Central vs Marginal Osteophytes

Marginal osteophytes, those found at the margin of the articular cartilage, are almost always present in patients with osteoarthritis and have been shown to be associated with knee pain.

Central osteophytes, those surrounded by articular cartilage on all sides, can also be found in osteoarthritis. Central osteophytes tend to occur adjacent to cartilage defects and are associated with more severe osteoarthritis than marginal osteophytes alone.

MRI is more sensitive than radiographs for detection of central osteophytes, because central osteophytes are obscured by the curved articular surface. When seen on radiographs, central osteophytes can be mistaken for free intra-articular bodies.

On MRI, a rim of fluid-like signal may be seen covering the surface of central osteophytes. This is thought to represent a thin rim of cartilage and is consistent with observations that central osteophytes are usually not visible on inspection of the articular surface at arthroscopy and gross pathology.

References

• McCauley TR, Kornaat PR, Jee WH. Central osteophytes in the knee: prevalence and association with cartilage defects on MR imaging. AJR Am J Roentgenol. 2001 Feb;176(2):359-64.
• Kindynis P, Haller J, Kang HS, Resnick D, Sartoris DJ, Trudell D, Tyson R. Osteophytosis of the knee: anatomic, radiologic, and pathologic investigation. Radiology. 1990 Mar;174(3 Pt 1):841-6.