11.2 · Fracture healing

How fracture healing differs from soft tissue healing

More complex and takes longer, involves formation of callus with bone remodeling, and no scar tissue is made

Fracture healing step 1

A clot forms in the medullary cavity, under the periosteum, and between the ends of the bone fragments

Fracture healing step 2

Adjacent bone tissue dies because torn blood vessels cannot exchange nutrients, waste, and gases

Fracture healing step 3

Inflammation is stimulated with vasodilation and infiltration of plasma, WBCs, growth factors, and mast cells; phagocytes remove dead tissue

Fracture healing step 4

Fibroblasts and chondroblasts lay down collagen fibers and cartilage on the fibrin network, forming the fibrocartilaginous callus or procallus

Fracture healing step 5

Osteoblasts from the periosteum and endosteum synthesize bone matrix that calcifies, forming a bony callus

Fracture healing step 6

Over subsequent months the callus is remodelled by osteoblasts and osteoclasts, with excess callus resorbed and trabeculae formed along lines of stress

Procallus

Initial fibrocartilaginous bridge between the bone ends