Possible causes of melanin deposits on the knees include stratum corneum accumulation, sunburn, post-inflammatory hyperpigmentation, etc., which can be removed with the help of enhanced nursing care, medication, and medical aesthetics. 1. Stratum corneum accumulation: long-term accumulation of aging stratum corneum in the knee area can lead to knee blackening and other knee melanin precipitation phenomena, such patients can use regular scrubs and other toiletries to clean the knee, after bathing, local application of vitamin E-containing body lotion and other methods of care to help lighten the melanin precipitation of the knee, which in turn helps to remove the melanin precipitation of the knee. 2. Sunburn: When patients are exposed to ultraviolet rays for a long time and do not pay attention to the sun protection measures for the knees and other leg skin, it may lead to melanin precipitation in the knee area. Such patients should pay attention to strengthen the sun protection measures to avoid further darkening of the knee, such as using sunscreen, sunscreen spray and other sunscreen products when going out; for serious symptoms can also try to use laser treatment and other medical measures. 3. Post-inflammatory hyperpigmentation: long-term friction, trauma, allergies, dermatitis and other local injuries in the knee area will stimulate the melanocytes in the skin, so that their hyperfunction, synthesize more melanin, which leads to the phenomenon of knee blackening. Such patients can apply topical creams such as cumeneoside cream ointment, hydroquinone cream, vitamin A cream, vitamin E cream to help lighten the melanin, and in severe cases, laser therapy, chemical peeling and other treatments can be tried. Melanin deposits in the knee should be timely consultation, it should be noted that the above treatment and medication should be carried out under the guidance of a physician, to avoid the occurrence of adverse reactions.