Impact of Body Position on Kyphosis Measurement in Osteoporotic Thoracolumbar Fractures

Overview

This study compared kyphosis measurements in patients with old thoracolumbar fracture kyphosis (OTFK) across standing, prone, and supine positions using full-length spine x-ray, CT, and MRI. Results demonstrated significantly reduced kyphosis angles in recumbent positions, with prone CT and supine MRI providing equivalent assessments of kyphosis flexibility.

Background

Osteoporotic vertebral fractures commonly lead to progressive kyphotic deformities, especially at the thoracolumbar junction. Accurate preoperative assessment of kyphosis severity and flexibility is critical for surgical planning, particularly to determine the extent of osteotomy required. While standing radiographs are standard, positional imaging such as prone CT and supine MRI may better reflect spinal flexibility and surgical correction potential. However, comparative data on these modalities in OTFK patients remain limited.

Data Highlights

Key Findings

• Mean kyphosis Cobb angle was significantly higher in standing position (39.58°) compared to prone CT (29.61°) and supine MRI (approx. 28.3°) (p < 0.001).
• No significant differences in kyphosis angles were found between prone FLS-CT and any supine MRI measurements (p > 0.05).
• Equivalence analysis showed all paired differences between prone CT and supine MRI were within ±5°, confirming clinical equivalence.
• Kyphosis flexibility ranged from 24.45% (prone CT) to 29.16% (midsagittal MRI), indicating substantial positional correction potential.
• Interobserver reliability was excellent across all imaging modalities with ICC values between 0.985 and 0.992.

Clinical Implications

Preoperative kyphosis assessment in OTFK patients should consider recumbent imaging positions, as standing measurements may overestimate deformity severity. Both prone full-length spine CT and supine MRI provide reliable and equivalent evaluations of kyphosis flexibility, aiding surgical planning and potentially minimizing the extent of osteotomy required. Utilizing these modalities can improve individualized treatment strategies and optimize outcomes.

Conclusion

Kyphosis severity in OTFK patients is significantly reduced in recumbent positions, with prone CT and supine MRI offering comparable and reliable measurements. These findings support the use of positional imaging to better assess spinal flexibility and guide surgical decision-making.

Related Resources & Content

1. Study Authors/2024 -- Impact of Body Position on Kyphosis Measurement