Trigger Wrist

Trigger Wrist

Trigger wrist is a rare cause of wrist pain and functional disability caused by inflammation and swelling of the wrist flexor tendon apparatus or by tumors or masses affecting the wrist flexor tendons. Commonly, the tendinopathy associated with trigger wrist is due to compression by the carpal bones, especially the hook of the hamate bone. Sesamoid bones in this region may also compress and cause trauma to the tendons. Trauma is usually the result of repetitive motion or pressure on the tendon as it passes over these bony prominences. If the inflammation and swelling become chronic, the tendon sheath may thicken, resulting in constriction. Frequently, nodules develop on the tendon, and they can often be palpated when the patient flexes and extends the wrists. Such nodules may catch in the tendon sheath as they pass under the transverse palmar ligament in a manner analogous to the more common trigger finger phenomenon, producing a triggering that causes the wrist to catch or lock. Other causes of trigger wrist include rheumatoid nodules, anomalous muscles (especially of the flexor digitorum superficialis), ganglion cysts, and pigmented villonodular synovitis. Trigger wrist occurs in patients engaged in repetitive activities such as playing the drums.

Common Causes of Trigger Wrist

  • • Tenosynovitis
  • • Anomalous muscles
  • • Rheumatoid nodules
  • • Fibromas of the tendon sheath
  • • Pigmented villonodular synovitis
  • • Ganglion cysts

Signs and Symptoms

The pain of trigger wrist is localized to the distal wrist and proximal palm, and tender nodules often can be palpated. The pain is constant and is made worse with active flexion/extension of the wrist. Patients note significant stiffness when flexing the wrists. Sleep disturbance is common, and patients often awaken to find that the wrist has become locked in a flexed position.

On physical examination, tenderness and swelling are noted over the tendon, with maximal point tenderness over the carpal bones. Many patients with trigger wrist experience a creaking or snapping sensation with flexion and extension of the wrists. Range of motion of the wrists may be decreased because of pain, and a triggering phenomenon may be noted. A catching tendon sign may be elicited by having the patient flex the affected wrist for 30 seconds and then relax but not unflex the wrist. The examiner then passively extends the affected wrist, and if a locking, popping, or catching of the tendon is appreciated as the wrist is straightened, the sign is positive.

Testing

Plain radiographs are indicated in all patients who present with trigger wrist to rule out occult bony pathological processes. Based on the patient’s clinical presentation, additional testing, including a complete blood count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging (MRI) and ultrasound imaging of the hand is indicated if joint instability, mass, tumor, or some other abnormality is suspected. The injection technique described later serves as both a diagnostic and therapeutic maneuver. Occasionally, surgical exploration is required to accurately ascertain the cause of trigger wrist.

Differential Diagnosis

The diagnosis of trigger wrist is usually made on clinical grounds. Arthritis or gout of the carpal or radioulnar joint may accompany trigger wrist and exacerbate the patient’s pain. Occult fractures occasionally confuse the clinical presentation. Trigger finger and carpal tunnel syndrome frequently coexist with the much less commonly occurring trigger wrist.

Treatment

Initial treatment of the pain and functional disability associated with trigger wrist includes a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. A nighttime splint to protect the wrists also may help relieve the symptoms. If these treatments fail, the following injection technique is a reasonable next step.

Injection of trigger wrist is carried out by placing the patient in the supine position with the arm fully adducted at the patient’s side and the dorsal surface of the hand resting on a folded towel. A total of 2 mL local anesthetic and 40 mg methylprednisolone is drawn up in a 5-mL sterile syringe. After sterile preparation of the skin overlying the affected tendon, the carpal bone beneath the tendon is identified. Using strict aseptic technique, at a point just proximal to the joint, a 1-inch, 25-gauge needle is inserted at a 45-degree angle parallel to the affected tendon through the skin and into the subcutaneous tissue overlying the tendon, with care taken to avoid the median nerve as it passes under the transverse carpal ligament and radial nerve and artery. If bone is encountered, the needle is withdrawn into the subcutaneous tissue. The contents of the syringe are then gently injected. The tendon sheath should distend as the injection proceeds. Little resistance to injection should be felt; if resistance is encountered, the needle is probably in the tendon and should be withdrawn until the injection can be accomplished without significant resistance. The needle is then removed, and a sterile pressure dressing and ice pack are applied to the injection site. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.

Physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes injection. Vigorous exercises should be avoided, because they will exacerbate the patient’s symptoms. Surgical treatment should be considered for patients who fail to respond to the aforementioned treatment modalities.

Complications

Failure to adequately treat trigger wrist early in its course can result in permanent pain and functional disability because of continued trauma to the tendon and tendon sheath. The major complications associated with injection are related to trauma to the inflamed and previously damaged tendon. The tendon may rupture if it is injected directly, so a needle position outside the tendon should be confirmed before proceeding with the injection.

Furthermore, the radial artery and superficial branch of the radial nerve are susceptible to damage if the needle is placed too far medially. Another complication of injection is infection, although it should be exceedingly rare if strict aseptic technique is used, along with universal precautions to minimize any risk to the operator. The incidence of ecchymosis and hematoma formation can be decreased if pressure is applied to the injection site immediately after injection. Approximately 25% of patients report a transient increase in pain after injection, and they should be warned of this possibility.

Clinical Pearls

The injection technique described is extremely effective in the treatment of pain secondary to trigger wrist. Coexistent arthritis or gout may contribute to the patient’s pain, necessitating additional treatment with more localized injection of local anesthetic and methylprednisolone.

A hand splint to protect the wrists also may help relieve the symptoms of trigger wrist. Simple analgesics and NSAIDs can be used concurrently with the injection technique, although surgical treatment may ultimately be required to provide permanent relief.

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