UCSD Musculoskeletal Radiology


MSK Classifications


AVN grading system

Steinberg modification of the Arlet and Ficat system


Grade 0.    Seen on MRI or NM, normal plain film-asymptomatic


Grade 1.    Seen on MRI or NM, normal plain film-symptomatic


Grade 2.    Mixed sclerosis and lucency on plain films, no collapse


Grade 3.     Cresentic collapse on plain films


Grade 4.    More significant collapse of femoral head


Grade 5.    Secondary OA of acetabulum


The combined necrotic angle of Kerboul


Only useful in stage 2 or less AVN to predict chance of collapse.


Add the necrotic angle of AVN on the coronal and sagittal images.


Less than 150 good prognosis - may spontaneously heal

Between 150 and 250 intermediate prognosis

Greater than 250 poor prognosis - will go on to collapse