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Updated: Aug 21, 2026
Establishing a Diaphyseal Femur Fracture Model in Mice
Published on: December 9, 2022
Characterization of a closed femur fracture model in mice
Michaele B Manigrasso1, J Patrick O'Connor
1Department of Orthopaedics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA.
Objectives:
The goal of this study was to develop and characterize a closed femur fracture model for mice that can be used for the molecular and genetic analysis of fracture healing.
Study Design:
Longitudinal time study of species-specific fracture healing.
Methods:
A protocol was developed for creating reproducible, closed femur fractures in mice. Impending fractures were stabilized by retrograde insertion of a 0.01-inch-diameter, stainless steel wire into the intramedullary canal. The intramedullary wire was held in place with a wedge made from the first 2 mm of a 30-gauge needle. Fractures were produced by 3-point bending. Fracture healing was assessed by radiography, histology, and torsional mechanical testing.
Results:
The mouse femur fracture technique produced good results with minimal loss of animals. Of the 246 mice used in the study, 22 mice were excluded due to poor fracture quality (8), loss of fracture stabilization (6), or to anesthesia death (8). Radiography showed a consistent pattern of fracture healing between mice with peak fracture callus volume evident at 10 (15 mice) to 14 days (18 mice) after fracture. Fracture bridging was apparent in all 3-week postfracture radiographs (35 mice). Histologic examination of 117 specimens at 9 time points showed chondrocyte differentiation within the fracture callus by 7 days after fracture, endochondral ossification occurring by 10 days after fracture, and bone remodeling evident as early as 3 weeks after fracture. Despite radiologic and histologic evidence of fracture bridging after 3 weeks, torsional mechanical testing of 68 mice at 3, 4, 6, and 12 weeks after fracture (group size of 15 to 18 mice at each time point) indicated that significant increases in structural or material strength did not occur until 6 to 12 weeks after fracture.
Conclusions:
Femur fracture healing in mice follows a typical endochondral ossification pathway with fracture bridging occurring approximately 1 week faster in mice than rats. This fracture model is amenable to the molecular and genetic analysis of fracture healing using different inbred, transgenic, and knockout strains of mice.
Insights
This study developed a reproducible mouse femur fracture model for studying healing. The model allows for molecular and genetic analysis of fracture repair, showing healing occurs via endochondral ossification.
Area of Science:
- Orthopedics
- Biomedical Engineering
- Skeletal Biology
Background:
- Fracture healing research requires reliable animal models.
- Understanding the molecular and genetic mechanisms of bone repair is crucial for developing new treatments.
Purpose of the Study:
- To develop and characterize a closed femur fracture model in mice.
- To enable molecular and genetic analyses of fracture healing.
Main Methods:
- A reproducible closed femur fracture was created in mice using intramedullary stabilization and 3-point bending.
- Fracture healing was assessed using radiography, histology, and torsional mechanical testing at various time points.
Main Results:
- The model demonstrated consistent fracture healing patterns, with bridging evident by 3 weeks radiographically.
- Histology confirmed endochondral ossification and bone remodeling by 3 weeks.
- Mechanical testing showed significant strength increases between 6 and 12 weeks post-fracture.
Conclusions:
- Mouse femur fracture healing follows endochondral ossification, with bridging occurring faster than in rats.
- This validated model is suitable for genetic and molecular studies of fracture repair in various mouse strains.
