Volar plate avulsion
On lateral view.
Disruption of extensor tendon causes avulsion fracture at DORSAL of DIP
Disruption of flexor mechanism causes avulsion fracture at the VOLAR side of DIP (little finger in the above figure)
At frontal radiograph, avulsion fracture of base of PIP; may look like mallet finger but avulsion fracture in mallet finger is better visible in lateral film.