Yes. The all contain various preparations of hyaluronic acid. They differ in molcular weight and frequency of injections needed. I do not believe the should be used alone, but in conjuction with nsaids, since the results are vbetter when both are used. Also, remember osteoarthritis of a joint may be primary, or secondary. The latter is caused by joint inflammation. This must be excluded.
Six. I believe there are six different types of joint replacement fluids. All a specific chemical known as hyaluronic acid. It is the main lubricating fluid inside our joints.