On this page
- A randomised trial exists, which is unusual here
- Cells during surgery, rather than instead of it
- The scaffolding caution
- Tears that are found, versus tears that hurt
- What the alternatives are
- Why cuff tears are hard to heal at all
- How it is given
- Reasonable expectations
- Questions to ask
- Frequently asked questions
- Requesting a medical evaluation
The rotator cuff is four tendons holding the shoulder joint together and moving the arm. Tears are extremely common with age, often painless, and sometimes disabling. Stem cell treatment for rotator cuff injury has been tested in a randomised trial — which puts it ahead of most conditions on this site, and makes the result worth reading carefully.
A randomised trial exists, which is unusual here
Most conditions marketed for cell therapy have no randomised evidence at all. This one does — A randomized controlled trial of stem cell injection for tendon tear.
A randomised controlled trial is the design that can separate treatment effect from natural improvement, placebo response and hopeful reporting. When one exists, it outranks any number of case series.
The reason to read it rather than to cite it is that a trial existing and a trial being positive are different things. Ask any clinic quoting this study what its primary endpoint was and whether it was met.
Cells during surgery, rather than instead of it
The other line of evidence is bone marrow aspirate concentrate applied at the time of surgical repair — Bone Marrow Aspirate Concentrate May Improve Healing and Function in Rotator Cuff Repair: A Systematic Review.
Read the verb in that title. “May improve” is what systematic reviewers write when the pooled data points in a direction without establishing it.
This is also a different intervention from what most clinics sell. It is an addition to an operation performed by a shoulder surgeon, not an injection offered as a way around one.
The scaffolding caution
A double-blind placebo-controlled study documented adverse effects from xenogenic scaffolding — material derived from another species — in this setting — Adverse effects of xenogenic scaffolding in the context of a randomized double-blind placebo-controlled study.
Negative and harm-finding results are the part of the literature marketing never quotes, and they are the part that tells you the field is being studied honestly.
It also illustrates that biological additions to shoulder surgery are not automatically harmless. Adverse events covers what has been documented more widely.
Tears that are found, versus tears that hurt
Rotator cuff tears are present in a large share of people over sixty who have no shoulder symptoms whatsoever. Scanning a painless shoulder often finds one.
This matters enormously for treatment claims. If a tear is found on imaging and the shoulder hurts, the tear is not automatically the cause, and treating it may not address the pain.
It also means improvement after treatment may reflect settling of an unrelated process — subacromial irritation, stiffness, referred neck pain — rather than anything happening at the tear.
What the alternatives are
Structured physiotherapy has good evidence for degenerative cuff tears and is the first-line treatment in most guidelines. Many patients do well without surgery.
Surgical repair is established for younger patients, acute traumatic tears, and those failing rehabilitation. Outcomes depend heavily on tear size and tissue quality.
A cell injection sits alongside those with far less behind it. That is worth knowing before it is presented as the modern option.
Corticosteroid injection is the other common offer, and it has a genuine short-term effect on pain with a recognised trade-off: repeated steroid exposure is associated with weaker tendon tissue. Where a regenerative injection is being compared to anything, that is usually the comparison being made.
Why cuff tears are hard to heal at all
Tendon heals into scar rather than into tendon. Repaired cuffs re-tear at rates that remain high in larger tears even in experienced surgical hands, and that is with the ends held together by sutures and anchors.
The tissue also degenerates before it tears. By the time a degenerative cuff gives way, the tendon at the edge is often thin and poorly vascularised, and the attached muscle may have shortened and infiltrated with fat. None of that reverses.
The biological argument for adding cells is aimed at exactly this problem — improving the quality of healing at a repair site. It is a sensible target. It is also why the honest studies are about surgery plus cells rather than cells alone.
How it is given
Ultrasound-guided injection into the subacromial space or around the tendon, or marrow concentrate applied at surgery.
Cell source varies — marrow, fat or donated cord tissue — and reporting of what was actually given is poor across this field, which makes trials hard to compare. Mesenchymal stem cell therapy covers the differences.
Platelet-rich plasma is frequently offered for the same complaint and is a different product entirely — PRP therapy.
Reasonable expectations
Possible pain reduction and functional improvement, on evidence that includes a randomised trial and remains mixed.
No reliable basis for expecting a full-thickness tear to close after an injection. Tendon ends under tension do not reattach because cells were introduced nearby.
For a massive retracted tear with muscle atrophy, no injection addresses the anatomy, and a shoulder surgeon should be the one advising.
Questions to ask
- Is my tear partial or full-thickness, and how large?
- Has a physiotherapy programme been tried properly first?
- What did the randomised trial in this condition actually find?
- Is this injection, or an addition to surgery? They are not the same offer.
Tendon injury covers the wider tendon picture, and cost in Thailand covers what a quotation should include.
Frequently asked questions
Will an injection close my tear?
There is no reliable basis for expecting a full-thickness tear to close after injection. Tendon ends under tension do not reattach because cells were introduced nearby.
There is a randomised trial — does that mean it works?
It means the question was tested properly. Ask what the trial found, not just that it exists. Results in this area are mixed.
Should I try this before physiotherapy?
Physiotherapy has good evidence for degenerative cuff tears and is first-line in most guidelines. Doing it properly first is reasonable.
My scan shows a tear but my other shoulder is fine. Is the tear the cause?
Not necessarily. Tears are common in painless shoulders over sixty, so finding one does not establish it is causing your symptoms.
What is bone marrow aspirate concentrate?
Marrow drawn from the pelvis and concentrated, applied during surgical repair. It is an addition to an operation, not an alternative to one.
Is there any evidence of harm?
A placebo-controlled study documented adverse effects from animal-derived scaffolding in this setting, so biological additions are not automatically harmless.
Requesting a medical evaluation
Nothing on this page establishes whether any treatment is appropriate for you. That needs your history, your imaging and your current medications read by a clinician. If you would like that review, send your records and we will tell you honestly whether there is anything worth discussing — including when the answer is no.
This page is general information, not medical advice, and does not create a doctor–patient relationship. Regenerative treatments discussed here are in most cases investigational. Discuss any treatment with a clinician who knows your history.