CASE 128

By: Nizar Al-Nakshabandi MD, FRCPC

HISTORY: 20-year-old male who had a door slammed on his finger.

What are your findings?

What is the differential diagnosis?

What are the causes?

FINDINGS:

The AP radiograph demonstrates no fracture or dislocation. Soft tissue swelling is seen at the region of the DIP of the 5th finger.

The lateral view of the fifth finger demonstrates a bony triangular avulsion fragment at the extensor aspect of the distal phalanx of the DIP joint. A flexion deformity at the DIP joint is seen.

DIFFERENTIAL DIAGNOSIS:

There is no differential diagnosis in this case.

DIAGNOSIS:

Mallet finger.

PEARLS AND DISCUSSION:

This is an injury that describes disruption of the extensor mechanism of the finger at the DIP. It is frequently seen in crush injuries or sports related injuries.

Clinically these patients are unable to extend the finger at the DIP. Flexion deformity at this joint is seen.

If ultrasound is done, there will be loss of the real-time movement of the extensor tendon. Complete or partial tear of the extensor tendon. Fluid can be seen at the site of insertion of the extensor tendon. An avulsion fragment can also be detected.

If this lesion is undetected, swan-neck deformity will result which usually require surgical intervention. Furthermore, if left untreated, secondary osteoarthritic changes of the DIP will occur.

Treatment is by splinting the DIP joint in fixed hyperextension.

FURTHER READING:

1.      Marinček B, Dondelinger RF. Emergency radiology, imaging and intervention. Springer Verlag. (2007) ISBN:354026227X. 

2.      Brukner P, Khan K. Clinical Sports Medicine Third Revised Edition. Springer. (2010) ISBN:1441959726. 

3.      Wieschhoff GG, Sheehan SE, Wortman JR et-al. Traumatic Finger Injuries: What the Orthopedic Surgeon Wants to Know. Radiographics. 2016;36 (4): 1106-28.