Isabella Zbinden1, Erich Rutz2, Jon A Jacobson3, Olaf Magerkurth4,5. 1. Department of Radiology, University of Basel, Petersgraben 4, Basel, 4031, Switzerland. 2. Department of Orthopedic Surgery, University Children's Hospital, Spitalstrasse 33, Basel, 4056, Switzerland. 3. Department of Radiology, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI, 48109-5326, USA. 4. Department of Radiology, University Children's Hospital, Spitalstrasse 33, Basel, 4056, Switzerland. dr.o.magerkurth@gmail.com. 5. Department of Radiology, Kantonsspital Baden, Im Ergel 1, 5404, Baden, Switzerland. dr.o.magerkurth@gmail.com.
Abstract
PURPOSE: To define osseous landmarks on tibia radiographs in order to establish age-related normal values characterizing physiological tibial bowing in children. MATERIALS AND 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). CONCLUSION: 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. KEY POINTS: • 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.
PURPOSE: To define osseous landmarks on tibia radiographs in order to establish age-related normal values characterizing physiological tibial bowing in children. MATERIALS AND 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). CONCLUSION: 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. KEY POINTS: • 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: F Hefti; G Bollini; P Dungl; J Fixsen; F Grill; E Ippolito; B Romanus; C Tudisco; S Wientroub Journal: J Pediatr Orthop B Date: 2000-01 Impact factor: 1.041