Shoulder Impingement Syndrome

What happens in shoulder impingement

The shoulder is a ball-and-socket joint. Four rotator cuff muscles and their tendons wrap around the ball to hold it in place and lift and rotate the arm. Above them sits the acromion, a bony shelf at the top of the shoulder blade, and between the two is a fluid-filled cushion called the subacromial bursa.

When you lift your arm, the space between the tendon and the acromion narrows. If the tendons are swollen, the rotator cuff is weak, the shoulder blade does not move well, or there is a bone spur, the tendons and bursa get pinched and irritated. Over time this leads to tendinitis, bursitis and tendon wear.

Many specialists now call it subacromial pain syndrome, because the pain often comes from tendon overload rather than pure mechanical pinching. This is part of why exercise works better than surgery to "make more space".

Symptoms of shoulder impingement

• pain on the front or outer side of the shoulder, often spreading down the outside of the upper arm toward the elbow
• a painful arc: pain when raising the arm out to the side between about 60° and 120°, easing above and below that
• pain reaching overhead or behind your back, such as fastening a bra or tucking in a shirt
• night pain, especially when lying on the affected side
• mild weakness and a feeling of the shoulder catching
• stiffness, though passive movement (when someone else lifts your arm) is usually much better than active movement

Pain usually builds gradually over weeks.

Shoulder impingement vs a pinched nerve

People often search for "shoulder nerve impingement", but impingement syndrome involves tendons, not nerves. A pinched nerve near the shoulder or in the neck (cervical radiculopathy) feels different:

Causes and risk factors

• Repeated overhead activity: swimming, tennis, volleyball, baseball pitching, weightlifting, painting, plastering and stocking shelves. See swimmer's shoulder.
• Muscle imbalance: a weak rotator cuff or poor control of the shoulder blade.
• Rounded shoulders and slouched posture, which tilt the shoulder blade forward.
• Age: tendons wear with age, so it is most common after 40.
• Bony changes: a hooked acromion, bone spurs or arthritis of the joint at the top of the shoulder.
• Calcium deposits in the tendon (calcific tendinitis).
• A sudden increase in activity, such as a new gym program.

How it is diagnosed

A doctor or physical therapist will ask about your activities and examine your shoulder and neck. Common tests include:

• Neer test: the examiner lifts your straight arm forward and up with your thumb pointing down. Pain suggests impingement.
• Hawkins-Kennedy test: with your arm raised to shoulder height and elbow bent, the examiner rotates the forearm downward.
• Painful arc test: pain as you raise the arm out to the side through the middle of its range.
• Empty can (Jobe) test: resisting downward pressure on the arm with thumbs down checks the supraspinatus tendon.
• Strength tests to check for a rotator cuff tear.

Imaging is not always needed. An X-ray shows bone spurs, the acromion shape, arthritis and calcium deposits. Ultrasound or MRI is used if a rotator cuff tear is suspected, symptoms do not improve after several weeks of exercise, or surgery is being considered. Many people over 50 have tendon changes on scans without any pain, so imaging is interpreted alongside the exam.

Treatment

Relative rest and activity changes

Avoid activities that cause pain, especially repeated overhead work, for a few weeks. Complete rest and immobilizing the arm in a sling is not advised, because it can cause stiffness and frozen shoulder.

Pain relief

• Ice packs for 15 minutes a few times a day.
• Acetaminophen (paracetamol) or NSAIDs such as ibuprofen or naproxen, following the label dose. Avoid NSAIDs if you have stomach ulcers, kidney disease or are on blood thinners, unless your doctor agrees.

Exercise therapy

A structured exercise program, usually with a physical therapist, is the most effective long-term treatment. Expect 6 to 12 weeks of regular exercises. Typical exercises include:

• Pendulum swings: lean forward and let the arm hang and swing in small circles to ease pain.
• Shoulder blade squeezes: draw the shoulder blades back and down, hold for 5 seconds.
• External rotation with a resistance band: elbow at your side bent to 90°, rotate the forearm outward.
• Wall slides and scaption raises within a pain-free range.
• Posterior shoulder stretches, such as a cross-body stretch.

Mild discomfort during exercise is acceptable, but pain that lasts more than an hour afterward means you should ease back.

Steroid injection

A corticosteroid injection into the subacromial space can reduce pain for several weeks, making it easier to do exercises. It does not fix the underlying problem, and repeated injections may weaken tendons, so they are usually limited.

Surgery

Arthroscopic subacromial decompression shaves bone from the underside of the acromion. Large randomized trials, including the UK CSAW trial, found it gave no meaningful benefit over placebo surgery for impingement pain without a tear. It is now reserved for selected people with persistent symptoms after a full trial of exercise, or combined with repair of a significant rotator cuff tear.

Recovery and outlook

Most people improve within 3 to 6 months with exercise and activity changes, although some have pain for longer. Athletes and manual workers can usually return gradually once they have full, pain-free movement and good strength. Without treatment, ongoing impingement can contribute to tendon degeneration and tears.

Prevention

• Build rotator cuff and shoulder blade strength, especially if you play overhead sports.
• Increase training loads gradually.
• Take breaks from overhead work, and keep tools and shelves within easy reach.
• Watch your posture at desks and phones.
• Warm up before sports.

Frequently asked questions

What are the symptoms of shoulder impingement?

The main symptoms are pain on the outside of the shoulder and upper arm when lifting the arm to the side or overhead, a painful arc in the middle of the movement, pain reaching behind your back, night pain when lying on the shoulder, and mild weakness. Numbness and tingling are not typical.

How do you test for shoulder impingement?

Doctors use physical tests such as the Neer test, Hawkins-Kennedy test, painful arc test and empty can test, along with strength checks. X-rays can show bone spurs or calcium deposits, and ultrasound or MRI is used if a rotator cuff tear is suspected or symptoms persist.

What are the best exercises for shoulder impingement?

Effective exercises strengthen the rotator cuff and shoulder blade muscles, such as external rotation with a resistance band, shoulder blade squeezes, scaption raises and wall slides, plus stretches for the back of the shoulder. A physical therapist can tailor a program, usually for 6 to 12 weeks.

How long does shoulder impingement take to heal?

Most people improve within 3 to 6 months with exercise therapy and activity changes. Mild cases may settle in a few weeks. Pain that persists beyond 6 months despite a good exercise program should be reassessed, often with imaging to look for a rotator cuff tear.

Is shoulder impingement a pinched nerve?

No. Shoulder impingement involves the rotator cuff tendons and bursa, not a nerve. A pinched nerve in the neck or around the shoulder usually causes burning or shooting pain that spreads down the arm with numbness or tingling, which needs a different assessment and treatment.

Do I need surgery for shoulder impingement?

Usually not. Studies show that decompression surgery offers little extra benefit over exercise and placebo surgery for impingement pain alone. Surgery may be considered when a significant rotator cuff tear is present or when months of well-performed rehabilitation have not helped.