How is staging of ALIF following posterior spinal arthrodesis to the pelvis related to functional improvement in patients with adult spinal deformity?

Abstract

Retrospective cohort. To compare postoperative functional improvement in patients who underwent staged versus non-staged anterior-posterior spinal arthrodesis for adult spinal deformity (ASD). In patients with ASD, spinal arthrodesis can be performed in 2 stages to avoid the physiologic insult of a lengthy surgery. The association between staged surgery and postoperative functional improvement has not been well studied. We included 87 patients (59 women) with ASD who underwent anterior-posterior spinal arthrodesis of > 5 levels with fixation to the pelvis from 2010-2014. Primary outcomes were the frequency of achieving at least a minimal clinically important difference (MCID) in the Scoliosis Research Society-22r (SRS-22r) Activity domain and the timeframe in which it was achieved. The secondary outcome was patient satisfaction (SRS-22r Patient Satisfaction domain). A Cox proportional hazard model was used to compare functional improvement over time between staged and non-staged groups. Our study was powered to detect a relative hazard ratio of 0.53, β = 0.20. α = 0.05. The frequency of achieving an MCID in SRS-22r Activity score did not differ significantly between the staged group (33/41 patients) and the non-staged group (34/46 patients) (hazard ratio 0.74; 95% confidence interval 0.41-1.36). Median times to achieving an MCID in SRS-22r Activity score were 191days (interquartile range: 86-674) in the staged group and 181days (interquartile range: 72-474) in the non-staged group (p = .75). The staged and non-staged groups had similar SRS-22r Patient Satisfaction scores at 3-9months postoperatively and at final follow-up (both, p > .05). Patients with ASD who underwent staged anterior-posterior spinal arthrodesis within 3months after index surgery were similarly likely to experience functional improvement in the same timeframe as patients who underwent non-staged surgery. Patient satisfaction did not differ significantly between staged and non-staged groups. III.