Recently in the media there has been a lot of interest in using Stem Cells to treat many medical conditions. This includes interest in treating orthopaedic conditions such as arthritis of the knee and hip.
As far as I am aware at this time (2014) there is no evidence for stem cells being successfully used to treat arthritis of the knee or hip. There are currently in Australia clinical trials being performed to assess the ability us stem cells to treat arthritis. None of these studies, that I am aware of, have published any positive results so far.
Even if stem cells do prove effective in the future, it is likely that they will be of use only in early arthritis.