Total knee replacement: on the path to a perfect alignment!

Background: Total knee arthroplasty (TKA) has evolved significantly since 1968; however, patient dissatisfaction rates persist between 10% and 20%. Current research to improve these outcomes focuses on optimizing limb alignment strategies and integrating robotic technology to achieve precise gap balancing and functional restoration.

Objective: This review aims to delineate various limb alignment philosophies in TKA, including mechanical, kinematic, and functional approaches, while evaluating the modern methodologies and technologies utilized to optimize component positioning.

Key Points: Mechanical alignment remains the conventional standard, targeting a neutral hip-knee-ankle axis of 180° ± 2°, though it often necessitates soft tissue release. Alternative strategies include kinematic alignment, which restores native pre-arthritic anatomy to minimize ligamentous intervention, and restricted kinematic alignment, which applies specific boundaries to avoid extreme phenotypes. Inverse kinematic alignment prioritizes the restoration of joint line obliquity. Functional alignment utilizes robotic assistance to customize bone resections based on individual soft tissue laxity. Technological adjuncts for achieving these targets range from conventional manual instrumentation and patient-specific instrumentation to computer-assisted navigation and robotic systems. These tools offer varying degrees of precision, with robotic and navigation systems providing real-time intraoperative feedback on alignment and gap symmetry.

Conclusion: Selecting an optimal alignment strategy is essential for achieving a balanced knee and improving clinical outcomes. While mechanical alignment is widely practiced, personalized approaches supported by robotic technology and advanced navigation are increasingly utilized to accommodate individual patient anatomy and potentially address persistent dissatisfaction rates.