From the case:
Patellar shape - Wiberg classification
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Wiberg classification for patellar shape.
Case Discussion
Wiberg classification is a system for describing the shape of the patella based mainly on asymmetry between the patellar medial and lateral facet on axial views of the patella.
Type I: the facets are concave, symmetrical, and of equal size.
Type II: the medial facet is smaller than the lateral facet and flat or only slightly convex. The lateral facet is concave.
Type III: the convex medial facet is markedly smaller than the concave lateral facet, and the angle between the medial and lateral facets is nearly 90°.