Correlation between the region of interest in digital radiography, Hounsfield units, and histological maturation on Wistar rats submitted to tibial fracture

Objective: Study the relationship between the region of interest (ROI) and Hounsfield units (HU) in the tibial bone callus. Methods: Twenty-one adult Wistar rats were submitted to tibial fracture. The fracture was radiographed after their euthanasia, and the bone calluses were analyzed histologically after being stained with hematoxylin and eosin. Euthanasia occurred between the 2nd and 6th weeks after fracture and fixation, thus obtaining various consolidation stages. Histologically, vessels, chondroblasts, connective tissue (collagen), maximum size of the chondrocyte, and the concentration of chondrocytes were quantified. Results: It was observed that the higher the HU, the more mature and closer to bone consolidation it is, proving that the use of ROI and bone callus measurement with HU is reliable for the histological process of maturation of the bone callus and can be safely used as proof of evolution of the bone healing process. Conclusion: The ROI was successfully used in digital radiography to observe HU in fractured bones. Level of Evidence IV; Therapeutic Studies; Case Series.