Arthroplasty for knee osteoarthritis is efficient - both from a patient and a cost-benefit point of view. Surgery should not await debilitating symptoms or progressive age and is expected to result in pain reduction, increased function and health-related quality of life and satisfaction. Patient information should modulate expectations by emphasizing the expected positive outcome with a low risk of complications. Mortality and morbidity is low although specific patients present a challenge regarding co-morbidities and surgery - necessitating individual planning.