• Tetsuro Ohba, Shigeto Ebata, Hiroki Oba, Kensuke Koyama, Hiroshi Yokomichi, and Hirotaka Haro.
• Department of Orthopaedic Surgery, University of Yamanashi, Chuo, Yamanashi, Japan.
• Spine. 2019 Oct 1; 44 (19): E1136-E1143.

Study DesignRetrospective observational study of a cohort of consecutive patients.ObjectiveTo determine 1) the correlation between clinical and radiographic outcomes and Global Alignment and Proportion (GAP) score, and 2) which preoperative parameters predominantly influence the risk for poor GAP scores.Summary Of Background DataAlthough numerous investigators have indicated their criteria for sagittal correction, it is still not unusual to observe poor outcome or complications even after ideal correction. The recently developed GAP score indicates spinopelvic alignment and setting surgical goals according to the score might decrease the prevalence of mechanical complications. However, there is no clear evidence of correlation between the GAP score and clinical outcomes, or which patient factors are preoperative predictors of poor postoperative GAP score.MethodsWe included 128 consecutive patients treated with spinal correction surgery who had a minimum 2-year follow-up. The correlations between clinical outcomes, increased proximal junctional angle, and GAP score were determined. Univariate and multivariate logistic regression analyses were conducted to clarify potential preoperative risk factors for poor GAP score.ResultsBased on total GAP score, 32 (25%) patients were grouped into proportioned, 50 (39.1%) into moderately disproportioned, and 44 (34.3%) into severely disproportioned spinopelvic alignment. Our present study showed a significantly positive correlation between Oswestry Disability Index, increased proximal junctional angle 2 years after surgery, and total GAP score. Uni and multivariate regression analysis showed a large global tilt was a risk factor for a poor GAP score and that the risk for a poor GAP score increased with ageing.ConclusionsBecause GAP score correlated with Oswestry Disability Index and increased proximal junctional angle 2 years after surgery, GAP score might define targets for sagittal spinopelvic alignment for favorable outcomes of corrective spinal surgery. A large preoperative global tilt is a potential predictor of poor postoperative GAP score.Level Of Evidence3.

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