Which Is More Predictive Value for Mechanical Complications: Fixed Thoracolumbar Alignment (T1 Pelvic Angle) Versus Dynamic Global Balance Parameter (Odontoid-Hip Axis Angle)

Abstract

Objective: In this study, we investigate about relationship between postoperative global sag-ittal imbalance and occurrence of mechanical complications after adult spinal deformity (ASD) surgery. In global sagittal balance parameters, odontoid-hip axis (OD-HA) angle and T1 pelvic angle (TPA) were analyzed Methods: Between January 2009 and December 2016, 199 consecutive patients (26 males and 173 females) with ASD underwent corrective fusion of more than 4 levels and were fol-lowed up for more than 2 years. Immediate postoperative and postoperative 2 years whole spine x-rays were checked for evaluating immediate postoperative OD-HA, TPA, and other parameters. In clinical outcomes, back and leg pain visual analogue scale, Scoliosis Research Society-22 spinal deformity questionnaire (SRS-22), Oswestry Disability Index (ODI), 36 -item Short Form Health Survey (SF-36) were evaluated. Results: Based on the occurrence of mechanical complications, a comparative analysis was performed for each parameter. In univariable analysis, mechanical complications were sig-nificantly much more occurred in OD-HA abnormal group (odds ratio [OR], 3.296; p < 0.001; area under the curve [AUC] = 0.645). In multivariable analysis, the result was much more related (OR, 2.924; p = 0.001; AUC = 0.727). In contrast, there was no signif-icant difference between normal and the occurrence of mechanical complications in TPA. In clinical outcomes (normal vs. abnormal), the differences of SRS-22 (0.88 +/- 0.73 vs. 0.68 +/- 0.64, p = 0.042), ODI (-24.72 +/- 20.16 vs.-19.01 +/- 19.95, p = 0.046), SF-36 physical com-posite score (19.33 +/- 18.55 vs. 12.90 +/- 16.73, p = 0.011) were significantly improved in OD-HA normal group. Conclusion: The goal of ASD surgery is to improve patient life quality through correction. In our study, TPA was associated with spinopelvic parameter and OD-HA angle was associ-ated with health-related quality of life and complications. OD-HA angle is predictable fac-tor for mechanical complications after ASD surgery.