The cheapest option here has four meta-analyses behind it.

PROLOTHERAPY

The cheapest thing on this menu has more randomized evidence behind it in knee osteoarthritis than several operations that are still routinely performed. That is an awkward sentence for a clinic that also sells the expensive options.

What the randomized evidence actually shows

Prolotherapy carries a reputation as fringe medicine, and that reputation has outlived the data by about a decade. In knee osteoarthritis the position is now this: multiple independent systematic reviews and meta-analyses of randomized controlled trials support hypertonic dextrose prolotherapy for pain and function.

One meta-analysis of randomized trials examined intra-articular and extra-articular dextrose against other injectates and physical therapy, reporting improvement in WOMAC pain and function. A second, with meta-regression across fourteen randomized trials, assessed effectiveness alongside compliance and safety. A third pooled eleven trials covering 837 patients and graded the strength of recommendation formally. A fourth systematic review reached the same direction of travel.

Set that beside arthroscopic partial meniscectomy for a degenerative tear, which was compared against sham surgery and performed no better — a point made in full on PRP for a meniscus tear. A cheap injection with four supporting meta-analyses is not the fringe option in that comparison.

It is not only the knee

The evidence base extends further than most people assume. A systematic review of randomized controlled trials in sports-related tendinopathies found prolotherapy a credible non-operative option across several sites. There is a review literature in chronic low back pain. And multispecialty consensus guidance on sacroiliac joint complex pain considers it among the injectate options — relevant to the picture on the spine and sacroiliac joint.

That breadth matters because the mechanism is not joint-specific. Which brings us to what it is actually doing.

A different mechanism, not a diluted one

It is easy to assume prolotherapy is PRP without the biology. It is not — it works along a different route.

A hypertonic dextrose solution placed at a ligament, an enthesis or inside a joint creates a brief, controlled osmotic and inflammatory stimulus. That stimulus provokes the local tissue to release its own growth factors and to restart a repair sequence that had stalled. PRP delivers growth factors from outside; prolotherapy asks the tissue to produce them.

There is a second effect that gets less attention and explains a good deal of the ligament and enthesis results: repeated dextrose injection appears to stiffen and tighten lax connective tissue. Where the underlying problem is laxity — a sacroiliac joint that moves too much, an enthesis that has lost its grip — that is a more directly relevant mechanism than a growth-factor bolus.

Where it is the better choice, not the lesser one

• Ligament and enthesis problems driven by laxity rather than by degeneration of the tendon body. This is where the mechanism fits the pathology best.
• Earlier-stage knee osteoarthritis, where the randomized evidence is strongest and the cost difference against PRP is substantial.
• Multiple painful sites at once. Treating four areas with dextrose is affordable; treating four with PRP frequently is not, and an untreated site is worth nothing.
• Anyone for whom cost is the deciding constraint. If the choice is a full course of prolotherapy or one PRP injection you cannot afford to repeat, the course is usually the better clinical decision, not merely the cheaper one.

The course is the treatment

One point decides whether this works for you, and it is not a clinical subtlety. Prolotherapy is a course, not an injection. Typically three to six sessions at intervals of a few weeks, because each one contributes an increment and the effect accumulates.

People who attend twice, feel a partial improvement and stop have not had prolotherapy. They have had part of it, and the meta-analyses that support it studied completed courses. Compliance was measured as a variable in one of them for exactly this reason. If the schedule does not fit your life, say so at the assessment and we will discuss something that does — that is a better conversation than an abandoned course.

How it compares with PRP, honestly

PRP delivers more biology in a single visit and has the larger literature. For a degenerate tendon body, or a joint further along, it is generally the stronger option, and where more again is needed there is bone marrow aspirate concentrate.

But “stronger” is not the only axis. Prolotherapy costs a fraction as much, has a benign safety profile, targets laxity in a way PRP does not, and is supported by randomized evidence in its own right rather than by extrapolation. There is a real category of patient for whom it is simply the correct answer, and we would rather send that person home with the cheaper course than sell them the expensive one.

That is not modesty. A clinic that recommends its highest-margin product to everyone eventually gets found out, and the patients who were oversold are the ones who tell people.

What a session involves

The solution is prepared and multiple small injections are placed at the target sites — entheses, ligament attachments, or intra-articularly depending on the problem. It stings during injection and for a short period afterward; that discomfort is the mechanism doing its work rather than a complication. Guidance is used where the target warrants it.

Dextrose concentration varies by target — lower intra-articularly, higher at ligament and enthesis sites — and that is a deliberate choice rather than a house recipe. Expect soreness for a day or two, and expect to be assessed against the previous session each time rather than treated identically at every visit.

What people ask about a course of prolotherapy

Is prolotherapy proven?

In knee osteoarthritis, it is supported by several independent meta-analyses of randomized controlled trials, which is more than can be said for some widely performed operations. In tendinopathy and low back pain the evidence is thinner but real. It is not fringe medicine and has not been for some years.

Why is it so much cheaper if it works?

Because dextrose is not a proprietary product and no device is required to prepare it. Cost tracks what a treatment is made of and who owns it, not how well it works.

How many sessions will I need?

Usually three to six, a few weeks apart. The course is the treatment; a partial course is not a smaller version of it.

Should I have this instead of PRP?

Sometimes, and we will tell you when. Laxity-driven problems, earlier-stage knee arthritis, several sites at once, or a budget that would otherwise buy one injection you cannot repeat — in those situations the course is the better clinical decision and not just the cheaper one.

Does it hurt?

It stings going in and stays sore for a day or two. That reaction is the intended stimulus rather than a side effect, which is a genuinely different thing from a treatment that hurts for no reason.

Related reading

• How PRP works
• Leukocyte-rich and leukocyte-poor PRP
• Spine and the sacroiliac joint
• PRP for knee osteoarthritis
• Bone marrow aspirate concentrate
• Am I a candidate?