The number of total knee arthroplasties performed per year has increased steadily. This increase will probably continue since the principal risk factors obesity and advanced age will increase as well. The results of total knee arthroplasty are influenced by many physical, psychological, and social factors, which are presented. These factors have not been taken into account sufficiently by most of the investigations performed so far. Therefore, very few long-term data on the quality of life and functional gain are available. Survival analyses of single centers exhibit serious methodological flaws and a simplified data presentation, which reduces the generalizability of these results considerably. A critical analysis of these results was performed. Total knee arthroplasty has positive effects on the patient's pain level, ability to walk, and quality of life. There are a number of reliable uni- and tricompartmental designs. The revision rate is influenced by age, sex, disease, fixation mode, and prosthetic design. Tricompartmental prostheses have a revision rate of about 7% after 10 years. The revision rate has continuously improved over the last decades. Studies on total knee arthroplasty can be improved considerably according to international standards in terms of methodology and presentation of the results. The results from the patient's perspective need to be taken more into account.