Interbody Fusion Rate in Extreme Lateral Interbody Fusion Surgery: A Proposal of Classification

Presented at SMISS Annual Forum 2018
By Luca Proietti
With Caterina Fumo , Luca Fresta , Andrea Perna MD, Ilaria Giannelli MD, Marco Renzi , Francesco Ciro Tamburrelli ,

Disclosures: Luca Proietti None Caterina Fumo None, Luca Fresta None, Andrea Perna MD None, Ilaria Giannelli MD None, Marco Renzi None, Francesco Ciro Tamburrelli None,


The main objectives of the lateral transpsoas approach to the thoracic and lumbar spine, also known as extreme lateral interbody fusion (XLIF), are the correction of the deformity and the interbody fusion with the use of wide footprint cages. In literature there is vagueness about classification of the lumbar interbody fusion rate yet.


We have elaborated a topographic method of classification based on the individuation of bony bridges between vertebral body endplates both inside the cage and around it. The aim of this work is to show our idea and the results of a preliminary study on 43 patients treated with XLIF surgical procedure.


The fusion rate has been evaluated with multislice CT scan. Nine degrees of ossifications were identified on coronal plane and four on sagittal plane. On the basis of these results the fusion rate has been classified as complete, incomplete or pseudoarthrosis. According to Pathria’s Criteria we analyzed joint articular surface degeneration on zygapophyseal joint. 43 patients with degenerative lumbar spine disease were included, with an average follow-up of 22.3 (12-53) months, from 2011 to 2018. 63 interbody cages were implanted, 1 (one) was used in every surgical procedure at least. Pre-operative and at least 12 months post- operative multislice computed tomography (MS-TC) were prescribed for all of them.


We identified a complete fusion of interbody space in 12,3% of the levels instrumented, in 72,5% an incomplete fusion, in 15,2% no bony bridges were founded between the superior and the inferior vertebral body endplate like pseudoarthrosis.


The therapeutic success of mininvasive antero-lateral surgical approaches are due to the primary mechanical stability of the vertebral unity of movement treated, reached with the instrumentation used, even if it is difficult to recognize a secondary stability due to the complete bony fusion between vertebral body endplates. Our objective is to establish a universal and effective method to identify interbody fusion rate after at least one year from XLIF surgical procedure.