Rotator cuff

The rotator cuff is a group of four muscles that start on the shoulder blade and attach to the head of the upper arm bone: supraspinatus, infraspinatus, subscapularis and teres minor. Their resting tension pulls the ball of the arm bone into the socket of the shoulder blade, which gives the shoulder joint much of its stability (TeachMeAnatomy).

What does the rotator cuff do?

As well as holding the joint together, each muscle has its own job (TeachMeAnatomy):

• Supraspinatus starts lifting the arm out to the side, doing the first 15 degrees alone, and then helps the deltoid up to 90 degrees.
• Infraspinatus and teres minor turn the arm outwards.
• Subscapularis turns the arm inwards.

Rotator cuff changes are common with age

Tendon wear in the rotator cuff is very common, and much of it causes no symptoms. A pooled analysis of 30 studies covering 6,112 shoulders found that abnormalities of the rotator cuff rose from 9.7% in people aged 20 or younger to 62% in people aged 80 and over. The authors concluded that cuff degeneration is common enough in people without symptoms to be considered a normal part of ageing, which makes it hard to tell when a change on a scan is the cause of pain (Teunis et al., 2014).

So if a scan report mentions a partial tear or tendinopathy, it is one piece of information, not the whole explanation.

Does desk work strain the rotator cuff?

• What the work studies show. A 2024 review of work-related shoulder disorders found the strongest evidence for raised arms, repetition, force and vibration as risks for impingement and tendon problems. Psychosocial pressures at work were also linked with rotator cuff problems (Versloot et al., 2024).
• Mouse use. In 2,146 technical assistants whose computer use was recorded, the risk of short-lived shoulder pain rose by 10% for each step up in weekly mouse time (from one quarter of the group to the next). But mouse and keyboard time did not predict prolonged or chronic neck or shoulder pain, while a few psychosocial factors did (Andersen et al., 2008).
• Posture. A rounded upper back is often blamed for shoulder pain. A systematic review of ten studies found moderate evidence of no difference in thoracic kyphosis between people with and without shoulder pain (Barrett et al., 2016).

More on the desk side is in shoulder pain from computer work, and the workstation checklist goes through your desk set-up.

What helps rotator cuff pain?

A common explanation for rotator cuff pain is “impingement”: the supraspinatus tendon rubbing against the bony arch above it (TeachMeAnatomy). A large UK trial tested the operation designed to fix that, which shaves away bone to make more room. In 313 people with at least three months of shoulder pain, results at six months were no better after the real operation than after a placebo one, in which the bone was left alone (Beard et al., 2018). That casts doubt on the idea that the rubbing itself is the main problem.

Exercise has better support. In a meta-analysis of randomised trials in shoulder impingement, exercise reduced pain more than no exercise, and exercises aimed at the shoulder did better than general ones, though the evidence was very low quality (Steuri et al., 2017). The NHS advises staying active, moving the shoulder gently, not stopping using it completely, and keeping up shoulder exercises for 6 to 8 weeks to stop pain coming back (NHS). Stretches for the area are on shoulder stretches.

When to see a doctor

See a GP if shoulder pain is getting worse or has not improved after two weeks, or it is very hard to move your arm. Ask for an urgent GP appointment or contact NHS 111 if the pain is sudden or very bad, you can’t move your arm, the shoulder has changed shape or is badly swollen, you have pins and needles that don’t go away or no feeling in the arm, it is hot or cold to touch, the pain started after a fall or injury, both shoulders are very painful, or you feel feverish or unwell (NHS). Pain and stiffness that last for months can be frozen shoulder rather than the rotator cuff.

Bavelu’s shoulder and upper back sessions are designed and filmed by physiotherapists.