Well E9 Before and after treatment
Stem Cell Therapy vs. Joint Replacement Surgery: How Patients Are Weighing the Decision
Contents: 8 sections
A knee or hip replacement has decades of registry data behind it; stem cell injections have small, short-term trial results of low certainty, and the American College of Rheumatology recommends against them. If arthritis already limits your daily life and nonsurgical care has not helped, none of the evidence cited here supports delaying a surgical opinion to try an injection.
The two options compared
| Joint replacement | Stem cell injection | |
|---|---|---|
| What it is | The damaged joint surfaces are replaced with an implant | Cells from your own bone marrow or fat are injected into the joint; nothing is removed |
| Evidence of benefit | OrthoInfo calls knee replacement "one of the most successful procedures in all of medicine" (OrthoInfo) | Knee trials against placebo: pain 1.2 points lower on a 10-point scale at three to six months, low certainty (Cochrane) |
| How long it lasts | Knee implants: 82.3% still in place at 25 years in a Finnish registry (NIHR) | Not established |
| Recovery | Most people "resume most normal activities of daily living within 3 to 6 weeks" after a knee replacement (OrthoInfo, above) | One visit and no implant; protocols for the weeks after differ |
| Main risks | Serious complications such as joint infection "occur in fewer than 2% of patients"; blood clots are among the most common complications (OrthoInfo, above) | Risks from the marrow or fat harvest and from the injection itself |
| Guideline and FDA status | Recommended when severe pain limits everyday activities and other treatments have not worked (OrthoInfo, above) | Recommended against for knee and hip arthritis (ACR); no stem cell product is FDA-approved for joints |
Sources for the table: OrthoInfo; Cochrane; NIHR; ACR.
What does a replacement offer?
For the knee, OrthoInfo describes surgery for people with “severe knee pain or stiffness that limits everyday activities” whose other treatments, “such as anti-inflammatory medications, cortisone injections”, have not worked. It says “More than 90% of modern total knee replacements are still functioning well 15 years after the surgery” and that there are “no absolute age or weight restrictions” (OrthoInfo, above). After surgery it advises against high-impact activities such as running and jumping, and lists walking, swimming, golf, light hiking and biking as realistic.
Registry data go further back. In the Finnish registry, 82.3% of knee replacements were still in place at 25 years (NIHR, above), and for hips, 57.9% of replacements in registry data lasted 25 years (NIHR). Those figures count only whether the implant was replaced. As a commentator in the knee summary put it, “An unhappy patient with an unsuccessful operation who does not have a further knee replacement operation is counted as a success” (NIHR, above). Ask your surgeon what share of patients are satisfied, not only how long implants last. The joint pages go further: knee arthritis and the trials behind each option and hip pain and when a replacement makes sense.
What does the stem cell evidence show?
The 2025 Cochrane review of knee trials found stem cell injections improved pain by about 1.2 points on a 10-point scale and function by about 14 points on a 100-point scale compared with placebo, at three to six months. The reviewers rated that evidence low certainty, suspected publication bias because up to three larger trials were withdrawn before reporting results, and found that no included study measured whether the joint changed on X-ray (Cochrane, above). The review gives no estimate for the years that matter when you compare an injection with an implant.
Whether an injection repairs cartilage has not been shown in people. A stem cell injection for a joint is not an FDA-approved product; what the FDA allows, and the risks of taking marrow or fat, are on our overview of FDA status and harvest risks.
If a clinic shows you a long-term study comparing injections with replacement, check three things: who the patients were (some published comparisons involved arthritis after osteonecrosis, a condition in which bone tissue dies, not ordinary wear-and-tear arthritis), whether the injection was the same one you are offered (some studies injected cells into the bone under the cartilage rather than into the joint), and how many people took part.
Do you have to try an injection before a replacement?
No. Among the treatments OrthoInfo expects to have been tried before a knee replacement, it names anti-inflammatory medicines and cortisone injections, not stem cells (OrthoInfo, above), and the rheumatology guideline recommends against stem cell injections for knee and hip arthritis (ACR, above). Exercise is what that guideline strongly recommends.
Should a younger person wait?
A replacement done at a younger age has more years in which it may wear out and need a second operation, so the question is fair. But OrthoInfo sets no age limit, and it describes replacement for pain that limits everyday activities after other treatments have not worked. While your symptoms stay short of that, waiting is an option; what matters is how the time is used. Exercise and the conventional treatments in the guideline have evidence for arthritis pain (ACR, above); a stem cell injection has not been shown to delay a replacement. Ask your surgeon how implant survival looks at your age and activity level.
What should you ask before deciding?
- Ask the surgeon: What does my X-ray show? What are the chances I will be satisfied with the result? What are my personal risks from surgery? What happens if I wait a year?
- Ask the injection clinic: What result do you expect for someone with my X-ray, and how will we measure it? What is the total price, including repeat injections? What will you tell me if the injection does not help?
Before paying any clinic, check it against the warning signs of a clinic that oversells.
The same points come up in the questions for a first consultation, and the consent form should repeat them in writing, as the checklist for reading a consent form shows. After any injection, the signs of infection that need a prompt call apply.
What if surgery is not an option right now?
Someone caring for a parent this year, who cannot manage several weeks of recovery, is making a timing decision rather than choosing between two treatments. The question is how to get through the months until surgery is possible, and the options for that include exercise, anti-inflammatory medicines and a steroid injection, which the guideline supports, as well as a biologic. An injection is a smaller procedure than surgery. But the evidence for benefit is small and uncertain, the product is not FDA-approved for joints, and you should expect to pay for it yourself unless your insurer confirms coverage in writing. If you choose it, do so knowing that it is not a proven bridge to anything, and that a properly overseen clinical trial is a safer place to try it.
Which comes first depends on severity
If your arthritis is severe, limits daily life and has not responded to exercise and conventional treatment, get a surgeon’s opinion; the evidence supports a replacement and does not support delaying it with a stem cell injection. If your arthritis is milder, the next step is the conventional treatment laid out in the comparison of regenerative and conventional pain treatment.
This page is general information, not medical advice.