Effects of novel β titanium alloy with high strenghth and low elastic modulus on bone healing of osteoporotic fracture in rats

Abstract

Objective To investigate the effects of a novel |3 titanium fixation with high strength and low elastic modulus on bone healing of osteoporotic fracture and its effects on stress shielding.Methods Forty female Sprague-Dawley rats were oophorectomized before establishment of femur fracture model.The fracture of left femur was stabilized by titanium alloy pin with high elastic modulus (110 Gpa,high elasticity modulus group) and the fracture of right femur by titanium alloy pin with low elastic modu-lus (30 Gpa, low elasticity modulus group).Six and 12 weeks later, the bone volume (BV) , total vol-ume (TV) and bone volume fraction (BVF) were detected by Micro-CT, and the maximum load was de-tected by biomechanical test.The effects of two titanium alloy pins on formation of bony calluses and me-chanical properties of bones were compared.Results Compared with the low elasticity modulus group, more collagen and bony callus, thicker bone trabeculae and more regular lamellar bone were found in the high elasticity modulus group.In low elasticity modulus group, TV (ROI1) was increased obvious-ly at week 6, with no statistical differences in BV (ROI 1), BV (ROI 2) and maximum load between two groups (P < 0.05).TV and BV in region ROI 1 in the low elasticity modulus group were significantly higher than that in high elasticity modulus group (P < 0.05) , while BV in region ROI 2 in low elasticity modulus group was significantly higher than that in high elasticity modulus group at week 12 postoperative-ly (P<0.05).Biomechnical test indicated that the maximum load in low elasticity modulus group was higher than that in high elasticity modulus group.Conclusions The novel B titanium alloy with high strength and low elastic modulus helps reduce effects of stress shielding, diminish bone resorption, in-crease the fibrous callus formation at the initial phase and improve the quality of bone healing at the later phase. Key words: Osteoporosis; Femoral fractures; Titanium; Rats; Elastic modulus