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Inter-trabecular bone formation: a specific mechanism for healing of cancellous bone

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ABSTRACT

Background and purpose: Studies of fracture healing have mainly dealt with shaft fractures, both experimentally and clinically. In contrast, most patients have metaphyseal fractures. There is an increasing awareness that metaphyseal fractures heal partly through mechanisms specific to cancellous bone. Several new models for the study of cancellous bone healing have recently been presented. This review summarizes our current knowledge of cancellous fracture healing.

Methods: We performed a review of the literature after doing a systematic literature search.

Results: Cancellous bone appears to heal mainly via direct, membranous bone formation that occurs freely in the marrow, probably mostly arising from local stem cells. This mechanism appears to be specific for cancellous bone, and could be named inter-trabecular bone formation. This kind of bone formation is spatially restricted and does not extend more than a few mm outside the injured region. Usually no cartilage is seen, although external callus and cartilage formation can be induced in meta­physeal fractures by mechanical instability. Inter-trabecular bone formation seems to be less sensitive to anti-inflammatory treatment than shaft fractures.

Interpretation: The unique characteristics of inter-trabecular bone formation in metaphyseal fractures can lead to differences from shaft healing regarding the effects of age, loading, or drug treatment. This casts doubt on generalizations about fracture healing based solely on shaft fracture models.

No MeSH data available.


Related in: MedlinePlus

Inter-trabecular bone formation in human distal radius 16 days after fracture. T indicates old trabeculae.
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Figure 0004: Inter-trabecular bone formation in human distal radius 16 days after fracture. T indicates old trabeculae.

Mentions: The inter-trabecular healing process after trauma starts with a hematoma, which is followed by inflammation (Kon et al. 2001). Inflammation is followed by mesenchymal cell condensations forming osteoid, which becomes woven bone (Figure 2). This is then remodeled into lamellar bone (Charnley and Baker 1952, Chen et al. 2015, Han et al. 2015). In small animals, about 7 days is sufficient for mineralized woven bone to be clearly visible by microCT and histology (Figure 3) (Sandberg and Aspenberg 2015a). In human distal radius fractures, osteoid is visible from as early as 2 weeks after fracture, as seen by hematoxylin and eosin histology (Figure 4) (Aspenberg and Sandberg 2013).


Inter-trabecular bone formation: a specific mechanism for healing of cancellous bone
Inter-trabecular bone formation in human distal radius 16 days after fracture. T indicates old trabeculae.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016903&req=5

Figure 0004: Inter-trabecular bone formation in human distal radius 16 days after fracture. T indicates old trabeculae.
Mentions: The inter-trabecular healing process after trauma starts with a hematoma, which is followed by inflammation (Kon et al. 2001). Inflammation is followed by mesenchymal cell condensations forming osteoid, which becomes woven bone (Figure 2). This is then remodeled into lamellar bone (Charnley and Baker 1952, Chen et al. 2015, Han et al. 2015). In small animals, about 7 days is sufficient for mineralized woven bone to be clearly visible by microCT and histology (Figure 3) (Sandberg and Aspenberg 2015a). In human distal radius fractures, osteoid is visible from as early as 2 weeks after fracture, as seen by hematoxylin and eosin histology (Figure 4) (Aspenberg and Sandberg 2013).

View Article: PubMed Central - PubMed

ABSTRACT

Background and purpose: Studies of fracture healing have mainly dealt with shaft fractures, both experimentally and clinically. In contrast, most patients have metaphyseal fractures. There is an increasing awareness that metaphyseal fractures heal partly through mechanisms specific to cancellous bone. Several new models for the study of cancellous bone healing have recently been presented. This review summarizes our current knowledge of cancellous fracture healing.

Methods: We performed a review of the literature after doing a systematic literature search.

Results: Cancellous bone appears to heal mainly via direct, membranous bone formation that occurs freely in the marrow, probably mostly arising from local stem cells. This mechanism appears to be specific for cancellous bone, and could be named inter-trabecular bone formation. This kind of bone formation is spatially restricted and does not extend more than a few mm outside the injured region. Usually no cartilage is seen, although external callus and cartilage formation can be induced in meta­physeal fractures by mechanical instability. Inter-trabecular bone formation seems to be less sensitive to anti-inflammatory treatment than shaft fractures.

Interpretation: The unique characteristics of inter-trabecular bone formation in metaphyseal fractures can lead to differences from shaft healing regarding the effects of age, loading, or drug treatment. This casts doubt on generalizations about fracture healing based solely on shaft fracture models.

No MeSH data available.


Related in: MedlinePlus