Dealing with Tendon Irritation / Tendinitis / Tendinopathy
Whether you’ve actually been diagnosed with tendinitis or even tendinosis, the truth is that your specific pathology doesn’t really matter.
What does matter?
What matters is that you understand how your tendons work and, better yet why it takes so long to recover from tendinitis/tendinosis.
Many people suffer from some sort of tendon irritation. If you’ve had it diagnosed, you’re physiotherapist, Dr, chiropractor may have told you that you have one of them, but what is the difference?
The Difference
The suffixes suggest that tendinitis is an inflammation of the tendon, tendinosis is a degeneration of the tendon, and tendinopathy is used as a clinical term to represent pain or pathology. At university I was taught to use tendinopathy as an umbrella term to describe tendinitis/tendinosis.
“Tendonitis is an inflammation of the tendon, tendinosis is a degeneration of the tendon”
We now know that it’s not as simple to categorise you’re tendon dysfunction neatly into one of these categories. There could be element of both of these changes in your tendon.
To fully understand how you’re tendinopathy and how rehab is guided; I think it’s useful to understand how normal tendons work.
How do Tendons Work?
Tendon is the connective tissue that joins muscle to bone
A tendon is the tissue that connects muscle to a bony attachment. Its function is to transfer load from the muscle it’s attached to move a limb, as well for energy storage. The tendon can store and release energy much like a spring.
For example during the gait cycle at heel strike, the Achilles tendon absorbs force, which is then released during the push off phase.
This energy storage occurs during fast activity such as when we walk, run or jump. This energy storage or ‘stretch shorten contraction’ of the tendon (SSC) benefits us in that it provides us with an efficient and powerful way to move as the muscle doesn’t have to work as hard since the tendon is storing and releasing energy with our movement. The negative side of this is that it is this SSC of the tendon is what leads us to injury (often with a history of overload).
What are Tendons made out off?
Tendons are made of tenocytes (tendon cells), collagen (connective tissue), and ground substance. The collagen is lined parallel to the load and resists tensile load; it is well organised and bonded well in a healthy tendon. The ground substance is a gel like substance around the tissues that binds water; this resists compressive forces.
The ground substance is smaller in tendons, but where compressive forces increase (such as near the bony attachment) there is an increase in larger proteoglycans (such as aggrecan) within the ground substance and becomes more cartilaginous in structure.
Tendons have a blood and nerve supply, and contrary to what was previously thought the Achilles tendon doesn’t have a poor blood supply, is has a uniform vascularity (meaning that there is even blood supply to all parts of the tendon). However cartilage has a poor vascularity, therefore the areas of the tendon that have changed into a more fibrocartaginous structure due to increased compressive forces have a poorer blood supply.
So if tendons do have a blood supply – can they heal after dysfunction and adapt?
Can Tendons heal?
Firstly let’s look at a study conducted by Heinemeir in 2013, where he looked at the Achilles tendon in people who had been exposed to nuclear bombs. Decades later the central core of the tendon still had nuclear material – suggesting no tissue renewal within this area of the tendon. The study indicating that the tendon core is formed during height growth and is essentially not renewed after, in contrast muscle indicated continuous turnover.
So to answer the question, yes tendons may adapt; however it is unlikely that the central core does. It also doesn’t seem to adapt to the same extent as muscles.
It is also interesting to note that tendon pathologies that show up on imaging do not change even after a person has gone through rehab and the pain has gone. Tendons without any pain to begin with may show up with pathologies on imaging. So what does this mean? Is a dysfunctional tendon able to adapt?
We know from experience, rehab does work in most cases: so are we really “repairing” the tendon with rehab? Or are we just working on the pain mechanisms and how our brain perceives it on a biochemical level? We may even just be desensitising the tissue and increasing the tendon’s load tolerance.
“rehab does work in most cases”
What we do know for sure is that pathology does not equal pain and a person’s rehab should be guided by how irritable or stable his or her pain is.
The best theory to explain tendon pathology today is the “Reactive-Degenerative” model proposed by (Scott 2007, Cook 2004, Cook & Purdam 2009)
- With increased load there will be an increase in cells within a tendon this then becomes a Reactive tendinopathy (where there is an increase in ground substance and diffused thickening of the tendon)
- With further breakdown in the matrix that affects the collagen crosslinks, there will now be a focal area of degeneration – tendon disrepair: Degenerative tendinopathy. (Much like wear and tear in cartilage – we do not have the skill at this time to repair/restore this area of the tendon)
What Causes a Tendinopathy?
- Stretch Shorten Cycle
As we discussed earlier – storing and releasing energy or the SSC can lead to injury. - Compressive Load
Very often I’ve also seen someone who has had an impact injury to a tendon eg repetative impact on an achilles tendon – leading to a tendinopathy developing.
OR biomechanical factors that lead to increased compressive forces on a tendon (against a bone) can also lead to changes in the tendon and a tendinopathy forming
Where do we go from here?
It is easier to reverse the process when in reactive stage, this may also be what happens when a normal tendon is put under a load (eg. straight after a training session – this does not necessarily correlate with pain).
What about when it gets to the degenerative stage? There may not be much we can do in terms of reversing pathology. But we can certainly affect pain and function, and that’s the most important thing!
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References:
Heinemeier, K. M. et al. ‘Lack Of Tissue Renewal In Human Adult Achilles Tendon Is Revealed By Nuclear Bomb 14C’. The FASEB Journal 27.5 (2013): 2074-2079. Web. 14 Feb. 2015.
Completesportscare.com.au,. ‘Blog | Complete Sports Care Camberwell, Hawthorn’. N.p., 2015. Web. 14 Feb. 2015.
Kannus, P. ‘Etiology And Pathophysiology Of Chronic Tendon Disorders In Sports’. Scandinavian Journal of Medicine & Science in Sports 7.2 (1997): 78-85. Web.
Kastelic, J., A. Galeski, and E. Baer. ‘The Multicomposite Structure Of Tendon’. Connective Tissue Research 6.1 (1978): 11-23. Web.
Finni, Taija, Paavo V. Komi, and Vesa Lepola. ‘In Vivo Human Triceps Surae And Quadriceps Femoris Muscle Function In A Squat Jump And Counter Movement Jump’. European Journal of Applied Physiology 83.4-5 (2000): 416-426. Web.
Cook, J.L, K.M Khan, and C Purdam. ‘Achilles Tendinopathy’. Manual Therapy 7.3 (2002): 121-130. Web.
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