Patella multipartita
Multipartite patella is an uncommon congenital abnormality that represents normal variant pathology and is a result of a failure of ossification during development. It is most commonly diagnosed as an incidental finding.
Clinical presentation
The vast majority of multipartite patellae are asymptomatic, but direct trauma may disrupt the synchondroses resulting in symptoms.
Pathology
Classification
Segmentation of the patella occurs when there is a failure of fusion of the ossification centers in early childhood. The most common type of segmentation results in separation of the upper outer quadrant which is called bipartite patella. More rarely, there may be a third segment resulting in a tripartite patella.
These are often incidental radiographic findings have been classified into three types - the saupe classification:
- type I: at the inferior pole (5% of all lesions)
- type II: at the lateral patellar margin (20%)
- type III: at the superolateral pole (75%)
Thus, by far the commonest location of segmentation anomalies in the patella occurs at the superolateral border.
Associations
Differential diagnosis
It is important to distinguish the multipartite patella from a patellar fracture in a symptomatic patient. If patellar fragmentation involves portions of the patella other than the upper and lower outer quadrants, then traumatic fracture should be considered.
Related pathology
- impingement of multipartite patella