Mechanical and biodegradable properties of absorbable hydroxyapatite/poly-DL-lactide screws

Fu Rong; You Xiao-bo; Zhong Zhen-dong; Li Yan

doi:10.3969/j.issn.2095-4344.2013.38.002

Abstract：BACKGROUND:Through compounding hydroxyapatite and poly-DL-lactide, the mechanical properties, physical and chemical properties of the implants can be enhanced. <br> OBJECTIVE:To detect the effect of hydroxyapatite/poly-DL-lactide composite internal fixation screws in canine femoral condyle cancel ous bone fracture repair. <br> METHODS:Forty-two beagle dogs were operated to bilateral femoral condyle fracture models. The left side was fixed using hydroxyapatite/poly-DL-lactide screws as experimental group;while the right side was fixed with pure poly-DL-lactide screws as control group. After 2, 4, 8, 12, 24, 36 and 48 weeks, conditions of fracture were observed using X-ray, femoral and screw specimens were observed histopathological y, and the bending strength and the average molecular weight were detected. The biological absorption rate, intensity decay rate and biodegradation rate were calculated. <br> RESULTS AND CONCLUSION:After 2-48 weeks, bilateral fractures were fixed wel and new bone grew wel , but the biological absorption rate of the screws in the experimental group was lower than that in the control group (P ≤0.01). In the first 2, 4 weeks, the bending strength of the experimental screws was higher than that of the control screw (P ≤0.05), but the biodegradable speed was slower in the former one (P ≤ 0.05 or P ≤ 0.01). The pathological changes were similar in the two groups. After 48 weeks, the fractures were healed and bone tissue reconstruction was completed. Compared with the pure poly-DL-lactide screws, the hydroxyapatite/poly-DL-lactide composite internal fixation screws have better fixation effects, biocompatibility, mechanical properties and biodegradability.