A 48-year-old female presents with third finger pain along with a palpable mass at the third metacarpophalangeal joint after an unspecified injury. Have a look at the supplied images without arrows and then the same images with arrows.
A. Is there a mass?
B.What do you think accounts for the palpable abnormality?
C. What is the underlying problem?
D. Is there an extensor tendon injury?
B. Swelling overlying the third metacarpophalangeal (MCP) joint.
C. Tear of the radial sagittal band of the extensor hood at the third MCP joint.
D. The extensor tendon itself remains intact.
As for the arrows, the red arrows on image 5 and 8 indicate swelling overlying the third MCP. The green arrow on image 6 shows a normal sagittal band of the extensor hood on the second digit, while the yellow arrows on images 6 and 7 point to the torn sagittal band of the third digit.
At the level of the MCP joint in the hand, the sagittal bands of the extensor hood (both radial and ulnar sided) blend with the extensor tendon dorsally, and the palmar plate volarly. This forms the extensor hood at this level and provides stabilization to the extensor tendon, aiding in the extension of the proximal phalanx. When there is injury to the extensor hood, the patient often complains of pain and swelling at the MCP joint, and sometimes complains of intermittent snapping sensation in the finger with movement (if there is subluxation of the associated extensor tendon with finger movement). For more case review, head to MRI Online.