What injury is characterized by the rupture of the extensor at its insertion?

The injury characterized by the rupture of the extensor at its insertion is known as Mallet Finger. This condition occurs when there is a disruption in the integrity of the extensor tendon at its distal insertion on the distal phalanx of the finger. As a result, the affected finger cannot extend at the distal joint, leading to a characteristic drooping or flexed appearance of the fingertip.

When a finger experiences a sudden impact or tension, particularly during activities such as catching a ball, the extensor tendon can rupture or avulse. This prevents the person from being able to straighten the tip of the finger, resulting in pain and a visible deformity. Prompt treatment is crucial to restore function, which often involves splinting to hold the finger in the correct position and allow for healing.

The other conditions listed involve different mechanisms of injury. For instance, Boutonniere Deformity involves a rupture of the central slip of the extensor tendon, resulting in an inability to extend the middle phalanx. Jersey Finger refers to an avulsion of the flexor tendon, preventing finger flexion, particularly when trying to grab an object. De Quervain's Tenosynovitis is an inflammation of the tendons on the side of