Experimental study on callus calcification and mechanical property of healing bone under low frequency and controlled micromovement / 上海第二医科大学学报

ABSTRACT

Objective To investigate the effects of external fixator with dynamic device under low frequency and controlled micromovement on the callus calcification and mechanical property of healing bone.MethodsForty-five sheep were performed transverse osteotomy with a gap of 2 mm on the mid-shafts of both tibias,and the hind limbs were fixed with unilateral external fixators connected to a controlled micromovement device.Ten days after osteotomy,one hind limb of each sheep was randomly selected for micromovement(30 min/d).According to different micromovement frequencies,the sheep were randomly divided into 3 groups 0.5 Hz group,1 Hz group and 5 Hz group(n=15).The amplitude of micromovement was 0.25 mm and the micromovement stopped by the end of the fourth week postoperation.The other hind limb of each sheep was served as control group without micromovement.Morphometry of callus was done at the end of 4,6 and 9 weeks after osteotomy.Bone formation velocity,bone mineral density and biomechanical properties were compared at the end of 9 weeks.Results The areas of mineralized bone and osteoid in different miromovement groups were larger than that of control group at the end of 4,6 weeks postoperation(P