AUTHOR=Zhou Zhilun , Yan Yang , Yu Hao , Yang Guanzhong , Su Hao , Zhang Tao , Fan Yubo , Zhao Feng
TITLE=Effect of Inter-Fragmentary Gap Size on Neovascularization During Bone Healing: A Micro-CT Imaging Study
JOURNAL=Frontiers in Bioengineering and Biotechnology
VOLUME=10
YEAR=2022
URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.808182
DOI=10.3389/fbioe.2022.808182
ISSN=2296-4185
ABSTRACT=Introduction: Neovascularization of the fracture site is of great importance for bone healing and could be influenced by local mechanical environment such as fixation stability and inter-fragmentary gap size. This study aims to reconstruct the neovascularization of the fracture site and explore the effect of inter-fragmentary gap size on the spatiotemporal structure of vascularity during bone healing.
Methods: Osteotomy was performed on 36 Sprague–Dawley (SD) rats on the right tibial diaphysis, and the fracture was given stable fixation with two different inter-fragmentary gap sizes. SD rats received stable fixation with either a small-sized inter-fragmentary gap (FSF1, 1 mm, n = 18) or a large-sized one (FSF3, 3 mm, n = 18). The left hind limbs were treated as the control group (CON). The animals were killed at different time points (2, 4, and 6 weeks postoperatively, n = 6, respectively) for vascular perfusion and micro-CT imaging.
Results: (a) At week 2 and 4, FSF1 group showed significantly higher vessel volume ratio (VV/TV) and vessel surface density (VS/TV) values than both CON and FSF3 group; there was no significant difference in either VV/TV or VS/TV values between CON and FSF3 groups. (b) At week 6, both FSF1 and FSF3 groups showed significantly higher VV/TV and VS/TV values than CON group; FSF3 group had a significantly higher VV/TV value than FSF1 group.
Conclusion: Different inter-fragmentary gap sizes greatly affect the timing of angiogenesis at the fracture site. Stable fixation with a small inter-fragmentary gap (1 mm) benefits neovascularization at the early stages during bone healing and reconstruction, while stable fixation with a large inter-fragmentary gap (3 mm) delays the occurrence of angiogenesis to a later phase.