Patella bipartita
A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect.
Epidemiology
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 9x more common in males than in females .
Clinical presentation
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.
Classification
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%
Radiographic features
Plain radiograph
A weight-bearing skyline view may demonstrate separation of the accessory fragment, which may indicate a symptomatic bipartite patella .
MRI
Bone marrow edema adjacent to the accessory fragment may indicate a symptomatic bipartite patella .
Treatment and prognosis
In the majority of cases, 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 .
Differential diagnosis
- patellar fracture: the superolateral accessory ossification center is characteristic of a bipartite patella. With a patellar fracture, the volume of the fractured components is equivalent to that of a normal patella.
- multipartite patella: the volume of the true patella plus that of the smaller ossification centers is greater than that expected of a normal patella.
Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Patella bipartita:
