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Limbs and Back > Rotator Cuff and Tendon > Flashcards

Rotator Cuff and Tendon Flashcards

1
Q

What are the four muscles of the rotator cuff?

A

Supraspinatus, Infraspinatus, Teres Minor and Subscapular

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2
Q

What is the function of the rotator cuff muscles as a whole?

A

They form a sleeve around the shoulder (Gleno-humeral) joint, compressing the humeral head into the glenoid cavity. They also provide stability for the joint.

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3
Q

Origin, Insertion, Innervation and Action: Supraspinatus

A

Origin: supraspinous fossa of scapula and deep fascia covering the muscle
Insertion: Greater tubule of the humerus
Innervation: Suprascapular Nerve (C5-C6)
Action: initiates first 15 degrees of abduction

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4
Q

Origin, Insertion, Innervation and Action: Infraspinatus

A

Origin: Infraspinous fossa of scapula and deep fascia covering muscle
Insertion: Greater tubule of humerus
Innervation: Suprascapular nerve (C5-C6)
Function: External/Lateral rotation

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5
Q

Origin, Insertion, Innervation and Action: Teres Minor

A

Origin: Lateral border of scapula
Insertion: Greater tubule of humerus
Innervation: Axillary Nerve (C5-C6)
Action: External/Lateral rotation

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6
Q

Origin, Insertion, Innervation and Action: Subscapularis

A

Origin: Subscapular fossa on scapula
Insertion: Lesser tubule of humerus
Innervation: Upper and lower suscapular nerves from posterior cord of brachial plexus
Action: Internal/Medial rotation

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7
Q

Tests for each muscle

A

Range of movement:
- Supraspinatus; forward elevation / aduction
- Infraspinatus & Teres Minor; external rotation with elbows at side
- Subscapularis; Internal rotation i.e. thumb behind back
Strength:
- Supraspinatus; Arms out in lateral plane, ‘don’t let me push arms down’
- Infra/TM; Arms tucked in and resisted external rotation
- Subscapularis; Belly press or push hands off back

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8
Q

What is the function of tendons?

A
  • Attach bones to muscle

- Connective tissue transmitting mechanical force of muscle contraction to the bones

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9
Q

What is responsible for the strength of tendons?

A

High tensile strength necessary to withstand stress of contraction
- Attributes to hierarchical structure, parallel orientation and tissue composition of tendon fibres (Collagen Type I)

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10
Q

What connections are made by tendons?

A

One muscle has 2 tendons; proximal and distil

  • Where tendon attaches to muscle; musculotendinous junction
  • Where tendon attaches to bone; osteotendinous junction
  • Proximal attachment; origin and distil attachment; insertion
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11
Q

What can be said about tendons attached to muscles generating a lot of power?

A

The tendons will be shorter and wider than those performing more delicate movements (long and thin)

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12
Q

Describe the hierarchical structure of tendons.

A
  • 3 collagen fibres make tropocollagen
  • 5 tropocollagen bound together form microfibrils
  • Microfibrils surrounded by an endotenon sheath in bundles to give primary fibre bundles
  • P. fibre bundles group to give secondary fibre bundles
  • S. fibre bundles grouped into a fascicle
  • Tendon; groups of fascicles bound by interior endotenon sheath and and exterior sheath of connective tissue (epitenon)
  • All bounded by paratenon
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13
Q

What is the composition of tendons?

A
  • Sparsely vascularised dense connective tissue
  • 20% Cellular (mostly tenocytes and fibroblasts)
  • 80% ECM (70% water, 30% solids i.e. Collagen Type I&III, elastin)
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14
Q

Function of tenoblasts in tendons.

A

Immature tendon cells, all different in shape and size, that elongate and become spindle shaped as they age - turning to tenocytes

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15
Q

Function of tenocytes in tendons.

A
  • Responsible for maintaining the turnover of ECM
  • Respond to mechanical load of tendon and adapt accordingly
  • Arranged in longitudinal rows for communication with adjacent cells through gap junctions
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16
Q

Describe the extra-cellular matrix of tendons.

A

Mainly Type I collagen fibres and proteoglycan (viscoelastic nature - stretch with strain and regain original shape again)

17
Q

What happens to the fascicles as we age?

A

They are small in diameter in children and grow in size until the age 20-29.
Then diameter gets smaller (linked to decrease in muscle strength)
- Diameter can also shrink if tendon gets damaged)

18
Q

How are tendons innervated?

A
  • Cutaneous, peritendinous and muscular nerves from the moyotendinous cross and enter the endotenon.
  • In paratenon; nerve fibres form rich plexuses and send branches to penetrate the epitenon.
  • Majority of nerve fibres terminate and reside on tendon surface.
  • Myelinated nerve endings for sensing tension and pressure and unmyelinateud for sensing and transmitting pain.
19
Q

What are the two types of blood supply to the tendon?

A
  • Intrinsic; at MTJ/OTJ i.e. origin and insertion points.
  • Extrinsic; synovial sheath supplying mid-tendon.
  • Important for tendon healing.
20
Q

What are the 3 phases of tendon healing?

A
  • Inflammation (Day 0-7)
  • Repair (Day 3-60)
  • Remodelling (Day 28-180)
    Under the action of cytokines and other mediators (PDGF and TGFBeta)
21
Q

Name and describe the first phase of tendon healing.

A

Inflammation

  • Erythrocytes, platelets and inflammatory cells (e.g. neutrophils, monocytes, macrophages) migrate from the epitendinous tissues (sheath, periosteum, soft tissues) and the epitendon and endotendon
  • They clean site of dead materials by phagocytosis
  • Also release phaso-active and chemo-tactic factors recruiting tendon fibroblast to begin collagen synthesis and deposition
  • Matrix proteins are laid down as scaffolding for collagen synthesis
22
Q

Name and describe the second phase of tendon healing.

A

Fibroblasts/Tenocytes migrate to injury zone and synthesise collagen Type III which is laid down in a random orientation.

4th week;

  • Intrinsic fibroblasts proliferate and these take over the healing process to synthesise and reabsorb collagen.
  • Production switched to Type I
23
Q

Name and describe the third phase of tendon healing.

A

Remodelling

  • Final stability acquired by normal physiological use of the tendon
  • Paired with cross-linking between fibrils to further increase tensile strength
  • Complete regeneration never achieved (thinner collagen fibres and defect remains hypercellular)
24
Q

What are the benefits of patient rehab?

A
  • Early controlled mobilisation will reduce scar adhesions and stimulates remodelling i.e. facilitates healing
  • Excessive loading would disrupt repair tissue
  • Optimal healing requires; surgery and mechanical stabilisation, minimal soft tissue damage and a good healing environment.
25
Q

What are the causes for tendon injuries?

A
  • Sudden severe trauma
  • Repetitive Injury (more common); a small stress can tear/degrade tissue if repeated e.g. typing, clicking a mouse, tennis
  • Bad posture increases stress on tendons
  • Infection or reaction to medication (unusual)
    Incidence of tendon injury increases with age
26
Q

What are the symptoms of tendon injuries?

A
  • Usually occurs at attachment point between bone and muscle
  • Dull, aching pain worsens with movement
  • Tenderness, redness, warmth, swelling
  • Rest Pain/Stiffness - pain during night
  • Tendinitis of shoulder; occasional snapping sound and possible freezing in shoulder joint
27
Q

How can tendon injuries be prevented?

A
  • Warm up before exercise
  • Sports equipment in good condition
  • Take regular breaks from repetitive exercises
  • Train properly; don’t over-exercise tired muscles or start a new sport without training
  • Strengthen muscles to reduce stress on soft tissue
  • Do range of motions each day
28
Q

How can tendon injuries be managed?

A
  • Mild exercise will reduce stiffness
  • Don’t move too much; worsens existing symptoms
    RICE
  • Rest; reduce amount/intensity of activities causing injury
  • Ice; 20mins every few hours
  • Compress; bandage
  • Elevate; Keep injury raised on pillow when sitting/lying down
29
Q

What are the healing times for tendinitis and tendinosis?

A 
Early Presentation
Tendinitis; days- 2 weeks
Tendinosis; 6-10 weeks
Chronic Presentation
Tendinitis; 4-6 weeks
Tendinosis; 3-6 months
30
Q

What is the order of treatment options for tendon injuries?

A
  1. Physiotherapy to strengthen tendons and muscles, preserving range of motion.
  2. Injections of corticosteroids - i.e. anti-inflammatory medications into area around tendon to help relieve swelling and pain BUT may increase risk of tendon rupture.
  3. Surgery (arthroscopic/open surgery)- for athletes / active individuals who will benefit. Not usually for older people as risk usually outweighs the benefit.
  4. OR platelet rich plasma injections
31
Q

Difference between acute and chronic tendon injuries w/example

A

Acute; rapid onset, severe symptoms and brief duration usually caused by direct impact. E.g. tendonitis.
Chronic; gradual onset with long duration involving very slow changes. E.g. tendonosis.

32
Q

What is the main muscle of the rotator cuff to be damaged and why?

A

Supraspinatus tendon

  • Passes through space of fixed dimensions so swelling of the muscle can produce significant impingement when arm is abduction.
  • Poor blood supply so repeated trauma makes it susceptible to degenerative change resulting in calcium deposition producing extreme pain.
  • Then, more susceptible to partial- or full-thickness tears may develop.
33
Q

Describe tendonitis.

A
  • Acute
  • Inflammation of a tendon resulting from micro-tears that happen when myotendinous unit overloads
  • Causes pain and swelling from tears in injured tissue
  • Direct trauma
34
Q

Describe tendonosis.

A
  • Due to failed healing or repetitive trauma to a tendon leading to a loss of collagen
  • This causes micro-tears resulting in a loss of strength and further injury
  • Increased Collagen Type III fibres so no alignment and failed linkage. This reduces the strength of the tendon.
  • Thickening on tendon sheath.
35
Q

What are the causes of rotator cuff tears?

A
  • More common in over 65s
  • Wear and tear (attrition)
  • Bone spurs
  • Acromion shape
  • Tendinopathy leading to tears
  • Acute trauma
  • Genetic
36
Q

What are the benefits of arthroscopic and open surgery for repairing tendons?

A 
Arthroscopic
- Less invasive
- Faster recovery
- Visualise whole joints
Open
- More invasive
- Still good long term results

Limbs and Back (6 decks)

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