title: Sacral rib: an uncommon congenital anomaly.
abstract: BACKGROUND
  Sacral rib represents an uncommon pathology in which rib-like structures arise from the sacrum. Supernumerary ribs may occur at any level of the spine, but supernumerary ribs in the sacrococcygeal area are extremely rare.
  
  
  OBJECTIVE
  To present the case of a patient with sacral rib and to discuss this entity with reference to the literature.
  
  
  METHODS
  A case report and literature review.
  
  
  METHODS
  A 17-year-old girl presented with low back pain and discomfort in bilateral gluteal regions. Radiographs and computed tomography (CT) of the pelvis showed a smooth-surfaced, rod-like bony structure attaching to the sacrum on the left side. The appearance was consistent with sacral rib. The sacrum was hypoplastic and deviated to the right. Magnetic resonance imaging (MRI) showed insertion of the gluteus maximus (GM) onto the coccyx only on the right side. The sacral rib existed beneath the left GM muscle and received a partial insertion from the left GM muscle. No ligamentous continuation between the sacral rib and coccyx was observed.
  
  
  RESULTS
  Conservative treatment relieved symptoms, so no surgical intervention was performed.
  
  
  CONCLUSIONS
  Sacral rib is a rare congenital anomaly for which surgical intervention is usually unnecessary. However, appropriate workups with CT and/or MRI should be considered for women, because sacral rib may cause complications during childbirth. In the literature, sacral/coccygeal rib is sometimes called "pelvic rib." However, sacral/coccygeal rib should be distinguished from pelvic rib, because pelvic rib originating from the ilium is considered to represent a different entity.
authors.affiliation: Department of Orthopedic Surgery, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. Electronic address: miyakosh@doc.med.akita-u.ac.jp.
authors.forename: Naohisa
authors.initials: N
authors.lastname: Miyakoshi
authors.affiliation: Honobono-en Long-Term Care Health Facility, 92-1 Kaidoshita, Showa-Okubo, Katagami 018-1401, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopedic Surgery, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Hongo
authors.affiliation: Department of Orthopedic Surgery, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shimada
mesh_terms: D000293:Adolescent; D002081:Buttocks / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000151:congenital* / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D011859:Radiography; D012272:Ribs / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology; D012447:Sacrum / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology
keywords: Congenital anomaly; Pelvic rib; Sacral rib; Supernumerary rib