Stieda process

Stieda process (not to be confused with a Pellegrini-Stieda lesion) refers to an elongated lateral tubercle of the posterior process of the talus ^1,3. It is often considered an anatomical variant.

It forms from fusion of a secondary ossification center at the posterolateral aspect of the talus with rest of the talus (this typically occurs between 7-13 years) where the fused segment remains longer than usual ⁴.

It is best appreciated on a lateral ankle radiograph or sagittal CT/MRI views. 

Related pathology

• acute fracture of the Stieda process
• it can be associated with posterior ankle impingement syndrome from impingement between the tibia and the calcaneus, especially in plantar flexion. In some symptomatic situations, it is resected ²

Differential diagnosis

It needs to be differentiated from an os trigonum (particularly if partially fused): which refers to a separate bony ossicle at the lateral tubercle of the talus.

History and etymology

It is named after L Stieda who is considered the first person to describe this in 1869 ⁵.