(A–F) Histomorphometric analysis of fracture healing at different stages after severe OVCFs. A large amount of necrotic bone and fibrous tissue still appeared after more than 1 month of fractures. Cancellous bone volume/tissue volume (BV/TV%), fibrous tissue volume/tissue volume (FV/TV%), endochondral bone volume/tissue volume (EBV/TV%), necrotic bone volume/tissue volume (NBV/TV%), woven bone volume/tissue volume (WBV/TV%), and lamellar bone volume/tissue volume (LBV/TV%) are indicated as mean±standard error of mean (SEM).