title: Is the iliolumbar ligament a reliable identifier of the L5 vertebra in lumbosacral transitional anomalies?
abstract: OBJECTIVE
  Sufficiently sized studies to determine the value of the iliolumbar ligament (ILL) as an identifier of the L5 vertebra in cases of a lumbosacral transitional vertebra (LSTV) are lacking.
  
  
  METHODS
  Seventy-one of 770 patients with LSTV (case group) and 62 of 611 subjects without LSTV with confirmed L5 level were included. Two independent radiologists using coronal MR images documented the level(s) of origin of the ILL. The interobserver agreement was analysed using weighted kappa/kappa (wκ/κ) and a Fischer's exact test to assess the value of the ILL as an identifier of the L5 vertebra.
  
  
  RESULTS
  The ILL identified the L5 vertebra by originating solely from L5 in 95 % of the controls; additional origins were observed in 5 %. In the case group, the ILL was able to identify the L5 vertebra by originating solely from L5 in 25-38 %. Partial origin from L5, including origins from other vertebra was observed in 39-59 % and no origin from L5 at all in 15-23 % (wκ = 0.69). Both readers agreed that an ILL was always present and its origin always involved the last lumbar vertebra.
  
  
  CONCLUSIONS
  The level of the origin of the ILL is unreliable for identification of the L5 vertebra in the setting of an LSTV or segmentation anomalies.
  
  
  CONCLUSIONS
  • The origin of the ILL is evaluated in subjects with an LSTV. • The origin of the ILL is anatomically highly variable in LSTV. • The ILL is not a reliable landmark of the L5 vertebra in LSTV.
authors: MRI, Radiology Department, Hospital for Special Surgery, 535 East 70th Street, New York, 10021, NY, USA, nadja.farshad@yahoo.com.
authors: Nadja A
authors: NA
authors: Farshad-Amacker
authors: Brett
authors: B
authors: Lurie
authors: Richard J
authors: RJ
authors: Herzog
authors: Mazda
authors: M
authors: Farshad
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008023:Ligaments, Articular / Q000002:abnormalities*; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012447:Sacrum; D013122:Spinal Diseases / Q000175:diagnosis*