Estimation of proximal junctional failure and associated risk factors in adult spine deformity surgery: an observational study from a single institution.

STUDY DESIGN

A retrospective observational cohort study.

PURPOSE

To estimate the proximal junctional failure (PJF) rate and identify associated factors.

OVERVIEW OF LITERATURE

Proximal junctional pathologies are challenging and common complications of adult spine deformity (ASD) surgery. However, the PJF rate was not accurately defined within the ASD cohort. A correct estimate of PJF incidence and associated factors will inform clinicians on reoperation risk and prevention strategies.

METHODS

This retrospective observational study included patients with degenerative or adult idiopathic thoracolumbar deformity, extended instrumentation, sacropelvic fixation, and more than 2 years of follow-up. Patients with post-traumatic or iatrogenic sagittal malalignment were excluded. Demographic and operative data were obtained from the electronic medical records. Preoperative and followup scoliosis radiographs were reviewed to calculate the spinal alignment parameters. Patients were categorized into the PJF and non- PJF groups using the modified Hart-ISSG criteria, and their demographic, surgical, and radiographic parameters were compared using descriptive statistics. Multivariable logistic regression models were fitted to estimate the association measures of PJF occurrence, and their odds ratios (ORs) were reported with corresponding 95% confidence intervals (CI).

RESULTS

Of the eligible 157 patients who underwent surgery between 2011 and 2018, 130 were included. The mean age was 64.6±8 years, and 73% of the patients were female. Moreover, 42 (32%) and 88 patients (68%) were allocated to the PJF and non-PJF groups, respectively. The mean change in the proximal junctional angle (△PJA) in the PJF group was 26°±8.2°, and 33 patients (79%) had a final PJA >20°, 4 (10%) had an additional upper instrumented vertebra (UIV)/UIV+1 fracture, and 5 (12%) had an additional screw dislodgement or fixation failure. Postoperative changes in PJA (OR, 1.23; 95% CI, 1.12-1.37; p <0.001), thoracic kyphosis (TK; OR, 1.06; 95% CI, 1.02-1.11; p =0.004), and the use of a proximal tether (OR, 0.22; 95% CI, 0.04-0.82; p =0.03) were associated with PJF.

CONCLUSIONS

In this study, the PJF rate was 32%, of which 67% of the patients underwent reoperation. Postoperative PJA and TK changes and the use of proximal tethers were significantly associated with PJF.