Lumbar axial loading device alters lumbar sagittal alignment differently from upright standing position: a computed...

Area of Science:

• Spine biomechanics
• Medical imaging analysis
• Radiographic assessment

Background:

• Axial compression devices are used to simulate standing positions during MRI and CT scans.
• Previous studies have not compared imaging during axial loading with actual standing posture.
• Understanding simulation accuracy is vital for diagnostic imaging.

Purpose of the Study:

• To evaluate if sagittal alignment during axial loading accurately simulates standing posture.
• To compare spinal alignment under axial loading versus true standing conditions.

Main Methods:

• 14 healthy volunteers underwent lumbar CT scans in standing, axial loading, and control (supine) positions.
• Compared changes in spinal length, disc height, and lordotic angles (segmental and total lumbar).
• Utilized a DynaWell compression device for axial loading simulation.

Main Results:

• Spinal length decreased significantly in both axial loading and standing positions compared to controls.
• Segmental lordotic angles at L2/3 and L3/4 increased in both conditions.
• L5/S disc lordotic angle decreased with axial loading (kyphotic change), but remained unchanged in standing compared to supine.

Conclusions:

• The compression device accurately simulates lumbar segmental alignment changes from L1/2 to L4/5.
• Axial loading induces a kyphotic change at L5/S, which differs from the standing posture.
• Awareness of these specific alignment alterations is essential for precise interpretation of imaging studies.