For 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 5 of this ninth edition, we have developed new approaches to analyze sagittal plane deformities. The sagittal plane has always been challenging to teach because the range of motion of the knee adds a level of complexity. Joint motion or lack of joint motion contributes to or compensates for sagittal plane deformities. Without understanding and quantifying the soft-tissue contribution, the deformity will not be fully addressed and corrected. We have developed two new angles to analyze the confounding factor of knee motion in the sagittal plane: the sagittal mechanical axes angle (SMAA) and the sagittal joint line angle (SJLA). We also developed three different ways to calculate the soft-tissue contribution: the Seesaw Method, the Formula Method, and the Table Method. We decided to present three options so that surgeons can select the method that best suits their learning style (from more visual to more mathematical). Using one of these three methods to carefully evaluate the soft-tissue contribution will allow for an accurate assessment and the creation of a successful treatment strategy. 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!