Managing adolescent idiopathic scoliosis (AIS) requires surgeons to carefully plan for sagittal balance to prevent Proximal Junctional Kyphosis AIS surgery complications. A new study published in the Global Spine Journal analyzed 282 patients to identify specific risk factors for PJK. Researchers categorized these individuals based on their 2-year follow-up results. Consequently, they found that certain sagittal shapes and alignment changes significantly influence the probability of developing junctional issues.

The investigation revealed that the level of the upper instrumented vertebra (UIV) differed significantly between the PJK and non-PJK groups. Specifically, the PJK group demonstrated a higher mean absolute change in the sagittal vertical axis (SVA). Moreover, the sagittal shape classification provided crucial insights. Patients with normal thoracic kyphosis or cervico-thoracic kyphosis were more prone to PJK. Conversely, those with hypo-thoracic kyphosis without thoracolumbar kyphosis showed lower risks.

Predicting Proximal Junctional Kyphosis AIS with Sagittal Mapping

Clinicians also assessed the Roussouly classification to understand how sagittal restoration impacts patient outcomes. They evaluated the correction relative to the functional T10 pelvic angle target. This assessment showed that improper restoration of the sagittal profile often leads to mechanical failure. Therefore, surgeons should aim for precise pelvic angle targets to ensure long-term spinal stability. Additionally, monitoring reciprocal changes in adjacent segments helps in identifying early signs of malalignment.

Furthermore, the study highlights the importance of maintaining proper thoracic kyphosis levels. Significant deviations in the sagittal vertical axis immediately after surgery often predict future PJK. Because these changes are often reciprocal, the alignment of the cervical and lumbar regions must also be balanced. Finally, achieving a harmonious sagittal profile reduces the stress on the proximal junction, thereby decreasing the risk of kyphotic progression.

Frequently Asked Questions

What are the primary indicators for PJK in AIS patients?

Key indicators include the UIV level and significant changes in the absolute sagittal vertical axis (SVA). Additionally, preoperative sagittal shapes like normal thoracic kyphosis or cervico-thoracic kyphosis increase the risk compared to hypo-thoracic shapes.

How does the Roussouly classification assist in surgery planning?

The Roussouly classification helps surgeons understand the patient's natural sagittal alignment. By aligning the surgical correction with these classifications and the T10 pelvic angle target, surgeons can minimize the risk of Proximal Junctional Kyphosis AIS developments.

Disclaimer: This content is for informational and educational purposes only. It does not constitute medical advice or a substitute for professional clinical judgment. Refer to the latest local and national guidelines for clinical practice.

References

1. Kim HJ et al. Sagittal Profiles and Their Reciprocal Changes Manifesting in Proximal Junctional Kyphosis Following Deformity Correction in Adolescent Idiopathic Scoliosis. Global Spine J. 2026 May 31. doi: 10.1177/21925682261455808. PMID: 42218624.


2. Lonner BS et al. Risk Factors of Proximal Junctional Kyphosis in Adolescent Idiopathic Scoliosis—The Pelvis and Other Considerations. Spine Deformity. 2017;5(3):181-188.


3. Roussouly P et al. Sagittal classification of the spinal shape and its equilibrium. Spine (Phila Pa 1976). 2005;30(3):346-353.