João Bosco Sales Nogueira
(Nogueira, Joao BS)INTRODUCTION :
Total Knee Arthroplasty (TKA) aims to reduce pain, improve range of motion, and enhance function and quality of life for individuals suffering from articular Insufficiency. Preoperative planning helps the surgeon anticipate challenges, achieve proper implant alignment, and minimize the risk of implant failure and soft tissue imbalance.
TKA PREOPERATIVE PLANNING :
During preoperative planning, surgeons typically outline the anatomical and mechanical axes of both the femur and tibia. Since the lower limb mechanical axis (LLMA) is naturally inclined by 3 degrees from the body’s center of mass, the tibial articular line has a slight varus (3 degrees), while the femoral articular line is positioned at 10 degrees of valgus.
Consequently, during the stance phase, the transverse axis of the knee remains perpendicular to the LLMA. Because the LLMA passes slightly through the medial compartment, force distribution across the knee is asymmetrical, with most knees experiencing medial forces during gait—known as the adduction moment. Several soft tissue structures counteract this moment, including the lateral capsule, LCL, cruciate ligaments, patellar ligament, popliteus, POL, and ITB.
Despite advancements in biomechanical understanding, the optimal strategy for prosthetic alignment remains a subject of debate. Anatomic, mechanical, and kinematic alignment concepts serve as the foundation for proper implant positioning. While each approach has its merits, key principles such as preserving joint line height, restoring kinematics, ensuring proper component sizing and positioning, and achieving balance remain paramount. The most traditional method of TKA preoperative planning is manual, but it has drawbacks such as lack of portability and the need for manual calculations of angles and distances. After developing a mobile application for preoperative TKA planning during his Master’s degree, the author has now created an innovative web-based application for TKA planning. Using DICOM files, this solution preserves image properties and scale. It offers surgeons both a freehand planning mode and a step-by-step guided planning approach.
EXECUTION :
The step-by-step planning method was applied to the execution of a varus osteoarthritis knee surgery, linking the most critical surgical steps to the corresponding TKA preoperative planning stages.