tissues and cartilage

Question 1

what are the different types of connective tissue

Answer 1

• cartilage,
• tendon,
• ligament, and
• fascia / skin
are composed of various materials which give rise to ther individual mechanical characteritic
- however all have a same proportion of collagen fibres and elastic fibres

Question 2

what are the types of cartilage

Answer 2

1- articular cartilage
2- elastic cartilage
3- fibrocartilage

Question 3

artilcular cartilage

Answer 3

lines the ends of long bones and provides resilience and stopes the bones from wearing away
- avascular
composition includes:
- Cartilage cell (the chondrocyte)
- 60-80% water
- solid matrix composed of: collagen (stiffness & strength) and proteoglycan (a highly hydrated gel)
- cannot remodel following a lesion

Question 4

elastic cartilage

Answer 4

• Supports tissues and give tolerance for repeated bending - eg. nasal septum, outer ear
• Similar structure to articular cartilage, except a higher proportion of elastic fibres.

Question 5

fibrocartilage

Answer 5

• intermediarty tissue between articular cartilage and other dense connective tissue
• withstands heavy pressures and has high tensile strength
• distrabutes load to reduce contact stress

Question 6

the mechanical properties of tendons and ligaments will vary dependant on

Answer 6

• The proportion of collagen to elastic fibres;

* The arrangement of these collagen fibres.

Question 7

fascia and skin

Answer 7

• High proportion of elastic fibres
• Collagen fibres in random arrangement
Very stretchy !

Question 8

ligaments

Answer 8

• Stiff, but more variable than tendon
• Average 90% collagen fibres
• Some collagen fibres not parallel
Somewhat resistant to deformation - ability
to maintain joint stability

Question 9

tendons

Answer 9

• Very stiff
• High proportion of collagen fibres
(99% -- only 0.8% elastic)
• Collagen fibres in parallel bundles.
Resistant to deformation - transfers muscle
force directly to the bony lever.

Question 10

ligament remodelling

Answer 10

1- hypertrophy
2- immobilisation
3- reconditioning
4- effects of exercise during immobilisation

Question 11

hypertrophy

Answer 11

Responds to mechanical demands placed upon it.
Ligaments shown to hypertrophy after a 6-week training
program (Tipton, 1970). Ligaments were stiffer and stronger

Question 12

Immobalisation

Answer 12

Using an animal model, Radin et al. immobilised the lower limbs for 8 weeks in plaster casts
Ligaments associated with immobilised joints showed a 40% decrease in max. Load-to-failure compared to controls Immobilised ligaments were less stiff and elongated more

Question 13

Reconditioning

Answer 13

Noyes studied the effect following 5-months of reconditioning (after the immobilisation)
But, there still existed a 20% decrease in max. load-to-failure It took 12 months for the ACL to regain full strength

Question 14

what is the ageing process

Answer 14

1. Ageing produces changes in ligaments that are
   similar to that resulting from immobilisation.
2. Older subjects can show a 2 - 3 fold reduction in
   * max load-to-failure;
   * energy storage capacity; and
   * stiffness

Question 15

explain overstreched ligaments

Answer 15

• when a ligament is stretched within the ‘eastic region’ it will generally return to its orginal length
• if stretched beyond the yeild point it becomes non functioning

Question 16

explain taping of joints

Answer 16

Ligaments can be made slack and unstressed by habitual

taping (similar to immobilisation effect).

Question 17

why tape a joint

Answer 17

• playing following an injury
• to prevent injury when the probability is high
  X but not the habitual use of taping - ligament becomes
  accustomed to lower loads

Question 18

tendon loading

Answer 18

1- the contractile ability (strength) of the attached muscle; the relative size of the tendon to that of the muscle.
2- the strenght of a healthy tendon
3- Tendons are also equistressed units so that force produced in the muscle is evenly distributed over the cross-sectional area of the tendon.

Question 19

why do tendons tear

Answer 19

1- age
2- tendons are subjected to external loads
3- location: the break may occur in the bone or the tisse either side of the tendon