Tendon thickening occurs as a result of tendinopathy, overload-related changes, previous injuries or metabolic and autoimmune disorders. Increased tendon dimension can also be a consequence of surgical procedures involving the tendon or tissue hypertrophy due to prolonged and regular physical activity. This results in the increase of the anterior-posterior (AP) dimension of the tendon observed in the MRI.
A descriptive scale with no specific reference values is used for the assessment of tendon thickness. The parameter is evaluated at the thickest point between the calcaneal tuberosity and the outline of soleus muscle belly. The reference point for the assessment is a healthy tendon without previous injury.
Assessment scale of changes in corresponding MRI images:
| Normal state | Mild changes | Moderate changes | Severe changes |
| No tendon thickening | Mild tendon thickening | Moderate tendon thickening | Severe tendon thickening |
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