Can an MRI Predict Stem Cell Therapy Results for Knee OA? First Author Dr. Junya Higuchi explains

At present, a pre-treatment MRI alone cannot accurately predict what will change after stem cell therapy.

The study did find that pre-treatment MRI findings — cartilage damage, osteophytes and bone marrow lesions — were associated with some of the clinical scores measured afterwards. The direction of that association ran opposite to what the research team had expected.

Note: this was a retrospective observational study without a control group. It does not establish or guarantee efficacy or safety.

When people consider regenerative medicine for knee osteoarthritis, the first question is usually whether it works at all.

But two people can receive the same treatment and have very different experiences afterwards. So is there anything we can know in advance?

That is exactly the question behind this study, published in 2020 in Regenerative Therapy, the English-language journal of the Japanese Society for Regenerative Medicine.

Key points

Study overview

Finding 1: pain changed mainly in the first month

The study tracked change using two measures.

The figures reported over six months were as follows.

More telling than the numbers themselves is when the change appeared.

VAS, KOOS-pain and KOOS-symptoms reached roughly 70 to 80 percent of their six-month average change within the first month.

This does not mean that 70 to 80 percent of patients improved, nor that pain fell by 70 to 80 percent. It means that most of the average change recorded over six months had already occurred by the end of the first month.

KOOS-activities of daily living and KOOS-sports and recreation, by contrast, changed gradually.

Pain shifts first. Function follows later.

Even when pain eases, stairs, long walks and sport do not necessarily become easier at the same time.

Finding 2: MRI findings were associated with outcomes, but in the opposite direction

This is the heart of the study, and the part that needs the most careful reading.

The 34 knees of 19 patients who had a pre-treatment MRI were scored using MOAKS.

Patients were not divided by how much they improved, but by whether each score reached its MCID.

The results were as follows.

Findings in the meniscus, ligaments and tendons, synovium and periarticular structures showed no significant association with any score.

The paper describes these data as implying that the stem cell therapy provided some beneficial effect even for patients whose disease had already advanced.

This does not mean “the worse the knee, the better it works”

There are three reasons.

Finding 3: no association with cell count, culture period or age

The study also examined factors other than MRI findings.

It is worth noting that this study was not designed as a trial comparing different cell doses, and the number of cells injected was not randomly assigned.

So “no association was found” is not the same as “cell count has no effect on what happens after treatment”.

Finding 4: symptoms and imaging did not move together

This is the part of the study that deserves the most attention.

Of all 57 knees, only four patients also had an MRI six months after treatment. The number is small, but the result is instructive.

The results of these four patients show that even when a knee feels better, a corresponding change will not necessarily be visible on MRI.

The researchers believe the reduction in pain may be related to reduced inflammation inside the knee joint. The paper also notes that several studies have reported improvement in pain and symptoms after treatment, but there is not yet sufficient evidence that cartilage or the meniscus grows back. A knee that feels more comfortable reflects an improvement in symptoms. Whether cartilage or the meniscus has actually been repaired still needs further examination and research to confirm.

Safety

No serious adverse events or complications were reported during the six-month observation period.

All of these reactions were transient and resolved completely within a few days to one week in every patient.

The physician behind this study

Dr. Junya Higuchi, director of Ginza YR Clinic, is the first author of this paper.

He trained in orthopaedic surgery at the University of Tokyo, building clinical and surgical experience across joint, spine, trauma and sports medicine, and earned his doctorate in medicine at the same university’s graduate school through research on mesenchymal stem cells.

This work was also presented at the Japanese Society for Regenerative Medicine in the same year, 2020.

What this study tells us

First, change has an order to it. Pain and symptoms shift first; daily activities and sport follow later.

Second, symptom relief is not cartilage regeneration. The paper infers that the clinical changes are more likely to stem from reduced inflammation than from tissue repair. Going into treatment expecting the knee to be restored is likely to lead to a gap between expectation and outcome.

Third, accurate prediction is not yet possible. Pre-treatment MRI findings were associated with later change, but imaging alone is not enough to predict the outcome for an individual patient. That is the paper’s own conclusion.

The value of this paper lies not in showing treatment results, but in stating clearly what remains unknown.

This article is provided for general medical information and does not guarantee any particular treatment outcome. Symptoms and progress vary between individuals. Please consult a physician for details.

So is pre-treatment assessment still worthwhile?

Yes — not to predict the outcome, but to confirm the following.

Knee pain does not always come from osteoarthritis. Rheumatoid arthritis, septic arthritis and referred pain from the lumbar spine can all present as pain in the knee.

At our clinic, the physician reviews the course of symptoms, physical examination findings, imaging and medical history together before judging on an individual basis whether regenerative medicine is appropriate. If it is not, we say so.

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