The name, mallet finger, is a bit of a misnomer as the finger does not look like a mallet. It is commonly defined as a sports-related injury, but often is not. It is sometimes called a "baseball finger". It may also be called a "drop finger" which is a more accurate description. The long and ring finger are most commonly injuried, and it occurs more often in men than in women. A mallet finger occurs when the extensor tendon is damaged.
Type II: Laceration at or proximal to the DIP joint with loss of tendon continuity
Type III: Deep abrasion with loss of skin, subcutaneous cover and tendon substance
Type IV: (A) Trans-epiphyseal plate fracture in children; (B) Hyperextension injury with fracture of the articular surface of 20-50%; and (C) Hyperextension injury with fracture of the articular surface usually > 50% and with early or late palmar subluxation of the distal phalanx
Mallet Deformity: (Baseball finger)--Wheeless' Textbook of Orthopaedics
Complication and Prognosis of Treatment of Mallet Finger--Wheeless' Textbook
Mallet Finger (Baseball finger)--American Academy of Orthopaedic Surgeons
Mallet Finger by Roy A Meals, Md--eMedicine article