Position of Bone Scintigraphy in the Diagnosis and Evaluation of Stages of Legg-Calvé-PerthesDisease

Overview

Bone scintigraphy using 99m Tc phosphate complexes is a suitable method for diagnosis and study of Legg-Cal-vé-Perthes disease (LCPD). The localization of the radiopharmaceutical in bone depends on bone perfusion andmetabolism.Legg-Calvé-Perthes disease is considered as avascular necrosis of the proximal femoral epiphysis, that canresult in a secondary arthrosis. One of the main theories of development of avascular necrosis suggests vasculardamage with production of an arterial or venous thrombosis of blood vessels of the epiphysis. Avascular necrosiswith revascularization during the disease has several scintigraphic images. Conway’s scintigraphic classificationof LCPD is derived from this theory. Conway differentiates two principal mechanisms of revascularization: 1.recanalisation stage A with recanalization of the existing vessels, 2. neovascularization - stage B, with formationof new vessels. These 2 principal stages are devided into substage 1 - 4. Bone scintigraphy was used to examine 67children (51 boys, 16 girls), those suffering from hip or knee pain with a limp were suspected of LCPD. Traumaand large strain during the sport activities were often present. 31 children suffered from LCPD. A pathologicalscintigram of the hip was found in all these children. From 36 children with a negative or equivocal X-ray only in8 children a pathological scintigram was found. A stage A - recanalization associated with good prognosis wasappeared in 25 children. A stage B - neovascularization associated with a foorer prognosis was found in 16 children.The correlation of scintigraphy of the hip with X-ray examination is necessary for the correct diagnosis of stageof LCPD according to Conway’s criteria. In our experience Conway’s classification is useful for evaluation of thedevelopment of the disease; this is important for the prognosis and treatment of LCPD.

Key words:
Legg-Calvé-Perthes disease, bone scintigraphy, Conway’s scintigraphic classification