Dark, scaly patches on the knees and elbows usually occur from a buildup of dead skin cells, often thickened due to friction from bumping your elbows or from the constant rubbing of tight clothing. A genetic disorder that results in thick, scaly patches called ichthyosis vulgaris also might be to blame. It may take time, but you can eliminate these patches and be happy to show your arms in public again.
Soak yourself in a hot tub for 10 to 15 minutes, paying attention that your elbows are submerged the entire time. If you'd prefer, soak your elbows alone in a basin filled with warm water for 10 to 15 minutes.
Work an exfoliating cleanser into your elbows using overlapping circles with a loofah.
Step out of the bathtub and pat your skin dry with a soft towel. Soak a washcloth with lemon juice and gently work the liquid into your elbows. Allow the lemon juice to soak into your skin for 15 to 20 minutes. Lemon juice is a natural skin lightener, and over time it will help eliminate your unwanted dark spots.
Apply a thick body butter or skin-softening oil to your elbows. Work the product into your dry, scaly skin for 1 to 2 minutes. Hollywood dermatologist Dr. Jessica Wu recommends using a product that contains lactic acid, which helps eliminate the dead skin cells that are making your elbows appear dark. Use a heavy butter or oil instead of lotion, which, according to Dr. Wu, isn't potent enough to absorb into your skin.
Speak to a dermatologist if you cannot eliminate the dark patches at home. According to the Mayo Clinic, many prescription topical creams are available to lighten your dark elbows, including those containing glycolic acid and retinoids.