Knee Injections:
"Regenerative" vs. Non-Regenerative
There are injections that merely control symptoms — and injections commercially labelled as "regenerative", which attempt to modify the biology of the knee. Understanding this distinction, and its real limits, is essential to making an informed decision.
Despite the efforts of scientific research and the commercial enthusiasm surrounding so-called "regenerative" injections, there is currently no robust evidence that any type of injection — PRP, hyaluronic acid or any other — is capable of regenerating the articular cartilage of the knee. What these substances can do is modify the biological environment of the joint, reduce inflammation in a more sustained way and, in some cases, slow the progression of the disease — but not rebuild destroyed cartilage. The use of quotation marks around "regenerative" throughout this page is intentional and reflects this clinical position.
The distinction most patients are unaware of
When we talk about a "knee injection", we are in fact talking about two groups with different mechanisms of action, clinical objectives and risk profiles. One treats the symptom directly. The other attempts to influence joint biology — which is why it is called "regenerative", although this term should not be interpreted as a synonym for cartilage reconstruction.
- They act on joint biology, not just on symptoms
- Longer-lasting effects, but with a more gradual onset
- Lower risk of joint deterioration with repeated use
- Best candidates: mild to moderate knee osteoarthritis, tendinopathies
- Rapid relief — effect within 24 to 72 hours
- Temporary effect: weeks to a few months
- Repeated use may deteriorate the articular cartilage
- Best candidates: acute inflammatory flares, preparation for surgery
Influencing the biology — not rebuilding cartilage
These injections use substances with an active role in the joint microenvironment — reducing inflammation in a more sustained way, improving lubrication or modulating synovial metabolism. The term "regenerative" is widely used in the literature and in clinical practice, but it must be understood precisely: none of these substances has demonstrated, in controlled clinical trials, the capacity to rebuild macroscopically lost articular cartilage.
How it works
A small sample of the patient's blood is centrifuged to concentrate the platelets. This preparation — rich in growth factors (PDGF, TGF-β, VEGF) — is injected into the joint, creating an anti-inflammatory and pro-anabolic environment that may reduce chronic synovitis and influence cartilage metabolism. There is no evidence of reconstruction of lost cartilage.
What to expect
- Initial analgesic effect in the first few weeks
- Peak efficacy between the 6th and 12th week
- Average duration: 6 to 12 months (varies with the degree of osteoarthritis)
- Usual protocol: 1 to 3 injections at intervals of 2 to 4 weeks
Main indications
Safety profile
- Autologous product — no risk of systemic allergic reaction
- Local pain/swelling may occur within 48–72h after injection
- Does not deteriorate the cartilage with repeated use
- No interaction with oral anticoagulants in most protocols
How it works
Hyaluronic acid (HA) is a natural component of synovial fluid. In osteoarthritis, its concentration and viscosity decrease. The injection of exogenous HA restores the viscoelastic properties of the joint fluid, reducing friction and improving cushioning. It also exerts an indirect anti-inflammatory effect via CD44 receptors. It does not regenerate cartilage, but may slow its degradation in some contexts.
What to expect
- Gradual effect: 4 to 8 weeks after the last injection
- Duration: 6 to 12 months (high molecular weight formulations)
- Protocol: 1 injection (cross-linked formulations) or 3–5 weekly
- Repetition possible without joint deterioration
Main indications
Available types
- Low molecular weight (e.g. Ostenil) — 3 to 5 weekly injections
- High molecular weight cross-linked (e.g. Durolane, Monovisc) — single dose
- Formulations combined with PRP — emerging protocol
Rapid control of inflammation — with clear limits
Corticosteroids are the most prescribed injection in the world. They are highly effective in the short term, but their repeated use raises important clinical questions that your doctor should weigh up with you.
How it works
Intra-articular corticosteroids suppress the inflammatory cascade via glucocorticoid receptors in the synovial cells — inhibiting prostaglandins, pro-inflammatory cytokines (IL-1β, TNF-α) and pain mediators. The result is a rapid and powerful reduction in synovitis and joint effusion.
What to expect
- Relief within 24 to 72 hours after the injection
- Maximum effect: 1 to 2 weeks
- Duration: 4 to 8 weeks (varies between patients)
- Recommendation: maximum 3 to 4 injections per joint per year
Main indications
Risks and limitations
- Repeated use associated with loss of articular cartilage (MRI studies)
- May mask the progression of the underlying disease
- Increased risk of joint infection in diabetic patients (transient)
- Not to be used in patients planning a knee replacement within the following 3 months
- Post-injection "flare" in 2–10% of cases (pain in the first 48h)
The three options side by side
| Parameter | Corticosteroid | Hyaluronic Acid | PRP |
|---|---|---|---|
| Type | Non-regenerative | "Regenerative" | "Regenerative" |
| Onset of effect | 24–72 hours | 4–8 weeks | 4–12 weeks |
| Duration of effect | 4–8 weeks | 6–12 months | 6–12+ months |
| Effect on cartilage | Potentially negative | Neutral / protective | No regeneration; may slow degradation |
| No. of injections | 1 | 1–5 (depending on product) | 1–3 (protocol) |
| Repeated use | Limited (<4/year) | Safe | Safe |
| Best indication | Acute flare, synovitis | Mild-to-moderate chronic knee osteoarthritis | Knee osteoarthritis + active injury |
| Pre-surgical use | Avoid in the 3 months before | No contraindication | May accelerate recovery |
Which one is right for your case?
Every clinical situation is different. These scenarios illustrate the reasoning, but the final decision is always made after assessment.
How an injection is carried out
All injections are carried out in an appointment setting. The procedure is quick, well tolerated and does not require hospital admission.
What patients ask most
• Corticosteroid — from around €100.
• Hyaluronic acid (viscosupplementation) — from around €200 (depending on brand and protocol: single high molecular-weight dose or 3–5 injections).
• PRP (platelet-rich plasma) — from around €350.
• Stem cells and Artrosamid® (newer options) — from around €2,500, but still without robust scientific evidence to justify the cost.
The final price depends on the product, the number of sessions and the facility.
Want to know which injection is right for your knee?
The correct selection depends on the diagnosis, the degree of osteoarthritis, the clinical history and your objectives. Book an appointment for an individualised assessment.
References
Clinical guidelines and scientific reviews supporting this information.
- McAlindon TE, et al. Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Knee Osteoarthritis: a randomized clinical trial. JAMA, 2017. PMID 28510679.
- Bensa A, et al. PRP Injections for Knee Osteoarthritis: clinically significant improvement influenced by platelet concentration — meta-analysis of RCTs. Am J Sports Med, 2025. PMID 39751394.
- Belk JW, et al. Platelet-Rich Plasma Versus Hyaluronic Acid for Knee Osteoarthritis: systematic review and meta-analysis of RCTs. Am J Sports Med, 2020. PMID 32302218.
- OARSI guidelines for the non-surgical management of knee osteoarthritis. Osteoarthritis Cartilage, 2019.
- AAOS — Management of Osteoarthritis of the Knee (Non-Arthroplasty), 3rd ed.
