European Spine Journal

, Volume 19, Issue 5, pp 732–738 | Cite as

Coronal plane segmental flexibility in thoracic adolescent idiopathic scoliosis assessed by fulcrum-bending radiographs

  • Carol-Claudius Hasler
  • Fritz Hefti
  • Philippe Büchler
Original Article


Knowledge about segmental flexibility in adolescent idiopathic scoliosis is crucial for a better biomechanical understanding, particularly for the development of fusionless, growth-guiding techniques. Currently, there is lack of data in this field. The objective of this study was, therefore, to compute segmental flexibility indices (standing angle minus corrected angle/standing angle). We compared segmental disc angles in 76 preoperative sets of standing and fulcrum-bending radiographs of thoracic curves (paired, two-tailed t tests, p < 0.05). The mean standing Cobb angle was 59.7° (range 41.3°–95°) and the flexibility index of the curve was 48.6% (range 16.6–78.8%). The disc angles showed symmetric periapical distribution with significant decrease (all p values <0.0001) for every cephalad (+) and caudad (−) level change. The periapical levels +1 and −1 wedged at 8.3° and 8.7° (range 3.5°–14.8°), respectively. All angles were significantly smaller on the-bending views (p values <0.0001). We noted mean periapical flexibility indices of 46% (+1), 49% (−1), 57% (+2) and 81% (−2), which were significantly less (p < 0.001) than for the group of remote levels 105% (+3), 149% (−3), 231% (+4) and 300% (−4). The discal and bony wedging was 60 and 40%, respectively, and mean values 35° and 24° (p < 0.0001). Their relationship with the Cobb angle showed a moderate correlation (r = 0.56 and 0.45). Functional, radiographic analysis of idiopathic thoracic scoliosis revealed significant, homogenous segmental tethering confined to four periapical levels. Future research will aim at in vivo segmental measurements in three planes under defined load to provide in-depth data for novel therapeutic strategies.


Idiopathic scoliosis Fulcrum-bending views Segmental stiffness Segmental flexibility 


Conflict of interest statement

No funds were received in support of this study. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Carol-Claudius Hasler
    • 1
  • Fritz Hefti
    • 1
  • Philippe Büchler
    • 2
  1. 1.Orthopaedic DepartmentsUniversity Children’s HospitalBaselSwitzerland
  2. 2.Medical Faculty, Institute for Surgical Technology and BiomechanicsUniversity of BernBernSwitzerland

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