Kinematic alignment in total knee arthroplasty: principles, outcomes, and evolving perspectives

Purpose Mechanical alignment (MA) has traditionally guided total knee arthroplasty (TKA), seeking neutral limb alignment for all patients. However, this uniform method disregards anatomical diversity and leaves up to 20% of patients dissatisfied. Kinematic alignment (KA) was introduced to address these limitations by restoring each patient's native pre-arthritic knee alignment. Methods A literature review conducted in April 2025 examined the rationale, biomechanics, clinical outcomes, implant considerations, and future directions of KA-TKA. Results KA replicates the knee's natural joint lines and ligament balance, avoiding the soft tissue and kinematic distortions inherent to MA. Biomechanical studies show that KA better reproduces native knee kinematics and more physiological gait patterns. Clinical evidence, including randomized trials and meta-analyses, demonstrates that KA provides superior joint perception, greater patient satisfaction, and comparable implant survivorship relative to MA. Long-term data extending beyond 10 years indicate that component positioning and prosthetic limb alignment have a negligible influence on implant loosening or revision rates. Implant selection also plays a key role, with medial pivot designs and posterior cruciate ligament retention further enhancing (i.e. symbiotic effect) the kinematic and clinical benefits of KA. Conclusions KA represents a validated, patient-specific alternative to the long-standing MA paradigm. By aligning prosthetic components to each patient's anatomy rather than enforcing a neutral axis, KA enhances TKA performance without compromising implant durability. Future research should focus on refining three-dimensional assessment tools and implant designs to optimize the reproducibility and longevity of KA-TKA.