Neurologic Comorbidities Predict Proximal Junctional Failure in Adult Spinal Deformity

Abstract

Study DesignRetrospective case-control matched cohort from a single institution. ObjectiveTo examine the contribution of nonmechanical factors to the incidence of proximal junctional failure (PJF) after adult spinal deformity (ASD) surgery. Summary of Background DataMultiple studies have reported on the prevalence of PJF following surgery for ASD. However, little is known about the contribution of nonmechanical factors to the incidence of PJF. MethodsWe identified a consecutive series of ASD patients who required revision surgery for PJF between 2013 and 2015. A matched cohort of ASD patients who did not develop PJF after surgical correction was identified based on age, gender, preoperative deformity type, number of fusion levels, and the lower instrumented vertebra level. We compared medical and surgical histories in the matched cohorts, with particular attention to the prevalence of preoperative neurologic comorbidities that might affect standing balance. Preoperative, immediate postoperative, and follow-up radiographs were reviewed to document specific characteristics of mechanical failure that resulted in PJF and required revision surgery. ResultsTwenty-eight cases of PJF requiring revision surgery were identified. The prevalence rates of preoperative neurologic comorbidities in PJF cohort were significantly higher than in non-PJF cohort (75% vs. 32%, p < .001). Neurologic comorbidities included prior stroke (4), metabolic encephalopathy (2), Parkinson disease (1), seizure disorder (1), cervical and thoracic myelopathy (7), diabetic neuropathy (4), and other neuropathy (4). The mean preoperative sagittal vertical axis in PJF cohort was more positive compared with the non-PJF cohort (144 mm vs. 65 mm, p = .009) There were no significant differences in immediate postoperative or follow-up radiographic parameters between cohorts. ConclusionsIn this study, risk factors identified for the development of PJF included nonmechanical neurologic comorbidities, emphasizing the need to look beyond radiographic alignment in order to reduce the incidence of PJF. Level of EvidenceLevel 3.