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Changes in the mechanical properties and composition of bone during microdamage repair.

Wang G, Qu X, Yu Z - PLoS ONE (2014)

Bottom Line: Both diffuse and linear microdamage decreased significantly with increasing time after surgery, with the diffuse microdamage disappearing after 8 months.In conclusion, the presence of mechanical microdamage accelerates bone remodeling either in the proximal or distal cortical bone.The bone hardness and elastic modulus decreased with microdamage repair, with the micromechanical properties being restored on complete repair of the microdamage.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Department of Orthopedic Surgery, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.

ABSTRACT
Under normal conditions, loading activities result in microdamage in the living skeleton, which is repaired by bone remodeling. However, microdamage accumulation can affect the mechanical properties of bone and increase the risk of fracture. This study aimed to determine the effect of microdamage on the mechanical properties and composition of bone. Fourteen male goats aged 28 months were used in the present study. Cortical bone screws were placed in the tibiae to induce microdamage around the implant. The goats were euthanized, and 3 bone segments with the screws in each goat were removed at 0 days, 21 days, 4 months, and 8 months after implantation. The bone segments were used for observing microdamage and bone remodeling, as well as nanoindentation and bone composition, separately. Two regions were measured: the first region (R1), located 1.5 mm from the interface between the screw hole and bone; and the second region (R2), located>1.5 mm from the bone-screw interface. Both diffuse and linear microdamage decreased significantly with increasing time after surgery, with the diffuse microdamage disappearing after 8 months. Thus, screw implantation results in increased bone remodeling either in the proximal or distal cortical bone, which repairs the microdamage. Moreover, bone hardness and elastic modulus decreased with microdamage repair, especially in the proximal bone tissue. Bone composition changed greatly during the production and repair of microdamage, especially for the C (Carbon) and Ca (Calcium) in the R1 region. In conclusion, the presence of mechanical microdamage accelerates bone remodeling either in the proximal or distal cortical bone. The bone hardness and elastic modulus decreased with microdamage repair, with the micromechanical properties being restored on complete repair of the microdamage. Changes in bone composition may contribute to changes in bone mechanical properties.

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Comparison of bone remodeling parameters in different regions at different time points.* means difference between R1 and R2 region at different time point. # means difference between four time point in each region, solid line referred to R1 region, dotted line referred to R2 region.(*<0.0.5, #<0.05).
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pone-0108324-g005: Comparison of bone remodeling parameters in different regions at different time points.* means difference between R1 and R2 region at different time point. # means difference between four time point in each region, solid line referred to R1 region, dotted line referred to R2 region.(*<0.0.5, #<0.05).

Mentions: By comparing the results between different regions, we found no significant difference between the different regions at 0 days. At 21 days and 4 months, the labeled surface and bone porosity areas were significantly higher in the R1 than in the R2 region. However, at 8 months, although the bone porosity was higher in the R1 region, the labeled surface area was not different from that in the R2 region. Mineral apposition rate (MAR) changed greatly after surgery, especially in the R1 region. MAR in R1 region is higher than it in the R2 region after 21 days and 4 months of surgery. (Fig. 5).


Changes in the mechanical properties and composition of bone during microdamage repair.

Wang G, Qu X, Yu Z - PLoS ONE (2014)

Comparison of bone remodeling parameters in different regions at different time points.* means difference between R1 and R2 region at different time point. # means difference between four time point in each region, solid line referred to R1 region, dotted line referred to R2 region.(*<0.0.5, #<0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4196754&req=5

pone-0108324-g005: Comparison of bone remodeling parameters in different regions at different time points.* means difference between R1 and R2 region at different time point. # means difference between four time point in each region, solid line referred to R1 region, dotted line referred to R2 region.(*<0.0.5, #<0.05).
Mentions: By comparing the results between different regions, we found no significant difference between the different regions at 0 days. At 21 days and 4 months, the labeled surface and bone porosity areas were significantly higher in the R1 than in the R2 region. However, at 8 months, although the bone porosity was higher in the R1 region, the labeled surface area was not different from that in the R2 region. Mineral apposition rate (MAR) changed greatly after surgery, especially in the R1 region. MAR in R1 region is higher than it in the R2 region after 21 days and 4 months of surgery. (Fig. 5).

Bottom Line: Both diffuse and linear microdamage decreased significantly with increasing time after surgery, with the diffuse microdamage disappearing after 8 months.In conclusion, the presence of mechanical microdamage accelerates bone remodeling either in the proximal or distal cortical bone.The bone hardness and elastic modulus decreased with microdamage repair, with the micromechanical properties being restored on complete repair of the microdamage.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Department of Orthopedic Surgery, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.

ABSTRACT
Under normal conditions, loading activities result in microdamage in the living skeleton, which is repaired by bone remodeling. However, microdamage accumulation can affect the mechanical properties of bone and increase the risk of fracture. This study aimed to determine the effect of microdamage on the mechanical properties and composition of bone. Fourteen male goats aged 28 months were used in the present study. Cortical bone screws were placed in the tibiae to induce microdamage around the implant. The goats were euthanized, and 3 bone segments with the screws in each goat were removed at 0 days, 21 days, 4 months, and 8 months after implantation. The bone segments were used for observing microdamage and bone remodeling, as well as nanoindentation and bone composition, separately. Two regions were measured: the first region (R1), located 1.5 mm from the interface between the screw hole and bone; and the second region (R2), located>1.5 mm from the bone-screw interface. Both diffuse and linear microdamage decreased significantly with increasing time after surgery, with the diffuse microdamage disappearing after 8 months. Thus, screw implantation results in increased bone remodeling either in the proximal or distal cortical bone, which repairs the microdamage. Moreover, bone hardness and elastic modulus decreased with microdamage repair, especially in the proximal bone tissue. Bone composition changed greatly during the production and repair of microdamage, especially for the C (Carbon) and Ca (Calcium) in the R1 region. In conclusion, the presence of mechanical microdamage accelerates bone remodeling either in the proximal or distal cortical bone. The bone hardness and elastic modulus decreased with microdamage repair, with the micromechanical properties being restored on complete repair of the microdamage. Changes in bone composition may contribute to changes in bone mechanical properties.

Show MeSH
Related in: MedlinePlus