Characteristics of distal junctional failure requiring revision after adult spinal deformity surgery.

Objective: The impact of immediate postoperative spinal tilt, and the lowest instrumented vertebra (LIV) levels and level fused (LF) even when achieving sufficient spinal restoration, on distal junctional failure (DJF) in adult spinal deformity (ASD) surgery remains unclear. We aimed to understand the risk factors for DJF to decrease revision ASD surgery.

Methods: Data from 681 ASD instrumentation surgeries at ≥ 4 levels and ≥ 2 years of follow-up were compared between patients with and without DJF. We evaluated the LF, LIV level, spinal alignment with Scoliosis Research Society (SRS)-Schwab sagittal modifiers (SMs), and clinical outcomes. Multivariable analyses estimated the risk of DJF considering adequate spinal restoration of SMs.

Results: Thirty-five patients required revisions with DJF. Preoperative characteristics were similar between the groups. The DJF group had significantly lower lumbar lordosis (LL) and thoracic kyphosis (TK), the larger sagittal vertical axis (SVA), and T1 pelvic angle (T1PA) immediate postoperatively, and lower SRS-22 pain scores. Furthermore, the DJF group had significantly more L4 and L5 LIVs and fewer S2 alar-iliac fixation (S2AIF). Multivariable analyses after adjusting for factors affecting SMs (SVA and LL) revealed that LIV at L3 (odds ratio [OR] = 11.4), L4 (OR = 6.4), S2AIF (OR = 0.12), and LF (OR = 1.26) was significant.

Conclusions: Immediate postoperative lower LL and TK, larger SVA and T1PA, and lower SRS-22 pain scores may relate to DJF. Moreover, LIV at L3 > L4 > L5>, S2AIF, and high LF may relate to DJF even under sufficient alignment restoration. The LIV and the LF should be carefully selected, even when restoring SMs, to prevent DJF.