title: T12 Sagittal Tilt Predicts Thoracic Kyphosis.
abstract: Retrospective review and analysis of lateral long cassette radiographs.
  
  
  
  The purpose of this paper is to assess whether certain radiographic features routinely seen on lumbar radiographs can predict a structural thoracic deformity.
  
  
  
  Obtaining proper sagittal alignment is an essential factor contributing to favorable clinical outcomes following spinal deformity surgery. The majority of patients treated with lumbar fusions do not undergo long cassette radiographs, and therefore physicians must rely upon clinical examination to determine the presence of a structural thoracic kyphotic deformity.
  
  
  
  A total of 193 consecutive lateral long cassette radiographs of outpatients without prior spine surgery presenting to a spine surgeon were independently reviewed. Statistical analysis was performed on sagittal parameters that included the T12 slope, pelvic incidence, sacral slope, T2-T12 and T5-T12 kyphosis, and T12-S1 lordosis, and correlated with patient demographics.
  
  
  
  The age of the patient combined with the sagittal slope of T12 can be used to assess a patient's risk of having a structural thoracic deformity defined in this series as >35 degrees from T5 to T12 and >40 degrees from T2 to T12. Based on our findings, for a given 20-year-old patient, the threshold T12 sagittal angle was about 17-18 degrees. This angle decreased 2-3 degrees per decade so that the threshold value was 12-13 degrees by age 40, 7-9 degrees by age 60, and 3-4 degrees by age 80.
  
  
  
  Age and the sagittal slope of the 12th thoracic vertebra are effective predictors of kyphosis between T2-T12 and T5-T12. This information may be used to determine the need for long cassette radiographs to further examine the possible presence of kyphotic deformity in the thoracic spine.
  
  
  
  Level IV.
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada. Electronic address: Stephen.Lewis@uhn.ca.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lewis
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Taylor E
authors.initials: TE
authors.lastname: Dear
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Zywiel
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Sam G
authors.initials: SG
authors.lastname: Keshen
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Y Raja
authors.initials: YR
authors.lastname: Rampersaud
authors.affiliation: Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
authors.forename: Sofia P
authors.initials: SP
authors.lastname: Magana
mesh_terms: D000328:Adult; D006801:Humans; D007738:Kyphosis / Q000473:pathology*; D008141:Lordosis / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D011379:Prognosis; D012189:Retrospective Studies; D013904:Thoracic Vertebrae; D055815:Young Adult
keywords: Kyphosis; Long cassette radiographs; Lumbar X-ray; T12 sagittal angle; Thoracic deformity