Topical glucosamine and Chondroitin products are a waste of money. Even oral versions are questionable in the results. Most studies of either or both together show no real benefit.
To answer the question, it is not a cure. It most like is not a reasonable treatment.
The best natural supplement in my opinion is omega 3 fatty acids. There is a lot of research that shows that it helps with inflammation and has many other benefits as well. Here is a link to information about omega 3 from one of the top arthritis sites.
http://arthritis-symp...ega-3-fatty-acids.htm