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Age-related changes in the human femoral cortex
E D Simmons1, K P Pritzker, M D Grynpas
1Department of Orthopaedic Surgery, Buffalo General Hospital, State University of New York.
Summary
Aging bone shows changes in density and formation, with older adults accumulating denser, potentially less remodelable bone. This suggests age-related bone alterations impact structural integrity and remodeling processes.
Area of Science:
- Biomedical Engineering
- Gerontology
- Orthopedics
Background:
- Bone structure and quality change with age.
- The precise nature of age-related qualitative bone changes requires further elucidation.
Purpose of the Study:
- To investigate age-related structural and mineralization changes in human femur bone.
- To characterize bone density and maturity across different adult age groups.
Main Methods:
- Density fractionation of midshaft femur samples from four age groups (20-25, 40-45, 60-65, 80-85 years).
- Chemical analysis for Ca, P, and Ca/P molar ratio.
- X-ray diffraction for apatite crystal size.
- Morphological studies for remodeling activity and porosity.
Main Results:
- Younger bone (20-25) is predominantly lower density.
- Middle-aged bone (40-45) shows increased mineralization.
- Older bone (60-65) indicates increased new bone formation (lower density fraction).
- Elderly bone (80-85) exhibits increased highest density bone (2.2-2.3 g/cc), possibly interstitial bone.
- No significant age-related changes in Ca, P, or apatite crystal size were observed.
- Increased remodeling, endosteal trabecularization, and intracortical porosity were noted in older groups.
Conclusions:
- Bone density and composition change with aging, with distinct patterns observed across adult life stages.
- Increased high-density bone in the elderly may represent less remodelable interstitial bone, impacting bone quality.
- While chemical composition and crystal size remain stable, structural and remodeling changes are significant indicators of aging bone.