This work aims to summarize clearly the current concepts in the surgical treatment of Osteoarthritis of the knee, including High Tibial or Femoral Osteotomy, Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty. This book can be read at different levels: basic chapters are particularly dedicated to non-specialized or junior surgeons, rheumatologists, radio logists and physiotherapists. More specialized aspects dealing with difficult cases and controversial topics are dedicated to highly specialized surgeons. Numerous chapters focus on difficult cases in primary TKA, such as TKA on stiff knees, TKA in case of severe deformity or TKA following HTO or failed UKA. Strategy and options in revision TKA are also discussed in the second part of the book. Thanks to its didactic approach, the reader will find quick answers to technical or conceptual difficulties. The use of numerous figures, X-rays and algorithms clarifies the statements and guides the reader throughout this book.