Acute horseshoe abscess of the hand after corticosteroid injection to treat trigger thumb.

Local corticosteroid injections are frequently used in the management of trigger finger. We present a case of a 56-year-old woman who developed an acute horseshoe abscess of the hand after injection of corticosteroid and local anaesthetic into the left thumb. This was managed successfully with intravenous antibiotics, operative intervention and early mobilisation. This case highlights the possible complications that can occur with such a minimally invasive procedure. The pathophysiology behind this condition is explained by communication between the radial and ulnar bursae. Knowledge of the anatomy of the hand and its variants is therefore essential to assist in diagnosis. Prompt clinical diagnosis and surgical management is required to avoid disastrous complications.