Fact-sheet: Dorsal defect of the patella
Updated on 09/30/2019 at 6:15 PM
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Definition
Subchondral lucency of the superolateral third of the patella,
typically seen in adolescents (prevalence: 0.3–1%).
Bilateral in one-third of cases.
Incidental finding.
Uncertain etiology:
- Incomplete variant of bipartite patella, with which this defect may also be associated,
- Ischemic origin,
- Microtraumatic.
Clinical features
May be associated with patellofemoral pain.
Radiography
Round osteolytic lesion on the frontal radiograph, surrounded by a peripheral rim of osteocondensation.
CT
CT arthrography:
Opacification of the overlying patellar cartilage ulceration allows opacification of the lucency.
MRI
On axial FatSat PD images,
the articular cartilage overlying the defect is continuous and thickened, filling in the subchondral defect.
A thin overlying cartilage ulceration may be present.