The short version
- A review of 189 randomized trials in The BMJ found that shockwave therapy, which sends short pulses of sound into the shoulder, probably reduces frozen shoulder pain in the first months.
- The average gain was about two points on a 0 to 10 pain scale compared with usual care, the only shockwave result the authors rated moderate certainty.
- Most of the trials were at high risk of bias, harms were poorly reported, and almost nothing is known about whether the benefit lasts.
Pulses of sound aimed at a stiff shoulder probably ease the pain of frozen shoulder for the first few months, according to a review of 189 trials published in The BMJ on November 4.
Frozen shoulder, or adhesive capsulitis, is the capsule around the shoulder joint turning thick, stiff and inflamed. It hurts, it limits how far the arm can move, and it is most common between 40 and 60 and in women. People are offered a long list of treatments, from steroid injections and drugs to surgery, with little head-to-head evidence to choose between them.
How the review was done
A team led from the Department of Orthopaedics at Xiangya Hospital, Central South University in Changsha, with co-authors in a dozen other countries, searched five databases to May 2025 and updated the search in November 2025. They kept only randomized trials in adults with frozen shoulder.
That gave 189 trials, 12,988 people with an average age of 54, and 59 different treatments. A network meta-analysis lets treatments that were never tested against each other be compared through a shared comparison, usually usual care. Each result was graded for certainty.
What shockwave therapy is
Extracorporeal shockwave therapy, or ESWT, delivers short acoustic pulses from a probe on the skin. A 2013 review in Medical Principles and Practice describes a shockwave as a rapid, single swing of acoustic pressure from positive to negative. Focused devices make the pulse with a spark in water, an electromagnetic coil or piezoelectric crystals and bring it to a point inside the tissue. Radial devices fire a small projectile against an applicator, so the energy is strongest at the skin and fades with depth.
How the pulses help is not settled. The same review lists proposals, among them cells responding to mechanical strain, nitric oxide, growth factors and new small blood vessels, and says the mechanisms are not fully understood. The BMJ press release describes the treatment as low-energy sound waves meant to stimulate blood flow and healing.
What held up
Only a few results reached moderate certainty, and shockwave therapy produced one of them.
- Pain. Against usual care, shockwave therapy cut short-term pain by an average of 1.97 points on a 0 to 10 scale. The authors say it probably reduces pain.
- Movement. Shockwave therapy may also improve function and how far the arm lifts forward and out to the side, but that evidence is low certainty, partly because direct and indirect comparisons disagreed.
- The other moderate result went to manipulation under anaesthesia, where a surgeon moves the arm while the patient is asleep. It improved how far the arm lifted forward by about 26 degrees on its own and about 33 degrees with a steroid injection.
Nearly everything else, including most comparisons between active treatments and almost all results beyond three months, was low or very low certainty.
The limits
Most of the trials feeding the main results were at high risk of bias. Disease duration, stage and earlier treatment were reported unevenly, so it is unclear who benefits most. Side effects were reported so inconsistently that the authors say comparative safety is highly uncertain, and that a missing report of harm is not evidence of no harm.
The full paper was not available to us. The figures here come from the abstract and the BMJ’s release, so we cannot give how many of the 189 trials tested shockwaves, the confidence interval around the two-point gain, whether the devices were focused or radial, or how many sessions people had. The results apply to primary frozen shoulder, the kind with no clear cause.
Why it matters
For people choosing among many options with thin evidence behind them, a treatment that probably takes about two points off that pain without needles or anaesthesia is useful to know about, and the authors suggest the findings can inform choices in the first six months.
What to watch is the gap the review exposes: well-run trials of shockwave therapy against the other common options, with honest reporting of side effects and a follow-up of a year or more.
