Influence of swan-like memory connector on the contents of local insulin-like growth factor Ⅰ during fracture union

Ren WANG; Xiaodong YU; Qingge FU; Shuogui XU; Chuncai ZHANG

ABSTRACT

BACKGROUND:

Swan-like memory connector (SMC) can form a three-dimensional fixation on long bone shaft,ensure the stability of fracture ends,and produce a continuous dynamic compressive stress on the fracture ends.Insulin-like growth factorⅠ (IGF-Ⅰ) regulates bone development and metabolism,cell differentiation,as well as mitosis.During the union process of fracture,IGF-I is effective to promote cellular proliferation,stimulate bone formation and result in chondrogenesis.

OBJECTIVE:

To quantitatively determine the effect of SMC and conventional dynamic compression plate (DCP) on the concentration of local IGF-Ⅰ in the union duration of rabbit humerus fracture.DESIGN,TIME AND

SETTING:

A controlled observational animal study was performed in the laboratory,Department of Orthopaedics,Changhai Hospital,the Second Military Medical University of Chinese PLA from January to May in 2007.MATERIALSSMC was Ni-Ti alloy panel,comprising 50%-53% Ni,was customized by Lanzhou Seemine Shape Memory Alloy Co.,Ltd.The temperature of shape recovery was (33±2) ℃.

METHODS:

Thirty adult New Zealand rabbits were used in this study and were processed into osteotomy.The experiment sides of rabbit humerus were cut and fixed with SMC at random,serving as SMC group,and the other sides were cut at the same position and fixed with DCP,serving as DCP group.Each five animals were put to death at the time points of 2,3,4,6,8,and 12 weeks after internal fixation.Specimens were obtained from the areas that were 0.5 cm besides the fracture line.MAIN OUTCOME

MEASURES:

Following internal fixation,the contents of local IGF-Ⅰ in the specimens of different time points (2,3,4,6,8,and 12 weeks) were determined in both SMC group and DCP group.

RESULTS:

In the SMC-treated group,the contents of IGF-I increased 2 weeks after internal fixation,reached the maximum at 6 weeks,and then decreased at 8-12 weeks.In the DCP-treated group,the contents of IGF-Ⅰincreased 2 weeks after internal fixation,reached the maximum at 8 weeks,and then decreased at 12 weeks.No significant differences were found between the SMC group and the DCP group at 2,8,12 weeks after internal fixation (P ＞ 0.05).Compared with the DCP group,the SMC group had a remarkably higher content of IGF-Ⅰ at the time points of 3,4 and 6 weeks (P ＜ 0.05).The difference was the most statistically significant at 4 weeks.

CONCLUSION:

Compared with conventional DCP,the SMC could better promote the secretion of IGF-Ⅰin fracture and facilitate the fracture union due to the continuous dynamic compressive stress and three-dimensional fixation.