An arthrosis is a joint, an area where two bones are attached for the purpose of motion of body parts, such as the hip or knee.An arthrosis (joint) is usually formed of fibrous connective tissue and cartilage. The ends of bones that are part of a joint have a smooth surface known as the subchondral bone. Over it lies the articular cartilage which is strong yet flexible connective tissue that protects the bone, allows for easier movement between the surfaces and also acts as a shock absorber.