Answer :
Final answer:
1) Injury to the extensor tendon.
Boutonniere deformity is caused by an injury to the extensor tendon, disrupting finger extension and leading to a characteristic bent position of the finger.
Explanation:
The cause of boutonniere deformity is 1) Injury to the extensor tendon. This type of injury disrupts the normal extension mechanism of the finger, leading to a characteristic deformity where the middle joint of the finger bends downwards (flexion) while the end joint may bend back upwards (hyperextension). This condition typically requires medical intervention for correction and can result from acute injury or from underlying conditions that lead to weakening of the extensor tendon.
