The importance of the hematoma for fracture healing in rats.

In 3 groups of rats, bilateral femoral fractures were produced. The fracture hematoma was removed on one side after 30 min, 2 days and 4 days in the 3 groups, respectively. The fractures were mechanically tested at 4 weeks. When the fracture hematoma was removed early, callus production, bending moment, and fracture energy were decreased. Removal of the hematoma at Day 2 or 4 impaired fracture healing even more, as both bending moment, bending rigidity and fracture energy were greatly decreased compared to the control fractures. We conclude that the fracture hematoma favors healing; removal of the hematoma after some days is more harmful to healing than when the hematoma is removed in the initial phase.