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

Study design: Retrospective cohort. Objectives: To compare postoperative functional improvement in patients who underwent staged versus non-staged anterior–posterior spinal arthrodesis for adult spinal deformity (ASD). Summary of background data: 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. Methods: 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. Results: 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 191 days (interquartile range: 86–674) in the staged group and 181 days (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 3–9 months postoperatively and at final follow-up (both, p >.05). Conclusion: Patients with ASD who underwent staged anterior–posterior spinal arthrodesis within 3 months 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. Level of evidence: III.