Explain Mallet finger and Boutonnière deformity.

let's explain these finger deformities.

• Mallet finger (also known as baseball finger or cricketer's finger) occurs when the insertion of the extensor tendon into the base of the terminal phalanx is torn. This usually happens due to a forceful blow on the fingertip, causing sudden and strong flexion of the phalanx. Sometimes, small pieces of bone may also be pulled away (avulsed). As a result, the distal phalanx remains in a flexed position, often with a swan neck deformity, and the person cannot voluntarily extend it. This injury is common in cricketers and baseball players.

• Boutonnière (button-hole) deformity is characterized by flexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal phalanx. It happens when the flexed PIP joint pushes through the extensor expansion after the central portion of the dorsal digital expansion ruptures, typically due to direct trauma to the end of the finger.