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PTA 230 (Ortho) > Ch 9: Ligament anatomy, mechanical properties, injury and repair > Flashcards

Ch 9: Ligament anatomy, mechanical properties, injury and repair Flashcards

1
Q

What is a band of grossly parallel, fibrous, dense connective tissues that connects bone to bone?

A

Ligament

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2
Q

What appears opaque, white band or cord like?

A

Ligament

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3
Q

What is composed of collagen, fibroblasts, extracellular matrix, and elastin?

A

Ligament

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4
Q

What is the predominant structural collagen in the body?

A

Type I

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5
Q

What type of collagen is very strong in mature scars?

A

Type I

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6
Q

What type of collagen is assembled in thin filaments and is more elastic in nature?

A

Type III

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7
Q

What type of collagen if usually seen in immature scars and is more prevalent in newborns and young children?

A

Type III

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8
Q

What is also found in ligamentous tissue?

A

Proteoglycans

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9
Q

What is protein-sugar conjugates that have major water-binding properties and appear to be responsible for controlling water composition and distribution in ligaments?

A

Proteoglycans

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10
Q

How much elastin are most ligaments composed of?

A

2%

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11
Q

What has a rich sensory innervation of specialized mechanoreceptors and free nerve endings that contribute to proprioception and pain?

A

Ligaments

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12
Q

What attaches bone to bone by indirect or direct transition?

A

Ligaments

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13
Q

What type of ligament insertion into bone represents a gradual change from specific ligament fiber to fibrocartilage to calcified fibrocartilage to bone?

A

Direct ligament insertion

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14
Q

What type of ligament insertion occurs when the superficial layers of ligament fibers attach directly in the periosteum, whereas deep fibers transition to bone by way of Sharpey’s perforating fibers?

A

Indirect ligament insertion

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15
Q

What is characterized behavior of ligament substance by direct influence?

A
  • Collagen composition
  • Proteoglycans
  • Glycosaminoglucans (GAG)
  • Orientation of fibers
  • Actions between extracellular matrix and ground substance
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16
Q

What factors affect the ligament mechanical and viscoelastic behavior?

A
  • Antaomical location
  • Cellular
  • Histologic
  • Ultrastructural
  • Biochemical
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17
Q

What do the unique difference between various ligaments influence?

A
  • Intrinsic healing abilities
  • PT procedures
  • Surgical interventions
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18
Q

What types of ligaments heal in a highly structured, organized, and predictable fashion?

A

Extraarticular ligaments

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19
Q

What are the four phases of ligament repair?

A
  • Phase I: Hemostasis, degeneration
  • Phase II: Inflammation
  • Phase III: Proliferation, migration
  • Phase IV: remodeling, degeneration
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20
Q

What types of ligaments do not heal spontaneously?

A

Intraarticular ligaments

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21
Q

What types of ligaments are considered Extraarticular?

A

MCL, LCL

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22
Q

What types of ligaments are considered intraarticular?

A

ACL, PCL

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23
Q

What tends to dilute hematoma formation between ends of injured ligaments, while preventing fibrin clot organization and ultimately limiting the intrinsic healing mechanism?

A

Intraarticular synovial fluid

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24
Q

Describe phase I (homeostasis and degeneration) of ligament trauma and healing

A
  • Inflammatory reaction to trauma of injury and repair cascade
  • Initially, injured ends of ligament retract and demonstrate highly disorganized appearance
  • Ligamentous microvascularity is disrupted
  • Hematoma forms between damage tissue
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25
Q

Describe phase II (inflammation) of ligament trauma and healing

A
  • Marked by the release of extremely potent chemical mediators of vasodilation, cell wall permeability, and pain in response to fibrin clot formation
  • Prostaglandins, histamine, bradykinins, and serotonin are mobilized to trauma sit to increase capillary permeability and profuse dilation of blood vessels
  • Allows for migration of specific inflammatory polymorphnuclear cells and lymphocytes to injured tissue to initiate action of ingestion (phagocytosis) to remove bacteria and dead tissue
  • Predominant cell types during acute inflammation: neutrophils and lymphocytes
26
Q

What are referred to as macrophages as they become phagocytes?

A

Monocytes

27
Q

Describe phase III (proliferation and migration) of ligament trauma and healing

A
  • Production of type III collagen, extracellular matrix, and proteoglycans by fibroblasts initiate beginning of phase III matrix and cellular proliferation after 2 days
  • Fibroblasts rapidly synthesize new extracellular matrix containing high concentrations of water, GAG; and relatively weak, fragile, immature type III collagen.
  • Neovascularization (angiogenesis) begins as granulation tissue attaches to damaged gap
  • Concentration of water, GAG, and type III collagen gradually decrease over several weeks
  • Inflammatory cytokines slowly remove from injury site
  • Fibroblastic activity synthesizes type I collagen during highly cellular repair
  • Decrease in vascularity within repair tissue as collagen concentration decreases
  • Matrix organization continues as fibrils of type I collagen align and arrange in response to applied stress
  • As density of collagen, elastin, and proteoglycans increase, tensile properties of repair tissue increases
28
Q

Describe phase IV (remodeling and degeneration) of ligament trauma and healing

A
  • Slow process that lasts 1 year or more
  • An overlapping transition from the matrix and cellular proliferation phase.
  • Active matrix synthesis decreases
  • Type III collagen transitions to type I collagen to improve stiffness
  • Remodeling is collagen organization and increases in tensile strength of repair tissue
29
Q

When intrinsically repairing extraarticular ligaments, what is the ultimate tensile strength after 1 year?

A

50-70%

30
Q

What is the most common of injury of joints?

A

Ligament sprains

31
Q

What is an injury to a skeletal ligament called?

A

Sprain

32
Q

What are the most common areas of sprains?

A

Knee

Ankle

33
Q

What is the percentage of MCL occurring compared to all knee injuries?

A

25-40%

34
Q

What factors affect ligament healing?

A

Blood supply
Function
Degree of injury
Mechanical stresses

35
Q

Which ligament heals better, MCL or ACL of knee?

A

MCL

36
Q

What 3 key conditions must be present for ligaments to remodel or heal properly?

A
  • Torn ligament ends must be in contact with each other
  • Progressive, controlled stress must be applied to healing tissues to orient scar tissue formation
  • Ligament must be protected against excessive forces during the remodeling process
37
Q

Rather than healing by true ligament regeneration how do untreated ligaments heal?

A

Scar tissue proliferation

38
Q

How long does it take untreated ligament tears that are biochemically inferior and possessing a large portion of type III immature collage to heal?

A

Greater than 40 weeks

39
Q

What are the grades of injury occurring to ligament tissue?

A

Grade I: miscroscopic tearing of ligament without producing joint laxity
Grade II: tearing of some ligament fibers with moderate laxity
Grade III: complete rupture of ligament with profound instability and laxity

40
Q

What grade of ligament injury occurs with a miscroscopic tearing of ligament without producing joint laxity?

A

Grade I

41
Q

What grade of ligament injury occurs with tearing of some ligament fibers with moderate laxity?

A

Grade II

42
Q

What grade of ligament injury occurs with complete rupture of ligament with profound instability and laxity?

A

Grade III

43
Q

What ligament grades are the most common?

A

Grade I and II

44
Q

How many knee sprains are classified as grade III sprains?

A

15%

45
Q

Which ligament grade sprain requires surgery?

A

Grade III

46
Q

How can we treat grade I and II ligament sprain injuries?

A
  • Protective braching
  • Comprehensive and progressive rehab
  • Appropriate strengthening
47
Q

What is often seen with primary ACL grade III injury?

A
  • Cartilage (menisci) injury
  • Injury related to MCL
  • Injury to Lateral collateral ligament
  • Injury to posterior cruciate ligament
48
Q

What are the factors that help determine whether to surgically repair ligament injuries?

A
  • Severity of injury (grade)
  • Anatomic location (biomechanical influences)
  • Vascular supply
49
Q

What process occurs when taking a graft from a tendon toward a tissue that closely resembles that of structural properties of a ligament?

A

Ligamentization

50
Q

What is the process/phases of ligamentization?

A
  • Necrosis (vascular supply is diminished after initial replacement, native cells diminish, hypocellularity occurs)
  • Revascularization (first 6-8 weeks at which acute inflammatory response is under control)
  • Cellular Proliferation (occurs as tissue begins to become more vascular, fibroblastic activity creates collagen and elastin)
  • Collagen formation and maturation (long-term process in which tissue gradually assumes a normal ligament appearance)
51
Q

Effects of immobilization on ligament tissue and associated structures?

A
  • Reduced physiologic motion
  • Decreased afferent neural input
  • Muscular atrophy
  • Ligament shortening
  • Reduction of water content, proteoglycans, and glycosaminoglycans
  • Bone loss, periosteal bone reabsorption
  • Articular (hyaline cartilage) erosion
  • Reduced ligament weight
  • Reduced ligament size
  • Reduced ligament strength
  • Adhesion formation
  • Increased ligament laxity
  • Joint stiffness related to synovial membrane adherence
52
Q

How long does it take for rigid immobilizations of joints to produce chemical and morphological changes in ligaments?

A

2-4 weeks

53
Q

After 8 weeks of immobilization, what occurs?

A
  • Lose 20% of weight
  • Significant atrophy
  • Marked infiltration of periarticular connective tissue
54
Q

After only 2 weeks of immobilization, what begins to occur?

A
  • Increased GAG synthesis and concentration
  • Decreased water content
  • Thickening of joint capsule and ligaments
  • Adaptive muscle shortening
  • Adhesion of formation of unopposed articular surfaces
55
Q

After only 4 weeks of immobilization, what begins to occur?

A
  • Biochemical and morphological changes more pronounced
  • Reduction of GAGs synthesis and water concentration
  • Fissures in articular cartilage
  • Increased ligament stiffness
  • Decreased capsular remodeling
  • Loss of normal fiber lubrication
  • Loss of spacing
  • Connective tissue disorganization
56
Q

After only 6 weeks of immobilization, what begins to occur?

A
  • Joint mobility significantly limited
  • Thickening in joint capsule, ligaments, and cartilage
  • Decreased ligamentous compliance
  • Progression of dense connective tissue remodeling (joint stiffness)
57
Q

During the first 2 weeks of immobilization, what appears to be the primary limiting factor in joint mobility?

A

Adaptive muscle shortening

58
Q

What does stress deprivation of ligaments secondary to immobilization lead to?

A

Atrophy

59
Q

What does motion, stress, and general physical activities prescribed for healing ligaments produce?

A
  • Hypertrophy

- Increased tensile strength

60
Q

What is related to the mode and duration of exercise used during rehabilitation?

A

Ligament and ligament-bone complex

61
Q

How long does it take to see the effects of mobilization and exercise after immobilization?

A

4 months-1 year

PTA 230 (Ortho) (55 decks)

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