Alternative names: Degenerative joint disease, spondylosis
Osteoarthritis (OA) is a disease that primarily affects the cartilage lining of the joints and the bones associated with the joints.
Cartilage allows the bones to glide over each other. When someone has osteoarthritis, this layer of cartilage starts to break down, causing bones to grind against each other. All the tissues surrounding the affected joint eventually become abnormal.
Outgrowths of bone form around the joint in an attempt at healing. Fragments of this bone can break off and irritate the joints, which lose their natural lubrication and become stiff and noisy. This causes pain and reduced motion.
Reviewed by Dr Stella Botha, rheumatologist at Groote Schuur Hospital, Cape Town (MBChB, MRCP, PhD), November 2017.