Platelet Injections for Stubborn Tendons, Trial by Trial

Why an injection that promises healing is such an easy sell

Because the alternative on offer sounds like nothing. When a rotator cuff tendon becomes painful and inflamed, the standard menu is rest, anti-inflammatories, physical therapy, and injections 1Ref 1American Academy of Orthopaedic Surgeons (OrthoInfo) (2024).Shoulder Impingement / Rotator Cuff Tendinitis.Lay-education account of shoulder impingement and rotator cuff tendinitis, and of its nonsurgical management — rest, NSAIDs, physical therapy, and injections — used for the article's description of the standard menu and its point that injections are part of that endorsed menu rather than excluded from it.. Read that list at 2am with a shoulder you cannot lift and it reads as a shrug. Then someone offers to repair the tissue instead of quieting it. Of course that lands.

Tendinopathy is a tendon that has turned painful and intolerant of load; shoulder pain of this kind is often written up as impingement or rotator cuff tendinitis on the referral 1Ref 1American Academy of Orthopaedic Surgeons (OrthoInfo) (2024).Shoulder Impingement / Rotator Cuff Tendinitis.Lay-education account of shoulder impingement and rotator cuff tendinitis, and of its nonsurgical management — rest, NSAIDs, physical therapy, and injections — used for the article's description of the standard menu and its point that injections are part of that endorsed menu rather than excluded from it.. The names change. The experience does not.

The pitch works on a grammatical trick. Relief is a verb about you. Repair is a verb about the tissue. One promises to change how the shoulder feels this month; the other promises to change what the shoulder is. The second is a far larger claim, and larger claims need larger evidence rather than more enthusiasm.

It is also a claim that travels well. A platelet preparation is offered for tendons, for joints, and — under the heading platelet-rich plasma skin — for faces. A mechanism that elastic might be a genuinely general repair signal, or a general-purpose story. Only the trials tell you which.

The most important tendon trial here is about doing less

It compared three treatments for a torn rotator cuff and found no winner. Adults with nontraumatic supraspinatus tears were randomized to physiotherapy alone, to acromioplasty plus physiotherapy, or to rotator cuff repair plus physiotherapy. At two years, with clinical and imaging follow-up, there was no significant clinical difference between the three groups 2Ref 2Kukkonen J, Joukainen A, Lehtinen J, et al. (2015).Treatment of Nontraumatic Rotator Cuff Tears: A Randomized Controlled Trial with Two Years of Clinical and Imaging Follow-up.Physiotherapy alone, acromioplasty plus physiotherapy, and rotator cuff repair plus physiotherapy produced no significant clinical difference at two years for nontraumatic supraspinatus tears, and conservative care is a reasonable initial option — the article's central tendon finding, and, via the trial's nontraumatic inclusion criterion, the explicit boundary of that conclusion..

Sit with the size of that. One group had the tendon surgically reattached. One group had bone shaved from the underside of the acromion. One group did exercises. Two years later the trial could not tell them apart on clinical outcome, and its conclusion was that conservative care is a reasonable initial option for these tears 2Ref 2Kukkonen J, Joukainen A, Lehtinen J, et al. (2015).Treatment of Nontraumatic Rotator Cuff Tears: A Randomized Controlled Trial with Two Years of Clinical and Imaging Follow-up.Physiotherapy alone, acromioplasty plus physiotherapy, and rotator cuff repair plus physiotherapy produced no significant clinical difference at two years for nontraumatic supraspinatus tears, and conservative care is a reasonable initial option — the article's central tendon finding, and, via the trial's nontraumatic inclusion criterion, the explicit boundary of that conclusion..

A torn tendon and a tendon that needs repairing are not automatically the same object. That is the finding that should reframe the platelet question. If surgically reattaching the tendon did not beat exercise at two years, then the premise underneath every repair-flavoured injection — that the tear is the problem and closing it is the solution — is not a premise this trial supports. The word nontraumatic in those inclusion criteria is load-bearing, and the last section of this page comes back to it.

A painkiller everyone believed in, tested

Paracetamol — the most ordinary painkiller there is. A systematic review of placebo-controlled trials measured it. For low back pain it was ineffective. For hip and knee osteoarthritis, the effect on pain and disability was small and not clinically important 3Ref 3Machado GC, Maher CG, Ferreira PH, et al. (2015).Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials.Paracetamol is ineffective for low back pain and gives only a small, not clinically important effect on pain and disability in hip and knee osteoarthritis — the article's demonstration that widespread use is not evidence, and that a placebo-controlled comparison is what settles the question.. Not weaker than expected — effectively absent.

That finding is here for one reason: it is the cleanest demonstration that widespread use is not evidence. Paracetamol was not a fringe product pushed by a clinic with a centrifuge. It was the safest, dullest, most consensus-backed thing on the shelf, and when the placebo-controlled trials were run and pooled, the effect was not there 3Ref 3Machado GC, Maher CG, Ferreira PH, et al. (2015).Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials.Paracetamol is ineffective for low back pain and gives only a small, not clinically important effect on pain and disability in hip and knee osteoarthritis — the article's demonstration that widespread use is not evidence, and that a placebo-controlled comparison is what settles the question..

If that can happen to paracetamol, it can happen to anything. The useful question about a treatment is never how many people use it, or how sensible the mechanism sounds. It is what happened when somebody compared it with a convincing fake.

A procedure everyone performed, tested

Arthroscopic surgery for the degenerative knee. A systematic review and meta-analysis of its benefits and harms found at most a small and short-lived benefit for pain, no benefit for function, and a set of harms that came along with it — a package the authors judged unsupported for middle-aged and older patients 4Ref 4Thorlund JB, Juhl CB, Roos EM, Lohmander LS (2015).Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms.Arthroscopic surgery for degenerative knee disease provides at most a small, short-lived benefit in pain and no benefit on function while carrying harms, and is not supported for middle-aged and older patients — the article's demonstration that a widely performed procedure can still lose to its comparator, and the source of its 'small and short-lived' pattern.. This was not an obscure operation.

Look at the exact shape of that result, because it is a shape you will meet again: small, and short-lived 4Ref 4Thorlund JB, Juhl CB, Roos EM, Lohmander LS (2015).Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms.Arthroscopic surgery for degenerative knee disease provides at most a small, short-lived benefit in pain and no benefit on function while carrying harms, and is not supported for middle-aged and older patients — the article's demonstration that a widely performed procedure can still lose to its comparator, and the source of its 'small and short-lived' pattern.. Not zero. A small, real, temporary improvement is the easiest result for a treatment to produce and the easiest to mistake for a repair. It is what you get from attention, from the ritual of a procedure, from the natural settling of a flare, and from a genuine but modest treatment effect — and from the outside, all four look identical.

Small and short-lived is the default result in this field. A treatment claiming more is claiming to be unusual, and unusual claims are the ones worth checking hardest.

Another injection with a measured ceiling

Epidural corticosteroid for sciatica, which has been meta-analysed properly. It produces small, short-term relief of leg pain and disability. It produces no meaningful long-term benefit. And — this is the endpoint that matters — it does not reduce the rate of subsequent surgery 5Ref 5Pinto RZ, Maher CG, Ferreira ML, et al. (2012).Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis.Epidural corticosteroid injections give small, short-term relief of leg pain and disability in sciatica but no meaningful long-term benefit and no reduction in subsequent surgery — the article's example of an injection with a measured ceiling, and its argument for judging an injection on a hard endpoint rather than a pain score.. The injection changes the month. It does not appear to change the trajectory.

That third endpoint is the one worth stealing. Pain scores are soft, self-reported, and they move for a dozen reasons that have nothing to do with the treatment. Whether people ended up having the operation anyway is hard. It either happened or it did not, and it is very difficult for a hopeful trial design to massage 5Ref 5Pinto RZ, Maher CG, Ferreira ML, et al. (2012).Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis.Epidural corticosteroid injections give small, short-term relief of leg pain and disability in sciatica but no meaningful long-term benefit and no reduction in subsequent surgery — the article's example of an injection with a measured ceiling, and its argument for judging an injection on a hard endpoint rather than a pain score..

So the question to put to any tendon injection is not whether the pain score improved. It is whether fewer of these people ended up needing the thing the injection was supposed to prevent. Other injections have their own measured ceilings — hyaluronic acid injection for the knee is its own question with its own page — and the pattern across this page's sources, small and short and not trajectory-changing 4Ref 4Thorlund JB, Juhl CB, Roos EM, Lohmander LS (2015).Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms.Arthroscopic surgery for degenerative knee disease provides at most a small, short-lived benefit in pain and no benefit on function while carrying harms, and is not supported for middle-aged and older patients — the article's demonstration that a widely performed procedure can still lose to its comparator, and the source of its 'small and short-lived' pattern.5Ref 5Pinto RZ, Maher CG, Ferreira ML, et al. (2012).Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis.Epidural corticosteroid injections give small, short-term relief of leg pain and disability in sciatica but no meaningful long-term benefit and no reduction in subsequent surgery — the article's example of an injection with a measured ceiling, and its argument for judging an injection on a hard endpoint rather than a pain score., is the sensible starting expectation. None of that is a verdict on platelets. It is a description of what the injection literature has looked like every previous time somebody measured carefully.

What the platelet trials would have to show

A bar, now that the field's habits are visible. This page cannot tell you whether PRP works for a tendon: the platelet trials are not among its sources, and a verdict with nothing behind it is worth nothing. But the sections above describe what a convincing platelet trial would have to do, which is more useful than a borrowed opinion.

• A sham arm, not a comparison with nothing. The paracetamol reversal only happened because someone ran placebo-controlled trials 3Ref 3Machado GC, Maher CG, Ferreira PH, et al. (2015).Efficacy and safety of paracetamol for spinal pain and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled trials.Paracetamol is ineffective for low back pain and gives only a small, not clinically important effect on pain and disability in hip and knee osteoarthritis — the article's demonstration that widespread use is not evidence, and that a placebo-controlled comparison is what settles the question..
• Follow-up past the point where a small, short-lived effect would have faded 4Ref 4Thorlund JB, Juhl CB, Roos EM, Lohmander LS (2015).Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms.Arthroscopic surgery for degenerative knee disease provides at most a small, short-lived benefit in pain and no benefit on function while carrying harms, and is not supported for middle-aged and older patients — the article's demonstration that a widely performed procedure can still lose to its comparator, and the source of its 'small and short-lived' pattern..
• A hard endpoint. Did fewer people go on to have the operation — the thing an epidural steroid failed to change 5Ref 5Pinto RZ, Maher CG, Ferreira ML, et al. (2012).Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis.Epidural corticosteroid injections give small, short-term relief of leg pain and disability in sciatica but no meaningful long-term benefit and no reduction in subsequent surgery — the article's example of an injection with a measured ceiling, and its argument for judging an injection on a hard endpoint rather than a pain score.?
• A comparator that is real care. Beating rest is not the question. The rotator cuff trial's physiotherapy arm, the one that matched surgery at two years 2Ref 2Kukkonen J, Joukainen A, Lehtinen J, et al. (2015).Treatment of Nontraumatic Rotator Cuff Tears: A Randomized Controlled Trial with Two Years of Clinical and Imaging Follow-up.Physiotherapy alone, acromioplasty plus physiotherapy, and rotator cuff repair plus physiotherapy produced no significant clinical difference at two years for nontraumatic supraspinatus tears, and conservative care is a reasonable initial option — the article's central tendon finding, and, via the trial's nontraumatic inclusion criterion, the explicit boundary of that conclusion., is the arm to beat — and the one most likely to be quietly skipped.

There is a documented reason to be careful rather than merely cynical. Low-value care for low back pain — unnecessary imaging, opioids, injections, and surgery — is widespread across the world, and the call in the literature is to reduce it 6Ref 6Buchbinder R, van Tulder M, Öberg B, et al. (2018).Low back pain: a call for action.Low-value care for low back pain — unnecessary imaging, opioids, injections, and surgery — is widespread globally and should be reduced; used only for the over-treatment claim that widespread use and good evidence come apart in this field, and explicitly scoped to back pain rather than tendons.. That finding is about backs, not tendons. What it establishes is that widespread use and good evidence come apart in this field.

The trial-by-trial work lives elsewhere in the library: the PRP RCT summary reads the platelet literature directly, prp vs cortisone sets the two needles against each other, and prp for knee arthritis takes the joint rather than the tendon. What prp injection cost adds is its own question, better answered before the decision than after.

Where an operation on a tendon is clearly the right call

The rotator cuff trial answers this by what it excluded. Its patients had nontraumatic tears — tendons that had frayed over years, not tendons torn by an event 2Ref 2Kukkonen J, Joukainen A, Lehtinen J, et al. (2015).Treatment of Nontraumatic Rotator Cuff Tears: A Randomized Controlled Trial with Two Years of Clinical and Imaging Follow-up.Physiotherapy alone, acromioplasty plus physiotherapy, and rotator cuff repair plus physiotherapy produced no significant clinical difference at two years for nontraumatic supraspinatus tears, and conservative care is a reasonable initial option — the article's central tendon finding, and, via the trial's nontraumatic inclusion criterion, the explicit boundary of that conclusion.. That single word is the boundary of the finding. A trial of degenerative tears says nothing about the tendon that ruptured when someone caught a falling ladder, and was never designed to.

Read the inclusion criteria. A trial's conclusion stops exactly where its population stopped. That is the most useful habit on this page, and it cuts in both directions. It is why conservative care first is well supported for a degenerative cuff tear 2Ref 2Kukkonen J, Joukainen A, Lehtinen J, et al. (2015).Treatment of Nontraumatic Rotator Cuff Tears: A Randomized Controlled Trial with Two Years of Clinical and Imaging Follow-up.Physiotherapy alone, acromioplasty plus physiotherapy, and rotator cuff repair plus physiotherapy produced no significant clinical difference at two years for nontraumatic supraspinatus tears, and conservative care is a reasonable initial option — the article's central tendon finding, and, via the trial's nontraumatic inclusion criterion, the explicit boundary of that conclusion.. It is equally why nothing in this article is an argument against operating on a tendon that a surgeon judges needs operating on.

The honest limit is that this page cannot hand you the full list of situations where surgery is clearly indicated. Those criteria are tendon-specific, and they belong to the guideline for that tendon and to a surgeon who has examined it. What can be said is that the list is real, and that its decisions are made tendon by tendon — whether a gluteal tendon repair beats an injection for a painful lateral hip, whether a biceps tenodesis is the right call rather than a tenotomy. Each is its own question with its own evidence.

And the standard menu is not a placeholder. Rest, anti-inflammatories, physical therapy, and injections are what orthopaedic guidance lists for a painful rotator cuff 1Ref 1American Academy of Orthopaedic Surgeons (OrthoInfo) (2024).Shoulder Impingement / Rotator Cuff Tendinitis.Lay-education account of shoulder impingement and rotator cuff tendinitis, and of its nonsurgical management — rest, NSAIDs, physical therapy, and injections — used for the article's description of the standard menu and its point that injections are part of that endorsed menu rather than excluded from it. — injections included, not grudgingly. The order of care exists because the cheap and reversible things sometimes work, not because anyone is withholding the good stuff. When they do not, the next step is still there.