A thin, curved radiodense line in the upper femoral metaphysis, which in the AP—or posterior— view extends laterally from the inferior border of the femoral neck. It runs within the neck for a distance, often reaching the superior border of the neck. The sagging rope sign is typical of Perthes’ disease and is attributed to ischaemic damage to the epiphyseal growth plate
DiffDx Spondyloepiphyseal dysplasia, achondroplasia, cretinism
sagging rope sign Pediatric orthopedics A thin opaque curved line, which in the AP–or posterior view extends laterally from the inferior border of the femoral neck–FN; the SRS is typical of Perthes' disease and is seen when ischemia and growth occur simultaneously; it implies epiphyseal growth plate damage DiffDx Spondylo-epiphyseal dysplasia, achondroplasia, cretinism.