Roughness and thickening of the skin on the knees may be caused by limited neurodermatitis, keratosis pilaris and other reasons. 1. limited neurodermatitis: limited neurodermatitis may be related to neuropsychiatric factors, scratching and chronic friction and other factors, manifested in the skin surface appeared in different sizes of flat papules, smooth surface or a small amount of scales, the affected area of the skin is rough, hypertrophic, surface scratches and hyperpigmentation. 2. Keratosis pilaris: Keratosis pilaris may be related to heredity, drugs and other factors, mainly manifested as local skin thickening, roughness, hyperkeratosis, large pores, flaking and other symptoms, friction and scratching, can be accompanied by skin itching and breakage. Rough and thickened skin on the knee may also have other causes, it is recommended to go to the hospital in time to improve the examination, to clarify the cause of the disease and then give targeted treatment.