MSK ligament and tendon

Question 1

What is a Tendon

Answer 1

Tendon are dense connective tissue which attach Muscle to bone.

They are made up of Longitudinally arranged collagen Fibres

Question 2

What are the most abundant form of collagen fibres in the body

Answer 2

Type 1 collagen = It comprises 70-80% of the dry weight of a normal tendon

Question 3

What are Tendon made up of

Answer 3

Collagen

Fibroblast cells:

Tenoblasts/Tenocytes = Immature tendon cells involved in the synthesis of collagen

Glycoproteins

Elastin

Question 4

What is the Function of Tendons

Answer 4

Store and return elastic energy
Transmit muscle forces to the skeleton for movement
Provide force feeback to the nervous sytem via golgi tendon

Question 5

What is the Stretch Shortening Cycle

Answer 5

This refers to the muscle action which occurs when active muscle lengthening is immeadiately followed by active muscle shortening to produce more force and move quicker.

Question 6

What are the 3 phases of Stretch Shortening Cycle

Answer 6

Eccentric / Lengthening - increases elastic tension in structural proteins increasing potential energy/stored energy

Aromatization / Isometric - Period between eccentric and concentric contraction

Concentric / shortening - Stretch reflex activates the muscle releasing potential energy as Kinetic energy producing more force

Question 7

Explain how Youngs Modulus can be applied to tendon adaption and injury

Answer 7

Tendons are exposed to large tensile forces

When a Tendon is stretched the length of the tendon increases

When the external stretching force is removed, the Tendon goes back to its normal state

If the force exceeds a certain magnitude the Tendon will rupture

This can be demonstrated by the stress strain curve

Question 8

Explain the 4 regions of the stress strain curve

Answer 8

Toe Region = Tendon Fibrils unwind from mechanical loading but the stress and strain remains minimal Non Linear

Elastic Region = Fibres begin to unfirl but they still have 100% elastic recoil, the Tendon deforms in a Linear fashion in the direction of the tensile mechanical load.
Yeild Point is the physiological upper limit of tendon starin.

Plastic Region = Tendon stretches beyond its Physiological limit and crosslink between collagen fibres fail. This can sometimes be a good thing i.e. if contracture is present. Stress and Strain are at the highest point.

Faliure Point = The tendon has stretched way beyond its physiological limit and Injury has occured. Notice the Stress curve drops off, this is because the Tendon has ruptured.

Question 9

What are the Tendon Injury Risk Factors

Answer 9

Age - Collagen Synthesis decreases from 30’s onwards and non enzymatic crosslinks increase (Diminish muscle quality and function)

Sex - Changes in estrogen levels affect collagen synthesis, spike in estrogen causes decrease in collagen crosslinking resulting in increased risk of injury

Medication - increased incidence of tendon rupture amongst individuals taking fluoroquinolone antibiotics corticosteroid therapy. NSAID inhibit healing.

Smoking - Decrease synthesis of type 1 and 2 collagen by 18% and 22% respectivley

Nutrition - good nutrition improves tissue recovery and collagen synthesis

Genetics