Trigger Finger Due to Anomaly of Lumbrical Insertion: A Case Report and Review of Literature.

Case: Trigger finger (TF), or stenosing synovitis, is a common condition that can usually be diagnosed by physical examination. We recently operated on a patient with TF who did not respond to conservative treatment. At surgery, we found an anomalous insertion of the fourth lumbrical muscle to the A1 pulley. This insertion was observed to cause mechanical narrowing of the pulley due to a pulling effect by the muscle, which was relieved by resection.

Conclusion: Although rare, the operating surgeon should be aware that local anatomical anomalies, such as insertion of a lumbrical into the A1 pulley, can be a cause of trigger finger.