If you mean ligaments, they are the tissues in the body that hold the joints together.
legaments legaments
Tendons and/or legaments
Torn legaments
sometimes swelling constant hurting or throbbing and hard to do serious work with the arm mentioned
Ligaments are the types of tissues that attach one bone to another in the human body. These fibrous connective tissues provide stability and strength to joints by holding the bones together.
According to the related link, monkeys can walk on 4 legs. They can also walk on 2 legs, but for shorter periods of times. As the state "4 legs", and not "limbs", monkeys probably have 4 legs, which answers you question.
Arthritis in itself has no effect on ligaments and muscles, However pain as a result of the build up of scar tissue and bone can lead to problems with these. I have feet that I have been told By rhuematologists are badly affected by RA, and that I must have a high pain threshold to still be walking around without a limp. Personally I would put this down to the fact that I spent most of my life in the building trade and as a result the muscles in my feet were always kept in tip top order giving the joints and bones good support. There were however short periods of time when I was forced to limp around as a result of inflammation in my feet.