[Complications of surgical treatment of spinal deformities: a prospective multicentric study of 3311 patients]

The incidence of complications secondary to surgical treatment of spinal deformations remains imprecise. The purpose of this prospective multicentric observational study was to assess the incidence of intra- and postoperative complications secondary to this type of surgery to detail the observed complications and to identify favoring factors.

For this study, we included 3311 patients who underwent surgery during a 12-month period for spinal deformation, defined as idiopathic or secondary scoliosis or kyphosis, irrespective of the localization, severity, or type of surgery performed. Four main categories of complications were studied: general, infectious, neurological, and mechanical. Pre- and intraoperative variables recorded were: epidemiological and morphological data, history of surgery for the same spinal deformation, comorbid conditions, type of deformation treated (nature, anatomic localization, severity, reducibility), type of surgery performed (approach, duration of the operation), operative blood loss, extent and localization of the fusion, associated neurological release, vertebral osteotomy or not, type of graft used. Two types of analysis were performed. The first was a descriptive analysis to detail the overall incidence of complications and the incidence of each of the four main categories. The second was a multivariate analysis designed to determine factors significantly associated with complication occurrence.

Mean age of the cohort was 27 +/- 18 years; 6.8% of the patients had had a prior operation for the spinal deformation. The deformation was scoliosis in 90% (mean angle 56 +/- 20 degrees) and kyphosis in 10% (mean angle 47 +/- 23 degrees). An isolated posterior approach was used for 72.5% of patients, an isolated anterior approach for 6.4%, and a combined anteroposterior approach for 21.1%. Seven hundred four patients (21.3%) had one or more complications (850 complications) during or shortly after their operation. The incidences of general, infectious, mechanical and neurological complications were: 5.7%, 4.7%, 11.5%, and 1.8% respectively. Globally, considering all types of complications, the following factors were found to be significantly associated with complication occurrence: patient age, ASA score, extent of the fusion, presence of vertebral osteotomy, inclusion of the sacrum in the arthrodesis, and initial angle of the treated deformation. For patients with scoliosis, the following factors were significantly associated with a secondary central neurological disorder: initial angle of the deformation, use of vertebral osteotomy, type of curvature with greater risk for thoracic curvatures and double thoracic and lumbar curvatures.

This work enabled us to determine the overall rate of complications after surgical treatment of spinal deformations. Certain risk factors related with complication occurrence were identified, but the heterogeneous nature of the population and the methodology used to identify these factors only allowed detection of trends. A future study by etiological group or focusing on specific complications should allow a more precise analysis of these risk factors. This overall rate of complications should be used to better inform patients and their family about the risks of this type of surgery.