[Effects of Swan-like Shape Memory Connector on stress shielding rate and callus development during experimental fracture healing process].
OBJECTIVE
To investigate the stress shielding rate, ultrastructural and biomechanical property of the healing bone fixed by Swan-like Shape Memory Connector (SMC) during experimental fracture healing in rabbits.


METHODS
Unilateral osteotomy of left humeral diaphysis was performed in 140 adult New Zealand rabbits. The humeral fracture was fixed with SMC in study group and 4-hole dynamic compression plate (DCP) in control group. The animals were sacrificed at the 2nd, 4th, 8th, 12th, and 16th weeks postoperatively. The humeral shafts were harvested for three-point bending tests and stress shielding rate examination. Samples from the fracture gaps were observed with scanning electron microscope.


RESULTS
Within an observation period of 12 weeks after operation, the stress shielding rates were significantly lower in study group than those in control group, and the bending strength and the bending rigidity were statistically higher. It was also found that collagen fibers in callus was arranged more regulate and early mineral deposition in study group.


CONCLUSIONS
These results suggest that SMC contributes to the proliferation and differentiation of osteoblasts, promoting the formation and calcification of bone matrix and enhancing biomechanical property of the healing bone, which might be closely correlated with a less stress shielding effect produced by SMC.
Department of Orthopaedics, Nanjing General Hospital of Nanjing Military Area Command, Nanjing 210002, Jiangsu, China. rk4587@sina.com.cn
Ke
K
Ren
Chun-cai
CC
Zhang
Guang-ye
GY
Wang
Jian-ning
JN
Zhao
Jian-wei
JW
Sun
D000818:Animals; D002146:Bony Callus / Q000503:physiopathology*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017102:Fracture Healing; D006810:Humeral Fractures / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008297:Male; D008855:Microscopy, Electron, Scanning; D009532:Nickel; D011817:Rabbits; D013314:Stress, Mechanical; D014025:Titanium
C040654:titanium nickelide; D009532:Nickel; D014025:Titanium