Shoulder bursitis is probably the most common diagnosis when it comes to painful shoulders. What is it, how does it occur, and how should you treat it?
What is a Bursa?
It’s a small fluid filled sac designed to reduce friction between moving parts in your joints. The main bursa in the shoulder is called the “subacromial / subdeltoid bursa” (SA/SD bursa) and it is the largest in the human body. It sits on top of the rotator cuff tendon and the bones, deep to the deltoid muscle, acting to reduce friction between the tendon and bones every time you lift your arm.
When it becomes inflamed it is a frequent generator of shoulder pain. You might hear this condition referred to as “subacromial bursitis”. Bursitis often coexists with other shoulder conditions like rotator cuff tendon injuries; the reasons why will become obvious why once you understand the anatomy and mechanism of injury.
The “subacromial space”, which is the gap between the two bones (the humerus and acromion process of the scapula) is usually small, averaging between 7-14mm. This space houses the supraspinatus (rotator cuff) tendon and the bursa. When you lift your arm up this small gap narrows several millimetres and there is gentle contact between the tendon and bones. The bursa acts to lubricate this motion and reduce friction so the moving parts can slide easily past one another.
What is Bursitis?
Bursitis indicates that this thin bursa has become inflamed, upon which it may thicken, swell, and look red and angry internally. The bursa has many sensory nerves and is capable of generating significant pain.
What Causes Bursitis?
Bursitis (and related rotator cuff tendon damage) are usually caused by repetitive mechanical overload known as “impingement” (repetitive compression of the bursa and suprapinatus tendon between the acromion and humeral head).
Less commonly trauma (a fall onto your outstretched hand that crushes the bursa / tendon between the bones) can trigger bursitis. The bursa may also become inflamed via other processes such as infection (rare) or calcific tendonitis (in which calcium deposits form in the underlying tendon).
The repetitive impingement process means that either movement of the:
scapula (shoulder blade),
humeral head,
or other related parts of the body
are not optimal.
Since the shoulder girdle is so heavily reliant on muscles to function, impingement almost invariably means that the muscles controlling shoulder motion are not functioning properly.
Why is Shoulder Motion & Shoulder Pain so Complex?
There's a lot more to fixing shoulder problems than looking at the shoulder in isolation, which never works!
To elaborate I’ll relate a conversation I had with a Physiotherapy student in the clinic who asked a question that beautifully illustrates this point: “Does treating the ribs directly help shoulder pain?”. I asked them to think about “What structures need to move properly for the shoulder to work properly”. At university we usually have students perform an exercise where you list out all the different parts needed to move and function correctly to lift the arm overhead. “Can you tell me at least 20 things that need to work properly for the shoulder to function normally”. The student thought a minute and came up with only 2 – the shoulder blade and humerus (ie the glenohumeral or shoulder joint). To follow their line of reasoning a bit further, I asked “what does the scapula attach to and have to move across?” The clavicle is the only direct bony attachment, so the AC and SC joints need to move properly for the shoulder to move. The shoulder blade is suspended from the neck and torso primarily by muscle, and moves across the rib cage, so every muscle, every rib, the sternum, the cervical and thoracic vertebrae all need to move properly as well. With 144 joints in the rib cage alone, there’s quite a lot of things that need to move properly for the arm / shoulder to move overhead normally without restriction or pain.
All of the ribs elevate in order to lift your arms overhead normally. The patient in question couldn’t do this and was using his lower back to arch backwards to get the arms elevated. Probably not good for the low back in the long run either…. But’s another story!
The point is that when assessing and treating bursitis and other types of shoulder pain, all of the muscles, nerves, arteries, veins, lymphatic vessels, ligaments, labrum (shoulder cartilage), the many joints of the entire thoracic spine (mid back), cervical spine (neck) and rib cage at a minimum need to be examined and be sufficiently functional for the subacromial space to be wide enough to avoid pinching the bursa. As a result, treatment involves examining and treating any of the above structures that are causing a mechanical or neural control change in the way entire spinal / rib cage / shoulder girdle complex moves.
No wonder simple surgical removal of the bursa doesn’t work that well – it is too reliant on the rehab and rest afterwards to succeed, when if you simply do the rehab and rest in the first place it removes the need for surgery! Remember that rest alone does not address the underlying causes….
For these reasons a "shoulder expert" is really a practitioner who excels in treating the entire body
State of the Art Treatment
As we alluded to above, the consensus is that surgery for bursitis or impingement offers no benefit over conservative care (Beard et al 2018; Ketola et al 2017; Lähdeoja 2019).
Rehabilitation of strength, restoring flexibility and motion lead to resolution because they begin to address the underlying causes. However bursal pain inhibits muscle function, and overly aggressive rehab can irritate the bursa and prevent it from healing and settling down.
As a result manual therapy treatment is often required to minimise pain and improve mobility to allow any necessary rehab to occur. The latest advances in manual therapy are particularly beneficial, accelerating the improvement in function of all the above structures to permit a less painful rehab process to occur (for more see my posts here, here and here). Fascial Counterstrain is a highly effective and gentle approach that David uses extensively to address dysfunction involving many of the structures including:
Labrum (cartilage)
Ligaments and neurogenic inflammation
Thoracic spine and rib (including rib cartilage) dysfunction
Cervical spine dysfunction
Nerve irritation
Arterial or venous dysfunction resulting in muscle guarding
Using this approach, the patient mentioned above was able to lift his arms overhead with minimal pain after one treatment. Rehab requires some professional assistance, as progressing too quickly often causes more bursal impingement and pain. It’s not the sort of thing that an internet-based program is recommended for. And the longer you leave it, the longer pain inhibits your muscles and the weaker they get.... Thus the longer it takes to recover!
As with all types of pain or injury, dealing with things as early as possible always produces superior outcomes compared to letting things become chronic, so act early and your recovery time and total cost of care will be markedly less – especially if you choose expert hands to guide your care.
References:
Beard D et al (2018): Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. Lancet 391 http://dx.doi.org/10.1016/S0140-6736(17)32457-1.
Ketola S et al (2017): Arthroscopic decompression not recommended in the treatment of rotator cuff
Tendinopathy. A final review of a randomised controlled trial at a minimum of follow-up of 10 years Bone Joint J Surg 99-B:799–805.
Klatte-Schulz F et al (2022): Subacromial Bursa: A Neglected Tissue Is Gaining More and More Attention in Clinical and Experimental Research. Cells 11:663.
Lähdeoja T et al (2019): Subacromial decompression surgery for adults with shoulder pain: a systematic review with meta-analysis.
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