Bone microstructure and volumetric bone mineral density in patients with global sagittal malalignment

Area of Science:

• Orthopedic Surgery
• Bone Biology
• Radiology

Background:

• Sagittal spinal malalignment can lead to significant complications after surgical correction.
• Low bone mineral density (BMD) and poor bone microstructure are identified risk factors for instrumentation failure in spinal surgery.

Purpose of the Study:

• To investigate differences in volumetric BMD and bone microstructure between normal and malaligned sagittal spinal alignment.
• To establish the relationships between vBMD, bone microstructure, and sagittal spinal/spinopelvic alignment.

Main Methods:

• Retrospective cross-sectional study of 172 patients undergoing lumbar fusion.
• Quantitative computed tomography (qCT) for lumbar spine vBMD assessment.
• Microcomputed tomography (μCT) for bone biopsy microstructure analysis.
• Measurement of C7-S1 sagittal vertical axis (SVA) and spinopelvic alignment.
• Univariate and multivariable regression analyses to determine associations.

Main Results:

• Patients with malalignment exhibited significantly lower lumbar vBMD (L1-L4) and reduced trabecular bone volume (BV) and total volume (TV).
• Higher SVA (malalignment) correlated with lower vBMD, BV, and TV.
• Pelvic tilt (PT) and lumbar lordosis (LL) showed significant associations with vBMD and microstructure parameters (trabecular number, separation, thickness).
• Multivariable analysis confirmed higher SVA is associated with lower vBMD (β = -0.269, p = 0.002).

Conclusions:

• Sagittal malalignment is linked to diminished lumbar vBMD and compromised trabecular bone microstructure.
• Patients with malalignment may face increased surgical complication risks due to poorer bone quality.
• Preoperative assessment of vBMD is recommended for patients with sagittal malalignment.