Normal variant of femoral condyle ossification

Normal variant of femoral condyle ossifications occurs due to variability of endochondral ossification of articular cartilage and can be easily confused with osteochondritis dissecans.

Epidemiology

• more often in boys (mean age of ~8 years) than in girls ¹

• often bilateral ^1,2

• typically located at the posteroinferior aspect of the femoral condyle, much more commonly lateral than medial ¹

Clinical presentation

• mostly asymptomatic ²

• sometimes knee pain without trauma ¹

Radiographic features

Plain radiograph

• irregular epiphyseal outline at the posteroinferior aspect of femoral condyle ²

• radiolucent zones represented uncalcified cartilage ²

MRI

• small accessory ossifications centers in the posteroinferior femoral condyle ¹

• spiculations ¹

• intact overlying cartilage ^1,3

• no adjacent bone marrow edema ^1,3

Treatment and prognosis

The radiological changes were observed to decrease in size or resolve over a period of ~10 months (range 1-38 months) although a minority stayed the same size or rarely grew; symptoms also resolved in this time period ^1,2.

Differential diagnosis

• osteochondritis dissecans (OCD) ³

• fracture