The Generation of Closed Femoral Fractures in Mice: A Model to Study Bone Healing

Williams, Justin N.; Li, Yong; Kambrath, Anuradha Valiya; Sankar, Uma

doi:10.3791/58122

Cited by 14 publications

(14 citation statements)

References 23 publications

(26 reference statements)

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“…Unilateral closed fractures were generated on the right femurs of male C57BL/6J mice at 10 weeks of age and stabilized using an intramedullary rod as described previously. 7,8…”

Section: Methodsmentioning

confidence: 99%

An Improved Methodology to Evaluate Cell and Molecular Signals in the Reparative Callus During Fracture Healing

Kambrath

Williams

Sankar

2020

J Histochem Cytochem.

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Approximately 5% to 10% of all bone fractures do not heal completely, contributing to significant patient suffering and medical costs. Even in healthy individuals, fracture healing is associated with significant downtime and loss of productivity. However, no pharmacological treatments are currently available to promote efficient bone healing. A better understanding of the underlying molecular mechanisms is crucial for developing novel therapies to hasten healing. The early reparative callus that forms around the site of bone injury is a fragile tissue consisting of shifting cell populations held together by loose connective tissue. The delicate callus is challenging to section and is vulnerable to disintegration during the harsh steps of immunostaining, namely, decalcification, deparaffinization, and antigen retrieval. Here, we describe an improved methodology for processing early-stage fracture calluses and immunofluorescence labeling of the sections to visualize the temporal (timing) and spatial (location) patterns of cellular and molecular events that regulate bone healing. This method has a short turnaround time from sample collection to microscopy as it does not require lengthy decalcification. It preserves the structural integrity of the fragile callus as the method does not entail deparaffinization or harsh methods of antigen retrieval. Our method can be adapted for high-throughput screening of drugs that promote efficacious bone healing:

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“…Unilateral closed fractures were generated on the right femurs of male C57BL/6J mice at 10 weeks of age and stabilized using an intramedullary rod as described previously. 7,8…”

Section: Methodsmentioning

confidence: 99%

An Improved Methodology to Evaluate Cell and Molecular Signals in the Reparative Callus During Fracture Healing

Kambrath

Williams

Sankar

2020

J Histochem Cytochem.

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“…An increase in metaphysis fractures, such as the proximal femur and distal radius, has become a public health concern in developed countries. Researchers have devised various animal models to elucidate the mechanism of fracture healing for developing effective clinical care [24][25][26].…”

Section: Animal Models Of Fracture Healingmentioning

confidence: 99%

Site-Specific Fracture Healing: Comparison between Diaphysis and Metaphysis in the Mouse Long Bone

Inoue¹,

Takito²,

Nakamura³

2021

IJMS

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The process of fracture healing varies depending upon internal and external factors, such as the fracture site, mode of injury, and mechanical environment. This review focuses on site-specific fracture healing, particularly diaphyseal and metaphyseal healing in mouse long bones. Diaphyseal fractures heal by forming the periosteal and medullary callus, whereas metaphyseal fractures heal by forming the medullary callus. Bone healing in ovariectomized mice is accompanied by a decrease in the medullary callus formation both in the diaphysis and metaphysis. Administration of estrogen after fracture significantly recovers the decrease in diaphyseal healing but fails to recover the metaphyseal healing. Thus, the two bones show different osteogenic potentials after fracture in ovariectomized mice. This difference may be attributed to the heterogeneity of the skeletal stem cells (SSCs)/osteoblast progenitors of the two bones. The Hox genes that specify the patterning of the mammalian skeleton during embryogenesis are upregulated during the diaphyseal healing. Hox genes positively regulate the differentiation of osteoblasts from SSCs in vitro. During bone grafting, the SSCs in the donor’s bone express Hox with adaptability in the heterologous bone. These novel functions of the Hox genes are discussed herein with reference to the site-specificity of fracture healing.

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“…A 24 G needle was introduced retrograde into the right femur according to previously established procedures 9 (Figure 1). For femur osteotomy, a medial 0.5-cm skin incision was made longitudinally along the femur.…”

Section: Surgical Proceduresmentioning

confidence: 99%

A novel mouse model to study fracture healing of the proximal femur

Haffner‐Luntzer

Weber

Lam

et al. 2020

Journal Orthopaedic Research

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The majority of fractures, especially in elderly and osteoporotic patients, occurs in metaphyseal bone. However, only a few experimental models exist to study metaphyseal bone healing in mice. Currently used mouse models of metaphyseal fracture healing are either based on drill hole defects, lacking adequate biomechanical stimulation at the site of fracture and therefore endochondral ossification in the fracture callus, or are introduced into the distal part of the mouse femur stabilized by a locking plate, which is challenging due to the small specimen size. Therefore, the aim of the current study was to develop a new mouse model to study metaphyseal fracture healing of the proximal femur. We chose a combination between an open osteotomy and a closed intramedullary stabilization. A 24 G needle was inserted into the femur in a closed manner, then an osteotomy was made with a 0.4‐mm Gigli wire saw between the third and the lesser trochanter of the femur using an open approach. Fractured femurs were analyzed using microcomputed tomography and histology at days 14 and 21 after surgery. No animals were lost due to surgery or anesthesia. All animals displayed normal limb loading and a physiological gait pattern within the first three days after fracture. We found robust endochondral ossification during the fracture healing process with high expression of late chondrocyte and early osteogenic markers at day 14 (d14). By day 21 (d21), all fractures had a bony bridging score of 3 or more, indicating successful healing. Callus volume significantly decreased from d14 to d21, whereas high numbers of osteoclasts appeared at the fracture callus until d21, indicating that callus remodeling had already started at d21. In conclusion, we successfully developed a novel mouse model to study endochondral fracture healing of the proximal femur. This model might be useful for future studies using transgenic animals to unravel molecular mechanisms of osteoporotic metaphyseal fracture healing.

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The Generation of Closed Femoral Fractures in Mice: A Model to Study Bone Healing

Cited by 14 publications

References 23 publications

An Improved Methodology to Evaluate Cell and Molecular Signals in the Reparative Callus During Fracture Healing

An Improved Methodology to Evaluate Cell and Molecular Signals in the Reparative Callus During Fracture Healing

Site-Specific Fracture Healing: Comparison between Diaphysis and Metaphysis in the Mouse Long Bone

A novel mouse model to study fracture healing of the proximal femur

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