A patient has resting DIP joint flexion due to loss of active extension at the DIP. The patient MOST likely has which of the following conditions?

A patient has resting DIP joint flexion due to loss of active extension at the DIP. The patient MOST likely has which of the following conditions?

• A. Mallet Finger
• B. Rheumatoid Arthritis
• C. Flexor Digitorum Superficialis Paralysis
• D. Middle Phalanx Dislocation

Answer: (A)

The DIP joint’s ability to straighten depends on the distal extensor tendon pulling on the distal phalanx. When that terminal extensor tendon is torn or avulsed from the distal phalanx, the DIP can’t be actively extended and settles in a flexed position at rest. This classic presentation is Mallet finger, typically caused by a sudden impact to a fingertip that’s flexed. The other conditions don’t fit this pattern. Rheumatoid arthritis causes broader, systemic joint deformities rather than an isolated loss of DIP extension. A flexor digitorum superficialis weakness would mainly affect flexion at the PIP joint, not cause the DIP to rest in flexion due to loss of extension. A dislocation of the middle phalanx implicates the PIP joint alignment and overall finger stability, not just a loss of active DIP extension.

The DIP joint’s ability to straighten depends on the distal extensor tendon pulling on the distal phalanx. When that terminal extensor tendon is torn or avulsed from the distal phalanx, the DIP can’t be actively extended and settles in a flexed position at rest. This classic presentation is Mallet finger, typically caused by a sudden impact to a fingertip that’s flexed.

The other conditions don’t fit this pattern. Rheumatoid arthritis causes broader, systemic joint deformities rather than an isolated loss of DIP extension. A flexor digitorum superficialis weakness would mainly affect flexion at the PIP joint, not cause the DIP to rest in flexion due to loss of extension. A dislocation of the middle phalanx implicates the PIP joint alignment and overall finger stability, not just a loss of active DIP extension.