Bipartite patella
A bipartite patella (two-part patella) is a patella with an unfused accessory ossification center at the superolateral aspect.
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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 nine times more common in males than in females 2.
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%
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 3.
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.
Related Radiopaedia articles
Anatomy: Lower limb
- skeleton of the lower limb
- joints of the lower limb
- hip joint
- knee joint
- tibiofibular joints
-
ankle joint
- regional anatomy
- medial ankle
- lateral ankle
- anterior ankle
- ligaments
- medial collateral (deltoid) ligament
- lateral collateral ligament
- additional structures
- ankle bursae
- ossification centers of the ankle
- variants
- regional anatomy
- foot joints
-
subtalar joint
- articulations
- ligaments
- associated structures
- mid-tarsal (Chopart) joint
-
tarsometatarsal (Lisfranc) joint
- ligaments
- intermetatarsal joint
- metatarsophalangeal joint
- interphalangeal joint
-
subtalar joint
- spaces of the lower limb
-
muscles of the lower limb
- muscles of the pelvic group
- inner hip group
- gluteal region
- lateral rotator group
- muscles of the thigh
- muscles of the leg
- anterior compartment of the leg
- posterior compartments of the leg
- lateral compartment of the leg
- muscles of the foot
- dorsal muscles
- plantar muscles
- 1st layer
- 2nd layer
- 3rd layer
- 4th layer
- accessory muscles
- muscles of the pelvic group
- vascular supply of the lower limb
- innervation of the lower limb
- lymphatic system of the lower limb
- lymphatic pathways
- anteromedial group
- anterolateral group
- posteromedial group
- posterolateral group
- lower limb lymph nodes
- lymphatic pathways
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