Mapping trabecular disconnection "hotspots" in aged human spine and hip

Area of Science:

• Bone histology and biomechanics
• Skeletal aging and failure
• Orthopaedic research

Background:

• Trabecular bone disconnection, characterized by real termini (ReTm), is a key factor in age-related skeletal failure.
• The structural impact of ReTm, particularly at vulnerable skeletal sites, remains poorly understood.
• Previous studies identified ReTm at the iliac crest, but their distribution in vertebrae and femora is less characterized.

Purpose of the Study:

• To map and characterize real termini (ReTm) in aged human vertebral bodies and proximal femora.
• To compare ReTm distribution in healthy aged bone with that in osteoporotic and osteoarthritic femora.
• To investigate the influence of sex, skeletal location, and disease on ReTm prevalence and distribution.

Main Methods:

• Histological analysis of large, thick (300 μm) bone slices from human autopsy samples (vertebrae and femora).
• A novel 2D/3D histological technique using silver staining to differentiate ReTm from planar artifacts.
• Mapping of ReTm using light microscopy and statistical analysis, comparing healthy aged bone with osteoporotic and osteoarthritic bone.

Main Results:

• ReTm populations were significantly larger and sector-specific in females compared to males.
• Vertebral ReTm clustered anterior/superiorly, while femoral head ReTm concentrated distally/superiorly and near the fovea.
• A transaxial polarity was observed, with 100% more ReTm on transverse struts than longitudinal struts.
• ReTm numbers increased in both osteoporosis and osteoarthritis, with polarized and sector-specific distribution maintained only in osteoporosis.

Conclusions:

• Trabecular bone disconnection hotspots are sex- and sector-specific, predominantly transaxial, and modulated by disease.
• These findings highlight ReTm as a critical, yet underappreciated, contributor to skeletal fragility.
• Understanding ReTm distribution is crucial for developing targeted interventions against age-related bone failure.