Connective Tissue Remodeling

Question 1

Physical Stress Theory

Answer 1

Changes in the level of physical stress cause a predictable adaptive response in all biological tissue

Mechanical forces direct cellular activity that can induce tissue adaptation

Question 2

Biochemical Changes with Immobilization

Answer 2

Decrease in collagen biosynthesis
(Decrease in enzyme activities, Decrease mRNA for type 1 and 3 collagen)

Increase in collagen degradation

Increase in weak cross-links

Decreased GAG, HA, & water content

Question 3

Morphologic Changes with Immobilization

Answer 3

Adhesions (scar tissue)
Less orderly arrangement of collagen fibers
Muscle shortens resulting in a loss of sarcomeres

Question 4

Contracture Trauma Process

Answer 4

Adaptive shortening of periarticular tissue
Collagen reorganization
Myofibroblast activation
Muscle shortening: loss of sarcomeres

Question 5

Adhesion Formation Trauma Process

Answer 5

Loss of gliding
Scar formation between two tissues that normally glide on each other (or “unfold”)

Question 6

Immobilization of Connective Tissue Leads to…

Answer 6

Decreased tissue stiffness (shortening)

Decreased load to failure (threshold changes)

Increased joint “stiffness” due to weakening and shortening of CT

Question 7

Three Phases of Wound Healing

Answer 7

Inflammation (0 - 5 days)
Fibroplasia / Repair (5 - 28 days)
Maturation / Remodeling (28 days - one year)

Question 8

Inflammation Stage

Answer 8

Necessary to start the healing process
- needed for the recruitment of neutrophils to destroy and degrade the environment
- recruitment of macrophages to clean up

Question 9

Fibroplasia (Repair) Phase

Answer 9

Fibroblasts secretes collagen
Tensile strength becomes greater than thickness at end stage

Question 10

Maturation (Remodeling) Phase

Answer 10

Improves the tensile strength of collagen
Continued loss of thickness reflects collagen turnover and remodeling

Question 11

Adhesions

Answer 11

Scar tissue that is between structures that would normally glide on one another (normal part of wound healing)

Undesired remodeling - Dense adhesion with attenuated tendon scar

Desired remodeling - flimsy adhesion with strong tendon scar

Question 12

Viscoelasticity

Answer 12

All biological tissues has it

Mechanical features:
Creep
Stress relaxation
Pre-conditioning

Transient in nature (blue jeans reference)

Question 13

Creep

Answer 13

Constant load (below elastic limit)
Deforms to a limit overtime

Ex: hanging wrist weight on stiff elbow

Question 14

Stress Relaxation

Answer 14

Constant length over time
Ex: locking stiff elbow in a splint at a fixed angle

Question 15

Preconditioning

Answer 15

Cyclic loading over time that creates deformation until a max load/stretch is tolerated (elastic limit)
Temporarily “all stretched out”
Allows valid ROM comparisons between sessions

Ex: repetitive (on/off) stretch on stiff joints

Question 16

Stretch Model

Answer 16

Low level damage must occur in order to produce permanent elongation
Followed by classical inflammation, repair and remodeling

Question 17

Growth Model

Answer 17

Application of holding the tissue in a moderately lengthened position for a significant time and allowing the CT to “grow”

“Mechanical forces direct cellular level activities influencing the tissue level processes of growth, remodeling and repair..”

Question 18

Rehabilitation Joint “Stiffness” Stress “Dosage”

Answer 18

Overdose - increase in pain, decrease in ROM
Underdose - no change
Therapeutic dose - increase ROM, pain OK

Question 19

TERT

Answer 19

Total end range time
TERT = Frequency x Duration
“Dosage”

Question 20

LLPS and how to increase it

Answer 20

Low load prolonged stress

Increase TERT:
Simple positioning
Static splints
Dynamic splints
Static progressive splints
Continuous passive motion machine

Requires long durations

Question 21

Muscle Stretching

Answer 21

Gains in muscle “extensibility”
ROM gains do occur with stretching programs
Significantly less time required than CT (30 seconds minimum)

Primary mechanism may be a change in sensory status, rather than true increased length