• Tibialis Posterior Tendinopathy on MRI can have a number of appearances.

• One of the features is tendon enlargement with the signal remaining normal.

• The normal tibialis posterior tendon should be less than twice the size of the adjacent Flexor Hallicus Longus (Green arrow).

• In this case its tibialis posterior (Pink arrow) significantly larger  and we can make a diagnosis of tibialis posterior tendinopathy on MRI based on the increased size.

The tibialis posterior tendon (Pink arrow) is enlarged (more than x2 the size) compared to the Flexor Digitorum Longus tendon (Green arrow) and is abnormal.