Sagittal spino-pelvic adjustment in severe Lenke 1 hypokyphotic adolescent idiopathic scoliosis patients
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The human standing position requires permanent reciprocal spino-pelvic adjustments to obtain a dynamic and economic posture. This study focuses on a hypokyphotic Lenke 1 adolescent idiopathic scoliosis (AIS) patients cohort and points out their particular lumbo-pelvic adaptive mechanisms to maintain a neutral sagittal balance.
Preoperative retrospective analysis of prospectively collected data on a monocentric cohort of 455 AIS patients planned for corrective surgery. Radiological low-dose system coupled with a validated clinical routine software allowed to obtain data from eighty-four hypokyphotic [thoracic kyphosis (TK) <20°] Lenke 1 patients and were separately analyzed. Bilateral Student and one-way ANOVAs were conducted for statistical analysis.
Mean Cobb angle was 46.3° (±7.2), TK was 11° (±7.1), sagittal vertical axis (SVA) was −10.1 mm (±30.9), pelvic incidence (PI) was 55.7° (±12.9). Fifty percents of patients were posteriorly imbalanced. Among them, patients with a low PI used an anteversion of their pelvis [indicated by a high pelvic tilt (PT) angle] but were not able to increase their lumbar lordosis (LL) to minimize the posterior spinal shift.
Hypokyphotic Lenke 1 AIS patients use lumbo-pelvic compensatory mechanisms to maintain their global balance with a poor effectiveness. Subjects with a low PI have a restricted range of LL adaptation. Attention should be paid during surgical planning not to overcorrect lordosis in the instrumented levels in case of non-selective fusion, that may induce posterior shift of the fusion mass and expose to junctional syndromes and poor functional outcomes in this particular patients.
KeywordsSagittal balance Pelvic incidence Thoracic scoliosis Adolescent idiopathic scoliosis
Compliance with ethical standards
This work has been approved by the Institution’s Ethics Committee.
Conflict of interest
No direct or indirect benefits consecutive to this work have been or will be received by any of the authors. No author received or will receive any form of financial or material support consecutive to the present work.
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