With persistent pain and swelling in the knee there is a possibility of infection. At this stage, infection has to be ruled out before deciding on the line if management. You need to have blood tests and also the fluid from the joint need to be taken out in sterile conditions and cultured. This will give more information about the possibility of infection. Once this is done then other causes will have to be investigated. Dr Vinu Raj Consultant Orthopaedic Surgeon MBBS MRCS FRCS(Trauma&Orth)

There should be no major issue, have you gone proper rehab there is much of chances of prosthetic failure if no proper physiotherapy done that time. So speak to your surgeon and may be now also you can seek some help from some physio...