Chronic posterior tibial tendon rupture is associated with flat foot deformity.

The tear is commonly noted behind medial malleolus (the significant site of friction).

Chronic posterior tibial rupture is divided into 3 types:

• type I: incomplete/partial tear with diffuse tendon enlargement showing intrasubstance degeneration/longitudinal splits.
• type II: partial tear with diffusely thinned tendon.
• type III: complete tear.

Two separate posterior tibial tendons secondary to longitudinal splitting giving the 'four tendon sign'.