What's Actually Going On
The Anatomy Behind the Pain
The rotator cuff is four tendons wrapping around the shoulder joint: supraspinatus, infraspinatus, teres minor, and subscapularis. Together they compress the ball of the upper arm into its shallow socket and coordinate virtually every shoulder movement. When two of these tendons develop degenerative tears — typically supraspinatus plus infraspinatus — the mechanical balance of the shoulder breaks down, producing pain, weakness, and night aches that disrupt sleep.
The "critical zone" of the supraspinatus, roughly 1 cm from where it attaches to the bone, has genuinely poor blood supply. Decades of use cause progressive fibre failure there — not from any single injury, but from the cumulative mismatch between loading and repair. The structural damage is real. What the research overturned is the assumption that structural damage drives clinical outcomes. Many full-thickness multitendon tears show up on MRI in people with zero pain, zero weakness, and zero reason to seek treatment.
The practical implication: a scan showing a tear does not predict how much it hurts, how disabled it makes someone, or whether it will respond to treatment. The symptoms do. Treat the person, not the image.
For women specifically, peri- and post-menopausal hormonal shifts reduce tendon collagen elasticity, making this presentation more common after age 50. Prospective cohort data also show that women achieve slightly lower functional scores on standardised shoulder questionnaires compared to men at 1-2 year follow-up — though the absolute improvement from treatment is still clinically meaningful and justifies the same conservative-first approach.
