STI 2 Unit 3: Physiology and Pathological Changes

Question 1

What are the 4 phases of the scar process?

Answer 1

1) Inflammatory Phase
2) Granulation Phase
3) Fibroblastic Phase
4) Maturation Phase

Question 2

What are the characteristics of the Inflammatory phase?

Answer 2

The first phase seen after trauma

• This phase begins immediately and may last 24-48 hours, injury causes chemical and mechanical changes which leads to the cardinal signs of inflammation: heat, redness, swelling and pain.
• Movement in the wound area would be disadvantageous, as it could lead to further tissue and/or clot disruption. Modalities aimed at decreasing inflammation and proper positioning, in addition to appropriate med. are of the most value at this point

Question 3

During the Inflammatory Phase, injured tissues release what?

Answer 3

Histamine is released by the injured tissues, resulting in vasodilation and the appearance of a reddened, hot, and swollen region

Question 4

What are the characteristics of the Granulation phase?

Answer 4

This begins when the macorphages and hystiocytes debride the area

• The granulation stage is so named becuase of the appearance of capillary buds, which, under a microscope, look like granules
• Healing cannot proceed further unless this increased connective tissue vascularity can meet the metabolic demands of the healing tissue
• Immobilization is essential during this phase to permit vascular regrowth and to prevent further micohemorrhages and tissue breakdown
• One closure in 5-8 days

Heat application at this point may cause increased bleeding in the fagile healing tissue

Question 5

What are the characteristics of the Fibroblastic phase?

Answer 5

• Fibroblast proliferate, and collagen synthesis is accelerated.
• As the fibroblast proliferate, new collagen is laid down in a disorganized manner in the area of the wound, the stretch of the wound is determined by collagen filaments or cross-links (allows for early controlled motion without disruption of the wound)
• Wound closure usually occurs at this stage, and the time frame varies depending on the vascularity and metabolic rate of the tissue
• Gentle handling of the wound is essential and gentle manual therapy techniques may be appropriate, this is designed to break up scar tissue which will inflame the wound leading to further collagen deposits

Question 6

What are the characteristics of the Maturation phase?

Answer 6

• This stage may last from 3 weeks to 12 months
• During this stage, collagen must change in order to reach maximum function. A reduction in wound size, a realignment of collagen fibers and an increase in the strength of the scar are all characteristics of this phsae

Question 7

What is the Fibrotic Process?

Answer 7

This is a homogeneous process involving an entire tissue area or the entire tissue “fabric” and does not have clear-cut stages.
- The Fibrotic process is cyclical. This process can continue as long as the irritant is present
- This is initiated by the production of an irritant, possibly exudates from nearby, acutely inflamed, traumatized tissue or a low-grade irritation or inflammation of the tissue

Question 8

What happens when non-traumatized joints are subject to immobilization?

Answer 8

Stress-deprived connective cells exhibit changes within 4-5 days. Intrinsic changes to periarticular connective tissues begin to limit mobility

Question 9

What was the study that Akeson, Amiel and Woo did with non-traumitized connective tissue?

Answer 9

They conducted a study primarily utilizing the knee joints, they immobilized lab animals by internal fixation for periods from 2 to 9 weeks. A pin was placed from the proximal third of the femur to the distal third of the tibial, presumably to avoid traumatizing the knee joint.
- The animals were then euthanized at various lengths
- The authors found fibrofatty infiltrate, especially in the capsular folds and recesses.
- The longer the immobilization, the greater the infiltrate found
- A more protected period of immobility also resulted in a change in the infiltrate’s appearance, which became more fibrotic
- The fibrious infiltrate created macroscopic adhesions in the recesses and capsular folds

Question 10

With the Study Akeson, Amiel and Woo conducted, what were their histological and histochemical findings?

Answer 10

They found several significant changes, the primary one being a significant loss in ground substance with no significant collagen loss.
- The primary components of lost ground substance were glycosaminoglycans (GAGs) and water.

Question 11

With the study Akeson, Amiel and Woo conducted, why were there significant amounts of ground substance lost and not collagen?

Answer 11

The half-life of non-traumatized collagen is 300-500 days, whereas the half-life of ground substance is 1.7-7 days.
- Also, with immobilization time of less than 12 weeks, collagen synthesis occurs at the same rate as collagen degradation.
- After 12 weeks, however, the rate of collagen degradation exceeded the rate of synthesis, and net amounts of collagen are lost