The pedicle freezing procedure by liquid nitrogen is a method for the reconstruction of tumor-bearing bone after malignant tumor resection. However, the regenerative mechanism of bone after the pedicle freezing procedure is unclear. We investigated the complete process from devitalization to revitalization of bone after the pedicle freezing procedure in 13 rabbits. After osteotomy the 5 mm distal femurs were immersed in liquid nitrogen, and the specimens were divided into frozen area and sub-frozen area. The bilateral femurs were harvested for evaluation of bone regeneration by histological and immunohistochemical examination (VEGF, CD31, BMP-2 and Runx2) from 1 week to 52 weeks. The diameter of operating femurs was compared with contralateral femurs from 6 weeks to 52 weeks. No viable cells could be found from 1 to 8 weeks in the frozen area, and a mean 1.83 cm necrotic range were detected in the sub-frozen area. The periosteal reaction, massive fibrous tissue and immature bone matrix invaded from the normal area to the necrotic area from 12 weeks. Subsequently, the necrotic bone was gradually replaced by newly formed bone by creeping substitution, with endochondral and intramembrane bone formation. The diameter of frozen femurs was significantly larger than the contralateral femur at the same period from 8 weeks to 52 weeks (P < 0.01). All immunohistochemical factors were positively expressed in both areas at different time points. The active osteoblasts and microvessel migrated from marrow cavity and periosteum into dead bone. This study suggested that the frozen bone not only provides a scaffold but also possesses excellent osteoinductive properties.
Keywords: Bone regeneration; Cryosurgery; Endochondral ossification; Frozen autograft; Liquid nitrogen; Revitalization; Tumor-bearing bone.
Copyright © 2019. Published by Elsevier Inc.