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Bipartite Patella


- See: multipartite patella

- Discussion:
    - a common congenital fragmentation or synchondrosis of the patella
    - occurs in approximately 1% of population but some have observed a much higher incidence;
    - most remain asymptomatic, but direct trauma may disrupt the synchondroses, causing symtoms that mimic those of fracture;
    - classification:
          - type I: inferior pole of the patella;
          - type II: lateral margin type;
          - type III: superolateral type;
    - diff dx:
          - stress frx: look for verticle fracture line;
          - Sindig-Larsen-Johanssen disease may resemble a type I bipartite patella;
          - patellar sleeve fracture
          - osteochondral frx:
                 - is distinguished from biparte patella:
                       - on basis of history of trauma;
                       - hemarthrosis of knee;
                       - point tenderness over defect
                       - distinct outline of frx on radiographs;
                       - unilateral defect (less than 45% of patients will have bilateral bipartite patella);
                       - rapid resolution of symptoms w/ fracture (w/ immobilization);

- Treatment:
    - type I patella:
          - patient with type I bipartite frx (lower pole) may at risk for fracture;
          - patients that present with pain and tenderness at the lower pole, should have all activites curtailed;
          - fractures occur along the synchondrosis and when displaced, operative fixation is considered;
    - type III patella:
          - superolateral bipartite patellae may become symptomatic and in some cases may require excision;
          - also consider limited detachment of vastus lateralis from the bipartite fragment which removes the stress on the fragment and which can allow spontaneous union

Painful Bipartite Patella. A New Approach to Operative Treatment.

Painful bipartite patella in young athletes. The diagnostic value of skyline views taken in squatting position and the results of surgical excision

Excision of Painful Bipartite Patella: Good Long-term Outcome in Young Adults.

Other links:

Bipartite Patella from the Orthopaedic Care Textbook