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All-Pedicle Screw Fixation With 6-mm-Diameter Cobalt-Chromium Rods Provides Optimized Sagittal Correction of Adolescent Idiopathic Scoliosis

Lamerain, Mayalen MD*; Bachy, Manon MD, PhD*; Dubory, Arnaud MD, MSc*; Kabbaj, Reda MD*; Scemama, Caroline MD*; Vialle, Raphaël MD, PhD*,†

doi: 10.1097/BSD.0000000000000413

Purpose: Recently introduced cobalt-chromium (CoCr) rods that rely solely on pedicle screws produce very good results in correcting scoliotic curves. All-pedicle screws constructs are also suspected of decreasing thoracic kyphosis. The current study was designed to evaluate sagittal correction in adolescent idiopathic scoliosis patients, using 6-mm CoCr rods and all-screw constructs.

Materials and Methods: A total of 61 patients treated by posterior spinal fusion and instrumentation, using all-pedicle screw constructs were included. The mean age at surgery was 15.4 years (range, 12–18 y). Forty-five patients (group A) were diagnosed with decreased thoracic kyphosis, and 16 patients (group B) had normal (35–50 degrees) thoracic kyphosis.

Results: The preoperative main Cobb angle was 62.93±19.38 degrees in group A and 73.45±22.13 degrees in group B. In group A, the postoperative main Cobb angle was 23.33±12.71 degrees. In group B, the postoperative main Cobb angle was 27.20±10.04 degrees. The T4–T12 thoracic kyphosis improved postoperatively from 18.15±10.29 to 28.18±8.35 degrees in group A. In group B, the postoperative T4–T12 thoracic kyphosis was 40.34±3.13 degrees. Statistical analysis showed a significant improvement between preoperative and postoperative values of T4–T12 thoracic kyphosis in group A. In group B, the differences in T4–T12 thoracic kyphosis values were not statistically significant.

Conclusions: Our result demonstrates a significant improvement of T4–T12 thoracic kyphosis in the hypokyphotic group of patients and confirms that CoCr rods can produce sagittal corrections in hypokyphotic adolescent idiopathic scoliosis patients. Our results confirm the benefit of combining all-pedicle screw constructs with a posterolateral translational in situ bending procedure to correct hypokyphosis directly.

*Pierre and Marie Curie University, Paris6, Department of Pediatric Orthopaedics, Armand Trousseau Hospital

Department for Innovative Therapies in Musculoskeletal Diseases, Armand Trousseau Hospital, the MAMUTH Hospital-University, Paris Cedex, France

The authors declare no conflict of interest.

Reprints: Raphaël Vialle, MD, PhD, Université Pierre et Marie Curie Paris6, Department of Pediatric Orthopaedics, Armand Trousseau Hospital, 26 avenue du Dr Arnold Netter, 75571, Paris Cedex 12, France (e-mail:

Received July 14, 2015

Accepted June 7, 2016

© 2017 by Lippincott Williams & Wilkins, Inc.