An athlete presents with signs and symptoms indicating a specific finger injury. Which injury may be indicated by point tenderness on the dorsal aspect of the DIP joint and an inability to actively extend the DIP joint, with full passive extension observed?

a) Mallet finger
b) Boutonniere deformity
c) Jersey finger
d) Swan neck deformity

A mallet finger is indicated by point tenderness on the dorsal aspect of the DIP joint and an inability to actively extend the DIP joint, with full passive extension present. This injury is caused by a disruption of the extensor tendon at the distal interphalangeal joint, commonly resulting from a blow to the fingertip. Therefore, the correct option is a) Mallet finger.

Explanation:

The injury that may be indicated by point tenderness on the dorsal aspect of the DIP joint combined with an inability to actively extend the DIP joint, yet full passive extension is possible, is most likely a mallet finger. A mallet finger occurs when there is a disruption of the extensor tendon at the distal interphalangeal joint (DIP). This condition is common in athletes and results from a blow to the tip of a finger, which forces the DIP joint into flexion while the extensor muscle is actively contracting.

For comparison, a Boutonniere deformity presents with a flexion of the PIP joint and hyperextension of the DIP joint, a Jersey finger involves an inability to flex the DIP joint due to a rupture of the flexor digitorum profundus tendon, and a Swan neck deformity is characterized by hyperextension of the PIP joint with flexion of the DIP joint. Correct diagnosis and treatment are essential for recovery, and in the case of mallet finger, it may include splinting the DIP joint in extension.