Osteoarthritis - (degenerative arthritis or simply OA) is the most common type of arthritis resulting in pain in the joints due to cartilage damage. Since artilage is necessary to act as cushion inside joints patients experience pain because bone surfaces become less protected. Pain usually occurs during walking and standing. Because of pain movements of joint are usually decreased which can result in muscle atrophy near the afected spot and ligaments may become more lax. This disease ususally include inflammation although many pacitents have very little or no inflammation at all.
Sympthoms include chronic pain, loss of mobility due pain and usually stiffness. This pain is like sharp ache or sensation of burning in local muscles and tendons. Also it can provoke musce spasm or contractions in the tendons. Sometimes there may be fluid in the joints which can increase pain.
It usually affects hands, feets, spine, hips and knees although it can also affect any other joint.
Treatment for this kind of arthritis consists of medication or other kind of interventions which will provide improved function of the joint and reduce the pain, although sometimes surgery may be necessary. This surgeru usually consists of fragment removal, repositioning bones or fusing bone with purpose of reducing pain and increasing stability.

Picture taken from Wikipedia