Role of Advanced Imaging in the Diagnosis and Management of Active Legg-Calvé-Perthes Disease.

Since the first description of Legg-Calvé-Perthes disease a century ago, the diagnosis, staging, prognosis, and treatment decisions have been based on plain radiographs. The goal of treatment is prevention of femoral head deformity, yet radiographic prognostic classifications are applied in the fragmentation stage, often after deformity occurs. These classifications are assigned too late in the progression of the disease to maximize the effects of intervention. Thus, alternative mechanisms to determine femoral head involvement earlier in the disease course are warranted. Increasingly, MRI has been used in the study of the disease. Gadolinium-enhanced and diffusion-weighted MRI has shown promising results that correlate with radiographic classifications and the early radiographic outcome. Advanced imaging has improved the assessment of hinge abduction, yet the exact definition remains controversial. The role of imaging in the management of Legg-Calvé-Perthes disease is rapidly evolving. New or refined imaging techniques may eventually allow earlier prognosis and treatment.