Hi,My Brother Is 26 Years Old And His Weight Is

Hi,My brother is 26 years old and his weight is around 95 kgs and his height is 5 Ft 8 inches..For about one month he is having pain his knee..Few days back he went to see the doctor ..The X rays suggested that there is gap in his knees..Please tell me what treatment should be done and is this a thing to worry? Also tell me some home remedies for this knee gap..