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Trabecular microfracture
1Division of Tissue Pathology, Institute of Medical and Veterinary Science, Adelaide, Australia.
Abstract:
Healing trabecular microfractures are a common feature in cancellous bone. These lesions, when observed in macerated cancellous bone slices, measure about 500 microns in diameter and surround fractures in trabeculae with microcallus. Whether microcallus is a structure acting primarily as a transient brace, preventing relative movement of the fragmented segments and enabling the trabecula to heal, or whether it is a permanent buttress reducing the stress on the fractured strut, preventing the healing process, is not known. Microfractures are the result of normal physical activity. Hence, the widespread occurrence of trabecular microfracture in cancellous bone implies that a reasonable rate of microfracture is physiologically tolerable. There are three putative effects for trabecular microfracture. One is that, in response to impulse loading, cancellous subchondral bone increases its rigidity due to osteosclerosis resulting from bone formed around microfractures. Another hypothesis is that, if sufficient trabecular microfractures occur, they will compromise the trabecular structure of the vertebra and the proximal femur leading to osteoporotic fracture. By inducing remodeling changes, microfractures have an effect on the maintenance of joint structure. There are two histological patterns for microfractures: an early stage, when actively forming woven bone is bridging the fracture; and a more common late stage, when woven bone is inactive. Femoral studies fail to demonstrate that an increasing number of healed or healing microfractures in osteoarthrosis causes the increase of bone in the head of femur. Only one study has reported a significant increase in the number of trabecular microfractures in osteoarthritic femoral heads compared with normal controls. This significant increase was in patients taking antiinflammatory drugs.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Trabecular microfractures are common in bone and may increase bone rigidity or lead to fractures. Their role in osteoarthrosis and bone remodeling remains unclear.
Area of Science:
- Bone biology and biomechanics
- Skeletal remodeling and repair
- Osteoarthrosis research
Background:
- Healing trabecular microfractures are common in cancellous bone, characterized by microcallus formation around fractures.
- The precise function of microcallus—whether transient brace or permanent buttress—and its impact on healing are unknown.
- Microfractures result from normal physical activity, suggesting physiological tolerance.
Purpose of the Study:
- To investigate the role and implications of trabecular microfractures in cancellous bone.
- To explore the potential effects of microfractures on bone rigidity, osteoporotic fracture risk, and joint structure maintenance.
- To examine the histological patterns and prevalence of microfractures in osteoarthrosis.
Main Methods:
- Histological examination of macerated cancellous bone slices to identify and measure microfractures and microcallus.
- Analysis of femoral studies to correlate microfracture incidence with osteoarthrosis and bone density.
- Comparison of microfracture prevalence in osteoarthritic femoral heads versus normal controls.
Main Results:
- Femoral studies did not show a link between increased healed/healing microfractures and increased bone in osteoarthritic femoral heads.
- One study reported a significant increase in trabecular microfractures in osteoarthritic femoral heads, particularly in patients using anti-inflammatory drugs.
- Two histological patterns of microfractures were identified: active woven bone bridging (early) and inactive woven bone (late).
Conclusions:
- The exact role of microcallus in trabecular bone healing and stress reduction requires further investigation.
- Trabecular microfractures may have diverse effects, including increased bone rigidity, potential compromise of skeletal integrity, and influence on joint remodeling.
- The association between increased microfractures and osteoarthrosis, especially with anti-inflammatory drug use, warrants further research.