THE EFFECT OF AXIAL DYNAMIZATION ON THE FRACTURE HEALING PROCESS

• Published in: Journal of The Showa Medical Association Vol. 51; no. 4; pp. 409 - 418
• Main Author: NISHIYAMA, Yoshinobu
• Format: Journal Article
• Language: Japanese
• Published: The Showa University Society 1991
• Subjects: axial dynamization; fracture healing
• ISSN: 0037-4342; 2185-0976
• DOI: 10.14930/jsma1939.51.409

The purpose of this study was to prove some of the benefits of axial dynamization in the fracture healing process. Midfemoral transvese osteotomies were performed on 22 mongrel canines. The femur of each animal was fixed with a dynamic axial fixation system that had a telescoping mechanism to provide axial dynamization at the osteotomy site. On the 21st day, one group of 11 was subjected to axial dynamization by weight bearing (dynamization group), while the other group was maintained relatively rigid throughout the study control group. At 7, 10, and 13 weeks after osteotomy, histological investigation and bone morphometric analysis of intracortical new bone formation were performed. The dynamization group showed early abundant intercortical new bone formation at 7 weeks, Haversian remodeling at 10 weeks, and evidence of bone union at 13 weeks. However, these were absent or negligible in the control group at the same times. In torsional testing, at 7 and 10 weeks of healing, the dynamization group was stronger than the control group. But at 13 weeks, the mechanical properties of the bones of the two groups were simillar to those of intact bone. The results suggest that axial dynamization stimulates intracortical new bone formation in early stages, and Haversian remodeling in later stages to promote fracture union.