Intervention; interposition; the act of a third person who interferes between two contending parties with a view to reconcile them or persuade them to adjust or settle their dispute.
Subchondral cyst formation is characteristic of osteoarthritis and can be routinely found on x-rays. A subchondral cyst is a fluid-filled sac that extrudes from the joint, consisting of thickened joint material (mostly hyaluronic acid, a substance found in the normal joint fluid that serves to lubricate the joint). Subchondral bone is the layer of bone just below the cartilage.
1 Epidermoid (sebaceous) cyst: usually benign swelling in the skin arising in the sebaceous gland, typically filled with yellowish sebum. These are usually easily seen as they lead to a swelling of the skin. If they become large enough, they can be painful and unsightly.  Breast cyst: a fluid-filled sac within the breast.