Cellular and Clinical Analyses of Autologous Bone Marrow Aspirate Injectate for Knee Osteoarthritis: A Pilot Study.
Kristina Wells, Michael Klein, Nicole Hurwitz and 5 others
PMID 32500620WHAT IT FOUND
Patients with mild knee osteoarthritis reported better function and less pain for up to 12 months after a single bone marrow aspirate injection into the knee.
This was a small uncontrolled pilot, so the injection cannot be shown to have caused the change.
Key findings
01The primary patient-reported knee outcome, KOOS-JR, improved over time, with clinically important gains at 3, 6, and 12 months.
02Current, usual, best, and worst numerical pain scores decreased over time, although best pain was already low at baseline.
03The injected aspirate was highly variable: median mesenchymal stem cell count was 238 per millilitre, and neither colony-forming units nor total nucleated cells predicted mesenchymal stem cell count.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
No control group or comparison treatment was used, so the observed improvement cannot be separated from natural history, placebo, or other care. Only 10 patients and 13 knees were included in the overall clinical and cellular analysis, after several withdrawals. Participants had mild radiographic knee osteoarthritis, so the results do not apply to moderate-to-severe knee osteoarthritis. The procedure was performed by one fellowship-trained physiatrist, so results may not transfer to other clinicians. Cellular analyses had technical problems: one marrow smear contained zero cells, red blood cells were not counted in some samples, and clotting affected interleukin-1 receptor antagonist measurement. The paper is a pilot study with a small sample, so it is not definitive evidence of efficacy.
Declared interests
The supplied text does not include a conflict-of-interest declaration. The article is labelled as supported by NIH extramural research.
The easy way to misread this
Do not read the improvement in pain and function as proof that bone marrow aspirate injection works for knee osteoarthritis. The study had no control group, analysed only 10 patients and 13 knees, and enrolled only mild cases, so natural history, placebo, and other care could explain the changes. The injection was given with sedation, local anesthesia, contrast guidance, and post-procedure instructions, so the aspirate alone cannot be isolated.