A search of the Net found there is such a thing as "Infectious Septic Arthritis" . The link is http://arthritis.about.com/od/infectious/Infectious_Septic_Arthritis. To quote, "Infectious arthritis is caused by a germ that travels through the body to a joint. The germ can be a bacterium, virus, or fungus. The germ can enter the body though the skin, nose, throat, ears, or through an open wound. Most often, infectious arthritis develops after an existing infection anywhere in the body travels through the bloodstream to a joint.".
What's the treatment? In my case anti-biotic (Ciporoxyl) and anti-allergy drugs, bed rest and lots of stretching and massage to try and get the right leg back in play. The good news? I suppose that this was a result of an infection and not some longer term disease.