What to ask about a sore knee

Sources

1. FORWARD, the longest disease-modifying osteoarthritis drug trial reported to date, gave intra-articular sprifermin (a recombinant FGF-18) or placebo to knee OA patients and followed 378 of them for 5 years. Sprifermin produced a significant, sustained dose-response INCREASE in total femorotibial cartilage thickness versus placebo - and WOMAC pain improved about 50% from baseline in ALL groups, including placebo. It is the cleanest demonstration in the literature that adding measurable cartilage and relieving pain are two different results, and that one does not deliver the other.

   Eckstein F, et al. — Long-term structural and symptomatic effects of intra-articular sprifermin in patients with knee osteoarthritis: 5-year results from the FORWARD study.. Annals of the rheumatic diseases, 2021. DOI: 10.1136/annrheumdis-2020-219181.

2. OA-11, a 56-week phase 3 double-blind placebo-controlled trial, randomized 513 knee OA patients (KL 2-3) to a single intra-articular injection of the Wnt-pathway modulator lorecivivint or vehicle placebo. Lorecivivint MISSED its primary endpoint: 12-week pain NRS change was -2.24 with drug versus -2.49 with placebo (p=0.185), no other endpoint showed a discernible treatment effect, and neither group lost meaningful medial joint space over 52 weeks. Even a purpose-built, well-funded disease-modifying candidate has not beaten a placebo injection.

   Yazici Y, et al. — A Phase 3, 56-week, randomised, double-blind, placebo-controlled study (OA-11) utilising patient-reported and radiographic outcomes evaluating the efficacy and safety of a lorecivivint injection in patients with moderate to severe knee osteoarthritis.. Clinical and experimental rheumatology, 2025. DOI: 10.55563/clinexprheumatol/hjt118.

3. The phase II trial of lorecivivint (SM04690), an intra-articular CLK2/DYRK1A inhibitor and Wnt-pathway modulator, is the reference for how a genuine disease-modifying osteoarthritis DRUG is developed - defined molecule, defined target, dose-ranging, radiographic endpoints - which is the standard against which an unstandardised autologous injectate should be read.

   Yazici Y, et al. — Lorecivivint, a Novel Intraarticular CDC-like Kinase 2 and Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase 1A Inhibitor and Wnt Pathway Modulator for the Treatment of Knee Osteoarthritis: A Phase II Randomized Trial.. Arthritis & rheumatology (Hoboken, N.J.), 2020. DOI: 10.1002/art.41315.

4. FDA states plainly that no stem cell, exosome, stromal vascular fraction, umbilical cord blood, Wharton's jelly or amniotic-fluid product has been approved for the treatment of ANY orthopedic condition - it names osteoarthritis, tendonitis, disc disease, tennis elbow, back pain, hip pain, knee pain, neck pain and shoulder pain individually. The only FDA-approved stem cell products in the United States are cord-blood-derived blood-forming stem cells for disorders of the hematopoietic system, and there are currently no FDA-approved exosome products.

   US Food and Drug Administration, Center for Biologics Evaluation and Research — Consumer Alert on Regenerative Medicine Products Including Stem Cells and Exosomes. FDA, 2020.

5. Medicare's National Coverage Determination covers autologous platelet-rich plasma ONLY for chronic non-healing diabetic, pressure or venous WOUNDS, and only under Coverage with Evidence Development inside an approved clinical research study. There is no Medicare coverage pathway for PRP as a treatment for osteoarthritis or any other joint indication, which is why these injections are quoted as cash prices.

   Centers for Medicare & Medicaid Services — Autologous Platelet-rich Plasma (Coverage with Evidence Development). CMS.gov, 2012.

6. MACI (autologous cultured chondrocytes on a porcine collagen membrane, Vericel; STN BL 125603) IS an FDA-LICENSED cell therapy - and its approved indication is narrow and specific: repair of symptomatic, single or multiple FULL-THICKNESS cartilage defects OF THE KNEE, with or without bone involvement, in adults. It is not approved for osteoarthritis. The existence of one licensed cartilage cell therapy for focal defects is the sharpest available way to show what a licensed 'regeneration' product actually looks like, and how far it is from an injection for a worn joint.

   US Food and Drug Administration, Center for Biologics Evaluation and Research — MACI (autologous cultured chondrocytes on porcine collagen membrane). FDA, 2024.

7. The RESTORE trial - a participant-, injector- and assessor-blinded RCT of 288 adults aged 50+ with symptomatic medial knee OA (Kellgren-Lawrence 2-3) - compared three weekly intra-articular PRP injections against saline placebo, with co-primary endpoints of 12-month knee pain and medial tibial cartilage volume on MRI. PRP did not beat placebo on either. It is the single best-designed test of the specific claim that PRP changes joint structure, and it was negative.

   Bennell KL, et al. — Effect of Intra-articular Platelet-Rich Plasma vs Placebo Injection on Pain and Medial Tibial Cartilage Volume in Patients With Knee Osteoarthritis: The RESTORE Randomized Clinical Trial.. JAMA, 2021. DOI: 10.1001/jama.2021.19415.