Week 3 - Tissue Response to Injury Flashcards
3 phases of the healing process?
Inflammatory Response Phase
Fibroblastic Repair Phase
Maturation-Remodeling Phase
5 signs of inflammation (SHARP)
Swell
Heat
Altered Function
Redness
Pain
Inflammatory Response Phase SEQUENCE (6 steps)?
1- Injury to cell
2- release Chem messengers
3- Vascular Reaction
4- Platelets/ leukocytes adhere to vascular wall
5- Phagocytosis
6- Clot formation
IRP 1 and 2?
Cell injury results in release of chemical messengers
- Histamine (vasodilation)
- Leuktrines/ prostaglandins (increases permeability)
- Cytokines
IRP part 3?
Vascular Reaction
- Initial vasoconstriction (5-10 min) to seal vessels
- Vasodilation (24-36 hrs) to increase blood flow
- Swelling is proportional to vessel damage
IRP stage 4?
Platelets adhere to exposed collagen fibers inside vessel = form PLUG
IRP stage 5?
Injured area gets walled of so Leukocytes can phagocytize foreign debris
IRP stage 6?
Clot formation
- 12-48hrs post
- thromboplastin converted to prothrombin and then thrombin which converts fibrinogen to fibrin which initiates clotting
Goals of the Inflammatory Response Phase?
Protect
Localize
Decrease injurious agents
Prepare for healing and repair
Fibroblastic Repair Phase?
- Cell proliferation/ regeneration
- Scar-tisse is formed
- Granulation tissue - a delicate CT fills the gaps as the clot is broken down
- Fibroblasts synthesize the extracellular matrix
- Fibroblasts start forming collagen (day 6-7) - laid at random (3 types)
3 types of collagen?
T1 = ligs., tendons, fascia, skin, bone, cartilage interstitial tissue
T2 = hyaline cartilage, vertebral discs
T3 = skin, blood vessels, smooth msc, nerves.
- most common cartilage laid in this phase
-low tensile strength
Maturation Remodelling Phase?
- Realign scar tissue along lines of tensile force
- Increased T1 collagen and decreased T3
- Tensile strength increases as collagen type is becomes more specialized
- By 3 weeks - firm + nonvascular scar exists - allows for proper function
- Usually not much scar tissue formed
- Maturation can take years
Bone vs Soft Tissue Healing?
IRP is identical
Fibroblastic Repair Phases
- osteoblasts form callus at injured site
- Callus = cartilage and collagen to fill fracture site
- immobilization required
MRP
- bony callus becomes strong
Chronic Inflammation causes?
IRP continues, then excessive fibrogenesis results in LT- tissue damage
- Overuse/ repetitive microtrauma
- Low levels of plasma cells, macrophages, lymphocytes, and fibroblasts cause damage to CT.
- Ganulized tissue and fibrous CT forms and healing process is prolonged
How to Optimize Healing Process?
Maintain some immobilization during IRP (for clot formation)
In FRP, add controlled activity (except for #) - use braces
In MRP, aggressive ROM and strength exercises - facilitates optimal remodelling and alignment
Be aware of too much pain/ inflammation –> may mean too much activity too soon
Factors that Affect Healing
- Extent of injuries
- Edema
- Hemorrhage
- Vascular Supply
- Tissue separation
- Msc Guarding
- Corticosteroids
- Humidity/ O2
- Infection
- Age, health, nurtition
- Initial First Aid
Soft tissue?
Anything not bone –> epithelial, connective, msc, nervous
Metaplasia?
Tissue changes to an abonormal type
Dysplasia
Abnormal Tissue development
Hyperplasia
excessive proliferation of normal cells
Cartilage Healing?
- limited ability b/c low blood supply
- No IRP unless subchondral bone is affected
- 2 months for normal collagen formation
Lig. Healing?
vascularized but less than msc/ bone so slower healing
- IRP w/in 72hrs
- FRP - over 6 weeks
- Up to 1 year for collagen fibers to fully align to Stress/ Strain
Intracapsular Ligs. (ACL/PCL)
- healing slowed by synovial fluid
- longer healing and probably surgery
- Fibrous scarring lengthens the ligs. = instability
- Limit immobilization
- Strengthen surrounding structures
Msc Healing?
- Follows the 3 stages of healing
- Myoblasts form that regenerate myofibrils
- Need active contraction to allow orientation of collagen fibers
- 6-8 weeks
Tendon Healing?
Collagen synthesis needed for tendon strength can result in fibrosis (excess synthesis)
- decrease smooth glide
- Goal of healing is to regain smooth glide (week 2)
- ## 4-5 weeks for full strength
Nerve Healing?
If cell body dies or if CNS n. = no regeneration
- PNS heals 3-4mm/day (better if further from Soma)
Modifying Soft-tissue Healing?
NSAIDs
- analgesics (for pain), reduce inflammation
- May delay healing in acute phase b/c decreased inflammation
Therapeutic Modalities
- Heat
- cold
- Electrical
Therapeutic exercise
- ROM, strength, neuromsc control
Bone Healing?
Follows 3 stages of healing
= bleeding = clot
- 1 week chondroblasts form soft callus
- immobilize 3-8 weeks
-
Healing for STress #
Identify Ealry and decrease activity
Wolfs Law?
Bone changes size/ shape/ structure to adapt to mechanical stress/ strain
- So, once healed bone needs to be placed under normal stress/ strain to regain tensile strength
Factors that affect # healing?
Blood supply (avascular necrosis - causes bone death0
- Immobilization (or lack of)
- Infection
- # severity
- # site
- age
