In this book, the complete development of an external intelligent knee prosthesis created by the Mechatronics Research Group (MRG) was presented. This project brought out several advances in the prosthetic field which the authors discuss in detail. The second chapter examines the use of finite element modeling for understanding knee prosthesis biomechanics, fundamental to answering clinical question in the field. Also looked at are the basic characteristics of knee prostheses that must be complied with in order to provide a safe and biomechanical performance to its users during walking. Other chapters present the main results from a project whose main focus was to evaluate the tibial inserts wear and to obtain the possibility to control the total knee prosthesis (TKPs) wear process; whether screening and decolonisation (S&D) is effective in reducing the rate of postoperative infection after elective knee joint arthroplasty and whether it's cost-effective; and finally, a review of the current literature, as well as some personal experiences, on assessing the reliability of patient specific instrument system in total knee arthroplasty (TKA).