The sagging rope sign in achondroplasia - Different from Perthes' disease

Viraj Uttamrao Shingade, Hae Ryong Song, Seok Hyun Lee, Seung Woo Suh, Chang Wug Oh, Jun Seok Hong

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Objective: The sagging rope sign is a radio-opaque line, seen on radiographs of the hips, with Perthes' disease. The main purpose of this study was to determine the incidence, cause and importance of this sign in achondroplasia, and to reveal how it differs from in Perthes' disease. Design: Serial radiograms, along with 2-dimensional and 3-dimensional CT images were studied in 42 achondroplasic patients. Patients: Forty-two achondroplasic patients, reported at our institute (for routine outpatient consultation, spine surgeries, deformity corrections, limb-lengthening procedures) were included in this study. There were 26 males and 16 females. Results: The sign was observed bilaterally, in all patients. Evaluation of CT images revealed spherical heads, with presence of circumferential overhang in all hips. This circumferential overhang, seen on 3-D CT scan, corresponded to the sagging rope sign on radiographs. Conclusions: Presence of the sagging rope sign in bilateral hips is a characteristic feature of achondroplasia. It usually appears before epiphyseal closure. Its cause, incidence, and nature differ from Perthes' disease, and its presence does not carry a bad prognosis in achondroplasia.

Original languageEnglish
Pages (from-to)923-928
Number of pages6
JournalSkeletal Radiology
Issue number12
Publication statusPublished - 2006 Dec


  • Achondroplasia
  • Sagging rope sign

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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