This book focuses on basic science, personal surgical experiences, clinical, functional and radiographic outcomes with special focus on challenging knees, such as severe varus and valgus deformities with associated bone defects, fixed flexion deformities, soft tissue contractures, and arthrodesed knees. The issue of patella treatment with or without resurfacing is addressed intensively. Early criterion-based rehabilitation and participation in sports are discussed as is the management of prosthetic or surgery related complications. Tips and tricks provided by experienced knee surgeons are indispensable in daily clinical practice.