Bipartite patella

A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect.

The superolateral accessory ossification center of the patella is usually present by 12 years of age and may persist into adult life. Prevalence of a bipartite patella occurs in approximately 2% of the population. It occurs bilaterally in about 43% of cases.

It is nine times more common in males than in females 2.

A bipartite patella is usually discovered incidentally in asymptomatic individuals. Only 2% of patients with bipartite patella experience symptoms. It may cause anterior knee pain, especially after trauma, sports injury, or overuse.

One method of classification according to H Saupe is as:

  • type I: inferior pole ~1%
  • type II: lateral margin ~20-25%
  • type III: superolateral portion ~75% 

In the majority of cases, a symptomatic bipartite patella improves without surgery. Surgical excision of the small fragment is recommended if conservative management fails and has been reported to give good results 3.

May be radiographically confused with a patellar fracture, but the superolateral accessory ossification center is characteristic of a bipartite patella.

Lower limb anatomy
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Article Information

rID: 12216
Section: Anatomy
Synonyms or Alternate Spellings:
  • Bipartite patellae

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