what causes flat spots under knees
Other Causes -- Here are a few more things that could contribute to the formation of dark spots on your elbows and knees: 1  Certain medications. 2  Certain diseases (obesity, Addison's syndrome, etc.) 3  Hormone imbalances.  Hyperpigmentation of the 1  skin. Active melanocytes in your elbows or knees.
However, the fact that they're not alive means that they will have a darker, dead appearance than healthy cells. When the dead skin cells build up on your elbows and knees, exposure to sunlight will cause them to darken, giving you those dark spots. Dirt -- Yes, it may be hard to hear it, but dirt can be a major cause of the dark spots on your elbows and knees.