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World Neurosurg. 2019 Mar;123:e85-e102. doi: 10.1016/j.wneu.2018.11.052. Epub 2018 Nov 20.

S1 Pedicle Subtraction Osteotomy in Sagittal Balance Correction. A Feasibility Study on Human Cadaveric Specimens.

Author information

1
Hospital General Universitario de Valencia, Valencia, Spain. Electronic address: vvanaclo@hotmail.com.
2
Instituto de Biomecánica, Valencia, Spain.
3
Hospital General Universitario de Valencia, Valencia, Spain.
4
ERESA, Valencia, Spain.
5
Instituto de Medicina Legal de Valencia, Valencia, Spain.
6
Medical School, University College London, London, United Kingdom.

Abstract

BACKGROUND:

A cadaveric feasibility study was carried out. Osteotomies to correct fixed sagittal imbalance are usually performed at L3/ L4.

OBJECTIVE:

To investigate the feasibility of S1 pedicle subtraction osteotomy to correct spinal deformity and spinopelvic parameters, achieving better results with more limited exposure. The data obtained will allow a fixation construct specific for this osteotomy to be designed.

METHODS:

S1 pedicle subtraction osteotomy was performed on 12 cadaveric specimens. Baseline and postprocedural computed tomography and biomechanical studies were performed. Data were analyzed with a fixation system SolidWorks model, and the redesigned fixation construct was described and analyzed with an ANSYS model.

RESULTS:

S1 pedicle subtraction osteotomy is technically feasible. The fixation can be achieved with L4, L5, and iliac screws connected with bars. The system can be reinforced with a polyetheretherketone cage placed anteriorly in the S1 body osteotomy site, a cross-connecting bar, a double iliac screw, or an anterior interbody cage placed at the L5-S1 disc. The fixation strength is improved by angulating the iliac rod channel 10°, adding a semi-sphere to the locking screw contact surface and 2 fins to its saddle. The redesigned construct showed suitable stress and deformation levels, achieving the expected biomechanical requirements.

DISCUSSION:

Compared with surgery on higher levels, S1 pedicle subtraction osteotomy allows greater correction with shorter fixation, because the osteotomy is performed at a more caudal level, modifying the spinopelvic parameters.

CONCLUSIONS:

S1 pedicle subtraction osteotomy is technically feasible. Finite element analysis results indicate that it has appropriate biomechanical properties.

KEYWORDS:

Finite element analysis; S(1) pedicle subtraction osteotomy; Sagittal profile; Spinal balance; Spinopelvic alignment; Spinopelvic parameters

PMID:
30465963
DOI:
10.1016/j.wneu.2018.11.052
[Indexed for MEDLINE]

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