Closed Fracture Healing: A Rat Model

T, Otto; Patka, P.; Haarman, H. J. T. M.

doi:10.1159/000129410

Cited by 17 publications

(24 citation statements)

References 12 publications

(16 reference statements)

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“…The fracture healing process is reportedly influenced by the mechanical environment at the fracture site [6,8,24]. In the present study, we observed cellular events at the fracture healing site using two MouseFix™ plates with different levels of flexibility.…”

Section: Discussionmentioning

confidence: 65%

“…Fixation properties between bone fragments affect morphological characteristics [6,8], and callus volume is high in a dynamic environment where the fracture site is unstable and slight strain exists [24]. However, previous studies on the relationship between fi xation stability and fracture repair processes have been limited to showing morphological changes involving the fracture callus, and the precise mechanism has yet to be fully elucidated.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Internal Fixator Stiffness on Murine Fracture Healing: Two Types of Fracture Healing Lead to Two Distinct Cellular Events and FGF-2 Expressions

et al. 2011

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This study aimed to clarify the relationship between the mechanical environment at the fracture site and endogenous fibroblast growth factor-2 (FGF-2). We compared two types of fracture healing with different callus formations and cellular events using MouseFix™ plate fixation systems for murine fracture models. Left femoral fractures were induced in 72 ten-week-old mice and then fixed with a flexible (Group F) or rigid (Group R) Mouse Fix™ plate. Mice were sacrificed on days 3, 5, 7, 10, 14, and 21. The callus volumes were measured by 3D micro-CT and tissues were histologically stained with hematoxylin & eosin or safranin-O. Sections from days 3, 5, and 7 were immunostained for FGF-2 and Proliferating Cell Nuclear Antigen (PCNA). The callus in Group F was significantly larger than that in Group R. The rigid plate allowed bone union without a marked external callus or chondrogenesis. The flexible plate formed a large external callus as a result of endochondral ossification. Fibroblastic cells in the granulation tissue on days 5 and 7 in Group F showed marked FGF-2 expression compared with Group R. Fibroblastic cells showed ongoing proliferation in granulation tissue in group F, as indicated by PCNA expression, which explained the relative granulation tissue increase in group F. There were major differences in early phase endogenous FGF-2 expression between these two fracture healing processes, due to different mechanical environments. Key words: callus formation, fracture, growth factor, internal fixator, mouse

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Section: Discussionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Influence of Internal Fixator Stiffness on Murine Fracture Healing: Two Types of Fracture Healing Lead to Two Distinct Cellular Events and FGF-2 Expressions

et al. 2011

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“…Several studies have reported that larger interfragmentary movement generally led to increased callus formation [19]. Several studies performed using models of rabbit osteotomized femur or rat osteotomized tibia with intramedullary rods for fixation have also reported that rigid fixation induces formation of a smaller callus [16,25].…”

Section: Discussionmentioning

confidence: 99%

“…The fracture healing process is influenced by the mechanical environment at the fracture site [1,4,19]. When the fracture is highly stable, with only a small gap between bone fragments, the gap is directly filled with the bone matrix.…”

Section: Introductionmentioning

confidence: 99%

Distribution of Bone Marrow-Derived Cells in the Fracture Callus during Plate Fixation in a Green Fluorescent Protein-Chimeric Mouse Model

et al. 2011

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Abstract:To clarify the distribution of bone-marrow-derived cells in fractures treated by plate fixation, fracture models were created using the green fluorescent protein (GFP) chimeric mouse. We observed 2 types of fracture healing processes with different types of callus formation and cellular events by using Mouse Fix™, a device allowing plate fixation on the mouse femur, and differences in the distribution of bone-marrow-derived cells between the 2 types. The GFP chimeric mice were created by bone marrow transplantation. Fractures were created on the left femurs of mice and stabilized with either rigid (Group R) or flexible (Group F) plates to prepare undecalcified fresh-frozen sections. In Group F, a large external callus and a large intramedullary callus were formed mostly by endochondral ossification. The cells that made up the intramedullary callus and callus in the fracture gap were GFP positive, but most cells of the external callus were not. In Group R, bone union was achieved mostly without external callus formation, bone apposition occurred directly in the gap, and a small intramedullary callus was formed. As observed in Group F, this group had GFP-positive cells in the callus within the fracture gap and in the intramedullary calluses. The results of this study provided direct evidence of the distribution of bone-marrow-derived cells in the callus of fractures treated by plate fixation under different stability conditions.

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“…The intramedullary pin provides bending stability to the tibia as it is healing. Previous studies have shown that the rigidity of the pin influences the healing process [18,22,25,27]. In general tibias with flexible pins heal slower and produce more callus than tibias with rigid pins.…”

Section: Introductionmentioning

confidence: 99%

Intact fibula improves fracture healing in a rat tibia osteotomy model

Shefelbine

Augat

Beck

2005

Journal Orthopaedic Research

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Rat tibia fractures are often used in fracture healing studies. Usually the fracture is stabilized with an intramedullary pin, which provides bending stiffness, but little torsional stiffness. The objective of this research was to determine the in vitro torsional rigidity of an osteotomized tibia with and without the fibula, and to determine if this difference influences the healing process in vivo. In vitro eleven rat tibias received an osteotomy, were stabilized with an intramedullary pin, and were tested in internal rotation to determine the torsional rigidity. The fibula was then manually broken and the torsional rigidity measured again. In vivo 18 rats received a tibia1 osteotomy, eight of which had an additional fractured fibula. After three weeks, the rats were sacrificed and the tibias were analyzed. Bone density in the fracture callus was measured with qCT. Bending rigidity and maximum breaking moment were determined in three-point bending. In vitro testing demonstrated that the torsional rigidity with an intact fibula was nearly two times higher than when the fibula was fractured. Though the torsional rigidity was still small in comparison with an intact bone, it resulted in a significantly different healing process in vivo. Rats with intact fibulas had significantly higher bone mineral density, bending rigidity, and maximum breaking moment compared to rats with a fractured fibula. These results indicate that torsional stability considerably affects the healing process. In a fracture model, it is critical to characterize the mechanical environment of the fracture.

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Closed Fracture Healing: A Rat Model

Cited by 17 publications

References 12 publications

Influence of Internal Fixator Stiffness on Murine Fracture Healing: Two Types of Fracture Healing Lead to Two Distinct Cellular Events and FGF-2 Expressions

Influence of Internal Fixator Stiffness on Murine Fracture Healing: Two Types of Fracture Healing Lead to Two Distinct Cellular Events and FGF-2 Expressions

Distribution of Bone Marrow-Derived Cells in the Fracture Callus during Plate Fixation in a Green Fluorescent Protein-Chimeric Mouse Model

Intact fibula improves fracture healing in a rat tibia osteotomy model

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