Tendons and Ligaments Flashcards

1
Q

What are ligaments?

A

Ligaments
•Resist distraction of two bony attachments
•Collateral ligaments
•Suspensory ligament

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2
Q

What are tendons?

A

Tendons
•Passively transfer force generated by muscle to bones to provide movement
•Cross over joints

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3
Q

What are tendons and ligaments made up of?

A

Fibrils -collagen
Fibres
Fascicles

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4
Q

What is the anatomical structure of a tendon?

A
•Endotenon
-Confluent with epitenon
-Around fascicles
-Contains vessels and nerves
•Epitenon
•Paratenon/tendon sheath
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5
Q

What is crimp?

A

•Crimp
•Wavy appearance of collagen fibrils under light microscope
•Responsible for part of the elasticity
•With loading core fibrils straightened first
 Site of pathological lesions

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6
Q

What is crimp effected by?

A

Crimping also reduced with age and long-term exercise

 Exercise accelerates age related degenerative changes

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7
Q

why do tendons take so long to heal?

A

have a very low blood supply (less than bone)

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8
Q

What is the blood supply of tendons?

A
•Blood supply
-Musculotendinous junction
-Osseous insertion
-Intratendinous along endotenon
•Diffusion
-Tendon sheath
-Synovial fluid
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9
Q

What is blood supply effected by?

A
  • Blood flow highest in foals
  • Decreases to adult levels by 3yo
  • Increased by exercise
  • Increased by injury
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10
Q

What are the cellular components of tendons and ligaments?

A
  • Ligaments possess much higher cell population than tendons
  • Tenocytes (tendon cells)
  • Formation and maintenance of ECM
  • React rapidly to mechanical stimuli
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11
Q

What is extracellular matrix made up of?

A
  • Determine biomechanical characteristics
  • 65% water
  • 30% collagen
  • 5% non-collagenous glycoproteins
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12
Q

What is collagen?

A
  • 80% dry weight
  • 95% type I collagen
  • Covalent cross-links determine strength
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13
Q

What are non-collagenous glycoproteins?

A
  • Cartilage oligomeric matrix protein [COMP]
  • Assists in organisation of collagen network
  • Proteoglycans
  • Structural integrity
  • Metabolism regulation
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14
Q
What is;
Tendinitis
Tenosynovitis
Adhesive tenosynovitis 
Desmitis?
A

tendinitis- inflamed tendons

tenosynovitis- inflammatory condition occurring within a sheath

Adhesive tenosynovitis- tendons within a sheath stick together

desmitis- ligaments inflammation

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15
Q

What is an extrinsic tendon and ligament injury?

A

percutaneous injury or displacement

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16
Q

What is an intrinsic tendon and ligament injury?

A

strain or sprain

most common type of injury in horses

17
Q

What is the range of tendon and ligament injuries?

A
  • Individual fibril or fibre slippage- microdamage
  • Individual fibril or fibre rupture- fibres out of alignment
  • Progressive rupture of fibres/fascicles
  • Complete rupture/tear
18
Q

What are developmental issues in tendons?

A

•Load during growth affects COMP levels
(cartilage oligomeric matrix protein)
COMP associated with tendon strength
Lack of exercise during growth period reduces tendon quality
Too much exercise during growth increases risk of damage
•Crimp development affected by exercise during development
•After skeletal maturity tendon has limited ability to adapt
•Period of optimal conditioning of tendon for athletic performance

19
Q

What is tendon mechanical degeneration?

A
•Mechanical degeneration
•Low-grade mechanical forces
 Cumulative fatigue microdamage
•Supra-maximal loading
 Clinical tendonitis
20
Q

What is hysteresis?

A
  • Loss of energy between loading and unloading cycles
  • Heat
  • Exercise-induced hyperthermia
  • Hysteresis loop
  • Up to 45ºC
  • Reduction in normal synthetic cell activity
  • Denaturing of ECM proteins
21
Q

What is the tendon injury, vascular compromise?

A

•Vascular compromise
•Blood flow limited/abolished under maximal loading
•Some areas poorly perfused
Predisposed sites
•Tenocytes relatively resistant to hypoxia (lack of oxygen supply)
•Enzymes
•Imbalance between matrix synthesis and degradation

22
Q

What is the tendon injury, tendinopathy?

A
  • Tendinopathy
  • Subclinical tendon degeneration
  • Clinical tendinopathy
  • Acute inflammatory phase
  • Subacute reparative phase
  • Chronic remodeling phase
23
Q

What does the acute inflammatory phase of tendon repair involve?

A
  • 1-2 weeks
  • Intratendinous haemorrhage
  • Oedema
  • Infiltration of WBC
  • Release of proteolytic enzymes (enzymes which break down bonds between animo acids)
  • May cause expansion of lesion
24
Q

What does the subacute reparative phase of tendon repair involve?

A
  • Starts a few days after injury
  • Peaks at 4 weeks
  • Angiogenesis
  • Accumulation of fibroblasts
  • Resident tenocytes
  • Endo/paratenon cells
  • Circulating monocytes
  • Synthesis of disorganised collagen (type III)
25
Q

What does the chronic remodelling phase of tendon repair involve?

A
  • Begins 6 weeks post-injury
  • Progresses for 6-24 months or more
  • Remodelling of disorganised scar tissue
  • Cross-linking of fibrils
  • Controlled loading promotes conversion and organised alignment of collagen fibrils
26
Q

How effective is the healing of the tendon sheath?

A
•Poor healing
•Lack of paratenon
 Lack of external blood supply
•Adhesion formation allows angiogenesis (development of new blood vessels) and cell infiltration
•Reduction of function of tendon
27
Q

How do tendons repair?

A
Healed tendon lacks mechanical
properties of original tissue
• Often stronger
• Poor elasticity
 Increased strain in adjacent
tendon

Re-injury common
• Same tendon
• Contralateral tendon
• Other supporting structures

28
Q

What are the functional characteristics of tendons?

A

Weight-bearing tendons
•Flexor tendons
•More elastic
•Energy stores

Positional tendons
•Extensor tendons
•Stiffer

29
Q

What are the functional characteristics of flexor tendons and suspensory ligaments?

A
  • Support fetlock joints during normal weight-bearing
  • Large loads due to hyperextension of fetlock
  • Considerable elasticity
  • Store energy for energy efficient locomotion
30
Q

What are superficial and deep digital flexor tendons?

A

•Highly pennate muscle
•Maximises power with minimal contraction distance
•Action: shock absorption
 Fast gaits: functions like pogo stick
 Reaches and maintains high speed with minimal energy expenditure