fracture , classification and fracture healing

Fracture, classification and Fracture healing

Dr Dipendra Maharjan

What do you see???

Fig. A Fig. B

Fracture• A disruption or break

in the continuity of the structure of bone

• Traumatic injuries account for the majority of fractures

Classification of fracture

• On the basis of etiology• On the basis of displacement• On the basis of communication with external

environment• On the basis of site of fracture• On the basis of fracture morphology• On the basis of stability

• On the basis of etiology– Traumatic– Atraumatic

• Pathological• Stress

fracture• Insufficiency

fracture

Stress Fracture

Pathological Fracture

Insufficiency Fracture

‘

Traumatic Fracture

• On the basis of displacement– Un-displaced– Displaced

Displaced FractureUn-displaced Fracture

• On the basis of communication with external environment– Closed Fracture– Open Fracture

• On the basis of site of fracture– Epiphyseal fracture– Metaphyseal– Diaphyseal• Upper third• Middle third• Lower third• Junctional

• On the basis of fracture morphology– Transverse– Spiral– Oblique– Comminuted– Impacted– Segmental– Avulsion

• On the basis of stability– Stable• Occur when a piece of

the periosteum is intact across the fracture

– Unstable• Grossly displaced• Periosteum completely torn

AO Classification

AO classification

Fracture Healing

What is fracture healing?

• Proliferative physiological state

• Restores the tissue to its original physical and mechanical properties

• Influenced by a variety of systemic and local factors

Types of Fracture Healing

• Primary Healing (Direct)

• Secondary Healing (Indirect)

• Distraction Osteogenesis

Primary Healing• Osteonal Healing

– Involves direct attempt by the cortex to reestablish itself

– Gaps in reduction heal by vessel ingrowth-mesenchymal cells- osteoblasts-osteoclast cutting cones

– Direct contact areas heal by cutting cones allowing passage of vessels

• Resembles normal remodelling

• Occurs only with anatomic reduction & rigid fixation

Secondary healing• Enchondral Healing

– Response of periosteum/ external soft tissues

– Recapitulation of embryonic intramembranous ossification and endochondral ossification

– Intramembraneous= peripheral to fracture

– Endochondral= adjacent to fracture

• Motion enhances periosteal response

• External soft tissue forms bridging callus (Periosteal bridging callus)

STAGES OF FRACTURE HEALING Cortical bone(FROST 1989)

• Inflammation phase– Stage of Hematoma Formation 1-2 Days– Stage of Inflammation 2-7 Days– Stage of Granulation

• Reparative phase– Stage of Soft Callus Formation 1-3 Weeks– Stage of Hard Callus Formation 3-6 Weeks

• Remodelling Phase >8. Weeks– Stage of Remodelling stage (Consolidation)– Stage of Modelling stage (Remodelling)

Inflammation Phase

• Hematoma (fibrin clot)• Macrophages• Inflammatory leukocytes• Osteoprogenitor cells• Hematopoietic cells secrete growth factors

• Granulation tissue

Reparative phase

• Primary callus response (2 weeks)• Inflammation triggers cell division and

angiogenesis• Chondrocytes secrete collagen and

proteoglycans• Creates fibrocartilage• Bone formation• Soft callus turns to hard callus (woven bone)

Re-modelling phase

• Begins during the middle of the repair phase• Continues up to years• Allows the bone to assume its normal

configuration• Wolff’s law– The stresses on the bone is directly proportional

to remodelling

Growth Factors

• Bone Morphogenic Protein– Osteoinductive– Mesenchymal cells to osteoblasts

• Transforming growth factor beta– Induces mesenchymal cells and osteoblast to

produce type II collagen– Regulates cartilage and bone formation in fracture

callus

• Insulin like growth factor II– Promote cell proliferation and matrix synthesis by

chondrocytes and osteoblasts– Responsible for formation of fracture callus

• Platelet derived growth factor– Stimulate osteoblast or osteoprogenitor cell activity– Promote bone formation

Principles of Fracture Healing

Stability and fracture Healing• Stability determines strain • Stain

– Strain is defined as change in fracture gap divided by the fracture gap (ΔL/L)– Highest fracture site strain is seen in a simple fracture

• Stability– Absolute stability – Relative stability

• Strain determines type of healing

– Strain less than 2% results in primary bone healing (endosteal healing).

– Strain 2% to 10% results in secondary bone healing (enchondral ossi cation).

– Strain greater than 10% does not permit bone formation.

The End!!!