Association between deformity angular distance ratio and neurological risk in patients undergoing three-column...

Postoperative neurological deficits are a significant concern for surgeons during spinal deformity correction surgery. Preoperative identification of high-risk patients can help ensure that appropriate measures are taken to minimize the risk of neurological deficits during these procedures. Previous studies have shown that patients with large Cobb angles or deformity angular ratios (DARs) are at higher risk for postoperative neurological deficits. However, some curves with similar Cobb angles and DARs may exhibit significantly different risks of neurological deficits during surgery. Existing methods for evaluating the degree of deformity cannot fully or accurately reflect the degree of spinal deformity. The aim of this study was to determine whether the deformity angular distance ratio (DADR) can reliably assess the neurological risks of patients undergoing three-column osteotomy (3CO).

A consecutive series of 266 patients with a deformity apex at T1-L1 who underwent 3CO at a single academic center from December 2010 to January 2024 were included in the study. Preoperative radiograph measurements were used to calculate DAR and DADR. Binary logistic regression was used to model the relationship between DADR and postoperative neurological deficits. Receiver operating characteristic analysis and the area under the curve (AUC) were used to assess the performance of the model.

The 266 patients had a median (IQR) age of 48.0 (30.0-60.0) years, with 128 (48.1%) females and 138 (51.9%) males. The incidence of postoperative neurological deficits was 11.3% in this series of patients. Among patients undergoing 3CO, sagittal DADR (OR 1.086, 95% CI 1.045-1.129; p < 0.001) and total DADR (OR 1.080, 95% CI 1.046-1.116; p < 0.001) were associated with an increased incidence of postoperative neurological deficits. A total DADR > 30.4 or a sagittal DADR > 26.4 were associated with a 30% incidence of postoperative neurological deficits, which increased to 50% when the total DADR reached 41.4 or the sagittal DADR exceeded 36.6. The overall predictive performances of sagittal DADR (AUC 0.781) and total DADR (AUC 0.799) for postoperative neurological deficits were comparable and considered to be good.

In patients undergoing 3CO for severe spinal deformities, the DADR can be used to quantify the severity of the deformity, which is strongly correlated with the risk of postoperative neurological deficits. Patients with a total DADR > 30.4 or a sagittal DADR > 26.4 are at much higher risk for developing new neurological deficits after surgery.