Influence of thoracolumbar kyphosis on postoperative spinal alignment in patients with Lenke type 5C adolescent idiopathic scoliosis

PURPOSE

This study aimed to examine the changes in thoracolumbar kyphosis (TLK) following correction surgery in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS) and to evaluate its influence on postoperative spinal alignment and clinical outcomes.

METHODS

Sixty-six patients with Lenke type 5C AIS were included and followed up for a minimum of 5 years after surgery. First, the patients were divided into two groups according to the preoperative TLK angle (Study 1; Kyphosis and Lordosis group). The patients were further classified into two groups according to the presence or absence of postoperative changes in TLK (Study 2; Changed and Maintained groups). Finally, the outcome variables were compared between these groups and analyzed for spinal alignment and clinical outcomes.

RESULTS

In Study 1, patients demonstrated a significant kyphotic change in the Lordosis group and a significant lordotic change in the Kyphosis group postoperatively. No statistically significant differences were found between the two groups when comparing the pre- and postoperative coronal and sagittal alignment. In Study 2, there were no statistically significant differences between the Changed and the Maintained groups in each spinal alignment pre- and postoperatively. Each domain of the Scoliosis Research Society 22-item questionnaire remained unchanged at 5 years postoperation.

CONCLUSION

In many patients with Lenke type 5C AIS, TLK changed significantly and approached 0° after surgery. However, the magnitude of the preoperative TLK and the presence or absence of improvement did not affect postoperative spinal alignment. Furthermore, the patients had satisfactory clinical outcomes irrespective of TLK modification.

LEVEL OF EVIDENCE

III.

Risk factors and clinical impact of persistent coronal imbalance after posterior spinal fusion in thoracolumbar/lumbar idiopathic scoliosis

OBJECTIVE

Persistent coronal imbalance (PCI) can develop postoperatively. In this study, the authors aimed to clarify the risk factors and clinical impact of PCI after posterior spinal fusion (PSF) in idiopathic scoliosis (IS) patients with a major thoracolumbar/lumbar (TL/L) curve.

METHODS

Data on 108 patients with Lenke type 5C or 6C IS who underwent PSF with a minimum of 2 years of follow-up were retrospectively analyzed. PCI was defined as coronal imbalance persisting 2 years after surgery. Radiographic parameters and clinical outcomes were compared between the PCI (+) and PCI (-) groups. Multivariate regression analyses of associated factors were performed to determine the risk factors for PCI.

RESULTS

Of the 108 patients, 48 (44%) had immediate postoperative coronal imbalance, and 10 of these patients (9%) had coronal imbalance persisting 2 years after surgery. The PCI (+) group had significantly worse postoperative subtotal and satisfaction scores than the PCI (-) group. Preoperative apical vertebral translation (AVT) of the TL/L curve (AVT-TL/L) and postoperative coronal balance (CB) were identified as independent risk factors for PCI. The cutoff values of preoperative AVT-TL/L at 49.5 mm (area under the curve [AUC] 0.835, p = 0.001, 95% CI 0.728-0.941, sensitivity 70.0%, specificity 72.4%) and those of postoperative CB at -27.5 mm (AUC 0.837, p < 0.001, 95% CI 0.729-0.945, sensitivity 78.6%, specificity 70.0%) were used to predict PCI. In selective fusion cases, older age (OR 2.110, 95% CI 1.159-3.842, p = 0.015), greater preoperative AVT-TL/L (OR 1.199, 95% CI 1.029-1.398, p = 0.020), and less postoperative CB (OR 0.855, 95% CI 0.743-0.983, p = 0.027) were independent risk factors for PCI.

CONCLUSIONS

Preoperative AVT-TL/L and postoperative CB are important parameters for predicting PCI. PCI adversely affects postoperative clinical outcomes. In selective fusion surgery, PCI tends to occur in older patients due to reduced flexibility and compensatory abilities.

[Comparison of spontaneous correction in thoracic curves after anterior versus posterior selective fusion in Lenke type 5C adolescent idiopathic scoliosis]

Objective: To analyze the long-term results and the influence factors of spontaneous correction of unfused thoracic curves in anterior and posterior selective fusions in Lenke type 5C adolescent idiopathic scoliosis (AIS). Methods: From January 2005 to December 2011, 89 Lenke type 5C AIS patients with a minimum of 5-year follow-up who underwent thoracolumbar/lumbar (TL/L) selective fusion in Spine Surgery of Nanjing Drum Tower Hospital were reviewed.Forty-six patients underwent anterior fusion (anterior group), while 46 underwent posterior fusion (posterior group). The following radiological parameters were measured and analyzed at pre-operation, post-operation, and latest follow-up: curve magnitude of primary thoracolumbar/lumbar and secondary thoracic curve, trunk shift, thoracic apical vertebral translation, upper instrumented vertebra tilt, thoracic kyphosis, proximal junctional angle, sagittal vertical axis. Independent sample t test was used to compare the above parameters between the two groups. Results: Compared with those in posterior group, anterior group were found with less fusion levels (5.4±0.6 vs 5.9±0.8, t=3.318, P=0.001) and longer operation time[(276±28)min vs (186±36)min, t=13.101, P<0.001]. Immediately after surgery, the spinal deformity was significantly corrected in the two groups. The mean spontaneous correction rates of the minor curve were 50%±21% and 56%±20% in anterior and posterior groups, respectively (t=1.489, P=0.140). After a mean follow-up of (6.8±1.7) years in anterior group and (6.3±1.3) years in posterior group, the spontaneous correction rate of minor curve was maintained at 46%±22% and 49%±19%, respectively (t=0.703, P=0.484), with no significant correction loss. Other radiographic parameters were also stably maintained. According to the correlation analysis, the spontaneous correction rate was significantly correlated with upper instrumented vertebra (UIV) tilt in both groups (anterior: r=-0.526, posterior: r=-0.399, both P<0.05). Conclusions: Both anterior and posterior selective fusion can achieve satisfactory spontaneous correction of unfused thoracic curves in Lenke type 5C AIS, with no significant difference between the two surgical approaches. UIV tilt is a key influence factor of spontaneous correction of thoracic curves.