Rotator cuff tear

What it means

The shoulder is held together at the top by a cuff of four small muscles and their tendons, which wrap over the ball of the arm bone like a hand cupping a baseball. They keep the ball centred in its shallow socket and let you lift, turn, and reach. A tear means one of those tendons — most often the one called supraspinatus — has frayed or split. The damage can range from a few worn-down fibres to a full hole right through the tendon.

Why it appears on a CT or MRI report

Reports describe which of the four tendons is torn (supraspinatus is the most common), whether the tear is partial or full thickness, where on the tendon the damage sits (along the upper surface, the underside, or through the whole tendon), and how big it is in millimetres. The radiologist will also note if the torn tendon has pulled back from the bone (retraction), if the muscle has shrunk or turned fatty (a sign of an older tear), and whether there is associated inflammation, fluid, or bursitis.

What it usually means

Rotator cuff tears come in two broad flavours. Acute tears follow a clear injury — a fall on an outstretched arm, a sudden lift, or a car accident — and tend to cause sharp pain, weakness, and trouble lifting the arm right away. Degenerative tears develop slowly as the tendons wear with age and turn up routinely on scans of people over 60, often without symptoms; one large study found rotator cuff tears in roughly half of people in their 70s, many of whom had no shoulder pain at all. So a tear on a scan doesn't automatically mean surgery. Many partial tears and even some full-thickness tears are managed well with physical therapy, anti-inflammatories, and activity changes. Larger, painful, or weakness-causing tears in active people are more likely to be considered for surgical repair.

When to follow up

Talk to your doctor if you have shoulder pain that wakes you at night, weakness when lifting or rotating the arm, trouble reaching overhead or behind your back, or pain that hasn't settled in a few weeks. They'll match the picture against your strength, range of motion, and how much the shoulder limits your day. Sudden complete inability to lift the arm after an injury, especially with numbness or weakness elsewhere, deserves urgent attention.

A plain-language way to picture it

Imagine an old garden hose where you've grabbed it the same way for years. The fibres along one side start to fray, threads pull loose, and eventually the hose develops a worn patch — sometimes a hole. The hose still works, but water seeps from the weak spot under pressure. The rotator cuff's tendons fray in the same gradual way, with the heaviest-used spot wearing first and a full hole forming only after years of stress.