Complications in Spinal Fusion for Adult Scoliosis. A Report of the Scoliosis Research Society Morbidity and Mortality Committee

Introduction: Scoliosis affecting the adult encompasses primarily both adult idiopathic and "de novo" degenerative deformities. Although, there are important differences between these scoliosis subtypes in terms of age at time of presentation, curve type and severity, and surgical treatment strategies; analysis and comparison of these two groups of patients is worthwhile as they represent the majority of adults undergoing spinal deformity surgery. The purpose of this study is to determine whether scoliosis subtype (degenerative vs idiopathic) is an independent predictor of complications and mortality in surgery for adult scoliosis (AS) by an analysis of the SRS M & M database of complications as submitted by its members.

Materials and Methods: This retrospective study used SRS Morbidity and Mortality data submitted for surgical cases performed from 2003-05. The null hypotheses are that: 1) the specific scoliosis subtype (degenerative vs idiopathic) has no effect on the overall rates of recorded complications in adults and 2) the specific scoliosis subtype (degenerative vs idiopathic) has no effect on the overall rates of recorded mortalities in adults. The classification of scoliosis as adult idiopathic or degenerative was made by SRS members submitting data. Of the 69,774 surgical cases submitted by SRS members in the years 2003 through 2005; 16,163 (23.2%) were performed for the treatment of scoliosis. The 2,852 patients (17.6% of scoliosis cases) identified as having spinal fusion for AS (age > 20) of either idiopathic origin (n = 1,543, mean age 42.4) or degenerative origin (n = 1,309, mean age 64.4) comprised the cohort under study. All reported complications were tabulated and totaled for these procedures with regards to scoliosis subtype, and statistical analysis conducted.

Results: Complications were reported in 394 (13.8%) of the 2,852 patients in this series. One-hundred and ninety (12.3%) of the 1543 idiopathic scoliosis patients and 204 (15.6%) of the 1309 degenerative scoliosis patients experienced complications. This difference was statistically significant (p <0 .01). There were seven deaths (0.45%) in the idiopathic group and (0.53%) degenerative (not significant (p="" 0.481)). The overall neurologic complication rate was 1.3% with six documented spinal cord injuries (0.21%) only one of which (0.04%) complete.

Conclusions: This study demonstrates that the complication rate for surgery for degenerative AS is significantly higher then idiopathic AS. The overall mortality rates, however are not significantly different. Limitations of this study include the difficulty of controlling for co-morbidities, age, curve severity and other potential relevant factors. Nevertheless, the data in this study may be used to counsel patients with regards to the nature and rates of complications associated with these diagnostic subtypes of AS in the hands of experienced spinal deformity surgeons.