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Osteocyte death and hip fracture
C R Dunstan1, N M Somers, R A Evans
1Metabolic Unit, Concord Hospital, NSW, Australia.
Insights
Osteocyte viability in the femoral head declines with age, a reduction potentially exacerbated by hip fractures. This age-related osteocyte death may impair the bone
Area of Science:
- Bone biology
- Gerontology
- Orthopedic research
Background:
- Osteocytes are crucial for bone maintenance and repair.
- Age-related changes in bone quality are a significant concern, particularly in elderly populations.
- Osteocyte viability is a key indicator of bone health and response to damage.
Purpose of the Study:
- To investigate the age-related changes in osteocyte viability in human bone.
- To compare osteocyte viability in the femoral head versus the lumbar vertebra.
- To examine the relationship between osteocyte viability, hip fracture, and bone repair capacity.
Main Methods:
- Assessment of osteocyte viability using lactate dehydrogenase activity in sawn, decalcified bone sections.
- Analysis of bone samples from the femoral head and lumbar vertebra across different age groups.
- Correlation analysis between osteocyte viability, microfracture callus incidence, and ultimate compressive strength in hip fracture patients.
Main Results:
- Osteocyte viability in the femoral head significantly decreased with age (88% in 10-29 years to 58% in 70-89 years).
- Osteocyte viability in the lumbar vertebra remained high (88%) and showed no age-related decline.
- In hip fracture patients, osteocyte viability was similar to age-matched controls but showed greater variation; lower viability correlated with reduced fracture callus formation.
Conclusions:
- A gradual, age-related reduction in osteocyte viability occurs in the femoral head, which may be more pronounced in hip fracture patients.
- Osteocyte death can impair the bone's ability to repair fatigue damage, potentially compromising bone quality.
- Lumbar vertebrae exhibit higher and more stable osteocyte viability compared to the femoral head.
Abstract:
The viability of osteocytes can be demonstrated in sawn decalcified sections of bone by their lactate dehydrogenase activity. In the cancellous bone of the femoral head, the proportion of lacunae containing viable osteocytes decreased from 88 +/- 7% (mean +/- SD) at 10-29 years to 58 +/- 12% (P < 0.001) by 70-89 years. Viability in the second lumbar vertebra was 88 +/- 3% in subjects aged 25-90 years and did not decrease with age. Mean osteocyte viability in the femoral head of 21 hip fracture patients aged 72-94 years was 58 +/- 21%, similar to controls of a similar age, though there was greater variation and, in five patients, osteocyte viability was less than 25%. In hip fracture patients, microfracture callus incidence correlated positively with osteocyte viability, with little or no fracture callus observed if the bone viability was low. Ultimate compressive strength did not correlate with osteocyte viability. In the femoral head there is gradual, age-related reduction in osteocyte viability that can be more pronounced in hip fracture. Osteocyte death may affect bone quality by impairing repair of fatigue damage.