Tendinopathy Flashcards
What is the function of a tendon?
- Transmit force
- Create, slow, stop or prevent movement
- Store and release elastic energy
What fraction of stored elastic energy contributes to hopping in humans?
One third
What are tendons primarily composed of?
Collagen
- 60-85% of dry mass
- Approx 95% type 1 collagen
What are the characteristics of collagen?
- Strong
- Elastic
- Highly organised
- Hierarchical structure
What are the components of tendons?
Cellular component (tenocytes)
Extracellular matrix
- Fibrous (collagen & elastin)
- Non-fibrous (ground substance - proteoglycans, glycosaminoglycans, water)
How is collagen aligned in tendons?
- Parallel to long axis of tendon
- Good for tensile strength not compression
What are tendon cells called?
Tenocytes
What are the characteristics of tenocytes?
- Produce & maintain tendon
- Spindle-shaped, spaced out, aligned
- Communicate via gap junctions
What are the tendon coverings?
- Endotenon: within tendon, conduit for blood vessels
- Epitenon: tightly adhered to outside of tendon
- Paratenon: Double layer sheath, loosely attached to outside
- Synovial sheath: true tendon sheath, only at areas of high friction, double layer lubricated by synovial fluid
Where are tendons compressed?
At pulleys
- Retinacula
- Annular & cruciate pulleys
- Wrap around pulley (tib post, achilles insertion)
Why is the term tendinitis no longer used?
- Research explosion in the last decade
- Now called tendinopathy
- More effective treatments
Where are tendons most likely to be injured?
- At either end (musculotendinous/osteotendinous junction)
- Exception: Achilles, most common in mid portion
What are some common names of tendinopathies?
- Tennis elbow (extensor carpi radialis brevis)
- Golfer’s elbow (medial elbow)
- Jumper’s knee (patella)
What tendinopathies are associated with AFL players?
Adductors
Proximal/distal hamstrings
What tendinopathy almost exclusively affects women?
Gluteus medius
What 4 features characterise tendon pathology?
- Altered number & activity of tenocytes
- Change in quantity & composition of ground substance
- Disorganisation of collagen fibres
- Neurovascular ingrowth
What are the two theories of how tendon pathology develops?
- Collagen theory
- Cell theory
2a. Biochemical theory
2b. Neurovascular theory
What is the collagen theory?
- Repeated loading causes micro tears
- Too much load & not enough rest = damage exceeds repair, chronic failed healing response
What is the cell theory?
- Cell senses load (tensile, shear, compression)
- Attempts to adapt to increased loading
= increased cell activity
= altered gene expression
= production of biochemical factors (2a)
= increase production of ground substance
= neurovascular growth (2b) - Cell death/degeneration
Why is there pain with tendinopathy (no inflammation)?
- Neurovascular supply
- Tenocytes produce signalling substances
- Nerves in the area have receptors for signal substances
- Ongoing debate
What is the sequence of events for tendinopathy?
- Abusive loading, causes
- Cell activation
- Lots of ground substance produced, causes
- Collagen separation, causes
- Hypoxia & other factors, stimulates
- Neovessels growth, which are related to
- Pain
What are the 3 stages of tendinopathy?
- Reactive (young, acute overload, direct impact)
- Tendon dysrepair (older, previous episodes, train through pain)
- Degenerative (older, long history of grumbling pain)
What is the clinical presentation of pain for tendinopathy?
- Well localised
- Load-related
- Worst at start of exercise
- Eases when exercising
- Returns after cool down
- Morning pain/stiffness (achilles)
What is the clinical presentation of change in load for tendinopathy?
- Unfamiliar exercise
- Type/amount
- Speed/hill running/surface
- Technique (forefoot running/minimal footwear)
- New equipment
