4For more than 30 years, we have taught limb correction surgery at the annual Baltimore Limb Deformity Course (www.DeformityCourse.com). We have used these hands-on experiences with our students to guide us when creating this book. The Art of Limb Alignment is a concise guide for beginners starting on their journey to master the art of limb alignment. Understanding limb alignment and malalignment is a critical task for surgeons who treat lower extremity deformities. The first task is to characterize the deformity: Is the bone angulated? In what direction is the bone angulated? What is the level of the deformity? Where is the apex of the deformity? What is the magnitude of the deformity? Is the bone short? Is it rotated on its axis? All these questions must be answered before correcting the problem. In Chapter 10 of this tenth edition, digital planning software (Bone Ninja app, available as an iPad app teaching tool through the App Store) is used to show the reverse planning method for femoral deformity. Reverse planning using manual methods was introduced by Rainer Baumgart in 2009. In a normal femur, the anatomic and mechanical axes deviate from each other by 5˚ to 7˚. By using reverse planning to "begin with the end in mind," the surgeon will minimize risk of unwanted mechanical axis deviation secondary this anatomic-mechanical axis divergence. In Chapter 13, the principles of MAP the ABCs are applied to common conditions seen in foot and ankle deformities. Foot and ankle deformity correction can be challenging to treat due to the compensation from the joints within the foot. This chapter shows step-by-step analysis and correction of four deformities: a pes planus foot with hallux valgus, cavus foot, rockerbottom midfoot, and ankle varus malunion. The Art of Limb Alignment is intentionally short, concise, and we hope, easy to master. The theme is that of student and teacher (sensei) embarking on a voyage to master the art of limb alignment. Enjoy the journey!