Histologic and histomorphometric evaluation of lyophilized amniotic membrane in bone healing: An experimental study in rabbit's femur

Amniotic membrane has been widely used in regenerative medicine especially ophthalmology. It has many advantages including anti-inflammatory, anti-fibrotic and antimicrobial properties. The purpose of the present work to study the effect of lyophilized human amniotic membrane on healing of bony defect in rabbits' femur. Eighteen male rabbits were used. Four mm wide and 5 mm deep defect was created in the femur diaphysis bilaterally in each rabbit. The defect of the right side was left empty (control), while the left side was filled with the amniotic membrane (study). Six rabbits were scarified at each of the experimental periods 2, 4 & 6 weeks postoperatively. The defect areas were dissected out and evaluated histologically & histomorphometrically. In the control group, at 2 weeks, woven bone spicules were seen extending from the periphery of the defect boundaries. At 4 weeks, the newly formed bone became more mature. At 6 weeks, the newly formed bone was more dense with newly formed osteons were seen. However, in the study group, the newly formed bone was much less in relation to the control group. Remnants of the amniotic membrane was seen folded at the center of the defect area surrounded by inflammatory cells. Histomorphometrically, the mean percentage of bone surface area in control group was higher than the study group in all experimental periods and the difference was statistically significant (p < 0.001). It was concluded that: freeze dried amniotic membrane is not suitable to enhance bone healing when used as a filling material in bone defects.