in better clinical outcomes than does injection into the sheath alone. ^[65]

Custom-made splinting of the metacarpophalangeal (MCP) joint is another conservative treatment, used in patients who do not wish to undergo a steroid injection or as an adjuvant to injection. Typically, a custom-made splint is used to hold the MCP joint of the involved finger at 10-15° of flexion, leaving the PIP and distal interphalangeal (DIP) joints free. The average length of splinting is 6 weeks. In patients with symptoms longer than 6 months, splinting as a sole treatment strategy does not seem to eliminate the triggering events. ^[21]

Although traditionally splinting has not been thought to be an effective treatment for TF, one study of thermoplastic splinting of MCP joint flexion showed improvement in stenosing tenosynovitis, the numeric pain rating scale, and the number of triggering events and also demonstrated an overall perceived participant improvement in symptoms. ^[68] Another study determined that 87% of patients who wore custom-made, thermoplastic orthoses for 8-10 weeks did not require an injection or surgical intervention in the 1-year follow-up after institution of the orthoses. ^[69]

Trigger digits that fail to respond to two or perhaps three injections may require surgical treatment, including dissection of the nodule on the tendon and surgical release of the A1 pulley, under local anesthesia.

The benefits of operative treatment of trigger finger and trigger thumb were outlined in three studies of surgical pulley release.

Between 1994 and 2004, Li et al treated seven children (nine thumbs; three right, two left, two bilateral) for trigger thumb with hyperextensible MCP anomaly (>60°) by surgical release of the first anular pulley (A1 pulley) and proximal advancement of the MCP volar plate. The patients (four girls, three 3 boys), who had a mean age of 46 months at surgery (range, 26-82 months), were observed over a mean follow-up period of 64 months (range, 1-8 years).

All patients in the study at last follow-up had returned to full activity without limitation or pain, and none of the patients had a recurrence of triggering or MCP hyperextension deformity, demonstrating, according to the authors, that trigger thumb with concomitant MCP hyperextension deformity can be treated in children by A1 pulley release and advancement of the volar plate. ^[13]

In a study of 93 trigger thumbs in 83 patients, Chao et al compared the results of miniscalpel-needle percutaneous release with those of steroid injection. At 12 months, 44 of the 46 trigger thumbs treated with the miniscalpel-needle release had satisfactory results (measured by visual analogue pain scale and patient satisfaction), but only 12 of 47 thumbs treated with steroid injection had satisfactory results. No nerve injuries occurred in either group. ^[70]

Trigger thumb in children almost always calls for surgical management. Trigger thumb in an adult not responding to corticosteroid tendon sheath injection needs surgery. The technique of release itself is irrelevant. Open and not percutaneous surgery is the norm for trigger thumb in children and adults alike, since the neurovascular bundles in the thumb are closer to the midline than in other digits. A single series (quoted above) comparing the efficacy of percutaneous surgery vis-a-vis a corticosteroid injection found surgery still to be more effective than injection treatment, but this technique of surgical release itself is not de rigueur.

Lange-Rieb et al presented long-term results of open operative treatment of TF and trigger thumb in adults. Of the operations performed, 210 (76%) were for a single-digit release and 76 (24%) for multiple digits. All operations were performed under tourniquet control with local anesthesia as outpatient procedures using a transverse incision just distal to the distal palmar crease or on the flexor crease of the thumb at the MCP joint. At latest follow-up (average, 14.3 years), 234 patients were evaluated, with no complaints, and there were no serious complications, such as nerve transection or bowstringing, or recurrence. ^[71]

Preparation for surgery

Preoperative considerations include the following:

• Only digits that actively trigger must be considered for operative release
• Neither PIP contracture nor thumb triggering is suitable for percutaneous release, and the A1 pulley always is transected under direct vision
• Patients with PIP joint contractures undergo a period of hand therapy and splinting prior to the procedure
• A tourniquet always is used to obtain a clean operative field
• Approximately 4-5 mL of 1% lidocaine is used to infiltrate the skin overlying the A1 pulley, with injection performed deeper to the tendon sheath
• The transverse incision is marked with a skin marker corresponding to the digit to be surgically treated (see the image below)
• The proximal edge of the A1 pulley coincides almost exactly with the distal palmar crease in the fourth and fifth rays, with the proximal palmar crease in the index and with the halfway point between the two creases in the middle finger

Operative details

The MCP joint is hyperextended to displace the neurovascular structures dorsally, minimizing the risk of injury.

A transverse incision measuring 1-1.5 cm is made over the involved metacarpal head. Blunt dissection is used to spread the subcutaneous fat and expose the tendon sheath.

The proximal edge of the A1 pulley is identified, and a scalpel blade is used to divide the entire A1 pulley in the midline under vision. Care is taken to avoid incising too distally and risk cutting into the A2 pulley, which can result in bowstringing. A study suggests that the proximal part of the A2 pulley can be safely incised if the release of the A1 pulley in isolation does not result in relief of triggering. ^[72] This is still experimental and is best left to hand or plastic and reconstructive surgeons.

The patient is asked to actively move the digit to confirm full release. Meticulous hemostasis is achieved with a bipolar cautery, and the wound is closed with two or three skin sutures. The hand is left free, and motion is encouraged immediately following the procedure.

If a percutaneous approach is favored, a pair of blunt-tipped, fine scissors is introduced through the incision, and the A1 pulley is transected (see the image below). Care is taken not to drift too distally. Disappearance of a grating sensation indicates complete section of the pulley through a separate, distal oblique incision.

A study by Rogo-Manaute et al showed that it is possible to use ultrasonographically guided percutaneous release to achieve a success rate of 100%. With adequate anatomic knowledge, technical training, and a basic ultrasound machine, sonographically directed A1 pulley release can be performed safely and successfully, thus offering an alternative to conventional open technique. ^[73]

On rare occasions, sectioning the A1 pulley does not relieve triggering, indicating that the A3 pulley might be involved. If that is the case, the A3 pulley requires division. This percutaneous technique as described here usually applies to most cases of triggering, exceptions being surgery for trigger thumb in children and triggering involved in conditions like RA, in which the nodule formation may be distal to the A1 pulley and for which open surgery may be required.

Trigger thumb

Surgery for trigger thumb is performed as follows. The A1 pulley is approached through a transverse incision in the flexion crease overlying the MCP joint (see the image below). Palpate the FPL to ensure that the incision is centered appropriately.

Bluntly dissect through subcutaneous tissue; identify and gently retract radial and ulnar neurovascular bundles. Expose the A1 pulley, identify its proximal and distal edges, and incise it longitudinally (see the first image below). ^[74]  Avoid injury to the underlying tendon (see the second image below).

Inspect the tendon nodule during full passive motion of the IP joint. Ensure that no further restrictions to excursion are present. A band of tissue proximal to A1 may exist that also requires release. ^[75] Observe FPL excursion while the patient actively flexes the thumb to verify a complete surgical decompression.

Deflate the tourniquet, obtain hemostasis, and close the incision with nylon. Dress the wound with a soft compressive bandage

Postoperative care

Active motion is encouraged on the day of surgery. Anti-inflammatory drugs and elevation are advised for a period of 2-3 days following surgery. Sutures are removed on postoperative day 10. ^[76]

Future treatment for TF may involve Kapandji enlargement-plasty of the A1 pulley. In this procedure, which is complex and technically demanding, the A1 pulley is enlarged by making a diagonal incision in it, followed by suture instead of simple longitudinal division, thus increasing the mean diameter of the canal.

In a study by Migaud et al, 15 patients who underwent this procedure and who were followed up for a mean period of 5 years had complete symptomatic relief without any recurrences. ^[77]

Physical therapy is generally not required for patients with TF. For cases of chronic TF, however, treatment may include a trial of heating modalities followed by sustained, nonballistic stretching of the flexor tendon, as well as soft-tissue mobilization of the A1 pulley. Following injection or surgery, a home exercise (stretching) program may be one component of treatment for patients. No therapy programs have been documented to improve TF.

If a trial of therapy is recommended for patients with chronic TF or for individuals who require postoperative hand therapy, the physician may refer them to either a physical therapist or an occupational therapist, depending on his/her preference and the therapists' availability. The treatment provided by an occupational therapist is very similar to the above-discussed physical therapy treatment. In addition, the occupational therapist may provide a patient with strategies for completing activities of daily living (ADL) with limited or no use of the affected hand while it is splinted or is recovering from surgery.

Corticosteroid injection

Potential complications of corticosteroid injection include the following:

• Infection - The use of sterile technique can minimize this problem
• Bleeding
• Weakening of the tendon
• Fat atrophy occurring locally at the injection site
• Nerve infiltration and subsequent nerve injury - This complication is uncommon; it can be monitored by assessing sensation throughout the affected digit

Bleeding

This can be minimized by applying direct pressure immediately after the procedure. Caution should be exercised before injecting a patient who is taking anticoagulants or an individual with a bleeding disorder

Weakening of tendon

Weakening of the tendon increases the risk of subsequent tendon rupture, a possibility that is of particular concern if the injection is performed incorrectly (specifically, if the injection is administered into the tendon itself rather than just within the tendon sheath). ^{[61, 78]}

A study demonstrated that ultrasonographically guided injections were safer than blind injections in that 30% of fingers injected blindly demonstrated dye within the tendon, while no tendon injected under ultrasonographic imaging was infiltrated with dye. ^[37]

The risk of tendon rupture may increase with multiple injections, although at least some clinical researchers (eg, Anderson and Kaye) found no episodes of tendon rupture after corticosteroid injection for TF, even with repeated injections. ^[63]

Fat atrophy

Fat atrophy can occur locally at the injection site if the corticosteroid is injected into the subcutaneous tissue. This complication can cause a cosmetic depression in the skin, and tenderness can result from the loss of padding provided by the fat.

Surgical release

If the surgeon maintains a careful surgical technique, the incidence of complications should be low. ^[71] Potential complications of TF surgery include the following:

• Tenderness over the site of the incision - This occurs quite frequently but usually settles on its own
• Adhesions and subsequent stiffness - This may develop with excessive handling of the tendon or delayed postoperative mobilization
• Digital nerve injury - Overall, this is extremely rare, even though the digital nerves lie within 2-3 mm of the midline; prompt repair or reconstruction is indicated in the event of this unfortunate complication; observation for suspected neurapraxia is appropriate; digital nerve transection is the most common complication reported after trigger thumb surgery; the radial digital nerve is injured more frequently because of its superficial location and oblique course over the flexor sheath
• Superficial scoring of the FDS tendon - This has been reported frequently but does not require further treatment
• Accidental cutting into the A2 pulley - This can cause bowstringing, with loss of full finger flexion; pulley exploration and reconstruction may be indicated if bowstringing does not resolve
• Scarring - This is more likely to occur after TF surgery than after trigger thumb surgery
• Recurrence - This has been reported but is extremely rare
• Infection - This is a risk in patients who are diabetic or immunosuppressed and may be problematic if septic flexor tenosynovitis results

Research has shown no statistically significant differences in surgical complication rates between persons with diabetes and those without it. This was also found to be true when patients with type 1 diabetes were compared with individuals who had type 2 diabetes. ^[50]