Effects of swan-like memory compressive connector on experimental humerus fracture healing / 中华骨科杂志

ABSTRACT

Objective To explore the effects of swan-like memory compressive connector(SMC) made of Ni-Ti shape memory alloy on stress shielding rate, struct ure and mechanical properties as well as the blood flow of cortical bone of expe rimental fracture healing. Methods Mid-shaft osteotomies of bilateral humerus we re performed in 56 rabbits. One side was randomly fixed with SMC, and the other side was plated with a 4-holes dynamic compressive plate (DCP). At 2, 4, 8, 12, 16,and 20 weeks after operations, the humeri in 8 rabbits were harvested. The st ress-shielding rate was measured using axial compressive test in situ samples. T he geometrical structure and bone density were examined by CT scans, and the mec hanical property was assessed by torsion tests. Blood flow was measured in real time using Laser-Doppler flowmetry. The cortical bone perfusion of 16 rabbits wa s measured at 10 time intervals (after periosteotomy, after fracture, instant af ter fixation, at 1, 3, and 7 days, and 2, 4, 8, and 12 weeks postoperatively). B lood flow was measured at outer and inner cortical bone beneath the fixation. Si multaneously, anteroposterior radiograph of the humerus was taken. Results The s tress-shielding rate in SMC group was significantly lower than that of DCP group (P