Rotator cuff tear or just a strain? How doctors tell

A strain and a tear can feel alike at first. Both hurt when you lift the arm, and both can ache at night. What usually points to a tear is real weakness: the arm will not lift or turn with normal strength, or it gives way. A doctor tells them apart with a careful examination and, when needed, an ultrasound or MRI scan.

What the rotator cuff is

The rotator cuff is a group of four muscles and their tendons that wrap around the ball of the shoulder joint. They hold the ball in its socket and help you lift and turn the arm. The tendon at the top of the shoulder is the one most often injured.

Strain, tendon irritation and tear

A strain or irritated tendon (often called tendinopathy) means the tendon is overloaded and sore, but still whole. It often follows a change in activity, such as painting a ceiling, a new gym routine or a lot of overhead work.

A partial tear goes part of the way through the tendon. The tendon is still attached to the bone, but it is thinner and weaker.

A full-thickness tear goes right through the tendon, leaving a hole, or pulls it off the bone completely.

Tears happen in two main ways:

• Injury. A fall on an outstretched arm, or lifting something heavy with a jerk. This is the usual cause in younger adults.
• Wear over time. The tendon slowly frays, often with no single injury. This is the most common type and becomes more likely after about 40, in the dominant arm, and in people who lift or work overhead.

Signs that suggest a tear

Signs that fit a strain or irritated tendon:

• pain when lifting the arm, often after a change in activity
• strength is mostly normal once the pain is controlled
• gradual improvement over a few weeks with rest from what hurts

Signs that point more towards a tear:

• clear weakness when lifting or turning the arm out
• pain at rest and at night, especially lying on that side
• a snap or sudden weakness after a fall or heavy lift
• a crackling feeling with certain movements
• trouble with everyday tasks such as combing your hair or reaching behind your back

These patterns overlap. Some tears cause little pain but leave the arm weak. Some strains are very painful. That is why an examination matters more than guessing.

How doctors tell the difference

Questions and examination

The doctor asks how the pain started, what makes it worse and whether the arm feels weak. They then:

• press to find the tender spots
• move the arm in different directions, and compare it with how far you can move it yourself
• test the strength of each part of the cuff with specific movements
• check the neck, because a trapped nerve there can cause shoulder and arm pain

Scans

• X-ray. Usually normal with a cuff problem, because tendons do not show. It rules out arthritis and other bone causes.
• Ultrasound. Shows the tendons and can show a tear. Quick, and good in skilled hands.
• MRI. Shows the size and position of a tear, and the quality of the muscle, which helps judge how old a tear is.

Treatment for a strain

• Keep moving the shoulder gently. Do not stop using it completely.
• Avoid the movements that hurt for a while, especially overhead lifting.
• Use paracetamol or ibuprofen if safe for you, and ice or heat for up to 20 minutes.
• Start shoulder exercises and keep them up for 6 to 8 weeks to stop the pain returning.

Most shoulder pain starts to ease within about 2 weeks of these steps. Full recovery can take months.

Treatment for a tear

Many tears are treated without surgery first. The AAOS reports that non-surgical treatment relieves pain and improves function in about 80 to 85% of patients. This includes physiotherapy to strengthen the muscles around the shoulder, anti-inflammatory medicine and, for some people, a steroid injection.

Rotator cuff repair may be advised when:

• pain continues despite 6 to 12 months of good non-surgical care
• the tear is large and the tendon tissue is good quality
• there is marked weakness and loss of function
• the tear came from a recent injury
• you are active, or use your arms overhead for work or sport

The repair reattaches the tendon to the bone, usually by keyhole surgery (shoulder arthroscopy).

When to see a doctor

See a doctor if shoulder pain is getting worse or has not improved after 2 weeks, if the arm feels weak, or if it is very hard to move. Seek help quickly if the pain followed a fall, if the shoulder has changed shape or is badly swollen, or if you have pins and needles or numbness in the arm. If shoulder pain comes with chest pain or breathlessness, call 998.