Tissue And Bone Healing

Question 1

What are the 5 phases of healing?

Answer 1

Injury
Hemostasis and degradation 
Inflammation
Proliferation and Migration
Remodeling & Maturation

Question 2

What occurs in the hemostatic response?

Answer 2

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

Question 3

What occurs during degradation?

Answer 3

Formation of a hematoma (blood clot outside of vessel)

Necrosis: if tissue damage is extensive/severe cells will die

Question 4

What 4 responses take place during inflammation?

Answer 4

Vascular Response
Humoral Response
Neurological Response
Cellular Response

Question 5

What are the three cardinal signs of inflammation?

Answer 5

Rubor (redness)
Calor (heat)
Dolor (pain)

Question 6

What occurs during the vascular response? What is hemoconcentration?

Answer 6

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

Question 7

What occurs during the humoral response via the complement system?

Answer 7

Humoral response is a complement system activated via antibody antigen association

It is a series of enzymatic plasma proteins that:

1. Increase vascular permeability
2. Stimulates phagocytosis
3. Act as chemostatic stimuli for leukocytes

Question 8

What cells are involved in the cellular response? What occurs during this response?

Answer 8

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

Question 9

What occurs during the neural response?

Answer 9

Cytokines stimulate the hypothalamus

Glucocorticoids regulate NK, T, B cells and macrophage function

Hypothalamus: mediates vascular response via the SNS

Question 10

What is the time frame for proliferation? What four process occur in this response?

Answer 10

Day 3-20

1. Neovascularization: formation of new blood vessels
2. Neoepithelialization: formation of new cells
3. Collagen formation
4. Wound contraction

Question 11

What cell creates collagen? What are the different collage orientations?

Answer 11

Fibroblasts

Random: for flexibility and rigidity
Parallel/Unidirectional: tensile strength

Question 12

What is the collagen timeline?

Answer 12

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

Question 13

Which phase is the longest, and what takes place in this phase?

Answer 13

Maturation: Day 9 forward

1. Collagen Synthesis (12-24 months) O2 DEPENDENT
2. Collagen Fiber Orientation: broken down and rearranged to withstand tensile strength
3. Scar relaxes, lightens, and strengthens

Question 14

What is the ultimate goal for healing?

Answer 14

Restoring prior function

Question 15

What factor determines whether lung tissue will heal?

Answer 15

Intact basement membrane

Yes: Pneumocytes (1 for gas exchange; 2 for surfactant)

Not intact: fibrosis in lungs

Question 16

What is neuroplasticity?

Answer 16

Rewiring of healthy function neurons NOT regeneration of new neurons

Question 17

Damage to the CNS stimulates the formation of what?

Answer 17

Fibrous glial scar made up of astrocytes, oligodendrocytes, and microglia

1. Forms physical barrier
2. Inhibits neuronal regeneration

Question 18

Describe peripheral nerve healing

Answer 18

Peripheral nerves can regenerate
Glial scarring is not an issue
Wallerian Degeneration: takes 7-14 days for peripheral n. To regenerate

Question 19

Cranial Nerve Healing

Answer 19

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

Question 20

What is the determining factor for muscle repair and healing?

Answer 20

Intact endomysium

Yes: muscle regeneration
No: necrosis/fibrosis

Question 21

How long does it take to regain normal tensile strength?

Answer 21

50 weeks

Question 22

What are the two causes of tendinopathy?

Answer 22

Repetitive trauma

Excessive loading

Question 23

What forms when the synovium of a tendon is injured?

Answer 23

Adhesion formation (prevents gliding of the joint)

Question 24

What is the rehab protocol for sutured tendons? (Rest, gentle PROM, AAROM)

Answer 24

Protected rest: 3-5 days
Gentle PROM: 5-28 days
AAROM: weeks 4-8

Question 25

What is the prognosis for ligament tears? (Which one is worse?)

Answer 25

Stage 1 > Stage 2 > Stage 3 tears

Capsular/Intracapsular > Extracapsular

Question 26

What occurs with articular cartilage repair?

Answer 26

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.

Question 27

Where is the meniscus most likely to heal?

Answer 27

Periphery because that is where it is highly vascularized (red-red zone)

Question 28

What is the healing capacity of intervertebral discs?

Answer 28

Minimal healing of the annulus only in the periphery

Majority of disk is avascular so lack of blood flow limits healing capacity