Osteophytes, more commonly known as "bone spurs", are outgrowths of bone tissue that form around damaged joints. This bone growth is thought to be a compensatory response to bone and ligament damage, and is meant to restrict movement of the joint to protect from further damage. Joints that are prone to damage from overuse and arthritis, such as those in the spine and hands, are most likely to develop osteophytes, though any bone can develop them. They can also form as a result of osteomyelitis (bone infection).
Osteophytes in the distal interphalangeal joint (DIP) are known as Heberden's nodes, and those in proximal interphalangeal joint (PIP) are called Bouchard's nodes. The presence or absence of PIP, DIP, and metacarpophalangeal joint (MCP) osteophytes provide a good clinical means of differentiating rheumatoid arthritis from osteoarthritis. In osteoarthritis, osteophytes are commonly seen in the DIP and PIP and rarely seen in the MCP. In contrast, patients with rheumatoid arthritis commonly present with osteophytic growth in the PIP and MCP, but rarely in the DIP.
Osteophytosis is most commonly seen in the spine and is a sign of spinal degeneration. In most cases the bone spur itself is not a source of back pain, though if a bone spur begins impinging a spinal nerve this can lead to symptoms of neuropathy along the affected dermatome.
This is the CT scan of cadaver 33446. Follow the vertebral column down to the level of T6 (time= 58, L11). Notice how the vertebral body of T6 is beginning to show signs of a bony outgrowth toward the right. Continue scanning down and you will see that this osteophytic growth continues throughout the thoracic vertebral bodies. Continue down to the lumbar vertebrae. At time= 75, N11 you will see a large osteophyte protruding into the left psoas muscle.
If osteophytes are causing severe enough impingement of spinal nerves as to warrant surgery, then oftentimes a spinal laminectomy will be conducted to widen the spinal canal. See the clinical case Laminectomy for more information on this procedure.