In this blog, we are going to take a look at extensor tendon injuries, and will briefly cover Sagittal band injuries, Mallet fingers and Boutonniere deformities.
Looking at the anatomy, the Sagittal bands arises from the volar plate of the MCP and insert onto the extensor hood with their primary. The main purpose is being able to keep the extensor mechanism tracking in the midline during flexion of the MCP joint.
You can see in these pictures that injury to the sagittal band results in the extensor tendon slipping off the middle of the MCP joint.
Common causes of sagittal band injuries is due to rheumatoid arthritis or more acute injuries from boxing.
Presentation is pain, swelling, and the patient can feel the extensor tendon snapping as they move from flexion to extension of the MCP joint.
The timing of the presentation of the symptoms dictates the best treatment. If the patient presents early, then patients are often treated conservatively with full time splinting.
For more chronic cases these patients require surgery which involves the direct repair of the sagittal band.
In some cases like rheumatoid arthritis, you have to treat the underlying problem such as an MCP joint replacement.