Predictive Probability of the Global Alignment and Proportion Score for the Development of Mechanical Failure Following Adult Spinal Deformity Surgery in Asian Patients

Abstract

Study Design. This is a multicenter retrospective review of 257 surgically treated consecutive ASD patients who had a minimum of five fused segments, completed a 2-year follow-up (53 ± 19 yrs, females: 236 [92%]). Objective. This study aimed to validate the predictive probability of the GAP score in an Asian ASD patient cohort. Summary of Background Data. The GAP score is a recently established risk stratification model for MF following ASD surgery. However, the predictive ability of the GAP score is not well studied. This study aimed to validate the predictive probability of the GAP score in an Asian ASD patient cohort. Methods. Comparisons of the immediate postoperative GAP scores between MF the and MF-free groups were performed. We evaluated the discriminative ability of the GAP score based on the area under the receiver operating characteristic curve (AUROC). The Cuzick test was performed to determine whether there is a trend between the GAP score and the incidence of MF or revision surgery. Univariate logistic regression analyses were performed to explore the associations between the GAP score and the incidence of MF or revision surgery. Results. No difference was observed in the GAP score between the MF and MF-free groups (MF vs. MF-free; GAP: 5.9 ± 3.3 vs. 5.2 ± 2.7, P = 0.07). The Cuzick analysis showed no trend between the GAP score and the risk for MF or revision surgery. Likewise, the MF rate was not correlated with the GAP score, as shown by the ROC curve (AUC of 0.56 [95% CI 0.48–0.63], P = 0.124). Univariate logistic regression confirmed no associations between the GAP score and the incidence of MF or revision surgery (MF; moderately disproportioned [MD]: OR: 0.6 [95% CI: 0.3–1.2], P = 0.17, severely disproportioned [SD]: OR: 1.2 [95% CI: 0.6–2.3], P = 0.69, revision surgery; MD: OR: 0.8 [95% CI: 0.2–2.8], P = 0.71, SD: OR: 1.2 [95% CI: 0.9–8.7], P = 0.08). Conclusion. In this multicenter study, in an Asian ASD patient cohort, the GAP score was not associated with the incidence of MF or revision surgery. Additional studies on the predictive ability of the GAP score in different patient cohorts are warranted. Level of Evidence: 3

The Effects of Global Alignment and Proportionality Scores on Postoperative Outcomes After Adult Spinal Deformity Correction

“…Specifically, we observed an increased risk in PJF rates in severely disproportioned patients, which supports earlier work in this area. 12,17,26 Our findings are also aligned with those of Yagi et al, 27 which suggested that at 2 years postoperatively, GAP-SD patients were at greatest risk of complications, including PJF.…”

The T4-L1-Hip Axis

“…Failure to define a thoracic alignment relative to lumbar alignment and using postural measures (eg, pelvic tilt or sagittal vertical axis) has likely contributed to the poor external validity of current alignment guidelines. [14][15][16][17][18] Our results redefine what should be considered a normal sagittal alignment and fill a critical knowledge gap. In our first aim and consistent with prior studies on sagittal balance, we found C2 tilt (also known as the Odontoid-Hip-Axis) had minimal variation and is an ideal measure of global sagittal balance.…”

“…However, PI explains only a fraction of the variation observed in normal lumbar lordosis. Furthermore, currently accepted alignment targets utilize postural measures (eg, pelvic tilt, sacral slope, or sagittal vertical axis) that are not directly modifiable in surgery, and none of the targets define a reliable method for alignment the thoracic spine, likely contributing to the poor external validity of current alignment guidelines 14–18…”

Improvement and International Validation of the Predictive Probability of the Patient Demographics, Radiographic Index, and Surgical Invasiveness for Mechanical Failure (PRISM) Model for Preventive Procedures in Adult Spinal Deformity Surgery

“…First, we did not incorporate all the preventive procedures in the present analysis. Terminal rod contour, administration of bisphosphonate, type of orthosis, and cement augmentation of UIV+1 vertebra may also prevent the development of MF 17,21,31,32 . The vast majority of our patient cohort used Jewett braces and did not have bisphosphonates before or after surgery.…”

“…Terminal rod contour, administration of bisphosphonate, type of orthosis, and cement augmentation of UIVþ1 vertebra may also prevent the development of MF. 17,21,31,32 The vast majority of our patient cohort used Jewett braces and did not have bisphosphonates before or after surgery. Additionally, in most of the procedures, the proximal tips of the rod were slightly over-bent (increased kyphosis) intraoperatively to decrease the chance of PJK, but we did not set a particular angle for the terminal contour of the rods.…”