Week 2 - Lecture 2* - Tissue injury (continued from last lecture)

Question 1

What is considered to be good tissue health? Make the difference between a healthy tissue and any tissue that is weakened .

Answer 1

• Healthy tissue resists changes in their shape • Any tissue weakened by disease or trauma may not be able to adequately resist the application of force

Question 2

What are tissue disuse?

Answer 2

Tissues adapt to decreased applied loads • Active and passive tissues become weaker • Less stress (load or force) to produce the same amount of strain (deformation)

Question 3

What are the basics of a tendon breakdown? Explain the difference between acute and chronic.

Answer 3

Weaker, stiffer and less likely to deform (reduced toe region) due to vascular, cellular and collagen-related changes associated with age • Acute: a known time and method of injury (partial tear to complete rupture) • Chronic: unknown onset but involves repetitive loading to cause damage

Question 4

What are the basics of ligament breakdown?

Answer 4

Insertion sites weaken with age, reducing strength and stiffness of tissue • Very sensitive to loading and loading history – without load rapid deterioration of biochemical and mechanical properties (reduced strength and stiffness) • When a ligament is taught for a particular joint position, an external load that results in any deformation of the tissue will exceed the elastic state and the ligament will fail

Question 5

What are the different tendon/ligament breakdown grades?

Answer 5

Question 6

What are the basics of cartilage breakdown?

Answer 6

• Disruption of synthesis and degradation in the ECM (softening)
• Lack of cyclical loading (immobility, bed rest) deprives tissue stresses required for healthy function
• Decreased stress leads to changes in collagen (weaker bonds and unorganized structural changes)
• Abnormal force transmission
• Less water, increased stiffness, more force translated to other tissues (e.g., bone) and experiences earlier plastic zone

Question 7

Explain the breakdown of cartilage with an image.

Answer 7

Question 8

What are the basics of bone breakdown?

Answer 8

Cortical bone stays well within the elastic region of the load-deform curve (very
little deformation)
• Sustained, repetitive loads over time à microtrauma
• Abrupt, high loads à fracture
• Absent mechanical forces à osteogenesis (fragile bone)

Question 9

What are the different types of fracture… bone breakdown?

Answer 9

Question 10

What are the basics of muscle breakdown?

*3 main factors = list and explain

Answer 10

• Age: reduced cross sectional area (# and size of fibers), decreased ROM and
power
• Immobility: decreased force production (smaller fibers, impaired activation)
• Injury: decreased force production (damaged sarcomeres, pain inhibition)
• Possible pain mechanisms

• • Reflex inhibition of motor units (to prevent further injury)
• • Central descending inhibition of injured muscles
• • Decreased motivation (cognitive effective)
• Reflex of motor units to prevent further injury = so if it is hot your taking away your hand and muscles contract but also antagonist muscles are asked to relax which could decrease how well the muscle worrk.

Question 11

What are examples of events that could cause some muscle to breakdown? (atrophy?***)

Answer 11

Contusions and strains are the most common
• Inadequate muscle flexibility
• Inadequate strength or endurance
• Uncoordinated muscle contraction
• Insufficient warm up
• Poor rehab

Question 12

Could medication also have an influence on muscle?

If yes, what kind of medications and why?

Answer 12

Corticosteroids
Weakening of passive tissue with prolonged use
Abnormal turnover of collagen fibers

Non-steroidal anti-inflammatory drugs (NSAIDs)
Interference with the healing process
Resultant healed tissue potentially weaker than if no NSAIDs consumed