Frozen shoulder or rotator cuff tear? How to tell them apart

Why the difference matters

A frozen shoulder gets better on its own, slowly. Treatment is about getting through it with less pain and keeping what movement you can. Forceful stretching usually makes it worse.

A rotator cuff tear does not heal back onto the bone by itself. Many tears, especially the ones that come with age, do well with exercises and never need an operation. But a tear from a fall or a heavy lift in an active person can get bigger, and if it is left for many months the tendon pulls back and the muscle behind it weakens and turns to fat, until it may no longer be repairable.

So both mistakes cost something: a torn cuff labelled frozen shoulder and left for a year, and a frozen shoulder pushed hard as if it were a tear. Shoulder pain has other causes too, but these two are the pair most often confused.

The test that separates them

It is simple. Try to lift your arm up in front of you. Then relax completely and let someone else lift it for you, gently, stopping if it hurts sharply.

• Frozen shoulder: the arm stops at about the same point whoever is lifting it. The joint itself has tightened, so it is stiff in every direction. Turning the forearm outwards with the elbow tucked at your side is often the most limited movement of all.
• Rotator cuff tear: you struggle to lift it yourself, but when someone else lifts it, it goes much further. The joint moves; the tendon that should move it is not doing its job.

It is not always that clear. In the painful early stage of frozen shoulder, pain limits everything and the test is harder to read. A shoulder can have both problems, and a torn cuff that has been kept still for long enough can stiffen as well. Those are the shoulders where a careful examination tells you more than a scan.

Shoulder surgery was the focus of my fellowship at Seoul National University Bundang Hospital in South Korea, and this is one of the distinctions a shoulder clinic makes every day. It is usually settled in the first ten minutes, with the arm in my hands.

Other clues

What you describe normally points the same way as the examination.

• How it started. A fall on an outstretched arm, a jerk while lifting, or a sudden pain followed by weakness suggests a tear. Frozen shoulder usually creeps up with no clear cause, though a spell of keeping the arm still after an injury can set it off.
• Stiff or weak. Frozen shoulder is mainly stiff. A torn cuff is mainly weak, and the arm may drop if you try to hold it out to the side.
• Night pain. Both cause it, so it does not help much. Lying on that side is painful in both.
• Diabetes and thyroid disease. Both make frozen shoulder more likely, and in diabetes it is often stiffer and slower to settle.
• Age. Frozen shoulder is commonest between forty and sixty. Cuff tears become more common with every decade after forty, and many people over sixty have a tear that causes them no trouble at all.

Do you need a scan?

Often not straight away. An X-ray helps rule out arthritis and calcium deposits in the tendon, and in both conditions it is usually normal. Frozen shoulder is diagnosed by examination; no scan confirms it.

When a tear is suspected, an ultrasound in experienced hands shows the cuff well. I use an MRI when an operation is being planned, because it shows the size of the tear, how far the tendon has pulled back and the condition of the muscle.

How each is treated

For frozen shoulder: pain relief, a steroid injection into the joint during the early painful phase, and gentle stretching that stays within what the shoulder will tolerate. Most shoulders loosen over eighteen months to three years. The few that are still very stiff after six to twelve months of proper treatment may need the tight capsule released by keyhole surgery.

For a torn cuff, it depends on the tear and on you. A worn tear in an older, less demanding shoulder often settles with physiotherapy that strengthens the muscles around it. A tear from a clear injury in someone active is usually better repaired early, while the tendon is still healthy enough to hold stitches. Rotator cuff repair is keyhole surgery; the recovery takes months, with four to six weeks in a sling and most of the work done in physiotherapy afterwards.

For a very large, long-standing tear that can no longer be repaired, especially once arthritis has set in, a reverse shoulder replacement is designed to work without the cuff.

Further reading

• American Academy of Orthopaedic Surgeons, OrthoInfo: Frozen shoulder.
• American Academy of Orthopaedic Surgeons, OrthoInfo: Rotator cuff tears.
• NHS: Frozen shoulder.

Common questions