Impact of Prior Cervical Fusion on Patients Undergoing Thoracolumbar Deformity Correction

Study Design. Retrospective analysis of prospectively collected data. Objective. Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction. Background. Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs. Methods. ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection. Results. Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs ( P <0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=−0.22, 95% CI=−0.43 to −0.01, P =0.038) and C2SPi (coeff=−0.72, 95% CI=−1.36 to −0.07, P =0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95% CI=0.01-0.28, P =0.040) and thoracolumbar lordosis (coeff=0.22, 95% CI=0.10-0.33, P =0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs ( P <0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes. Conclusions. Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection. Level of Evidence. IV.