Catterall developed a four-group classification on the basis of the appearance of the CFE at maximum resorption. Although this classification has been helpful in retrospective analysis of The short-term prognosis relates to the femoral head deformity at the completion of the healing stage. Two radiographic techniques evaluate the sphericity of the femoral head at the completion of the disease process, which correlates with the risk for degenerative osteoarthritis as an adult. In the Mose circle criteria, a transparent template with concentric circles is placed over the anteroposterior and Lauenstein lateral radiographs. Prevention of femoral head deformity and secondary osteoarthritis are the only justifications for treatment.
Containment is continued only until there is early radiographic subchondral reossification.