Asymmetrical pedicle subtraction osteotomy in the lumbar spine in combined coronal and sagittal imbalance.

INTRODUCTION: Degenerative scoliosis is a three-dimensional deformity that can present in some instances with fixed sagittal and coronal imbalance. Pedicle subtraction osteotomy (PSO) is an effective technique that allows correction with a posterior approach. When a combined coronal and sagittal imbalance is present, asymmetric PSOs could be an optimal choice to correct deformity on both planes.
METHODS: The asymmetric wedge resected from the vertebral body has to be shorter in the side of coronal imbalance, while a higher side cut has to be performed in the site opposite to the coronal imbalance. This allows to restore both coronal and sagittal alignment after osteotomy closure. An adequate preoperative planning is mandatory to correctly assess the geometry of the wedge to obtain the necessary correction.
CONCLUSIONS: The few studies present in literature show good results in terms of correction, even if the difficulty of this technique is certain.