Radiologic Evaluation of Fractures

how do you describe a fracture?

• anatomic site and extent

• type

• alignment

• direction

• special features

• associated abnormalities

• special types

what is a comminuted fracture?

more than 2 fracture segments

what is an incomplete fracture?

• one cortical margin remains intact

• relatively stable

• seen predominantly in short, flat, or irregularly shaped bones

• mostly seen in children or in people with metabolic disorders

how do you describe displacement?

• describe position of distal fragment in relation to proximal

• position refers to relationship of fragment to normal structure

what is angulation named for?

• the direction of angular displacement of the distal fragment in relationship to the proximal fragment

• the direction of the apex of the angle formed by the fracture segments

what causes a transverse fracture?

• results of a bending force

• occurs at right angles to the longitudinal axis

what is a longitudinal fracture?

approximately parallel to the shaft

what causes oblique fracture?

result of combined forces of compression, bending, and torsion

what causes a spiral fracture?

spirals along long axis of bone due to torsion

what is impaction?

• results from compression forces related to axial loading

• bone is driven into itself

what are the types of impaction fracture?

• depression fx

• compression fx

what is an avulsion fx?

• fragments of bone are pulled away from the main body of bone OR passive resistance of a ligament against a tensile force

• occurs at bone prominence

what is a stress fx?

• repetitive minor trauma on normal bone

what causes stress fractures?

chronic high-frequency, low level loading does not allow bone sufficient time to heal and remodel

what are the types of stress fracture?

• fatigue fx

• insufficiency fx

what is a fatigue fx?

• excessive stress on healthy bone

• normally in young/active people

what is an insufficiency fx?

• normal stress on a pathologic bone

• typically in old, inactive people

what is an epiphysis?

the end of a bone

what is a physis?

epiphyseal growth plate

what is a metaphysis?

proximal to the physis

what causes difficulties with fx assessment in children?

• epiphyseal growth plates

• dense growth lines

• secondary centers of ossification

• large nutrients foramina

what is a greenstick fx?

• shaft is fracture on the tension side while the cortex and periostium remain intact on the compression side

what is a torus fracture?

• impaction fracture that result in buckling of the cortex

• predominantly at the metaphyseal region because of the amount of cancellous bone and newly remodeled trabecular bone present

what is plastic bowing?

• compression forces exceed the point in which elastic recoil returns

• type of incomplete fracture (microfracture)

describe a type 1 epiphyseal growth plate fracture

• fracture line extends through the physis, separating and displacing the epiphysis from the normal position

what type of fracture is this?

type 1

what is the prognosis for type 1 fractures?

good for normal growth

describe a type 2 epiphyseal growth plate

fracture line extends through the physis and exits through the metaphysis creating a triangular wedge that displaces with the epiphysis

what is the prognosis for a type 2 fx?

good for normal growth

what type of fx is this?

type 2

describe a type 3 fx?

fx line that extends from the joint surface through the epiphysis across the physis

what type of fx is this?

type 3

describe a type 4 fx

fracture line extends from the joint surface through the epiphysis, physis, and metaphysis

what is the prognosis for a type 4 fx?

partial growth arrest is possible and surgical fixation may be necessary

what type of fx is this?

type 4

describe a type 5 fx

fracture is a crush type injury that damages the physis by compression

what is the prognosis of a type 5 fx?

eventual growth arrest may be the only indication of this injury

what type of fx is this?

type 5

what is the name of the classification for growth plate fractures?

Salter-Harris

what does SALTER stand for?

1. Straight across

2. Above

3. Lower

4. Through Everything

5. cRush

what happens in callus formation?

• hematoma forms

• metabolic reaction occurs

• organization/ossification

• new bone proceeds towards and bridges the gap

• callus is formed

what are the phases of fracture healing?

1. hematoma

2. inflammation

3. soft callus

4. hard callus

5. remodeling

what happens during the hematoma phase?

• bleeding

• fibrin clot will form

what happens during the phase of inflammation?

• cells involved

  • cells

  • macrophages

  • mesenchymal cells

• stem cell migrate to the fracture and form the granulation tissue and will release growth factors

• granulation tissue tolerates the greatest strain before failure

what two types of meds make fx healing harder and why ?

• COX-2 inhibitors and NSAIDs

• depress Runx2 which is important for differentiation of osteoblasts

what is secondary bone healing?

• healing through cartilage formation

• lack of stability helps the formation of cartilage which later on can change to endochondral ossification

what happens when a hard callus is formed?

type 2 collagen changes to type 1

what is type 1 collagen?

bone

what is type 2 collagen?

cartilage

blood flow is need to give the fracture site nutrients to heal. when does blood flow increase and when does it return to normal?

• 2 weeks

• 3 months

what happens during the remodeling phase?

• the woven bone will be replaced by stronger, laminar bone

• fracture healing will be complete with the continuation of the medullary cavity

when does the remodeling stage begin and end?

• 2 weeks

• continues for many years

how does the endochrondral bone formation occur?

• chondrocyte proliferation then hypertrophy

• matrix mineralization

• chondrocytes die

• vascular invasion, ossification, and remodeling to lamellar bone

what are the growth factors involved in fracture healing and what do they do?

• bone morphogenetic protein

• transforming growth factor beta (TGF-B1)

• insulin-like growth factor 2 (IGF2)

• platelet-derived growth factor (PDGF)

what does bone morphogenetic protein do?

osteoinductive causing the undifferentiated mesenchymal cells to differentiate into osteoblasts

what does transforming growth factor beta (TGF-B1) do?

will make the mesenchymal cells produce type 2 collagen and proteoglycans trying to produce endochondral ossification

what does insulin-like growth factor 2 (IGF-2) do?

stimulate type 1 collagen

what does platelet-derived growth factor (PDGF) do?

• attracts inflammatory cells to the fracture site (chemotactic)

• released from platelets