Key words: Stem cells, knee osteoarthritis, ortho-biologics
Why is this study important?
Knee osteoarthritis (OA) is a massive clinical challenge. For many, it means daily pain, reduced mobility, and eventually, joint replacement. As clinicians, we are always looking for effective, low-risk treatments that delay or reduce the need for surgery.
In recent years, “stem cell” injections using fat tissue—especially micro-fragmented adipose tissue—have become a popular go-to treatment in the private sector. This “point-of-care” cellular therapy is marketed as regenerative and is often expensive (1). But does it work?
This new high-quality randomised controlled trial, with two years of follow-up, puts the treatment to the test. It is the first fully blinded study to compare a single injection of micro-fragmented adipose tissue to a placebo (saline) injection in patients with moderate knee OA (2).
How did the study go about this?
Researchers recruited 120 adults with moderate tibiofemoral knee OA (Kellgren-Lawrence grade 2–3). Everyone underwent liposuction to harvest abdominal fat, but only half received an intra-articular injection of their own micro-fragmented adipose tissue. The other half received a simple saline injection into the knee joint.
Both groups were blinded—they didn’t know which treatment they received. Patients were followed up for two years, and their outcomes were measured using the KOOS4 (Knee Injury and Osteoarthritis Outcome Score), Tegner activity scale, and other metrics of function, pain, and quality of life. Stem cell presence and viability was analyzed in the laboratory.
What did the study find?
The bottom line: there was no significant difference between the micro-fragmented adipose tissue injection and the placebo saline injection.
Yes, both groups improved. But no, the micro-fragmented fat did not do better than saline at any time point (6, 12, or 24 months). The improvements in both groups were statistically and clinically meaningful, suggesting a strong placebo effect or natural symptom fluctuation in OA.
A few more details:
- KOOS4 scores improved in both groups.
- No difference in return to sport, work status, or activity levels.
- No major side effects occurred, but minor discomfort from liposuction was reported.
- The micro-fragmented adipose tissue injection contained approximately 1 million viable stem cells, but this didn’t translate into better clinical outcomes.
What are the key take-home points?
Don’t believe the hype (yet): Despite being marketed as a “stem cell therapy,” this form of fat injection didn’t outperform saline in a rigorous fully blinded trial and is fundamentally different from a treatment with expanded stem cells.
Patient communication is key: If you are a clinician offering or discussing this treatment, you should inform your patients that current evidence does not support its superiority over saline.
Saline might not be so ‘inert’: Saline injections themselves may have a therapeutic or placebo effect, reminding us to be thoughtful about what constitutes a “control” treatment.
Research over marketing: More robust, unbiased trials are needed to investigate if point-of-care cell-based therapies should become standard care. Until then, clinicians and policymakers should tread carefully.
Final word: This trial adds a much-needed dose of scientific rigor to a field often dominated by commercial interests. For now, exercise therapy, weight management, education, and shared decision-making remain our best tools for managing moderate knee OA.
Blog authors
Kristoffer W Barfod, Jasmin Bagge
References:
1) Rubin R. Study: Business Booms for Unlicensed and Unproven Stem Cell Treatments. JAMA 2022;327:414.
2) Wiggers TG, Winters M, Van den Boom NA, et al. Autologous stem cell therapy in knee osteoarthritis: a systematic review of randomised controlled trials. Br J Sports Med 2021;55:1161–9