Ultrasound of flexor digitorum apparatus in acute and chronic pathology

The flexor digitorum apparatus (FDA) of the finger consists of two flexor tendons located within their osteofibrous tunnel, reinforced by the pulley apparatus and the supporting volar plates. The FDA is essential for facilitating hand grasping functions, and pathology affecting the FDA can result in functional impairment of the hand. These injuries can be open or closed in nature and are commonly the sequelae of acute trauma or chronic overuse. This article includes an overview of the anatomy of the FDA, ultrasound scanning technique and common pathologies that sonographic assessment may encounter. The anatomy of the finger and its variants is complex, and an ultrasound can only be accurate if the operator possesses comprehensive knowledge of these structures.