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What is tendonitis?
Let us begin with a brief overview of tendon function and structure. Tendons are the fibrous connective tissues which attach a muscle to the bone. The primary function of a tendon is to transmit the force from the muscle which permits movement. Close inspection of tendons reveals the presence of rope-like collagen proteins. These proteins bundle together to form fibrils.
Essentially, tendonitis is a breakdown of the collagen proteins within the tendon. Many times, this breakdown occurs rapidly as the result of sudden stress or movement. However, it can also occur over a period of time, as in the case of gradual tendon overload. Finally, ageing and certain medical diseases such as diabetes or obesity can also contribute to the development of tendinopathy. Overall, the condition is common in the general population, even more so than osteoarthritis.
For the most part, patients with tendonitis complain of pain arising from their tendon. The pain often occurs after an activity that stresses the tendon. Common activity/tendon correlations include running and the Achilles tendon, jumping for the patellar tendon or playing tennis or golf for the tendons of the elbow. Finally, tendonitis pain is usually inflammatory, which means it warms up with the activity and often gets worse during cool down.
With these points in mind, most cases of tendonitis are easily identified through accurate description of the pain. Nevertheless, an examination is always useful to exclude other causes of pain arising from structures such as muscle, ligaments or joints. For example, some causes of knee pain in runners is due to cartilage injury of the knee joint rather than the tendon.
Likewise, imaging can be helpful to identify the more complex cases. MSK ultrasound shows typical changes of tendonitis with tendon swelling, collagen breakdown and large blood vessels. The advantages of MSK ultrasound are that it is inexpensive and readily available, often at the first consultation. However, some cases require a more detailed MRI scan to get a clearer picture of the changes in the tendon. MRI is particularly useful in hamstring or hip tendons, for example.
Previously, doctors thought that tendonitis simply produced active inflammation. Accordingly, they would suggest taking anti-inflammatory tablets such as ibuprofen or diclofenac. Remember, they believed that the acute inflammation played a key role in the development of tendinopathy.
However, we now know that in tendonitis, tendons swell with water and then undergo a gradual breakdown of their collagen proteins. This relatively new understanding of the progression of tendonitis has led to a change in common treatment approaches. More recent studies suggest that anti-inflammatory medications delay or even slow down healing.
Considering these discoveries, physical therapy and exercise are now the most useful and effective treatments for tendonitis. Physical therapy must be supervised by an experienced physiotherapist. An important rehab principle for tendonitis is that the load placed on the tendon should be relatively heavier but less frequent for lower limb tendons (such as Achilles tendon). Conversely, load should be light and frequent for upper limb tendons (such as tennis elbow or shoulder rotator cuff). Another important principle in treatment is to find the critical factor that caused the tendonitis, such as an error in training or a weakness in the locomotive chain.
Essentially, pain often improves with exercise therapy, but the how and why is unknown. It could be due to the direct stimulating effect of exercise on collagen fibres. Alternatively, it could an indirect effect of increased muscle strength and reduced load on the tendon. In fact, improvements in tendon pain and function occur regardless of the type exercise done. For example, in Achilles pain, concentric exercise which forces muscle to shorten while contracting has a similar positive effect to eccentric exercise where the muscle lengthens with contraction.
In addition to exercise therapy, doctors or physiotherapists may use other techniques to improve the results of exercise. One such treatment is shockwave therapy, where sound waves produced by pressurised air are delivered directly to the diseased tendon. The sound waves initiate an inflammation, which stimulates the body’s own healing capacity. Another treatment is Nitric Oxide patches, which are applied to skin over the tendonitis and work to improve tendon healing and reduce pain.
In addition to shockwave, various types of injection therapy are used in more difficult cases. Dr Masci has performed research on the effects of different injections in tendonitis. A recent review co-authored by Dr Masci suggests that there are no clear favourites. However, there is increasing evidence that cortisone can cause harm when used for some tendons such as tennis elbow. It should be noted that surgery has little role to play in the treatment of many types of tendinopathy. A recent review of surgery found that outcomes are no different to physiotherapy despite risks such as infection or poor wound healing.
In conclusion, tendonitis involves the breakdown of collagen proteins in the tendon. The condition is quite common in active people. Pain in the tendon post-activity is a common presentation. Imaging such MSK ultrasound can confirm swelling and collagen breakdown. Exercise is effective for most cases. Occasionally other treatments such as shockwave or injections can help patients recover.
Dr Masci is a Sports and Exercise Medicine doctor with an expertise in the management of general musculoskeletal injuries including tendonitis. An expert in MSK ultrasound with a specialisation in ultrasound-guided injections for joints and tendons, he has written 20 peer-reviewed papers on tendonitis. He is a recognised tendon specialist and has presented on tendonitis at international conferences including Arsenal football conference. Dr Masci consults at OneWelbeck. For enquiries, please contact firstname.lastname@example.org or visit his website www.sportdoctorlondon.com