Osteoarthritis is caused by the breakdown of cartilage in one or more joints. Cartilage serves as a cushion between the bones of joints, allowing the bones to glide over one another and absorb the shock from physical movements.
Osteoarthritis progresses in stages:
- joint space begins to narrow and osteophytes form
- joint space disappears as cartilage wears away and bone rubs on bone in the joint
- subchondral cysts appear
- bone tries to repair itself and there is bone remodeling
What is a subchondral cyst? What is the recommended treatment for a subchondral cyst?
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 normal joint fluid that serves to lubricate the joint).
Subchondral bone is the layer of bone just below the cartilage. When someone has osteoarthritis, there is increased blood flow and other changes that develop in the subchondral layer -- subchondral sclerosis (increased bone density), subchondral cyst formation and increased pressure within the bone -- all of which may cause osteoarthritis pain.
The formation of a subchondral cyst is indicative of an early phase of osteoarthritis. It is often the case that the subchondral cyst improves without medical attention, although the disease itself does not go away. If the subchondral cyst causes discomfort, Nonsteroidal anti-inflammatory drugs (NSAIDs) may provide relief, as would avoiding activities that irritate the joint involved.
The recommended treatment for a subchondral cyst is to just leave it alone. A subchondral cyst should not be lanced or removed, especially because removal would cause an increased risk of infection or possible problems with wound healing.
Sources:
Radiographic Assessment of Osteoarthritis. Swagerty DL. et al. American Family Physician. July 15, 2001. What are subchondral cysts and how are they treated? Doyt Conn, MD. Arthritis Today. Accessed 5/26/2008.
http://www.aafp.org/afp/20010715/279.html
http://www.arthritis.org/osteoarthritis-questions.php#1
