Patellar dysplasia means an abnormally-shaped patella.

Wiberg Type 1 patella

Wiberg Type 1 patella

Wiberg Type 2 patella

Wiberg Type 2 patellar dysplasia

Wiberg Type 3 patella

Wiberg Type 3 patellar dysplasia

wiberg type 4 patellar dysplasia

Wiberg Type 4 patellar dysplasia


Classification of Patellar Dysplasia

The Wiberg classification of the shape of the patella, based upon the relative lengths of the facets, is widely used to describe different patellar shapes.


The unstable patella

A discussion about patellar instability, the factors that may cause the patella to sublux or dislocate, and what can be done about it.

Illustrated article showing how the patella starts its engagement with the groove of the trochlea.

This is the Editor's interpretation of a paper published in the orthopaedic literature in 2016.

Patellar instability and dislocation

Discussing how the anatomy can affect the tendency to dislocate the patella.



The patella morphology in trochlear dysplasia--a comparative MRI study. Fucentese SF, von Roll A, Koch PP, Epari DR, Fuchs B, Schottle PB. Knee. 2006 Mar;13(2):145-50.

See also: