title: Radiographic evaluation of ventral instability in lumbar spondylolisthesis: do we need extension radiographs in routine exams?
abstract: OBJECTIVE
  To determine the usefulness of acquiring extension radiographs for the evaluation of the degree of spondylolisthesis.
  
  
  METHODS
  Routine radiographs of the lumbar spine were retrospectively evaluated in 87 patients (mean-age 63, range 32-86) by two independent radiologists. All patients received radiographs in standing neutral, flexion and extension position. Vertebral body depth, sagittal translational displacement and lordosis angle were measured and slip percentage (SP) was calculated on standing neutral, flexion and extension radiographs. Statistical analysis was performed with a two-sided t test. Inter- and intraobserver reliability was assessed using the kappa-coefficient.
  
  
  RESULTS
  There was no statistically significant SP-difference between neutral standing and extension images. Ventral instability was diagnosed in 25-34 % (cut-off >8 % SP-difference) for neutral versus flexion comparison. The detection rate of flexion-extension radiographs representing the extremes of motion was lower with 15-22 %. Inter- and intraobserver reliability was good to excellent.
  
  
  CONCLUSIONS
  Slip percentage in routine standing extension radiography ultimately does not differ from that obtained in a static neutral standing view. Extension radiography may therefore be omitted in a routine work-up of ventral instability in lumbar spondylolisthesis.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, 53105, Bonn, Germany, claus.christian.pieper@ukb.uni-bonn.de.
authors.forename: Claus Christian
authors.initials: CC
authors.lastname: Pieper
authors.forename: Simon Frederik
authors.initials: SF
authors.lastname: Groetz
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nadal
authors.forename: Hans Heinz
authors.initials: HH
authors.lastname: Schild
authors.forename: Pascal Dominique
authors.initials: PD
authors.lastname: Niggemann
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013168:Spondylolisthesis / Q000000981:diagnostic imaging*
references.citation: Radiology. 2007 Oct;245(1):62-77
references.pmid: 17885181
references.citation: Spine (Phila Pa 1976). 1985 Apr;10(3):262-76
references.pmid: 3992347
references.citation: Med J Aust. 1946 Apr 6;1:465-9
references.pmid: 21025815
references.citation: J Spinal Disord Tech. 2008 Aug;21(6):409-12
references.pmid: 18679095
references.citation: BMC Musculoskelet Disord. 2011 Apr 05;12:69
references.pmid: 21466688
references.citation: Spine (Phila Pa 1976). 1982 Jul-Aug;7(4):374-89
references.pmid: 7135070
references.citation: Spine (Phila Pa 1976). 1985 Apr;10(3):280-6
references.pmid: 3992349
references.citation: Spine (Phila Pa 1976). 1990 Jun;15(6):571-6
references.pmid: 2402698
references.citation: Spine (Phila Pa 1976). 1987 Mar;12(2):119-29
references.pmid: 2954216
references.citation: Radiol Clin North Am. 2001 Jan;39(1):55-71, v-vi
references.pmid: 11221506
references.citation: Lancet. 1986 Feb 8;1(8476):307-10
references.pmid: 2868172
references.citation: Eur Spine J. 2012 Feb;21(2):256-61
references.pmid: 21670945
references.citation: Lancet. 2012 Feb 4;379(9814):482-91
references.pmid: 21982256
references.citation: Radiology. 1946 Sep;47:249-62
references.pmid: 20997774
references.citation: J Spinal Disord Tech. 2009 Oct;22(7):479-85
references.pmid: 20075810
references.citation: Skeletal Radiol. 2009 Jun;38(6):529-33
references.pmid: 19198833
references.citation: Spine (Phila Pa 1976). 1994 Aug 1;19(15):1697-703
references.pmid: 7973963
references.citation: Spine (Phila Pa 1976). 1991 May;16(5):562-71
references.pmid: 2052999
references.citation: Spine (Phila Pa 1976). 1985 Mar;10(2):150-3
references.pmid: 3159103
references.citation: J Spinal Disord. 1992 Dec;5(4):383-9; discussion 397
references.pmid: 1490034
references.citation: Eur Spine J. 2008 Mar;17(3):327-335
references.pmid: 18026865
references.citation: J Orthop Sports Phys Ther. 2011 Mar;41(3):130-40
references.pmid: 21289452
references.citation: Clin Radiol. 1983 Jul;34(4):405-11
references.pmid: 6872445
references.citation: Spine (Phila Pa 1976). 1990 Aug;15(8):741-50
references.pmid: 2237624
references.citation: Clin Orthop Relat Res. 1982 May;(165):110-23
references.pmid: 6210480
references.citation: J Biomech. 1977;10(11/12):681-7
references.pmid: 606716
references.citation: Spine (Phila Pa 1976). 2003 Apr 15;28(8):819-27
references.pmid: 12698127
references.citation: Spine (Phila Pa 1976). 2011 Oct 15;36(22):E1463-8
references.pmid: 20838368
references.citation: J Bone Joint Surg Br. 1957 Feb;39-B(1):6-22
references.pmid: 13405944
references.citation: Clin Radiol. 2002 Jul;57(7):632-9
references.pmid: 12096864