Bipartite patella

Case contributed by Sumit Verma
Diagnosis certain

Presentation

Tripped over a construction cable while walking causing him to fall directly onto his right knee. Patient presented with progressive swelling and pain and only able to partially weight bear. Physical Examination - pre-patellar swelling with minimal tenderness to medial aspect of knee and patella with limited active/passive range of movement.

Patient Data

Age: 50 years
Gender: Male

Right knee joint

x-ray

Nil acute bony injury. A linear lucency noted to the lateral aspect of the patella in keeping with a bipartite patella.

Case Discussion

A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center. It is usually discovered incidentally. However,  2% of patients with bipartite patella experience symptoms such as anterior knee pain, especially after trauma (as with this patient), sports injury, or overuse.

There are three types of Bipartite Patella:-

  • type I: inferior pole ~1%
  • type II: lateral margin ~20-25%
  • type III: superolateral portion ~75% (as with this patient)

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