External (periosteal) vs internal (endosteal) callus; bridging and uniting fragments. Primary (contact) healing has minimal/no callus under rigid stability; secondary healing forms abundant callus under relative stability. Radiographic callus reflects mechanical environment and biology; hypertrophic callus suggests instability. Histology: woven bone → lamellar bone remodeling along stress lines.
What type of callus forms on the outer surface of bone during fracture healing?
Which type of callus is primarily responsible for restoring the internal architecture of bone?
What type of callus is most abundant during secondary healing under relative stability?
What histological feature characterizes the early stage of callus formation?
What does a hypertrophic callus suggest about the stability of a fracture?
Which type of callus forms directly between the fracture fragments?
What is the primary difference between primary and secondary fracture healing?
Which type of callus provides early stabilization at the fracture interface?
During which phase of fracture healing does callus formation primarily occur?
What radiographic appearance is expected with adequate callus formation during fracture healing?
