Which injury involves the rupture of the flexor digitorum profundus at its insertion on the distal phalanx?

The injury that involves the rupture of the flexor digitorum profundus at its insertion on the distal phalanx is referred to as Jersey Finger. This condition occurs mainly in sports injury scenarios, particularly in football, when an individual's finger becomes caught in an opponent's clothing or equipment while trying to grasp the ball.

In this injury, the flexor digitorum profundus tendon, which is responsible for flexing the distal interphalanx joint, undergoes a rupture at its insertion point on the distal phalanx. This leads to an inability to flex the affected finger at that joint. Clinically, patients may present with an inability to flex the distal segment of the affected finger, and the finger may even remain extended when attempting to make a fist.

The other injuries mentioned are related but do not involve the specific tendon rupture at the distal phalanx. For instance, Bennett's fracture involves the base of the first metacarpal bone, Mallet finger is characterized by the inability to extend the distal phalanx due to an injury to the extensor tendon, and Kienbock's disease refers to avascular necrosis of the lunate bone in the wrist, which does not involve a tendon rupture.