Table 1.

Commonly referenced classifications of mallet finger injuries

Doyle [11]
Type I	Closed injury, with or without small dorsal avulsion fracture
Type II	Open injury, laceration of tendon
Type III	Open injury with loss of skin, subcutaneous cover, and tendon substance
Type IV	Mallet fracture
A	Transepiphyseal plate fracture in children
B	Hyperflexion injury with fracture of articular surface of 20 to 50%
C	Hyperextension injury with fracture of the articular surface >50% and with early or late volar subluxation of distal phalanx
Wehbé and Schneider [12] (for bony mallet injuries)
Type Ia	Fractures without subluxation of the distal interphalangeal joint
Type IIa	Fractures with subluxation of the distal interphalangeal joint
Type IIIa	Epiphyseal and physeal injuries
Subtype A	Fracture fragment involving less than one-third of the articular surface of the distal phalanx
Subtype B	Fracture fragment involving one-third to two-thirds of the articular surface
Subtype C	Fragment that includes more than two thirds of the articular surface
Burton [13] (for chronic mallet injuries)
Stage I	Supple, passively correctable deformity
Stage II	Fixed contracture, contracted lateral bands
Stage III	Fixed contracture, joint fibrosis, collateral ligament and palmar plate contractures

^aEach of these fracture types may be divided into three subtypes. Any of these fractures may be accompanied by hyperextension of the proximal interphalangeal joint.