**1. Introduction**

There is approximately 20 percent of the patients with dissatisfaction following TKA whether pain or having postoperative problems [1, 2]. In the previous literatures, reporting of complications and adverse events after TKA was not standardized with several definitions being proposed. Healy et al. published a list of 22 TKA complications and their standardized definitions including these three common problems, which were endorsed by The Knee Society to improve quality measurement and consistent with ICD-9 codes [3]. Stiff TKA could produce pain and diminish functional ability, whereas PJI and periprosthetic fracture might cause severe morbidity. Early detection and appropriate management are the key success to resolve these problems which would enhance patient's outcome and improve satisfaction.
