What is the Difference Between Osteophytes and Syndesmophytes?

Osteophytes and syndesmophytes are both osteoproliferative lesions found in the spine, but they have distinct differences:

1. Orientation: Osteophytes run horizontally, while syndesmophytes run vertically. Osteophytes typically protrude perpendicular to the spine, whereas syndesmophytes run parallel with the spine.
2. Location: Osteophytes are osseous outgrowths that form above or below the endplate margin, while syndesmophytes are located inside a spinal ligament or at the attachment of a ligament or tendon.
3. Etiology: Osteophytes are degenerative osteoproliferative lesions, while syndesmophytes are inflammatory osteoproliferative lesions. Osteophytes are associated with medical conditions such as osteoarthritis, while syndesmophytes are associated with ankylosing spondylitis (AS) and other conditions like ochronosis, fluorosis, reactive arthritis, and psoriatic arthritis.
4. Bridging: Syndesmophytes bridge across the joint, unlike osteophytes, which are non-bridging.

In imaging testing, osteophytes and syndesmophytes can look very similar and can be difficult to differentiate. However, understanding the differences in orientation, location, etiology, and bridging can help in distinguishing between these two types of lesions.

Comparative Table: Osteophytes vs Syndesmophytes

Here is a table comparing the differences between osteophytes and syndesmophytes:

Osteophytes and syndesmophytes are both types of osteoproliferative lesions formed in the spine, and they can look similar in imaging scans. However, they have different origins and are associated with different medical conditions. Osteophytes are degenerative lesions that originate from the vertebral body, while syndesmophytes are inflammatory lesions that originate from the annulus fibrosus of the intervertebral disc.