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Shoulder

Rotator cuff pain and impingement

Pain in a specific arc as you lift the arm — fine at the bottom, painful in the middle, often easier again at the top.

What it typically feels like

  • A painful arc partway through lifting the arm sideways
  • Weakness lifting or holding something out in front
  • Pain reaching into a back seat or a high shelf
  • An ache down the outside of the upper arm

The rotator cuff is four small muscles whose job is to hold the ball of the shoulder centred in its socket while the big muscles move the arm. They are often described as the guardians of the shoulder joint, and when they stop doing that job well, the tendons get pinched in the narrow space above.

The painful arc

The characteristic sign is a band of pain partway up. Lifting the arm out to the side is comfortable at first, hurts through the middle range, then often eases again near the top. That is the tendon being compressed as it passes through the tightest part of its travel.

What usually causes it

  • Overhead volume — throwing, swimming, pressing, racket sports, or a weekend of decorating.
  • Poor shoulder blade control, so the space the tendons run through does not open as the arm lifts.
  • Rounded posture, which narrows that space before you have even moved.
  • A stiff mid-back, forcing the shoulder to make up the difference.

What treatment involves

Releasing what is restricting the movement, settling the irritated tissue, and restoring the shoulder blade mechanics that create space for the tendon.

Then strengthening — specifically the cuff and the muscles controlling the shoulder blade. This is a control problem more than a tissue problem, and strengthening is what makes the improvement stick.

What is actually in the shoulder

The most mobile joint in the body, and mobile for a specific reason: the socket is shallow, roughly the size of a golf tee holding a golf ball. Almost all of its stability is muscular, which is why the muscles matter so much here.

Glenohumeral joint
The ball and socket itself. A large humeral head sitting on a small, shallow glenoid — enormous range, very little bony stability.
Rotator cuff
Four muscles — supraspinatus, infraspinatus, teres minor and subscapularis — whose job is to hold the ball centred in the socket while the big movers do the lifting. Supraspinatus is the one most often irritated.
Subacromial space
The narrow gap between the top of the arm bone and the bony roof above it, with a tendon and a bursa running through it. Reduce that space and the contents get compressed — the pinch felt midway through lifting the arm.
Scapulothoracic movement
The shoulder blade must glide and rotate on the rib cage for the arm to get overhead. If it does not, the joint runs out of room early and the cuff takes the impact.
Acromioclavicular joint
The small joint on top of the shoulder where the collarbone meets the shoulder blade. Distinctive because pain sits precisely on the point of the shoulder rather than deep inside it.

Why it goes wrong

The painful-arc pattern — comfortable at the bottom, sore in the middle, easier again at the top — is the signature of something being compressed in that narrow subacromial space. Most of the time the underlying cause is not the tendon itself but the shoulder blade failing to move properly beneath it, which is why treatment that only chases the sore spot tends to disappoint.

3D anatomy See the structures involved on the interactive model

The honest next step

This page describes what is common, not what you have. The only way to know is to have it assessed — and your first session includes a full assessment, so you leave knowing what is actually going on.

Book an assessment Call 07922 884 788