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Tendinitis or tendinopathy? What really happens when tendons get cranky!!

Tendons are soft tissue structures that join muscle to bone. Some are long and stringy such as what you can feel behind your knees at the sides, or the back of your hand. Some are thick bands like the Achilles tendon attaching the calf muscle to the heel bone, or they can be short and wide such as the attachment of the gluteal muscles to the pelvis.

Tendons are mostly made up of a protein called collagen (around 86%), tendon cells called tenocytes, elastin (around 2%), and various other cells that sit around and in between the collagen. When tendons are unhappy, they can be very painful! But why do they get upset and what is physically happening to the tendon?

Tendons are very fussy when it comes to load. Just like Goldilocks’ porridge, load needs to be ‘just right’, not too little and not too much. If tendons are overloaded or underloaded they can get cranky, particularly if the increase in load follows a period of low load. E.g. Someone runs 5km daily, they get sick and don’t run for a month, then when they resume running, they pick up where they left off. The month of not running underloads. then the resumption of the same level overloads – versus starting at a lower level and building back up again.

The Achilles tendon is the only tendon that can have pathology in the middle of it – often characterised by a painful lump. The Achilles can also have pathology at the insertion (where it attaches to the bone) and all other tendons are the same, with pathology at the attachment region such as the elbow, the patella tendon of the knee, hamstring attachment to the pelvis, rotator cuff at the shoulder, and gluteal attachment to the pelvis.

The function of tendons is to store and release energy to assist with the ability to move quickly and spring or bounce – however to much springy business is what can also overload tendons. And because the unhappy bit of the tendon is near the bony attachments, motions that stretch the tendon across the bone cause the tendon to get compressed, e.g. Achilles tendon attachment being compressed over the heel bone as the ankle bends.

So, the perfect storm for something like the Achilles tendon, is to return to running up hills or a sport like basketball, after a long period of rest, without graduating load.

But what is going on in the tendon exactly when it gets cranky?

When most people think if pain or injury, they think of inflammation, inflammation is a chemical reaction. Inflammatory chemicals are irritating, and they hurt. When we put the suffix -itis after a word like tendon, we get tendonitis. But is a cranky tendon actually inflamed? No, it isn’t!

But wait, what?

Cranky tendons are not inflamed, so anti-inflammatory medicines don’t work. The term tendonitis actually needs to be officially thrown away, but the term still pervades the medical world. Instead, we say tendinopathy  – which simply mean ‘pathological tendon’ or ‘something is wrong with the tendon but it isn’t inflamed’.

What we do call a cranky tendon is ‘reactive’.

Inside a tendon there are cells called tenocytes, which are located in between bundles of collagen fibres. Like a rugby scrum, a tendon works optimally when all players are doing their job and are all tightly packed together. If there is stress on the tendon (from too much activity all of a sudden or to much springy business), the tenocytes get to work by producing substances like proteoglycans which are ‘hydrophillic’ – they love and attract water. Increased proteoglycan production draws water into the stressed-out tendon causing the tendon to swell, causing the characteristic tendon lump – hence the lump is water, not inflammation. This swelling pushes apart the collagen fibres and they become disorganised. Think of an unpacked rugby scrum – it doesn’t properly work right?

Reactive tendon pathology is reversible (because collagen in still intact), with a short period of relative rest, followed by the application of appropriate loading. However reactive tendons can go onto to becoming heavily disorganised in their structure, and parts of the tendon structure may become degenerative – here collagen is broken down and this is not reversible.

Tendon degeneration is actually very common and typical as we age. A degenerative tendon is not painful. It is not to be feared either as the surrounding tendon tissue adapts to compensate for the part that doesn’t work anymore. Our bodies are super clever! What can hurt is a reactive tendon – thought due to mechanical nociception i.e. movement, load, compression, stretch of abnormal tissue sensitizes nerve endings. Think of a bruise on your skin that doesn’t hurt till you poke it.

So, what do you do if you have a cranky tendon?

There is no one size fits all approach but there are considerations

  • Don’t stretch it or compress it – lengthening a tendon compresses it against bone if an insertional tendinopathy and the stretch itself compresses the tendon internally

  • Do place the tendon in a shortened position e.g. elevate heels with Achilles tendinopathy such as wearing boots or added heel raise wedges inside shoes, place 2 pillows between knees for gluteal tendinopathy when laying on side

  • Don’t do bouncy stuff, which includes using theraband – remember tendons hardest job is to control storage and release of energy, which is lengthening followed by a quick shortening (bouncy stuff can be done later, just not early)

  • Avoid resting and exercising with the tendon stretched over the bony attachment e.g.

    • Insertional Achilles tendinopathy – avoid calf stretches, heels hanging over a step to calf raise, low shoes or bare feet

    • Gluteal tendinopathy – avoid laying on side with knees resting together, standing with hip sticking out sideways, crossing legs, sitting with hips lower than knees

  • Don’t bother with anti-inflammatory medications or injections, better to use over the counter pain relief such as paracetamol to take the edge off if required. If there is a bursitis co-existing, this advice may change - see point below

  • Don’t push through pain that is worsening or significant – a cranky reactive tendon may need a period of relative rest and once reasonably manageable, then start loading the tendon.

  • Don’t be fooled by how a tendon feels during exercise as it tends to warm up and feel better – assess response to an activity over the next 24 hours

Loading tendons is advised in a sequence and this is where a practitioner such as a physiotherapist, osteopath, or myotherapist with training in tendon rehab can help to individualise an action plan. The sequence involves:

1.      Isometric holds (hold muscle in a shortened contracted position)

2.      Isotonic / heavy slow resistance (moving slowly with heavy resistance/weight)

3.      Dynamic exercises (springy and faster stuff) replicating sport or recreational need

4.      Return to sport/recreation

Tendon rehab takes time. 6-12 months is not uncommon with successful rehab.

Do tendons need scans to diagnose them? Generally speaking, no. A thorough assessment that includes an history of overloading (often after under-loading), clearance of the spine as a possible causing of symptoms, specific location of symptoms (except the hip which can produce diffuse all leg pain with gluteal tendinopathy) and clear reproduction of symptoms with loading tests.

How about bursitis? – Bursitis is inflammation of the bursa which is a tissue that sits between two structures to help reduce friction. An inflamed bursa is never a pathology that exists all by itself for no reason – it will accompany tendon attachment pathology or be from direct trauma. The shoulder and hip are a great example – bursitis will accompany weakness of the rotator muscles, tendinopathy at the attachment point and usually a stiff adjacent region of the spine. Anti-inflammatory meds and corticosteroid injections may help in the short term, but they don’t deal with the underlying cause.

What’s the takeaway?

Tendinopathy take time to get better. Cranky sore tendons are not inflamed, they are full of water and weakened making them easier to overload. Get help with rehabilitation and understand it takes time. Bursitis does not exist in isolation. Avoiding stretching and bouncing in the beginning. Progress loading patiently over time…did we mention time?


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