The computerised method will improve the success of replacements and prevent costly and unnecessary revisions to existing implants, researchers say.
Modern knee replacement is a highly successful method of relieving the pain and disability of knee osteoarthitis, which usually affects those aged over 40.
Studies suggest that almost one in two people will suffer from symptomatic osteoarthritis - the degeneration of joint cartilage and underlying bone - of the knee during their lifetime.
More than 90,000 knee replacements are performed in the UK each year, but this figure is expected to rise by more than 600 per cent by 2030 due to an ageing population, obesity and younger people having the surgery.
Patients often require a second knee replacement or "revision".
Researchers at the University of Bath have developed a semi-automated computer program to assess the condition of a knee replacement, a task usually performed by surgeons. The technique gives an independent score for the region surrounding a hip or knee replacement which can progressively worsen with loosening.