From the Cleveland Clinic

September 21, 2018 / Orthopaedics

‘Stem Cell’ Injections: Emerging Option for Joint Pain Relief?

One potential option to repair a damaged knee and avoid surgery

'Stem Cell' Injections: Emerging Option for Joint Pain Relief?

Are you suffering from chronic joint pain? If so, you may have heard about “stem cell” injections and may want to ask your doctor whether these injections are right for you. If you want to avoid the surgical route of repairing a damaged knee or treating an arthritic shoulder, novel cell-based injections are becoming available and may give you the relief you need. However, this is a dynamic field and multiple questions remain unanswered.

What are stem cells?

Stem cells are special types of cells with the ability to multiply and self-renew. They also have the potential to replicate into specialized cell types forming potentially any tissue in your body. In other words, they can become a cartilage cell, a muscle cell or a nerve cell, says orthopedic surgeon Anthony Miniaci, MD.

“They have a tremendous capacity to differentiate and form different tissues, so that’s the thought behind regenerating cartilage, regenerating nerve cells and healing any injured tissues,” he says.

There are multiple sources of adult stem cells found in your body, including bone marrow or fat, although you can also receive stem cells from donor sources, Dr. Miniaci says.

“However, the term ‘stem cell’ is often widely and inappropriately overused in orthopaedics to include all kinds of treatment with uncharacterized, minimally manipulated cells, and even therapies that do not contain stem cells at all,” explains orthopaedic surgeon Nicolas Piuzzi, MD.

How cell-based treatment works

The treatment team harvests cells from your bone marrow or fat, or uses donor cells. Later on, your treatment team injects the cells precisely into your joint, ligament or tendon.

Theoretically, the cells when delivered will adjust inflammation and/or then divide and duplicate themselves and develop into different types of cells depending on the location into which they have been injected.

However, for patients with a severe loss of cartilage or no cartilage at all, a cell-based injection is unlikely to create a new joint, Dr. Miniaci says.

“Severe loss of cartilage typically leads to bone erosion or bone deformity, so a cell-based injection is highly unlikely to work in terms of reversing those changes,” he says.

It can, however, improve your symptoms of pain and swelling.

“The earlier you can treat someone’s joint pain, the better chance this has of working, making it less painful for the patient, less inflamed, and improve their function,” he says.


To date, there have not been any major adverse events reported associated with cell-based therapies in orthopaedics.

The main risk from a cell-based injection is probably in harvesting the cells. For example, when taking the cells from your bone marrow, the treatment team inserts a needle into your pelvis and removes some bone marrow cells and blood.

“However, the risk of having a complication during or after bone marrow aspiration in orthopaedics is minimal,” Dr. Piuzzi says.

“If you’re taking cells from fat, you can remove some out from under the skin,” Dr. Miniaci says. “To consider, anytime you make incisions or insert sharp instruments into a patient’s body, they can have problems such as acquiring an infection.”

Treatment is in its infancy

While the use of cell-based injections to treat joint pain holds much promise, Drs. Miniaci and Piuzzi caution that this treatment option is still very new. Researchers need to study its safety and determine if they are effective or not.

“We don’t have proof indicating that cell-based injections actually repair the joint,” Dr. Miniaci says.

He explains that if you have cartilage or bone damage, stem cells could differentiate and produce bone and cartilage and other tissues. So, theoretically, they could heal damaged tissue within a muscle, tendon, bone or cartilage.

“That’s the theory behind it, but this type of treatment and research is just in its infancy,” he says.

“We really don’t know what’s effective, what’s not effective, how many cells are necessary, how many actual injections you need and how often,” he says. “Nobody knows how well or even if it works yet. But we will eventually.”

Anecdotally, Dr. Miniaci finds that some patients can have improvement in their symptoms with cell-based injections. But he has not seen any proof yet that they are regrowing or regenerating a joint.

“Many people think that they’re going to come in with their arthritic joint and leave with a newer version of their knee joint. That doesn’t happen,” he says.

“What does occur is a biological reaction which makes the environment in their joints a little healthier, which probably makes it less inflamed, and as result, gives them less pain.”

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