A&P - 6.5 Fractures: Bone Repair

fracture

• a crack or a break in a bone (broken bone)

closed reduction

manual manipulation of a broken bone to set it into its natural position without surgery

open reduction

surgical exposure of a bone to reset a fracture

classification of fractures

• classified by their complexity, location, and other features

  • whether the bone penetrates the skin

    • simple

    • compound

  • orientation of the break

    • transverse

    • linear

  • position of the bone ends after the fracture

    • non-displaced

    • displaced

simple (closed)

bone breaks cleanly but does not penetrate the skin

compound (open)

broken ends of bone protrude through the tissue and skin

transverse

break occurs perpendicular to the long axis of a bone

linear

breaks parallel to the long axis of the bone

non-displaced

the bone ends retain their position

displaced

the bone ends are out of normal alignment

types of fractures

• some fractures may be described using more than one term because it may have features of more than one type (e.g., an open transverse fracture)

  • closed fracture

  • open fracture

  • transverse fracture

  • spiral fracture

  • comminuted fracture

  • impacted fracture

  • greenstick fracture

  • oblique fracture

transverse fracture

occurs straight across the long axis of the bone

oblique fracture

occurs at an angle that is not 90 degrees

spiral fracture

bone segments are pulled apart as a result of a twisting motion

communicated fracture

several breaks result in many small pieces between two large segments

impacted fracture

one fragment is driven into the other, usually as a result of compression

greenstick

a partial fracture in which only one side of the bone is broken

open (or compound) fracture

a fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection

closed (or simple) fracture

a fracture in which skin remains intact

fracture repair

• the healing of a bone fracture follows a series of progressive steps

  • a fracture hematoma forms

    • when a bone breaks, blood flows from any vessel torn by the fracture, the blood begins to clot forming a fracture hematoma

    • the disruption of blood flow to the bone results in the death of bone cells around the fracture

  • internal and external callus form

    • within 48 hours after the fracture, chondrocytes from the endosteum have created an internal callus by secreting a fibrocartilaginous matrix between the two ends of the broken bone

    • periosteal chondrocytes and osteoblasts create and external callus of hyaline cartilage and bone, respectively, around the outside of the break

    • this stabilizes the fracture

  • cartilage of the callus is replaced by trabecular bone

    • eventually internal and external calli unite, compact bone replaces spongy bone at the outer margins of the fracture, and healing is complete

  • remodeling occurs

fracture hematoma

blood clot that forms at the site of a broken bone

internal callus

fibrocartilaginous matrix, in the endosteal region, between the two ends of a broken bone

external callus

collar of hyaline cartilage and bone that forms around the outside of a fracture