Mechanical complications in adult spinal deformity and the effect of restoring the spinal shapes according to the Roussouly classification: a multicentric study

Eur Spine J. 2020 Apr;29(4):904-913. doi: 10.1007/s00586-019-06253-1. Epub 2019 Dec 26.

Abstract

Purpose: To evaluate the incidence of mechanical complications in patients with adult spine deformity (ASD) treated by restoring the normal shape according to the Roussouly classification.

Methods: This is a retrospective multicentric study with a minimum follow-up of 2 years. Patients operated on with fusion for ASD (minimum performed fusion: L2 to sacrum) were included. Patients with a history of previous spinal fusion of more than three levels were excluded. Spinal and pelvic parameters were measured on the preoperative and the immediate postoperative follow-up. All mechanical complications were recorded.

Results: A total of 290 patients met the criteria of inclusion with a minimum follow-up of 2 years. Mechanical complications occurred in 30.4% of the cohort. The most common complication was PJK with an incidence of 18% while nonunion or instrumentation failure (rod breakage, implant failure) occurred in 12.4%. 66% of the patients were restored to the normal shape according to the Roussouly classification based on their PI and had a mechanical complication rate of 22.5%, whereas the remaining 34% of patients had a complication rate of 46.8% (p < 0.001). The relative risk for developing a mechanical complication if the algorithm was not met was 3 (CI 1.5-4.3; p < 0.001) CONCLUSION: In the recent literature, there are no clear guidelines for ASD correction. Restoring the sagittal spinal contour to the normal shapes of Roussouly according to the PI could serve as a guideline for ASD treatment. Ignoring this algorithm has a threefold risk of increased mechanical complications. We recommend this algorithm for treatment of ASD.

Level of evidence: IV cross-sectional observational study. These slides can be retrieved under Electronic Supplementary Material.

Keywords: Adult spinal deformity; Complications; Degenerative spine; Roussouly classification; Scoliosis.