6-9 Fractures Fractures are cracks or breaks in bones that are caused by physical stress Fractures are repaired in four steps: Spongy bone of internal callus Cartilage of external callus Fracture hematoma External callus Spongy bone of external callus Dead bone Bone fragments Periosteum Internal callus External callus 1 Fracture hematoma formation: Immediately after fracture, extensive bleeding causes a large clot to form (fracture hematoma). 2 Callus formation: Internal and External calluses form, producing an internal spongy bone network and an external seal of cartilage and bone. 3 Spongy bone formation: The external seal of cartilage is replaced by bone; struts of spongy bone unite the broken ends. Fragments of dead bone have been removed. 4 Compact bone formation. Initial swelling subsides with remodeling. Almost as good as new!

the types of fractures… (Be able to match a description of the type of fracture with its name, this would make a great question on the lab exam, eh?…) Fractures are named according to their external appearance, location and the nature of the crack or the break in the bone The broadest general categories are: Closed (simple) fractures that are completely internal and can only be visualized by x-rays Open (compound) fractures that project through the skin, which can complicate the condition with secondary infection Many fractures fall into more than one category, because terms overlap…

Transverse fractures break a bone shaft along its long axis ulna

Displaced fractures produce new and abnormal bone arrangements. (Nondisplaced fractures retain the normal alignment)

Compression fractures occur in vertebrae subjected to extreme stresses Compression fractures occur in vertebrae subjected to extreme stresses. (like falling on your backside in an abrupt “sitting” manner)

Spiral fractures are produced by twisting stresses that spread along the length of the bone. tibia

Epiphyseal fractures tend to occur where the bone matrix is undergoing calcification and the chondrocytes are dying. Clean transverse fractures heal well (for obvious reasons) if treated properly. femur

Comminuted fractures shatter the affected area into many bony fragments. femur

Greenstick fractures are a partial fracture, where one side of the shaft is broken and the other side is bent. This happens frequently in children. radius

Colles fractures are a break in the distal portion of the radius Colles fractures are a break in the distal portion of the radius. (typically caused by extending your hand to cushion a fall)

Pott’s fractures occur at the ankle and affect both bones of the leg. (this is a common sports injury)