Hi, thanks for your question. Knee pain, swelling, with crackling sound most likely indicate a tear in the cartilage or other structures such as the meniscus which make up the knee joint. Most of these tears result from trauma to the knee. I have had a few patients present with such symptoms in the past, and I placed them on topical pain killers such as diclofenac ointments, as well as oral painkillers. Application of ice packs several times daily also helps reduce the pain and swelling. However, all of these are conservative measures, and a visit to a doctor who surgically treats diseases of bones and joints, an orthopaedic surgeon, is very important to determine the severity of the tears and determine if surgery would be necessary. While you wait to schedule a visit with an orthopaedic surgeon, employ those strategies above to minimize the pain and swelling. Best wishes to your husband, please contact me hereon if you have more questions.