Posterior spinal fusion for adolescent idiopathic thoracolumbar/lumbar scoliosis clinical outcomes and predictive radiological factors for extension of fusion distal to caudal end vertebra

  1. S. B. Roberts, MSc, MRCS, Specialty registrar in Orthopaedics1 Author Profile;
  2. A. I. Tsirikos, MD, FRCS, PhD, Consultant orthopaedic and spine surgeon1 Author Profile; and
  3. A. S. Subramanian, D.Orth, DNB. Orth, FRCS, Consultant orthopaedic and spine surgeon1



  1. Correspondence should be sent to Mr A. I. Tsirikos; e-mail:atsirikos@hotmail.com


Clinical, radiological, and Scoliosis Research Society-22 questionnaire data were reviewed pre-operatively and two years post-operatively for patients with thoracolumbar/lumbar adolescent idiopathic scoliosis treated by posterior spinal fusion using a unilateral convex segmental pedicle screw technique. A total of 72 patients were included (67 female, 5 male; mean age at surgery 16.7 years (13 to 23)) and divided into groups: group 1 included 53 patients who underwent fusion between the vertebrae at the limit of the curve (proximal and distal end vertebrae); group 2 included 19 patients who underwent extension of the fusion distally beyond the caudal end vertebra.

A mean scoliosis correction of 80% (45% to 100%) was achieved. The mean post-operative lowest instrumented vertebra angle, apical vertebra translation and trunk shift were less than in previous studies. A total of five pre-operative radiological parameters differed significantly between the groups and correlated with the extension of the fusion distally: the size of the thoracolumbar/lumbar curve, the lowest instrumented vertebra angle, apical vertebra translation, the Cobb angle on lumbar convex bending and the size of the compensatory thoracic curve. Regression analysis allowed an equation incorporating these parameters to be developed which had a positive predictive value of 81% in determining whether the lowest instrumented vertebra should be at the caudal end vertebra or one or two levels more distal. There were no differences in the Scoliosis Research Society-22 outcome scores between the two groups (p = 0.17).

In conclusion, thoracolumbar/lumbar curves in patients with adolescent idiopathic scoliosis may be effectively treated by posterior spinal fusion using a unilateral segmental pedicle screw technique. Five radiological parameters correlate with the need for distal extension of the fusion, and an equation incorporating these parameters reliably informs selection of the lowest instrumented vertebra.

Cite this article: Bone Joint J 2014;96-B:1082–9.


  • The authors would like to thank H. Sharp and E. Brady (specialist nurses) who collected the SRS-22 questionnaires.

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

    This article was primary edited by J. Scott and first proof edited by G. Scott.

  • Received January 20, 2014.
  • Accepted May 13, 2014.



Josh Sandberg

Josh Sandberg is the President of Ortho Sales Partners and Partner for The De Angelis Group. He also serves as Co-Founder and Editor of OrthoSpineNews.

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