Osteophyte

An osteophyte, or more colloquially a bone spur, is any projection from a bone where it meets a joint. They usually, but not always, occur within the joint capsule. They can be caused by any damage to the surface of the joint, the most common cause being arthritis.
Typically, the patient will feel pain at the site of an osteophyte, but many cases are asymptomatic. Generally, the pain is managed with NSAIDs or steroids. However, osteophytes on the spine (which get more common as a patient ages) often cause pain where they impinge on nerves in the same area.
Osteophyte at Wikipedia