Knee pain is one of the top two or three reasons that patients come in to see me. In older patients the knee pain often comes from wear and tear of the knee. The knee surface has a shiny layer of cartilage both at the end of the femur and the tibia. When there is breakdown of the cartilage from either an injury, age, weight or no specific injury then that is what we call arthritis or degenerative joint disease.
What happens is that inside the knee there is synovial fluid which circulates between the bones. As arthritis sets in the fluid can become thinner and lose its elastic properties of cushioning the knee joint. I often tell patients to think of the fluid in your knee joint like engine oil. Over time engine oil will break down and lose its lubricating properties. Synovial fluid is similar in that when arthritis sets in there are little nooks and crannies on the knee joint surfaces that do not get well lubricated. For your car you can go to your nearest Quick Lube and get an oil change. The last time I checked Quick Lube does not do knee joints.
A little over twenty years ago a product was developed using rooster combs to inject into the knee to lubricate it. Over the years there have been advancements in the joint lubrication field where the fluid is now synthesized in a lab and there are no animal products. The products now have better cushioning properties and they are all grouped under the name: viscosupplementation.
I use Orthovisc which involves three injections into the knee joint one week apart. It coats the rough areas of the knee and provides up to 6 months of relief. The injections are done in the office and the patient is able to walk right out and resume most activities within a day. I often tell my patients that Orthovisc is like getting an oil change along with STP which makes the knee joint fluid thicker. It provides more lasting relief then a steroid injection.
One word of advice is avoid going to any facility that you see advertised that states that their facility uses the latest image guidance or ultrasound to inject the knee. They are injecting the same product as I described and charging double or triple the normal rate. Any competent orthopedic surgeon can inject the knee without imaging.
Gel injections are only indicated for the knee in the U.S. It has been used in other joints with osteoarthritis, but that is not FDA approved and is considered "off label". Many patients that I see with osteoarthritis of the knee may need a knee replacement, but for personal reasons do not want to go that route. Gel injections are a much more conservative route and it may be the answer for your knee pain.