04/06/2022
What is tendinopathy?
Simply put, it is an abnormal tendon in pain due to overload. In other words, tendinopathy does not exist without overload.
Jill Cook presented a continuum model of tendon pathology.
It is broken down into 3 stages. 1st stage is called reactive tendinopathy, which is caused by acute compressive or tensile load or direct trauma to the tendon. It sometimes presents with minimal thickness in the affected tendon. This is natural for the tendon to reduce stress by increasing its cross-sectional area.
What does a tendon contain?
It majorly have water, up to 90%. When you take it out of the tendon, it mainly contains type 1 collagen, which is responsible for tensile strength of the tendon. Importantly, it also has ground substance, which consists of glycosaminoglycans, proteoglycans and other proteins. What they do is attracting water from the blood into the tendon when the tendon is loaded. The tendon needs that fluid to reduce stress, which is a normal process for the tendon to adapt the given load.
However, once it is overloaded, that is a different story. It gains increased accumulation of water in the tendon, which will derange the arrangement of the collagen fibres of the tendon.
That is a reactive tendinopathy. It can present with pain and minimal tendon swelling but not all the time.
It still has good collagen integrity, which still helps the tendon reverse to its normal state with optimal load management.
If not, then it can experience the 2nd stage of the continuum model of the tendon pathology, which is called "tendon dysrepair". What is it?
It presents similar to reactive tendinopathy. However, the biggest difference between those 2 stages is greater breakdown of the extracellular matrix of the tendon. It has more accumulation of water in the tendon. It presents with more disrupted tendon arrangement. However, it still has a good collagen integrity, which means an ability to reverse to its normal state.
However, the last stage, degenerative tendinopathy, can present with cell dysfunction and death that can compromise protein production in the tendon. Due to the lack of the protein, it has poor collagen integrity, which can lead to risk of tendon rupture.
It distinctly demonstrates neurovascular ingrowth. What does it do?
It is created to compensate for hypoxia of the degenerative tendon.
Why?
Tendons dont have good blood supply. Once it is degenerative, it even has less of it. Therefore, the increased neurovascular ingrowth delivers blood to the degenerative tendon.
However, some studies show that it does not seem to repair the affected tendon and does not appear to cause pain. It is debatable about how changes in neurovascular structures impact on the tendon pain and function.
Jill Cook support that there is no inflammatory proliferation process in the tendinopathy. However, there are many studies that describe increased inflammatory cells and markers in the tendinopathy. This may be due to different methods of identifying the inflammatory cells between studies. Therefore, this is still debatable about whether or not the overloaded tendon is inflamed.
BUT
Does this affect your clinical management?
No! Why?
We mainly treat our patients, based on their symptom behaviours. We do not have to know what tendon cellular environment is formed. We understand that reactive tendinopathy responds well to anti-inflammatory medications. This makes people think that there is inflammation. Possibly. BUT We understand that prolonged usage of meds and steroid injection can prevent collagen synthesis of the tendon, which will slow down its healing process.
Regardless of the inflammatory or non-inflammatory tendon status, the key factor for the development of tendinopathy is a mechanical load!
Back to what I said above. Tendinopathy does not occur without overload. We find the optimal load to the individuals' tendon, so as to enhance the tendon load capacity. So, the tendon can absorb shock and release energy in stretch shortening cycle activities, which are heavy fast loading activities, such as basketball, running, changing directions.
What is stretch-shortening cycle?
It is a high (heavy)- fast load. For instance, when you hit the ground, your tendon rapidly elongates and stores energy, then when you push off, it recoils to release energy.
As this activity is heavy fast loading to the tendon, it can increase the risk of the tendinopathy.
Wasalat's physio diary.