Thursday, February 16, 2012

Jammed Finger

Photo by ToastyKen

A "jammed finger" is a common injury of the proximal interphalangeal (PIP) joint. It is an imprecise term, which subsumes a variety of injuries that are typically related to axial loading and hyperextension forces.

The injury results in swelling around the joint, reflecting soft tissue injury.

Photo by xadrian

Mild forces result in disruption of the volar plate, a collagenous structure that forms the floor of the joint. In this case, a 43 year old male suffered an injury to his finger two years ago, and reinjured his finger several weeks before he was sent for his MRI.

A sagittal T2 fatsat image reveals disruption of the volar plate of the PIP joint (red arrow) and dorsal subluxation of the middle phalanx (yellow arrow):

A sagittal intermediate image better depicts the torn, macerated volar plate:

Here is a normal volar plate, for comparison:

Volar plate injuries can be a pure soft tissue injury, but can also be associated with fractures at the attachment of the volar plate on the base of the middle phalanx. With more substantive force, there can be tears of the collateral ligament, and this can create joint instability.

Most volar plate tears are treated conservatively, with splinting and buddy taping. If an injury cannot be reduced, one should suspect interposition of soft tissue structures.  Fracture-dislocations that are unstable, exhibit persistent subluxation of the middle phalanx, or involve large portions of the articular surface should be referred for surgical fixation. 

Vic David MD

1 comment:

adam said...

What are the risky activities that can cause this condition? Although the article image seems to suggest basketball, but I guess the 43-year old man did not play basketball to hurt his finger twice? I believe wearing a thumb brace could have prevented further injuries before the scan.