Doctors have a number of options when it comes to joint injections.

Doctors have a number of options when it comes to joint injections.

The next generation of joint injections

Joints sometimes hurt. Like well-oiled machines, occasionally the oil runs thin, the surfaces become corroded, small particles become trapped and the components get out of line.

Pain happens when the surrounding nerve fibers become irritated. Swelling happens as the vessels in the lining of the joint bring new cells, to remove the irritants and provide healing factors to the damaged tissues. The cascade of injury and repair goes on every day in every joint of the body.

To relieve the symptoms of injured joints, traditionally, physicians have recommended ice, compression, elevation, plus massage and anti-inflammatory drugs. However, this approach does not address the cause of the irritation, pain and swelling in the first place.

To repair the cause, many physicians are now turning to injections, which work to stimulate and speed up the body's natural healing process. To understand how these injections work, it's helpful to know how the body responds to injury.

The tissue injury response cycle goes like this: When damaged, tissue bleeds due to the disruption of the blood vessels. The blood released causes swelling. Swelling causes the recruitment of more vessels and cells, which release breakdown enzymes and build up growth factors that have both clean up ability and repair ability. Repair occurs by the production of proteins, predominantly collagen, which is laid down either as scar tissue or as new tissue depending on the stimulation and environment. The collagen then matures over time. The enzymes and growth-factor soup works synergistically to create healing.

Today, physicians can choose from a range of injections that mimic normal healing:

1. Platelet-rich plasma or growth factor injections: One component of the blood stream is platelets. Platelets are cell-like particles that are smaller than red or white blood cells. These tiny platelets release a soup of growth factors at the site of injury. They help in the clotting process by sticking to the walls of the damaged blood vessels and plugging the rupture. The most important compound is PDGF, or platelet-derived growth factor, which causes stem cells (more on those in a minute) to be released from vessel walls and migrate to the site of injury. Physicians are able to take a small amount of a patient's blood, isolate and concentrate the platelets by spinning the blood in a centrifuge, and inject the growth factors they release directly into the injured area, where they promote the body's natural healing response.  2. Stem cell injections: Stem cells are immature cells that have not developed into their final cell type. Embryonic stem cells can transform into virtually any cell, while adult stem cells can only change into a specific family of cells. Stem cells also recruit growth factors to speed up the healing process. They are pericytes, which means they live on vessel walls. The more vascular the tissue, the more stem cells there are, so fat and bone marrow have the most. The cells can be harvested in a physician's office using special needles, then concentrated in a centrifuge and injected. They migrate naturally to sites of injury and begin the repair process.

3. Anti-inflammatory injections: The compounds in the blood repair soup that most influence inflammation can be isolated in a unique incubation method that permits a potentially higher concentration of the factor called IL1RA to be delivered to a site of injury.

4. Lubrication injections: The body's natural joint lubricant is called hyaluronic acid. This oil has been used to diminish the symptoms of arthritis by a series of injections. Unfortunately, it only lasts in the joint for a few hours but the effect, when it works, seems to last for months.

Our experience with these injections reveals the 30-30-30 rule. Thirty percent of all patients seem to have a superresponse to the injections, 30 percent a moderate response and 30 percent no response at all. We cannot yet predict who will respond. There are no complications known to them since they are natural products, mostly from the patient. However, they are costly. It seems clear that stem cells have tremendous potential but are unruly. Growth factors only work in concert with other factors.

Tissue repair and subsequent healing occurs in a temporal sequence, meaning that specific combinations of factors and cells must appear at defined times, just like the plumbers have to show up at the construction site after the framing is done and not before, but they also have to be scheduled to show up and be directed on what to do when they get there.

This may change in the future. In the pipeline, there are advances in isolating specific stem cells and proteins that appear to have beneficial effects and that may not just be targeted to specific functions but may also act as general contractors. To get these, new isolation techniques, most likely using magnetic-type nanoparticles to pull apart only the labeled factors and then inject the customized matrix and director cells, will occur.

Until then, we recommend you use the office home brew soup of growth factors, lubricants, anti-inflammatory and stem cells, if they work for you.

Dr. Kevin R. Stone is an orthopedic surgeon at The Stone Clinic and chairman of the Stone Research Foundation in San Francisco. He pioneers advanced orthopedic surgical and rehabilitation techniques to repair, regenerate and replace damaged cartilage and ligaments. For more info, visit

FeaturesKevin R. Stone

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