Bipartite patella

Case contribution: Dr Radhiana Hassan


  • A 71 years old man
  • Underlying hypertension and IHD
  • Complaint of right knee pain
  • History of twisting knee with mild swelling
  • Able to ambulate without aid
Knee radiographs in AP and lateral views
Knee radiograph ‘skyline’ view

Radiographic findings:

  • There is a well-defined linear line seen at superolateral aspect of right patella (yellow arrows) separating the patella.
  • The line has well corticated bone borders
  • No displacement of the bone fragment
  • No associated soft tissue swelling at knee region

Diagnosis: Bipartite patella


  • A bipartite patella is a patella with an unfused accessory ossification centre at the superolateral aspect.
  • Prevalence of bipartite patella is about 2% of population
  • It occurs bilaterally in about 43% of cases.
  • It is more common in male than females.
  • Mostly are asymptomatic but patient can present with knee pain after trauma or overuse.
  • Different location: superoplateral portion (75%), lateral margin (20-25%) and inferior pole (1%).
  • Differentiation with fracture; most common patella fracture is transverse (linear fracture is very uncommon), fracture commonly occurs after direct trauma to knee and  volume of fracture fragment usually equivalent of normal patella
Author: radhianahassan