• Definition: Inflamed or thickened flexor tendons no longer slide freely and without resistance through the annular ligaments. This results in a snagging, snapping or triggering phenomenon. Although the affected person can at first still actively bend or stretch the finger by increased exertion, as the symptoms progress the active force is no longer sufficient and the other hand is used to unblock the finger ray. Although the process may eventually lead to complete blocking of the finger, this rarely occurs. There are many possible causes; snagging is often painful.
• Overview: Ligaments running across the phalanges (annular ligaments A1-5) form a canal with the phalanges. Surrounded by the tendon sheath, the flexor tendons slide back and forth in this canal. If the canal is too narrow in relation to the tendon – e.g. due to thickened annular ligaments and thickened flexor tendons – the tendons can no longer glide freely. The annular ligaments have a very different clinical relevance. The conflict is mainly between the flexor tendons and the annular ligament closest to the palm – the A1 annular ligament.
  Symptoms: Initial movement pain in the palm of the hand at the base of the affected finger. The saccade-like or trigger movement of the finger is typical, giving the disorder its name. Patients can initially still actively resist the movement, later only passively and in rare cases not at all. The finger is then blocked in the bent position.
• Diagnosis: The medical history and clinical examination are characteristic (pathognomic). Further examinations are indicated only in very unusual cases.
• Differential diagnoses: Trigger finger following a cut finger injury may be caused by partially severed flexor tendons. A medical history should be taken to check for causes of tendon sliding tissue inflammation, such as rheumatological diseases.
• Therapy: Cortisone infiltration of the flexor tendon canal under local anaesthetic is an option in many cases. Ultrasound-guided severing of the annular ligament with a needle has also been documented. The standard procedure is to divide the A1 annular ligament under open surgery. Here the skin is opened at the base of the affected finger at the level of the palm and above the annular ligament under local anaesthesia, and the annular ligament is then divided in direct view. It is rarely necessary to remove the inflamed tendon sheath. Removing half of the superficial flexor tendon is an option in rare cases and in cases of recurrence and atypical pain above the base phalanx. This has no effect on finger movement or strength.
• Post-operative care: You can once again use your finger and hand normally in your everyday life following infiltration and can remove the dressing over the injection site on your own the next day.
  You can safely go ahead and move your hand freely again after surgery. Depending on the type of work, you can carry out physically demanding work with your hand again in from two to four weeks. Depending on progression, ergotherapeutic post-operative care can improve the results of the operation.
• Prognosis: The longer the symptoms persist and the more pronounced they are, the higher the risk of recurrence or insufficient improvement of symptoms after injection. Patients with diabetes also have an increased risk of relapse.
  Cortisone injections may alter blood sugar levels for a few days in this group of patients. Although patients may not feel the pain right after the injection under the local anaesthesia, it will return after 30 minutes to two hours (once the effect of the local anaesthetic wears off). Pain may even increase slightly subsequently since a closed system (the flexor tendon sheath) has been filled with additional volume. The effect of the cortisone often leads to relief of symptoms in about one week.
  The standard operation regularly yields good results. Incomplete annular ligament division, vascular nerve injury, recurrence and the bowstring phenomenon are rare. Sometimes the scar is painful or prominent and can be improved by occupational therapy. I currently do not offer the ultrasound-guided needle cutting technique, as the literature documents a considerable number of concomitant injuries (most frequently partial flexor tendon injuries), although their clinical relevance has not been conclusively confirmed. Depending on the type of work, you can carry out physically demanding work with your hand again in from two to four weeks. Depending on progression, ergotherapeutic post-operative care can improve the results of the operation.