These are swellings that appear on the side of the knee joint. Patients are aware of a lump developing on the outside of the knee. The lump is often, but not always, painful as the meniscal cyst is associated with a meniscal tear.
Meniscal cysts arise from a torn meniscus that has a type of tear called a horizontal cleavage tear or a complex tear that includes a horizontal component. They most commonly arise from the lateral (outer) meniscus. They are filled with gel-like joint fluid.
Different treatments have been proposed to remove these cysts. We favour internal decompression (drainage) of the cyst after trimming the horizontal tear during an arthroscopy. This is usually successful in resolving the problem.