A nonterminal equine mandibular model of bone healing.

The research is centered around the development of a nonterminal large animal bone defect model on horses, meant to assist in assessing the effectiveness of regenerative and pharmacologic treatments aimed at enhancing bone healing.

Study Design and Methodology

• The research was conducted as an in-vivo experimental study with six adult gelding horses as subjects.
• The researchers used radiographic guidance under general anesthesia to create a 13.5 mm diameter bilateral, full thickness mandibular defects in the horses with a custom surgical jig and coring bit.
• After a period of 16 weeks, a 23 mm diameter core that encompassed the healing defects and the surrounding parent bone material were removed for evaluation
• On the 14th day before the final core harvest, oxytetracycline was administered to label bone-forming surfaces.

Method of Assessment

• The researchers qualitatively assessed the healing by using decalcified hematoxylin and eosin (H&E) stained and undecalcified fluorescent labeled sections.
• The fraction of trabecular to cortical bone (Tb.V/Ct.V), bone volume fraction (BV/TV), tissue mineral density (TMD), and apparent bone mineral density (aBMD) were all quantified using microcomputed tomography.
• The researchers then compared these figures between the left and right sides using Wilcoxon signed rank test.

Results and Conclusions

• It was found that the bone volume fraction (BV/TV) was not significantly different between the defects on the left and right sides.
• Bone deposition occurred centripetally from the border of the original defect, filling an average of 67% (± 16% standard deviation) of the defect after 16 weeks.
• From their experimentation, the researchers concluded that this large animal model has the potential to be used in the comparison of regenerative and pharmacologic products intended to enhance bone healing.