Abstract
BackgroundThe use of a closed fracture model has become the preferred model to study the fracture healing process, given that the periosteum and the soft tissue surrounding the fracture site play an important role in the fracture healing process. Some techniques like osteotomy, drilling the long bones and the use of the guillotine-like apparatus to induce fracture are characterized by some undesirable effects and complications. The aim of this study is to optimize and evaluate an in vivo fracture model using three-point bending pliers that can be used to study secondary bone fracture healing in rats.MethodsModified three-point bending pliers were used as a device to create the closed rat tibial bone fracture that was prefixed with an intramedullary pin (23 G × 11/2″) in rats. The exact location of the induced closed fracture was along the long bone. The presence of bone comminution, and the fracture bone alignment were immediately examined after the induction of the fracture until the 6th week.ResultsAll fractures induced were transverse, located in the middle to proximal one third of the tibia, and they all healed without complications. Bone union as shown radiographically occurred within 2–3 weeks postoperative. The average angle of the fracture line with the axis of the tibia was 89.41 ± 2.11°. The lateral and anterio-posterior pin angulation views were 167.33 ± 3.67° and 161.60 ± 4.87° respectively. The average length of proximal end of the fractured bone in comparison with the whole length of intact bone was 41.02 ± 3.27%. There was a significant difference in percentage of the gross callus area and gross callus index, while there was no significant difference in X-ray callus index. There was no significant difference of the gross callus area between slight comminution (n = 4) and non comminution (n = 21).ConclusionThe optimized rat tibial fracture model resulted in mainly transverse tibial mid-shaft fractures with minimal bone comminution and absence of surrounding soft tissue damage. The size area of consequent soft callus formation and the extent to which the closed fracture model was reproducible are very good outcomes making it feasible for in vivo laboratory research use.
Highlights
The use of a closed fracture model has become the preferred model to study the fracture healing process, given that the periosteum and the soft tissue surrounding the fracture site play an important role in the fracture healing process
In the experiment using 8 weeks old rat cadavers (n = 65), the result showed that non comminution, transverse and mid-shaft of the tibia were the predominant fractures (Table 1)
Data comparison between the tibia (n = 3) and femur (n = 3) showed no significant difference between the two groups for the comminution fracture type and location (Two-tailed t-Test)
Summary
The use of a closed fracture model has become the preferred model to study the fracture healing process, given that the periosteum and the soft tissue surrounding the fracture site play an important role in the fracture healing process. Handool et al Journal of Experimental Orthopaedics (2018) 5:13 through a hyaline cartilage tissue that is subsequently mineralized to woven bone through endochondral (indirect) bone formation (Shapiro, 2008; Ghiasi et al, 2017). This results in the fracture being stabilized and the tissue is later remodeled. The ideal experimental fracture should be of consistent site, with the standard degree of bone damage, soft tissue injury, stability and displacement of the bone fragments, and the time needed for bone union should be standardized (Greiff, 1978). The surrounding muscles contribute to stabilization and strengthening of the long bone fracture (Otto et al, 1995; Loi et al, 2016)
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