‘Mallet finger’ is a common traumatic lesion resulting in flexion deformity of distal interphalangeal joint. The basic pathology of this condition is
**Core Concept**
Mallet finger is a type of extensor tendon injury at the distal interphalangeal (DIP) joint, leading to a flexion deformity due to the inability of the extensor tendon to extend the DIP joint. This condition is often caused by a sudden, forceful flexion of the DIP joint, resulting in a rupture or avulsion of the extensor tendon.
**Why the Correct Answer is Right**
The basic pathology of mallet finger involves a disruption of the extensor tendon mechanism, specifically the extensor digitorum longus (EDL) tendon, which inserts on the base of the distal phalanx. The EDL tendon plays a crucial role in extending the DIP joint. When this tendon is injured, the DIP joint becomes fixed in a flexed position, leading to a flexion deformity. The injury can be classified into two types: type I, where the tendon is partially ruptured, and type II, where the tendon is completely ruptured.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because mallet finger is not caused by a disruption of the flexor tendon mechanism. The flexor tendons, such as the flexor digitorum longus (FDL) tendon, are responsible for flexion of the DIP joint, not extension.
**Option B:** This option is incorrect because mallet finger is not a type of ligament injury. While ligament injuries can occur in the hand, mallet finger specifically involves a tendon injury.
**Option C:** This option is incorrect because mallet finger is not a type of fracture. While fractures can occur in the hand, mallet finger specifically involves a tendon injury, not a bone fracture.
**Option D:** This option is incorrect because mallet finger is not a type of nerve injury. While nerve injuries can occur in the hand, mallet finger specifically involves a tendon injury, not a nerve injury.
**Clinical Pearl / High-Yield Fact**
Mallet finger is often seen in athletes who participate in sports that involve catching or throwing, such as baseball or basketball. It is essential to diagnose and treat mallet finger promptly to prevent long-term deformity and dysfunction.
**Correct Answer:** C.