I get asked quite a bit whether knee gel injections will help or harm a planned stem cell procedure. To review, these injections (also sometimes called rooster comb injections since some are derived from rooster combs) go by the brand names SynVisc, Supartz, Hyalgan, OrthoVisc, Euflexxa, Monovisc, Visccure (UK). They are all hyaluronic acid (HA) of different molecular weights (actually the sodium hyaluroate salt) and live in a family of medications called viscosupplements because they increase the viscosity of the synovial fluid (the knee’s natural fluid). The crazy name hyaluronic comes from the Greek word “hyalos” which means “vitreous”. This is because they were first isolated from the vitreous gel inside the eye which also has a high uronic acid content (hence the “uronic” part of the chemical name). The concept behind their use is that by beefing up the synovial fluid in arthritis, there would be more cushioning in the damaged joint. These knee injections are used in patients with moderate to severe knee arthritis and have also been used in other arthritic joints such as hips, ankles, and fingers. They also improve the chemical composition inside the arthritic joint (changing the toxic witches brew of cartilage breakdown chemicals to a healthier chemical mix). A recent Spanish study also showed that hyaluronic acid injections are an economic booster to health systems as they delay the need for joint replacement. In essence, unlike toxic steroids and anesthetics, they are a net positive to the joint. So if you want to get knee gel injections before a knee stem cell injection, they will likely help the effort of cleaning up a toxic arthritic knee. However, there are two key rules you need to follow: guidance and making sure the doctor doesn’t add anything cartilage toxic to the HA. First, guidance means that the doctor uses ultrasound or x-ray to make sure he or she is actually placing the medication in the joint. Why? The rate of the doctor actually missing the joint will go up or down with the injection route taken and the weight of the patient. The “miss rate” can be as high as 20-40%! In addition, if the doctor gets the HA outside the joint, the risk for bad complications can go way up as some of the medications if placed outside the joint can cause a “pseudoseptic joint” (a red and angry joint that looks like it’s infected but really isn’t). Second, and perhaps even more important, is that the doctor adds nothing toxic to the knee gel injections. It’s very common for example for physicians to add a local anesthetic to the HA because they believe it will help with post injection soreness. First, all common local anesthetics are toxic to the joint’s stem cells and many are also toxic to the cartilage. The most commonly used anesthetic for joints is Marcaine/Bupivicaine and it’s highly toxic to both stem cells and cartilage cells! In addition, many doctors will want to add a high dose steroid, which is also toxic to stem cells and cartilage cells. So injecting the good HA is made bad by adding joint toxic substances to the mix! The upshot? HA is a net positive for patients that are considering stem cell therapy. However, making sure it actually gets inside the joint and avoiding the addition of toxic substances are critical to making sure a net positive doesn’t get turned into a net negative!