C. Path Week 3: WOUND/FRACTURE HEALING

Healing by primary intention

Healing of closely apposed surfaces eg. Incision wound

Healing by secondary intention

Healing of open wounds eg. Avulsion wound

Stages of secondary intention wound healing

- Within 2 hours - bleeding, coagulation forms

- Day 1 - dehydration of coagulum, scab forms

- Day 1 - acute inflammation at wound margins (exudate/infiltrate)

- Day 2-3 - Vascular granulation tissue forms replacing acute inflammatory exudate/infiltrate. Fibroblasts, vascular sprouts and macrophages.

- Day 2-3 - Re-epithelialisation occurs where epithelium at wound margins regenerates towards injured tissue.

- Day 3-30 - Fibrous granulation tissue fully developed, collagen deposition occurs, myofibroblasts form (contain actin and myosin and contribute to wound contraction)

- Re-epithelialisation complete

- Several months - complete blanching of scar, wound fully healed.

Debridement

Wound needs to be appropriately cleaned to remove foreign debris, bacteria, necrotic tissue, excessive blood clot. Eg. Avulsion wounds

Simplification

Wound margins need to be approximated (by suture) to diminish time required for healing.

Complications of healing:

Cicatrisation - excessive scarring eg. Burn/scarring.

Keloid - masses of collagen scar even after trivial trauma eg. Vaccination, genetic disorder.

Excessive granulation tissue - Disruption of granulation tissue interferes with wound closure/healing Must be surgically removed E.g. ingrown toenail.

Delaying factors in wound healing: Localised factors

Act in vicinity of wound

1) Lack of adequate immobilization - granulation tissue is damaged

2) Lack of O2 (blood supply) - healing is an energy dependent process

3) Previous radiation exposure -reduces capacity for repair

4) Unsuccessful débridement - promotes infection & inflammation

5) Infection - the most important factor

Delaying factors in wound healing: General factors

Affect the whole body

1) Malnutrition - lack of protein, Vitamin C, zinc (required for collagen synthesis)

2) Increasing age - metabolic reactions slow down, systemic disease, malnourishment

3) Hormonal effects - Corticosteroids delay healing

4) Low temperature - ¯ rate of cell division

5) Other systemic disease e.g. Diabetes mellitus (poor blood flow)

Fractures

A fracture is any loss of continuity in the structure of a bone

Types of fractures:

- Transverse - horizontal across bone

- Oblique - on an angle across bone

- Spiral - twists around bone axis

- Avulsion - bone chipped away

- Comminuted fracture - shattered into pieces

- Complete fracture - bone is separated into 2 or more

- Incomplete - fracture half way through bone

- Compound - protrudes through skin

- Simple - doesnt break skin or muscle tissue

- Compression - spinal vertebrae collapsing

- Dislocation - fracture/dislocation occur at same time

- Double fracture - 2 breaks

- Greenstick - bone cracks and bends on one side.

- Impacted - when broken ends are jammed together

- Indirect - fracture occurs at different site to impact

Stages of fracture healing cont:

1 - 3 months - Definitive callus formation Woven bone removed by osteoclasts Orderly bone tissue laid down in Haversion systems by osteoblasts Bony spicules aligned along the lines of stress

3 - 12 months - Remodelling Surplus bony callus is removed by combination of osteoclastic erosion & orderly osteoblastic osteoid synthesis Resulting in near perfect bone regeneration

Complications of fracture healing

1 - Fibrous union Instead of bone, collagenous tissue is laid down, i.e. scar! Occurs with excessive movement or if soft tissues become interposed between the bony ends Can result in a pseudo-arthrosis - "false joint"

2 - Deformity, Angulation, Displacement - due to bone malalignment - prevented by inlay or onlay fixation

Delaying factors of fracture healing - Localised factors

LOCALISED FACTORS

1) Movement: More important in fractures

2) Infection: Osteomyelitis, gangrene, may need to amputate a limb

3) Lack of O2 (blood supply): An important factor (avascular necrosis of femoral head → arthroplasty, prosthesis)

4) Localised bone disease: Bone tumours can delay or completely prevent fracture healing

Delaying factors of fracture healing - Generalized factors

GENERALIZED FACTORS

1) Malnutrition: Lack of calcium, protein, vitamin D

2) Generalized vascular disease: Atherosclerosis

3) Generalized bone disease: Osteoporosis, osteomalacia

4) Other systemic diseases: Diabetes mellitus

5) Increasing age: efficiency of bone regeneration

Fracture Healing

Fractured bone ends should be in close apposition & fracture should be immobilized otherwise bone will not set in its anatomically correct position

Fracture Healing

Fractures can be immobilized through the use of splinting, pinning, plaster casts, traction.

Soft tissue damage is treated to prevent infection - bone then regenerates

Stages of Fracture healing

Day 1 - Hematoma formation, Acute inflammation

Day 2 - Demolition by osteoclasts Necrotic fragments of bone removed Broken ends of the bone are decalcified Fibrovascular granulation tissue formation (ingrowth of capillaries and fibroblasts from surrounding tissue)

Day 7-25 - Provisional callus formation Mesenchymal precursor cells develop into osteoprogenitor cells (these differentiate into osteoblasts and chondroblasts) Osteoblasts migrate into granulation tissue and deposit osteoid tissue, producing a woven bone pattern External and internal callus formation

Types of Wounds

Contusion - haematoma or bruise

Abrasion - scrape or graze

Avulsion - large open wound

Puncture - small, deep, penetrating wound

Laceration - torn, mangled tissue

Missile injury - high velocity puncture injury

Surgical wound - incisions, limited damage

Still learning (17)

You've begun learning these terms. Keep up the good work!