Shoulder impingement (subacromial pain syndrome) is pain, felt especially when lifting the arm, from the rotator cuff tendons that move the shoulder and the bursa lying over them; it is closely related to rotator cuff tendinitis and tears [1][4]. Most people improve within a few months with activity changes, pain control and regular exercise, with a steroid injection if needed; decompression surgery for impingement alone is not recommended, while repair may be considered for some rotator cuff tears [1][4][5].
What is the rotator cuff and how does impingement arise?
The rotator cuff is made up of four muscles and tendons around the head of the upper arm bone; it lifts and rotates the arm and keeps the joint in place [2].
Pain can come from inflamed tendons (tendinitis), an inflamed slippery sac over them (bursitis) or impingement. In impingement the space between the bony point at the top of the shoulder (the acromion) and the tendons narrows as the arm is raised, irritating the tendons [1]. Current guidelines also use the terms 'subacromial pain syndrome' or 'rotator cuff disease' for this picture [4].
Is impingement the same as a tear?
Over time tendons can wear and partial or full-thickness tears can develop. A tear can follow a sudden strain such as a fall or heavy lifting but more often develops slowly with age-related wear [2].
In impingement the tendon is intact but irritated; in a tear part or all of the tendon has come apart [1][2].
What symptoms are typical?
A sudden (injury-related) tear usually causes severe pain and weakness straight away. A wear-related tear may hurt little at first, so long-lasting shoulder pain and loss of strength should be assessed [2]. Symptoms usually start mildly and build up [1][2]:
- Pain at the front and outer side of the shoulder, sometimes running down the side of the arm
- Pain that increases lifting the arm above head height or reaching
- Night pain, especially when lying on the sore shoulder
- Weakness: difficulty dressing, washing hair or reaching behind the back
- Clicking in some movements
Who is more likely to get it?
Impingement and rotator cuff problems mostly arise from a mix of repeated strain and age-related change; they can follow a minor injury or start with no clear cause [1][2]. Main factors:
How is it diagnosed?
The doctor examines range of movement and strength; which movements bring on the pain helps guide the diagnosis [1].
An X-ray can show a bony spur on the acromion and help exclude other causes. The state of the tendons, and whether a tear is present, where it is and how big, is assessed with MRI or ultrasound [1][2].
Non-surgical treatment
Treatment rests on non-surgical measures. Rather than keeping the sore shoulder completely still, the advice is to cut back on the movements that provoke pain and keep using the shoulder gently [1][3]:
- Rest and activity changes, especially fewer overhead movements for a while [1]
- Anti-inflammatory painkillers [1][2]
- Physiotherapy and exercise: stretching and strengthening are central, and continuing exercises for 6 to 8 weeks helps stop pain coming back [1][3]
- Steroid injection: can be given into the bursa if other measures do not give enough relief, alongside rather than instead of exercise [1]
Is surgery needed?
Subacromial decompression, in which the bony spur and inflamed bursa are cleared through the arthroscope, used to be common for impingement that did not respond to non-surgical care [1]. A Cochrane review including studies against placebo (sham) surgery found no meaningful extra benefit for pain, function or quality of life [5]. An international guideline based on this evidence makes a strong recommendation against decompression surgery for subacromial pain lasting more than 3 months [4].
Rotator cuff tears are a separate matter: repair may be considered for pain lasting 6 to 12 months despite appropriate treatment, large tears, tears from a recent injury that cause marked weakness, or active people who use the arm hard overhead [2].
How long does recovery take?
For impingement and tendinitis, pain usually takes 2 to 4 months to settle fully, and in some people up to a year [1]. Shoulder pain can last six months or longer; gentle movement and continuing exercises matter during this time [3]. Return to strenuous work or sport is planned in steps according to pain and strength [1][3].
When not to wait
See a doctor if the pain does not improve within two weeks, keeps getting worse or the shoulder becomes very hard to move. Urgent assessment is needed for [3]:
- Sudden or very severe shoulder pain
- Being unable to move the arm
- A change in the shape of the shoulder or marked swelling
- Tingling or numbness in the arm, or the arm feeling hot or cold
- Pain or inability to lift the arm that began after a fall or blow
- Pain in both shoulders at once, or pain with a fever
Frequently asked questions
- What is the difference between impingement and a tear?
- In impingement the tendons and the sac over them are irritated but the tendon is intact; in a tear part or all of the tendon has come apart [1][2].
- Does impingement settle without surgery?
- In most people yes; with activity changes, pain control and regular exercise the pain usually eases over a few months. Decompression for impingement alone has not been shown to add meaningful benefit over sham surgery [1][4][5].
- Why is my shoulder worse at night?
- Night pain is typical of rotator cuff problems and is often worse when lying on the sore shoulder [1][2].
- Will a steroid injection be given?
- If rest, medication and physiotherapy do not give enough relief, a steroid injection can be given into the bursa; it should be considered alongside the exercise programme, not instead of it [1].
- Does every rotator cuff tear need surgery?
- No. Many tears can be managed without surgery; surgery comes up with long-lasting pain, a large tear or marked weakness after an injury [2].
At our clinic we first work out by examination and, where needed, imaging whether the pain comes from impingement or a tear, and then agree with you an exercise-based plan.
Sources
- Shoulder Impingement/Rotator Cuff Tendinitis. American Academy of Orthopaedic Surgeons (OrthoInfo), 2024. orthoinfo.org
- Rotator Cuff Tears. American Academy of Orthopaedic Surgeons (OrthoInfo), n.d.. orthoinfo.org
- Shoulder pain. NHS (nhs.uk), 2023. nhs.uk
- Subacromial decompression surgery for adults with shoulder pain: a clinical practice guideline. BMJ (Vandvik PO, et al.), 2019. pubmed.ncbi.nlm.nih.gov
- Subacromial decompression surgery for rotator cuff disease. Cochrane Database of Systematic Reviews (Karjalainen TV, et al.), 2019. pubmed.ncbi.nlm.nih.gov
This article is general information and does not replace an examination or imaging. If you have symptoms, see a doctor.
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