title: Tibial bowing in children - what is normal? A radiographic study.
abstract: OBJECTIVE
  To define osseous landmarks on tibia radiographs in order to establish age-related normal values characterizing physiological tibial bowing in children.
  
  
  METHODS
  Five hundred and twenty-six patients aged 0-17 years with normal radiographs of the lower legs were identified and retrospectively reviewed by two blinded radiologists. In anteroposterior (ap)/lateral (lat)-views, 3 lines defined tibial length and angulation. Line-A connecting proximal to distal corner of tibial metaphysic, lines B and C corresponding to corners of tibial metaphysis. Angle A/B defines proximal, A/C distal tibial-angulation. Tibial curvature is defined by distance of line-D parallel to A and tangential to tibial cortex. Normal values were calculated with linear-regression. Intra-/Interreader agreement were tested with a Bland-Altman-plot.
  
  
  RESULTS
  Intrareader-agreement: Reader 1 showed a bias of -0.1, standard-deviation of bias was 1.9 and 95 %-limits-of-agreement -3.9- 3.7. Reader 2: -0.01, 2.4 and -4.7- 4.7. Interreader: 0.2, 1.6 and -2.9- 3.3. Angle-A/B ap was 80-100°, increasing with age (86.5-88); angle-AC ap was 82-107°(96.8-90.5), angle-AB lat was 81-107°(93.0-98.0); angle-AC lat was 76-102 (89.5-86.5); depth of curve ap was 0-11 % (8-3.5) and lat 2-13 %, (8.5-3.5).
  
  
  CONCLUSIONS
  Age dependent tibial bowing can be assessed with this new measurement system and age-related normal-values characterizing physiological tibial bowing in children is established.
  
  
  CONCLUSIONS
  • Tibial Bowing is diagnosed on conventional radiographs. • Existing Methods provide limited level of confidence. • New methods provide easy to assess landmarks in all patient ages. • Existing methods require higher radiation dose compared to new method presented.
authors.affiliation: Department of Radiology, University of Basel, Petersgraben 4, Basel, 4031, Switzerland.
authors.forename: Isabella
authors.initials: I
authors.lastname: Zbinden
authors.affiliation: Department of Orthopedic Surgery, University Children's Hospital, Spitalstrasse 33, Basel, 4056, Switzerland.
authors.forename: Erich
authors.initials: E
authors.lastname: Rutz
authors.affiliation: Department of Radiology, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI, 48109-5326, USA.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Jacobson
authors.affiliation: Department of Radiology, University Children's Hospital, Spitalstrasse 33, Basel, 4056, Switzerland. dr.o.magerkurth@gmail.com.|Department of Radiology, Kantonsspital Baden, Im Ergel 1, 5404, Baden, Switzerland. dr.o.magerkurth@gmail.com.
authors.forename: Olaf
authors.initials: O
authors.lastname: Magerkurth
mesh_terms: D000293:Adolescent; D001847:Bone Diseases / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015588:Observer Variation; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging*
keywords: Imaging; Lower extremity deformities; Pediatric; Radiograph; Tibia