Lecture 28 - Tendon and Ligament

Question 1

Ligament

Answer 1

Connect bone to bone

Question 2

3 functions of a ligament

Answer 2

1) Hold skeleton together
2) Provide stability to joints
3) Limit freedom of movement

Question 3

What are the 2 structural components of ligaments

Answer 3

1) Cells
2) ECM composed of Type I collagen and elastin

Question 4

T or F: Type I collagen fibrils are densely packed in ligaments

Answer 4

T

Question 5

What are 2 methods of attachment for ligaments

Answer 5

1) Direct: Fibers attach directly to bone
2) Indirect: Ligaments attach to superficial (blend into periosteum) or deep fibers (attach directly to bone)

Question 6

Do ligaments have blood supply

Answer 6

Yes, but vascularization varies by ligament

Question 7

What are the 2 types of nerves that innervate ligaments

Answer 7

1) Mechanoreceptors
2) Pain

Question 8

Stress strain curve of a ligament

Answer 8

Question 9

What are the 3 grades of ligament sprains

Answer 9

Question 10

4 phases of ligament injury healing

Answer 10

Question 11

What are 4 structural changes that occur to ligaments after healing

Answer 11

1) Altered proteoglycan and ratio of collagen fiber types
2) Failure of collagen cross-link maturation
3) Persistence of small collagen fibril size
4) Abnormal innervation

Question 12

What 4 factors effect ligament healing

Answer 12

1) Grade of injury (size of gap)
2) If the injury was isolated (heals better)
3) Type of ligament as some heal better than others due to different vasculature
4) Whether contact was made between ligament ends (ACL vs MCL injury)

Question 13

What are the 2 phases of healing with a patellar tendon graft following an ACL reconstruction and describe them

Answer 13

1) Intra-articular healing: Necrosis, vascularization, cell proliferation, collagen formation, and remodeling and maturation occur
2) Bone to tendon healing within the bone tunnel: Bone plugs to bone tunnel and tendon to bone tunnel form

Question 14

Tendon

Answer 14

Connect muscle to bone

Question 15

What are 2 functions of tendons

Answer 15

1) Force transmission between muscle and bone
2) Energy storage

Question 16

What 3 cells make up the tendon and their function

Answer 16

1) Tenoblasts: Immature tenocytes
2) Tenocytes: Synthesize collagen and all components of ECM
3) Chondrocytes: At bone insertion

Question 17

What are the 2 components of the ECM of tendons and what is found within these components

Answer 17

1. Fibrillar Component: Type I and III collagen, elastin
2. Interfibrillar Component: Proteoglycans, glycosaminoglycans

Question 18

Glycosaminoglycans function

Answer 18

Allows for greater tensile loading

Question 19

What is the hieararical order of tendons

Answer 19

1) Endotenon
2) Epitenon
3) Paratenon
4) Synovial tendon sheaths

Question 20

Endotenon

Answer 20

Covers primary, secondary and tertiary fibre bundles

Question 21

Epitenon

Answer 21

Loose connective tissue sheath that covers whole tendon and contains vascular, lymphatic and nerve supply to tendon

Question 22

Paratenon

Answer 22

Loose connective tissue that consists of type I and III collagen, and elastin that acts as an inner lining for synovial tissue

Question 23

Synovial Tendon Sheath

Answer 23

Found in areas of increased mechanical stress because it provides lubrication to reduce friction

Question 24

What are 2 points of attachment for tendons

Answer 24

1) Bones: Can be direct (bone) or indirect (periosteal)
2) Muscle: Blending of collagen fibers and muscle cells

Question 25

Where is the structurally weakest site mechanically for the muscle-tendon unit

Answer 25

Where the muscle attaches to tendon

Question 26

What is the consequence of tendons having a low metabolic rate

Answer 26

They heal slower with injury

Question 27

T or F: Tendons have vasculature in all 4 of its layers

Answer 27

T

Question 28

Where would we find reduced blood flow in tendons

Answer 28

Around bony prominences

Question 29

Where can we find tendons that have hypovascularity

Answer 29

1) Supraspinatus 2) Achlles tendon

Question 30

What are 3 types of mechanoreceptors for tendons and their function

Answer 30

1) Pacinian corpuscles: pressure and vibration 2) Ruffini endings: stretch 3) GTO: pressure and tension (at insertion of tendons into muscles)

Question 31

Tensile strength of tendons is related to

Answer 31

thickness and collagen content

Question 32

T or F: Strenuous activities place high demand on tendon, with eccentric contractions generating the highest force on a tendon

Answer 32

T

Question 33

Stress-strain curve for a tendon

Answer 33

Question 34

What are 2 types of tendon injury and how they occur

Answer 34

1) Tendon rupture: laceration, degeneration 2) Tendinopathy: overuse

Question 35

What are the 4 phases of healing for a tendon injury

Answer 35

Question 36

For a quadriceps tendon tear describe how and where it occurs and its signs/symptoms

Answer 36

Question 37

Treatment of a quadriceps tendon tear depends on what 3 factors

Answer 37

1. Size of tear 2) Activity level 3) Age of individual

Question 38

When would we do surgical treatment vs conservative treatment for quadriceps tenon tear

Answer 38

Surgical: Complete tear Conservative: Partial tear

Question 39

T or F: A quadriceps tendon tear results in a 50% decrease in weakness of the quad

Answer 39

T

Question 40

T or F: After remodeling, biomechanical and mechanical properties always return back to normal

Answer 40

F, the tendon tissue nerve matches intact tendon tissue

Question 41

What is a common site for a chronic tendon rupture

Answer 41

Supraspinatus

Question 42

What are 3 irreversible changes of a tendon rupture on muscle tissue

Answer 42

1) Atrophy 2) fatty infiltration 3) Loss of muscle strength

Question 43

Describe surgical repair effects on a tendon rupture

Answer 43

Tendon to bone healing does not result in normal tendon-bone insertion site and frequent re-separation occurs that can fill in with scar tissue causing loss of function

Question 44

What are 3 terms that are used to describe overused tendons

Answer 44

1. Tendinopathy: Tendon overuse 2. Tendinosis: Describes the extracellular matrix imbalances in tendinopathy 3. Tendinitis/Tendonitis: Inflammatory condition

Question 45

What are 3 age-related changes that affect tendon and ligament tissue

Answer 45

1. Loss of water content from matrix reduces ROM 2) Increased cross-linking increases stiffness and reduces ROM 3. Loss of elastic fibers cause less give to tendons and ligaments

Question 46

What are 4 effects of immobilization of ligaments and tendons

Answer 46

1) Decreased collagen content 2) Decreased cross-linking of collagen making weaker biomechanically 3) Subperiosteal bone resorption at ligament insertion site 4) Decrease in tensile strength of ligament

Question 47

What are 3 effects of exercise on tendons and ligaments

Answer 47

1) Increased collagen concentration and cross linking resulting in increase tensile strength and stiffness 2) Tendon hypertrophy from chronic increased loading 3) Structural and mechanical changes