Shoulder impingement syndrome: why the name is changing, and why exercise comes first

Where did the "impingement" idea come from, and why is it being questioned?

The concept of "impingement" was proposed in the 1970s: as the arm is raised, the bony roof called the acromion was thought to pinch the rotator cuff tendons passing beneath it, and treatment was thought to be shaving this bone to "make room." This model justified hundreds of thousands of surgeries over decades. Yet accumulating evidence has revealed the model's weak points:

• The relationship between the shape of the acromion and pain is not as strong as was believed; many people whose imaging shows "impingement-prone" anatomy have no pain at all.
• Pain cannot be reduced to a single tissue or mechanism: a decrease in the tendon's load capacity (tendinopathy), sensitivity of the neighboring bursa, loading habits, central pain processes, and psychosocial factors may all play a role together — mechanical crushing does not alone explain the picture.
• The most critical evidence: surgery that shaves the bone did not prove superior to sham surgery that does not touch the bone at all (below).

For this reason, the international literature tends to abandon the term "impingement syndrome"; in its place, rotator cuff related shoulder pain or subacromial pain syndrome is used. The debate over the name is not an academic detail: telling a patient "the bone in your shoulder is pinching the tendon" both creates fear of movement and lays the groundwork for unnecessary surgery.

The surgical evidence: CSAW and FIMPACT

Two independent, randomized, placebo-surgery-controlled trials are the turning point in this field:

Based on these data, the systematic review and the 2019 international rapid guideline (BMJ Rapid Recommendation) published a strong recommendation against decompression surgery in subacromial pain syndrome: the evidence that surgery has no added benefit over placebo is of high certainty; against this stand its cost, recovery time, and rare but real risk of complications. The Cochrane review reached the same conclusion. An important boundary: this evidence is not for full-thickness rotator cuff tear, frozen shoulder, or instability, but for decompression performed with a diagnosis of subacromial pain (impingement).

First-line treatment: graduated exercise

At the center of treatment is a graduated, structured exercise program targeting the rotator cuff and the muscles around the shoulder blade (scapula):

• Systematic reviews show that exercise improves pain and function and, in many patients, removes the need for surgery; in FIMPACT the exercise arm improved to a degree that produced no clinically meaningful difference from the surgical arms.
• Recovery is slow: meaningful improvement usually takes 12 weeks and beyond; patience and consistency are as important as the technique itself.
• Mild-to-moderate pain during exercise that settles in a short time is considered acceptable in most programs; pain that increases and carries over to the next day indicates that the dose needs to be adjusted.
• An interesting finding: in the large GRASP trial (Lancet 2021), a comprehensive program progressed under physiotherapist supervision and a single session of high-quality education from a physiotherapist + a home program produced similar results at 12 months. That is, the magic is not in a particular exercise prescription but in the regular and graduated reloading of the shoulder; nonetheless, a supervised program is still valuable in the patient who needs follow-up, has low self-confidence, or does not improve.

Load management is the other half of the work: the trigger that starts the pain is most often a sudden increase in overhead activity (painting, swimming, throwing, weight training); this load is pulled back and gradually rebuilt.

Who gets it, and what is its course?

Rotator cuff related pain is the most common cause of shoulder pain and is seen most often in those over 40 and in those who do overhead activity (swimmers, volleyball players, handball players, painters, electricians). The trigger is most often a sudden increase in shoulder load; however, factors such as age, diabetes, and smoking also affect tendon health. The course is generally benign: a significant proportion of patients improve within months with load adjustment and exercise. On the other hand, if the picture is left to itself, it can last a long time; continuing to overload the shoulder overhead for months with pain, thinking "it will pass anyway," is also not right. If night pain is prominent, if there is sudden loss of strength, or if the pain started after a trauma, evaluation is needed without delay.

Cortisone injection: a short-term tool, not a lasting solution

A corticosteroid (cortisone) injection into the subacromial space can relieve pain; however, randomized evidence shows that this effect is short-term:

• In the GRASP trial, the injected group was somewhat better at week 8; by month 12 the difference was gone.
• Meta-analyses give a similar result: a small and temporary reduction in pain, no difference in the long term.
• For this reason, cortisone is not "the treatment itself"; it is a tool that can be used as a bridge to exercise in a patient whose pain is severe enough to prevent starting exercise. Avoiding repeated injections is the generally accepted approach; there is concern about adverse effects on tendon tissue.

Shockwave therapy (ESWT): its real place is calcific tendinopathy

Extracorporeal shockwave therapy (ESWT) is a needle-free, surgery-free method that applies pressure waves to the area from outside. In the shoulder, the evidence splits in two:

• In calcific tendinopathy — a calcium deposit within the tendon visible on ultrasound/X-ray — randomized trials and meta-analyses suggest that especially focused ESWT can reduce pain and can contribute to the dissolution (resorption) of the calcium deposit; however, the protocols used (energy level, number of sessions) are highly variable, and the certainty of the evidence is low to moderate. For this reason, ESWT is an option that may be considered in selected calcific cases resistant to exercise. In needle lavage (barbotage/lavage), the picture is more cautious: in a sham-controlled randomized trial published in 2023, ultrasound-guided lavage + cortisone was not found superior to the sham procedure at 4 and 24 months.
• In rotator cuff tendinopathy without calcium deposit, the evidence is weak; the Cochrane review showed no clinically important benefit. In this group, ESWT is not routinely recommended.

In which situation does surgery still come onto the agenda?

The fact that decompression is not superior to placebo does not mean "no surgery has a place in the shoulder." A traumatic full-thickness rotator cuff tear (especially in a young, active patient), marked loss of strength, and selected cases that do not improve despite long and high-quality conservative treatment require surgical evaluation. The message here has narrowed but is clear: there is no evidence for shaving bone with a diagnosis of "impingement"; tear surgery is a separate topic and is evaluated by its own indications.

For clinicians

In the terminology debate, the current trend is to use "rotator cuff related shoulder pain" (Lewis) or "subacromial pain syndrome" (Dutch guideline, Diercks 2014) instead of "subacromial impingement"; the extrinsic mechanical compression predicted by the Neer model is not supported as an isolated etiology. CSAW (n=313, three-arm) and FIMPACT (n=210, double-blind, sham-surgery-controlled) together show with high certainty that acromioplasty has no specific effect; FIMPACT's 10-year follow-up (Kanto 2025) confirmed that decompression provides no benefit in the long term either against placebo or against exercise. The Lähdeoja meta-analysis and the BMJ Rapid Recommendation (2019) published a strong recommendation against it on this basis. The content of the exercise prescription is heterogeneous; the absence of a SPADI difference at 12 months between the progressive program and best-practice advice in GRASP suggests that the loading principle and patient education are more decisive than the dose. Subacromial corticosteroid effect peaks at 6–8 weeks and then disappears; the number of injections should be limited because of concern about adverse effects on the tendon with repeated injections. In ESWT the evidence is specific to calcific tendinopathy (especially focused protocols and type I–II deposits), but the protocols are heterogeneous and the certainty of the evidence is low to moderate; it may be considered in selected cases. In non-calcific tendinopathy, Cochrane (Surace 2020) showed no clinically important benefit. In barbotage/lavage, Moosmayer 2023 (BMJ, sham-controlled) showed that lavage + steroid was not superior to sham at 4 and 24 months. In the differential diagnosis, adhesive capsulitis, full-thickness tear, the acute resorptive crisis of calcific tendinitis, cervical radiculopathy, and glenohumeral osteoarthritis should be kept in mind; in traumatic tear and marked weakness, early imaging and surgical consultation should not be delayed.

Frequently asked questions

Related articles

• Rotator cuff tear: surgery or exercise?
• Recurrent shoulder dislocation: what happens after the first dislocation, and when does surgery come up?
• Frozen shoulder (adhesive capsulitis): does it resolve on its own, and what helps in treatment?

Scientific references

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.