Tissue And Bone Healing Flashcards
What are the 5 phases of healing?
Injury Hemostasis and degradation Inflammation Proliferation and Migration Remodeling & Maturation
What occurs in the hemostatic response?
Sealing off of blood vessels
Platelets create fibrin lattice which provides wound with tensile strength during inflammation
Platelets release growth factors that summon the inflammatory response
What occurs during degradation?
Formation of a hematoma (blood clot outside of vessel)
Necrosis: if tissue damage is extensive/severe cells will die
What 4 responses take place during inflammation?
Vascular Response
Humoral Response
Neurological Response
Cellular Response
What are the three cardinal signs of inflammation?
Rubor (redness)
Calor (heat)
Dolor (pain)
What occurs during the vascular response? What is hemoconcentration?
Vasodilation takes place pushing fluid into the interstitial space to cause edema (membrane permeability increases)
Hemoconcentration: increased viscosity of blood to prevent leaking of fluid from the wound
WBC line the blood vessel
What occurs during the humoral response via the complement system?
Humoral response is a complement system activated via antibody antigen association
It is a series of enzymatic plasma proteins that:
- Increase vascular permeability
- Stimulates phagocytosis
- Act as chemostatic stimuli for leukocytes
What cells are involved in the cellular response? What occurs during this response?
Killing and removing bacteria
T-lymphocytes: activate inflammatory mediators
B-Cells: plasma cells that antiBodies that bind to bacteria and prepare them for phagocytosis
Macrophages: Phagocytes that kill bacteria and remove waste
What occurs during the neural response?
Cytokines stimulate the hypothalamus
Glucocorticoids regulate NK, T, B cells and macrophage function
Hypothalamus: mediates vascular response via the SNS
What is the time frame for proliferation? What four process occur in this response?
Day 3-20
- Neovascularization: formation of new blood vessels
- Neoepithelialization: formation of new cells
- Collagen formation
- Wound contraction
What cell creates collagen? What are the different collage orientations?
Fibroblasts
Random: for flexibility and rigidity
Parallel/Unidirectional: tensile strength
What is the collagen timeline?
Day 7: Type III collage is laid down (weak)
Day 12: Type III is replaced by type I (stronger/tensile)
Day 21: MAX collagen production; 20% strength restored
6 weeks: 80% strength restored
Which phase is the longest, and what takes place in this phase?
Maturation: Day 9 forward
- Collagen Synthesis (12-24 months) O2 DEPENDENT
- Collagen Fiber Orientation: broken down and rearranged to withstand tensile strength
- Scar relaxes, lightens, and strengthens
What is the ultimate goal for healing?
Restoring prior function
What factor determines whether lung tissue will heal?
Intact basement membrane
Yes: Pneumocytes (1 for gas exchange; 2 for surfactant)
Not intact: fibrosis in lungs
What is neuroplasticity?
Rewiring of healthy function neurons NOT regeneration of new neurons
Damage to the CNS stimulates the formation of what?
Fibrous glial scar made up of astrocytes, oligodendrocytes, and microglia
- Forms physical barrier
- Inhibits neuronal regeneration
Describe peripheral nerve healing
Peripheral nerves can regenerate
Glial scarring is not an issue
Wallerian Degeneration: takes 7-14 days for peripheral n. To regenerate
Cranial Nerve Healing
Some cranial nerves heal like the CNS and others like the PNS
CNS: 1,2,6,9,10,11,12
PNS: 3,4,5,7
8 –> regeneration possible but rare
What is the determining factor for muscle repair and healing?
Intact endomysium
Yes: muscle regeneration
No: necrosis/fibrosis
How long does it take to regain normal tensile strength?
50 weeks
What are the two causes of tendinopathy?
Repetitive trauma
Excessive loading
What forms when the synovium of a tendon is injured?
Adhesion formation (prevents gliding of the joint)
What is the rehab protocol for sutured tendons? (Rest, gentle PROM, AAROM)
Protected rest: 3-5 days
Gentle PROM: 5-28 days
AAROM: weeks 4-8
What is the prognosis for ligament tears? (Which one is worse?)
Stage 1 > Stage 2 > Stage 3 tears
Capsular/Intracapsular > Extracapsular
What occurs with articular cartilage repair?
Articular cartilage is avascular tissue
Heals by forming fibrous scar on bone
Micro fracture surgery performed to remove calcified cartilage via the drilling of small holes in subchondral bone. Bleeding allows for cartilage regeneration.
Where is the meniscus most likely to heal?
Periphery because that is where it is highly vascularized (red-red zone)
What is the healing capacity of intervertebral discs?
Minimal healing of the annulus only in the periphery
Majority of disk is avascular so lack of blood flow limits healing capacity
