How Do You Know If Your Shoulder Pain Is Tendonitis?

Questioning the symptoms of a problem is essentially questioning how to recognize that problem. How can you tell if your shoulder pain is actually tendonitis?

When someone experiences pain, it is sometimes easy to quickly and directly identify the cause. For instance, imagine you’ve just taken a hard fall on your shoulder. The resulting pain is intense and highly debilitating. An X-ray reveals a fracture. Mystery solved.

In the case of shoulder tendinitis, as you might already suspect, it’s unfortunately a bit more complicated.

I’m writing this article to shed as much light as possible on this situation, drawing from:

my experience as a physical therapist;
a thorough dive into the international scientific literature on all relevant topics;
and incidentally, my personal experience of living with recurrent pain in my left shoulder for over 10 years – among other things!

May you find the answers to your questions in this article, and hopefully a bit more! 🙂

Last update: 28 may 2024
Disclaimer: no Affiliate links. Complete disclosure in legal notices.
Written by Nelly Darbois, physical therapist and scientific writer

Summary

Shoulder Tendinitis: What Is It?

Before diving into the specifics of how to identify shoulder tendinitis, let’s start by understanding what shoulder tendinitis is.

Tendinitis or Tendinopathy? Shoulder or Rotator Cuff?

The terms “tendinopathy” and “tendinitis” both refer to issues with tendons, which can be thought of as cables connecting muscles to bones.

In theory, “tendinitis” is an inflammation of a tendon. Therefore, logically, shoulder tendinitis is an inflammation of a tendon in the shoulder. The term “tendinopathy” is more general; it indicates that there is a tendon problem, but does not specify the nature of the problem.

You might sometimes encounter the expressions “rotator cuff tendinitis” or “rotator cuff tendinopathy.” The term “rotator cuff” refers to a specific group of four shoulder muscles:

supraspinatus
infraspinatus
subscapularis
teres minor

Figure 1 – The image on the right is a right shoulder viewed from the front. The image on the left is a right shoulder viewed from the back. 1 – clavicle; 2 – scapula (shoulder blade); 3 – scapular spine; 4 – coracoid process; 5 – acromion; 6 – humerus; 7 – acromioclavicular joint; 8 – glenohumeral joint; 9 – subacromial bursa; 10 – rotator cuff; 11 – supraspinatus; 12 – subscapularis; 13 – infraspinatus; 14 – teres minor; 15 – biceps brachii. Source: Jmarchn CC – By SA

Thus, it is more accurate to refer to “rotator cuff tendinitis” rather than “shoulder tendinitis.” This specifies which muscles are thought to have an affected tendon.

From here on, I will mostly use the term “shoulder tendinitis,” which aligns with the terms most commonly used by the general public.

What Is Tendon Inflammation?

When we talk about tendon inflammation, we are referring to the inflammatory activity within that tendon. This inflammatory activity is measured by the quantity of certain biological markers in the tendon.

These inflammation markers are [Rees, 2014]:

▪️ certain types of immune system cells (which can travel throughout the human body; for example, macrophages);

▪️ certain types of chemical substances such as:

proteins (for example, cytokines);
enzymes (for example, cyclooxygenases);
and peptides (for example, the substance known as “substance P”).

In short, a nice cocktail of biochemistry!

Measuring this activity requires laboratory techniques, and, above all, sampling pieces of the tendon that we want to examine. This means that in practice, to determine if someone indeed has shoulder tendinitis, other more indirect approaches must be used.

In summary: shoulder tendinitis = inflammation of a shoulder tendon;
inflammation of a tendon = presence of biological markers of inflammation in that tendon (chemical substances).

How to identify shoulder tendinitis: what symptoms?

To be as sure as possible that someone has shoulder tendinitis, it would be necessary to manipulate their tendons and examine the pieces in the laboratory.

Today, due to its invasive nature, this approach is reserved for researchers.

Let’s focus on the other approaches used to identify if someone has shoulder tendinitis:

the approach involving direct contact with the person, requiring only minimal equipment (referred to as clinical approach);
radiological approach (ultrasound or MRI).

Identifying Shoulder Tendinitis: The Clinical Approach

On a clinical level, meaning by examining the person directly with minimal equipment, shoulder tendinitis can be suspected when:

⚫ the person complains of shoulder pain (this is, of course, the main symptom);

⚫ muscle weakness can be observed due to the pain, most often on two specific types of movements:

lifting the arm;
performing an external shoulder rotation (see figure 2 to understand what an external shoulder rotation is; otherwise:

1️⃣ let your arms hang down by your sides;
2️⃣ bend one elbow at a right angle, let’s say your left elbow;
3️⃣ keeping the elbow at a right angle, bring your hand to your stomach: you’ve just performed an internal shoulder rotation;
4️⃣ still keeping the elbow at a right angle, bring your hand back to its starting position: you’ve just performed an external shoulder rotation).

After ruling out other causes, if the pain cannot be explained otherwise, it can be attributed to tendinitis. In other words, it’s the absence of other symptoms than pain that points to an explanation of tendinitis type. (Source: Lewis, 2015)

Figure 2 – Several ways to perform an external shoulder rotation: image (A) (method not described in the text), raise the arm horizontally to the side and bend the elbow. While maintaining this position, if you tilt your hand and forearm backwards, you perform an external rotation (tilting them forward performs an internal rotation). Image (B), I have described the method in the body of the article. Source : Jung-Hu Sung

It should be noted that this approach is not specific to shoulder tendinitis. It can also be used to suspect the presence of:

a tendon problem in general, without necessarily determining whether this problem is inflammatory in nature (this is referred to as tendinopathy rather than tendonitis);
bursitis: inflammation of the synovial (or serous) bursa located under the acromion (the acromion is part of the shoulder blade). This synovial bursa is a kind of flattened sac that reduces friction between the shoulder blade and certain tendons of the shoulder (see Figure 1).

In other words, the clinical approach does not allow for distinguishing between:

tendonitis;
another type of tendinopathy (for example, a degenerated tendon without inflammation, known as tendinosis, where the tendon is disorganized in structure);
or bursitis.

Under these conditions, how can one differentiate without delving into the inside of the shoulder? In practice, you may be prescribed an imaging examination such as an ultrasound or MRI. Let’s now see how useful this radiological approach really is.

In summary:

▪️ Clinical approach to identify shoulder tendinitis = directly examine the person using minimal equipment (for example, in your family doctor’s office);

▪️ What symptoms to look for in identifying shoulder tendinitis?

– Shoulder pain leading to certain muscle weaknesses (such as difficulty lifting the arm);

– The absence of symptoms other than the preceding one, after having sought to eliminate a whole range of other possible causes to explain the pain.

▪️ The clinical approach alone does not ensure that there is indeed tendinitis.

Identifying Shoulder Tendinitis: The Radiological Approach

From a radiological standpoint (ultrasound or MRI), shoulder tendinopathy can be identified by observing certain radiological abnormalities in one or more shoulder tendons [Robinson, 2009; Hodgson, 2012].

However, this approach does not differentiate between [Rees, 2014]:

enthesitis: inflammation not of the tendon itself, but of one of its attachment points in the bone (a specific area known as the enthesis);
tendonitis: inflammation of a tendon;
tendinosis: degeneration of a tendon (the structure of the tendon is disorganized);

Example of an MRI image of the shoulder (right shoulder viewed from the front). Source : Balaji Umamahesvaran

At this stage, we find ourselves somewhat at an impasse. To go further and truly determine if there is tendonitis, it would be necessary to manipulate the tendons and analyze the fragments in a laboratory. However, this is not done in everyday clinical practice.

What can be concluded from such a situation?

We can conclude that when you are told you have tendonitis, in reality what is being done is:

assuming you have tendonitis; no certainty in this matter is possible given our current examination methods;
assuming that this tendonitis explains the majority of your pain.

There is a slight problem here.

Let’s say, indeed, that you do have tendonitis. Let’s consider the first assumption above as valid. But what if the second assumption was, in fact, incorrect? In other words, what if your tendonitis did not explain the majority of your pain? Let’s explore this now.

What if your shoulder pain was more than just tendonitis?

Imagine someone experiencing shoulder pain of the type that could lead to a diagnosis of tendonitis. That is, shoulder pain:

which leads to muscle weakness in certain movements (particularly for lifting the arm or performing an external shoulder rotation);
for which there is no satisfactory explanation among all known explanations (especially those requiring urgent or semi-urgent management – see the following section for more details).

The latest scientific research suggests that this type of pain is explained by a multi-localized inflammatory state [Lo, 2022; Lo, 2023]. This means a situation where inflammation markers are found in:

certain shoulder tendons (so there is indeed tendonitis, but not exclusively);
the subacromial synovial bursa;
the glenohumeral joint (the joint between the humerus and the shoulder blade);
the blood serum (serum is a part of the blood, like oil is part of a vinaigrette sauce).

However, it should be noted that this explanation:

▪️ is still largely to be confirmed;
▪️ would essentially apply to individuals:

experiencing pain for more than 3 months and not following trauma;
over 40 years old;
not engaged in intensive sports activity.

For others, to date, research is lacking to explain what could be the cause of their shoulder pain.

Thus, in any case, assuming tendonitis to explain the majority of shoulder pain cannot be justified by the current state of knowledge.

But then, why continue to talk about “shoulder tendonitis” in these circumstances? Let’s dwell on this point for a moment.

So why talk about shoulder tendonitis?

If there’s no justification for thinking that tendonitis alone can explain the bulk of shoulder pain, why mention shoulder tendonitis at all?

Answering such a question might require an entire separate article, but I’ll venture here with a few hypotheses:

1️⃣ It seems easier to tell someone “you probably have tendonitis” than “you probably have a multi-localized inflammatory condition blah blah blah” or “I’m not sure.” And this is especially true since the word “tendonitis” is part of common language.

2️⃣ If the word “tendonitis” is part of common language, the practice of self-diagnosing tendonitis seems to be quite common.

I recall many patients saying to me, “I hurt here. It must be tendonitis, don’t you think?” (In this regard, my own father is one of the champions of self-diagnosing tendonitis!).

3️⃣ Faced with “tendonitis-like” shoulder pain, some professionals may be tempted to recommend anti-inflammatories (applied locally or orally).

Thus, the combination “tendonitis = inflammation of a tendon = anti-inflammatories” seems easy to present and explain.

However, is this good practice? Should health professionals concerned use a different term? Or should they simply express their uncertainties and not use any specific term? I leave these questions open.

In summary:

clinical and radiological approaches do not confirm the presence of tendonitis;

the only way to be sure is to directly manipulate the tendon for sampling and analysis (an approach reserved for researchers);

in any case, current science does not support the assumption that tendonitis can explain the majority of shoulder pain.

What are the possible causes of shoulder pain?

In the case of shoulder pain, what symptoms lead to suspecting tendonitis? Let’s recap:

there’s the pain itself, which is the main symptom;
certain muscle weaknesses caused by the pain (identifiable by movements that cannot be done to full strength due to the pain);
and most importantly, there’s the absence of other symptoms than the pain itself.

That is to say, before supposing tendonitis, it’s crucial to carefully eliminate all other possible causes of the pain.

The diagnosis of tendonitis is therefore a diagnosis by elimination. That’s why it seems interesting to me to know what we’re primarily trying to rule out.

The major categories of possible causes for shoulder pain are [Rees, 2021]:

🔴 Causes requiring urgent management:

fractures or muscle ruptures following trauma;
infections;
tumors;
shoulder dislocations following trauma, epileptic seizure, or electrical shock;

🟡 Causes requiring specific management as quickly as possible (although less urgently than the previous ones):

systemic rheumatic diseases (e.g., rheumatoid arthritis);

⚫ Other causes:

traumatic or non-traumatic shoulder instabilities (e.g., in individuals with hypermobility);
acromioclavicular joint disease (joint between the acromion, part of the shoulder blade, and the clavicle);
glenohumeral joint disease (joint between the humerus and the shoulder blade):
🔹 adhesive capsulitis (involvement of the joint capsule, the structure that seals the joint);

🔹 isolated arthritis (joint inflammation).

If you have shoulder pain and all these causes have been ruled out, then some may tell you that you have shoulder tendonitis.

In summary: Shoulder tendonitis is inflammation of a shoulder tendon; tendon inflammation is measured by the presence of biological markers of inflammation (chemical substances) in the tendon.

The symptoms of a suspected tendonitis are:

🔹 shoulder pain that hinders the performance of certain movements;

🔹 the absence of other satisfactory explanations among all available explanations to explain the pain; in other words, the absence of other symptoms than the pain itself!

The problem is that neither these symptoms nor radiological examinations (ultrasound or MRI) guarantee 100% the presence of tendonitis.

In any case, nothing suggests that tendonitis can explain the majority of shoulder pain.

***

Here’s what I wanted to tell you about this! I wish you a very good recovery! Do you have any comments or questions? Your comments are welcome 🙂 !