The Effection And Mechanism Of Micromovement On The Bone Healing

Objective This study tried to explore the effect and mechanism of micromovement on fracture healing, so as to make the dynamic axial external fixator be more widely used.Methods 132 New Zealand rabbits with tibial fracture were randomly divided into micromovement group and fixation group. The changes of fracture-site microcirculation at different time were measured with Laser Doppler Perfusion Monitor.The bone mineral density(BMD) was measured with dual energy X-ray absorptionmetry. The bending stiffness, torsional stiffness and torsional strength were determined with biomechanical tests.The expression and positive index of TGF-β1, BMP2, bFG, VEGF and its mRNA were quantitatively analysised by Immunology Histochemistry(IHC) and In Situ Hybridization(ISH). So , we deected the TGF- β1, BMP2, bFGF, VEGF distribution and contents of callus in protein level and in mRNA level.Results 1. At Id after operation, the local blood flow of the micromovement group and the fixation group was all greatly decreased. It recovered to normal level at 7d after operation. At 14d, the local blood flow of two groups was both higher than normal level, and the blood flow of micromovement group was higher than that of fixation group(P<0.05).The peak of fixation group was at 21d and decreased gradually. The peak ofmicromovement group was at 28d. Compared the blood flow, there was statistical difference between micromovement group and fixation group at 21d, 28d, 42d (P<0.01) . The blood flow of two groups was higher than normal level at 56d(P<0.05), but there was no statistical difference between two groups((P>0.05).2. At 14d after operation, the BMD of the micromovement group and the fixation group was just 10% the same as normal, there was no statistical difference between two groups(P>0.05).The BMD of two groups was increased greatly at 21d and 28d, the BMD of micromovement group was higher than that of fixation group(P<0.01). At 42d, the BMD of micromovement group was higher than normal level. At 56d, the BMD of two groups were both higher than normal level, but there was no statistical difference between micromovement group and fixation group (P>0.05) .3. (1) At 14d after operation, the bending stiffness of the micromovement group and the fixation group was just 3% of the normal level, there was no statistical difference between two groups(P>0.05).The bending stiffness of two groups was increased at 2Id, but no statistical difference existed between two groups(p>0.05). At 28d and 42d, the bending stiffness of two groups was increased greatly, and the bending stiffness of micromovement group was higher than that of fixation group, there was statistical difference between two groups (P<0.05).At 56d, the bend stiffness of two groups were both increased to the normal level, there was no statistical difference between micromovement group and fixation group (P>0.05) . (2) At 14d and 21d after operation, the torsional stiffness of micromovement group and fixation group was very low, there was nostatistical difference between two groups(P>0.05).The torsional stiffness of two groups was increased at 28d, that of micromovement group was higher than fixation group, and statistical difference existed between two groups(P<0.01). The torsional stiffness of micromovement group was higher than that of fixation group at 42d after operation, statistical difference existed (P<0.01). The torsional stiffness of micromovement group was normal at 56d, and that of fixation was lower , there was statistical difference between two groups (P<0.05) . (3) At 14d and 21d, the torsional strength of micromovement group and fixation group was too low to test. The torsional strength of two groups was greatly increased at 28d, micromovement group was increased higher than fixation group, The statistical difference existed between two groups(P<0.05). The torsional strength of micromovement group was increased to the normal level at 56d, that of fixation group was only 80% of normal level, statistical difference existed (P<0.01).4. (1) TGF- β1 and TG...