Back Pain Doctor
Shockwave Therapy and EMTT for Sacroiliac Joint Pain
These two devices sit at opposite ends of the evidence spectrum, and describing them the same way would be dishonest. Focused shockwave at the sacroiliac joint has two randomised trials behind it — both small, both short, and each finding an effect the other did not. EMTT has none, here or in any other musculoskeletal condition.
Shockwave: the sham-controlled trial
| Parameter | Moon 2017, Journal of Back and Musculoskeletal Rehabilitation |
|---|---|
| Design | Prospective, randomised, sham-controlled trial |
| n | 30 (15 shockwave, 15 sham) |
| Active treatment | 2,000 shocks at the maximum energy the patient tolerated (energy flux density 0.09-0.25 mJ/mm²), probe perpendicular to the posterior sacroiliac joint line and moved up and down along it |
| Sham | 2,000 shocks with the probe oriented parallel to the joint line — an active sham, so participants still felt the device |
| Co-interventions | Participants asked to avoid all other conservative treatment, including anti-inflammatories, during the study |
| Outcomes | 10 cm numeric rating scale and Oswestry Disability Index at baseline, 1 week and 4 weeks |
| Pain result | Shockwave group fell from 6.42 (95% CI 5.19-7.66) at baseline to 3.64 (2.29-4.99) at 4 weeks, p<0.05. Sham group unchanged at every point. Between-group difference at 4 weeks significant: 3.64 versus 6.18. |
| Function result | Oswestry Disability Index improved at 1 and 4 weeks in the shockwave group but not significantly, and there was no significant between-group difference in ODI at any point. |
What this trial does and does not establish
- It establishes that focused shockwave over the sacroiliac joint line produced more pain reduction than a credible sham over four weeks. That is a stronger design than most of what exists in this field.
- It does not establish any effect on function. Disability scores did not separate from sham at any point — which is the outcome most people actually care about.
- It does not establish anything beyond four weeks. There is no longer follow-up.
- Thirty participants is a small trial. It has not been replicated.
This trial is the reason the description of shockwave for sacroiliac pain on this site has been corrected. It was previously described as having no trial evidence at this joint, which was wrong. The evidence is limited, short and pain-only — but it exists, and saying otherwise understated it.
The second trial, and the outcome it moved
A second randomised trial appeared in 2024. It is larger than the first and asks a different question: not whether focused shockwave beats a sham, but how it compares with hands-on treatment, and whether the two together do better than either alone.
| Parameter | Tan 2024, Journal of Orthopaedic Surgery and Research |
|---|---|
| Design | Prospective randomised trial, three parallel arms, no sham |
| n | 90 (30 focused shockwave, 30 manual therapy, 30 both) |
| Population | Postpartum women with sacroiliac joint dysfunction — a specific group, not the general population of sacroiliac pain |
| Follow-up | 1 and 2 weeks, with adverse events tracked to 2 months |
| Pain | At 1 week, comparable to manual therapy. At 2 weeks, the authors report shockwave inferior to manual therapy for pain relief. |
| Function (Oswestry Disability Index) | Better than manual therapy at 1 week (p<0.001); comparable by 2 weeks. |
| Both together | Lower pain than manual therapy at 1 week and lower than shockwave alone at 2 weeks. Highest cure rate of the three arms at 73.3 per cent, against 66.7 per cent improvement in the shockwave arm. |
| Adverse events | None observed in any arm over the two-month period |
Reading the two trials together
- They do not agree about which outcome moves. The sham-controlled trial found a pain effect and no function effect. This one found a function effect at one week and, by two weeks, pain relief that lagged behind hands-on treatment.
- The honest reading is that both effects are small and neither is securely established — not that one trial is right and the other wrong. Two small trials measuring different comparators at different time points will do this.
- What they agree on is safety: no serious adverse events in either.
- The finding that survives both is the combination. The strongest arm in the 2024 trial was shockwave and manual therapy together, which is an argument for using it alongside the rehabilitation programme rather than as a treatment in its own right.
- Neither trial followed anyone beyond four weeks. Nothing here supports a claim about durable benefit.
Two caveats belong with the 2024 trial. It had no sham arm, so some of the difference between groups may be the effect of receiving a device treatment rather than of the shockwaves themselves — which is precisely what the sham in the earlier trial was designed to control for. And one of its authors is listed under product research and development at a shockwave device manufacturer. That is disclosed here for the same reason the industry authorship on the fusion trials is disclosed on the referral page.
The rest of the shockwave literature, and why it carries less weight
| Source | What it is | How it is weighted here |
|---|---|---|
| Notarnicola 2020, J Biol Regul Homeost Agents | Published as a letter reporting conservative shockwave treatment of sacroiliac joint pain | Reported in a journal of contested standing and in a format that does not permit full methodological appraisal. Noted, not relied on. |
| Schöder 2025, Orthopädie | German-language narrative review of shockwave for low back pain, covering facet joints, myofascial pain, trigger points and the SIJ | Useful for describing technique and the radial-versus-focused distinction. Both senior authors are affiliated with private shockwave centres, and a narrative review is not designed to establish efficacy. Weighted accordingly. |
| Zhang 2021, Zhongguo Gu Shang | Retrospective study of 30 patients with ankylosing spondylitis and sacroiliac bone marrow oedema on MRI, treated with focused shockwave added to standard oral medication | A different condition. Pain and SPARCC scores improved more than the medication-only group at one month, with no difference in disease activity index or inflammatory markers. Retrospective, small, and relevant to inflammatory sacroiliitis rather than to mechanical SIJ pain. See ankylosing spondylitis. |
Focused or radial?
The Moon trial used a focused device delivering energy flux densities of 0.09 to 0.25 mJ/mm² directed at the posterior joint line. The sacroiliac joint and its interosseous ligament lie deep, and focused shockwave is the modality that reaches that depth — radial devices deliver their energy superficially and disperse it.
That makes focused the appropriate device where the target is the joint line itself. Radial shockwave has a different and legitimate role in this region: treating a tender gluteal or lumbar muscle that is contributing to the overall pain picture. It is a myofascial treatment there, not a treatment for the joint, and it is described that way rather than blurred into the same claim.
EMTT: no trials, said plainly
A PubMed search for extracorporeal magnetotransduction therapy at the sacroiliac joint returns no records. That is not a shortage of good trials; it is an absence of trials.
This is the same position taken across the whole of this site for EMTT, and it is not specific to the sacroiliac joint. There is no published randomised controlled trial of EMTT in any musculoskeletal condition. The supporting work is laboratory work — a study showing increased tenocyte proliferation, migration and collagen expression in cultured human tendon cells. The nearest human evidence for a related electromagnetic therapy is negative: a randomised trial of pulsed electromagnetic field therapy added to eccentric exercise for Achilles tendinopathy found no improvement in outcome scores or tendon neovascularity over eccentric exercise alone.
Much of the EMTT literature is affiliated with the manufacturer, which is part of why it is described this way.
What that means if EMTT is discussed with you
- It is offered only as an adjunct alongside treatment that does have evidence — never as the plan itself.
- It is not offered as a reason to defer or replace rehabilitation, an injection, or a referral.
- The absence of trial evidence is stated before it is used, not after.
- If cost is a consideration, this is the first thing to leave out.
How these fit in the plan
Focused shockwave is used here alongside the rehabilitation programme, not instead of it and not as a course of its own. That is the arrangement the trial evidence actually supports: in the 2024 trial the combined arm outperformed either treatment given alone, and in the sham-controlled trial the window in which shockwave helped was the short one in which pain is the obstacle to doing the loading work.
The expectation set before starting is modest and specific: a short-term effect on pain, on function, or on both, of a size that makes the programme easier to do. The two trials disagree about which of those moves, and neither followed anyone past four weeks, so a claim about lasting change would not be supported.
It is non-invasive and low-risk, with no serious adverse events in either trial, which is a legitimate reason to try it before an injection rather than after.
A short course with a defined review point, not an open-ended series. If the programme is no easier to do after it, that is the answer, and the plan changes rather than the course extending.
EMTT is discussed only where someone asks about it or where it is being added alongside shockwave in the same session, and always with the evidence gap stated.
Related on this site
- EMTT — the treatment page
The full statement of the evidence position for this device.
- The rehabilitation programme
What shockwave is meant to create a window for.
Common questions
Does shockwave therapy work for sacroiliac joint pain?
Focused or radial shockwave for the SIJ?
How many shockwave sessions would I need?
Is EMTT effective for sacroiliac joint pain?
Is shockwave therapy covered by Medicare?
Evidence reviewed
Every clinical statement on this page traces to one of the sources below, including the ones that point the other way. Where a study is small, unblinded or authored by people with a commercial interest in the result, that is noted alongside it rather than left out.
- Extracorporeal shock wave therapy for sacroiliac joint pain: a prospective, randomized, sham-controlled short-term trial (Moon et al, J Back Musculoskelet Rehabil 2017;30(4):779-784) ↗
Thirty patients, 2,000 shocks at 0.09-0.25 mJ/mm², active sham with the probe oriented parallel to the joint line. Significant between-group difference in pain at 4 weeks; no significant difference in Oswestry Disability Index at any point.
- Effectiveness of focused extracorporeal shock wave versus manual therapy in postpartum patients with sacroiliac joint dysfunction (Tan et al, J Orthop Surg Res 2024;19(1):28) ↗
Prospective randomised three-arm trial, 90 postpartum women, focused shockwave versus manual therapy versus both, outcomes at 1 and 2 weeks. Shockwave produced a lower Oswestry Disability Index than manual therapy at 1 week (p<0.001) but pain relief inferior to manual therapy by 2 weeks; the combined arm had the highest cure rate at 73.3 per cent. No sham arm, and an author is affiliated with a shockwave device manufacturer.
- Conservative treatment of sacroiliac joint pain with extracorporeal shockwave therapy (Notarnicola et al, J Biol Regul Homeost Agents 2020;34(2):697-703) ↗
Published as a letter. Noted for completeness; the format does not permit methodological appraisal and the journal's standing is contested.
- Shockwave therapy for low back pain (Schöder et al, Orthopädie 2025;55(3):190-197) ↗
German-language narrative review covering facet joints, myofascial pain, trigger points and the sacroiliac joint. Both senior authors are affiliated with private shockwave centres.
- Electronic focusing high-energy extracorporeal shockwave with oral medication for ankylosing spondylitis (Zhang et al, Zhongguo Gu Shang 2021;34(11):1020-4) ↗
Retrospective, 30 patients with sacroiliac bone marrow oedema on MRI. Pain and SPARCC scores better than medication alone at one month; no difference in BASDAI, ESR or CRP. A different condition from mechanical SIJ pain.
- Focused shockwave therapy — the treatment page on this site
How focused shockwave is delivered here, and its evidence across other conditions.
Last reviewed 2026-09-04. This is general information about a condition and its treatments, not personal medical advice, and it is no substitute for assessment by a clinician who has examined you.
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