Neurologic Comorbidities Predict Proximal Junctional Failure in Adult Spinal Deformity.
STUDY DESIGN
Retrospective case-control matched cohort from a single institution.


OBJECTIVE
To examine the contribution of nonmechanical factors to the incidence of proximal junctional failure (PJF) after adult spinal deformity (ASD) surgery.


SUMMARY OF BACKGROUND DATA
Multiple 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.


METHODS
We 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.


RESULTS
Twenty-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.


CONCLUSIONS
In 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 EVIDENCE
Level 3.
['Arima|Hideyuki|H|', 'Glassman|Steven D|SD|', 'Dimar|John R|JR|', 'Matsuyama|Yukihiro|Y|', 'Carreon|Leah Y|LY|']
D000368:Aged D016022:Case-Control Studies D015897:Comorbidity D005260:Female D006801:Humans D015994:Incidence D008297:Male D008875:Middle Aged D011183:Postoperative Complications D012086:Reoperation D012189:Retrospective Studies D012307:Risk Factors D013121:Spinal Curvatures D013123:Spinal Fusion D017211:Treatment Failure
Neurologic comorbidity Proximal junctional failure Revision surgery Sagittal vertical axis Adult scoliosis Adult spine deformity Correction surgery Proximal junctional kyphosis