Wiberg classification of patella shape

Last revised by Joshua Yap on 3 Apr 2024

Wiberg classification is a system used to describe the shape of the patella based mainly on the asymmetry between the patellar medial and lateral facets on axial views of the patella. Increasing number type indicates a larger degree of asymmetry.

Classification

  • type I (or type A)

    • roughly symmetrical, equal-sized facets

    • concave facets

    • although presumably the ideal shape of the patella, it is in fact rather uncommon, occurring in only 10% of the general population

  • type II (or type B)

    • slightly smaller size of the medial facet

    • flattening of the medial facet

  • type III (or type C)

    • markedly smaller size of the medial facet

    • more vertical orientation of the medial facet

    • convex aspect of the medial facet

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