The sagging rope sign: a critical appraisal.

Certain features of the sagging rope sign recently analysed by Apley and Weintroub (1981) are examined in detail. Evidence is presented to show that the line is a radiological shadow cast by the lateral edge of a severely deformed femoral head rather than a condensation of the spongiosa within the neck. An explanation is offered to explain the common association of the presence of this radiological sign with premature epiphysial fusion.