National Physical Therapy Examination (NPTE) Practice Exam

A patient presents with an inability to extend the distal phalanx of their finger after a traumatic event. What is the likely diagnosis?

1. Mallet finger

2. Boutonniere deformity

3. Trigger finger

4. Ulnar drift

The correct answer is: Mallet finger

The likelihood of a diagnosis being mallet finger stems from the specific scenario of distal phalanx extension inability after trauma. Mallet finger occurs when there is an injury to the extensor tendon at its insertion on the distal phalanx, typically caused by a sudden impact, which prevents the distal phalanx from being extended. This injury leads to the characteristic inability to straighten the fingertip, often leaving it in a flexed position. The mechanism of the injury described—related to a traumatic event—aligns perfectly with the etiology of mallet finger. In this condition, the extensor tendon is either ruptured or avulsed from the bone, which directly results in the observed dysfunction. The presentation is consistent, as the patient will exhibit an inability to actively extend the distal phalanx, confirming the diagnosis. The other conditions mentioned, such as boutonniere deformity, trigger finger, and ulnar drift, involve different anatomical structures and mechanisms. Boutonniere deformity affects the central slip of the extensor hood, leading to a different finger positioning and extension inability, while trigger finger primarily involves the flexor tendon with a locking mechanism. Ulnar drift is associated with rheumatoid arthritis and does not generally present similarly to