New Cochrane review weighs up the latest evidence on stem cell injections for osteoarthritis – Australia’s most common joint disease
A new Cochrane review published today weighs up the latest evidence on stem cell injections for knee osteoarthritis – a debilitating condition that affects over 2 million Australians and costs the health system more than $4 billion each year.
The findings highlight how much uncertainty remains around the potential benefits of this increasingly popular treatment option.
‘We know knee osteoarthritis is the most common joint disease here in Australia and around the world,’ says Dr Sam Whittle, a Senior Consultant Rheumatologist from Adelaide’s Queen Elizabeth Hospital who leads the global Cochrane research team.
‘Unfortunately, it’s also a very complex condition to treat because it impacts the whole knee joint – including the bone, cartilage, ligaments and muscles. Patients experience pain and swelling that can impair movement and daily activities, leading to diminished quality of life over time.’
With no available cure for knee osteoarthritis and limited effective non-surgical treatments for long-term symptom management, stem cell therapies have become the focus of both hope and hype. A range of as yet unproven procedures with high out-of-pocket costs have proliferated worldwide, while the scientific evidence on their potential benefits and harms has failed to keep pace.
‘It's vitally important that healthcare professionals, funders, patients and policymakers have up-to-date and high-quality evidence about stem cell treatments,’ says Dr Whittle. ‘That's why our team of Cochrane researchers has designed and published this new 'living' review – a continually updated resource that incorporates new evidence as it emerges. With major clinical trials underway in Australia and globally, our team will be looking for new studies every three months and updating this review as the evidence base grows.’
The primary question driving this review was clear: do stem cell injections slow the progression of disease and lead to improvements in pain, function and quality of life, or do they cause harm?
‘Overall we found no evidence of an important benefit, though there was a small improvement in pain and function in those who received stem cells compared with placebo injections. Put simply, if there’s a benefit, it’s probably quite minor, but we can’t be very certain about this until more trials are completed.’
The science behind stem cell injections: what does the current evidence tell us?
‘Stem cells are a special type of cell that can develop into mature cells in different parts of the body, including cells that produce cartilage, bone and fat tissue,’ Dr Whittle explains. ‘In theory, they could rebuild cartilage, improve joint structure and reverse the damage caused by osteoarthritis. If anyone could demonstrate stem cells can actually do this in practice, that would be groundbreaking. To date though, we've seen very mixed results.’
‘Over 40 systematic reviews of stem cell injections for knee osteoarthritis have been published, with findings ranging from negative to neutral to very positive. This has proved confusing for healthcare providers and patients alike, and led to considerable research waste.’
For this definitive living review, Cochrane researchers looked at 25 studies involving 1341 participants, including eight studies with 459 participants that directly compared stem cell injections to placebo injections. The studies were conducted in Europe, the Middle East, Asia, the USA, South America, the United Kingdom and Australia. Three larger studies couldn’t be included in the final analysis, as they were conducted but withdrawn by their investigators before reporting results.
Key findings
The review found:
Stem cell injections may provide small improvements in pain and function compared with placebo injections but showed no significant impact on quality of life or overall treatment success. The clinical significance of these modest improvements remains unclear.
The benefits and risks of stem cell injections compared with no treatment, routine care, or glucocorticoid injections remain uncertain.
Despite claims about regenerative effects, there is insufficient evidence regarding stem cell injections' impact on structural progression in the knee joint.
Safety data remains limited, with serious adverse events being infrequently reported. While all joint injections carry some risk of complications like septic arthritis, the potential long-term concerns related to therapies that promote cell growth remain unknown.
It's still unclear which methods of stem cell harvest, isolation, expansion, storage, injection technique, or dosage might be most effective, if any.
‘Across all our results we can see there remains a great deal of uncertainty around the benefits and harms of stem cell injections, and low certainty in the evidence due to different studies using different reporting methods, protocols and standards.’ Dr Whittle says.
‘This ongoing uncertainty is frustrating for everyone wanting to find and access the most effective treatments, and ultimately a cure for this condition. The good news is that there are several major clinical trials are underway that could significantly impact our understanding of stem cell treatments – including a large trial run out of Sydney that will effectively double the size of our meta-analysis. Our living review team will be screening for new evidence every three months from here on in, and as we accrue those important, large, well-conducted trials, we should get much higher confidence in our estimate of effect, and ideally some more concrete conclusions as results come in over the next two to five years.’
‘As research continues, we look forward to incorporating new findings that can help inform clearer guidance, policy and decision-making around stem cell treatments for knee osteoarthritis.’
