Myths and Facts on Components Rotational Alignment in Total Knee Arthroplasty
Background: Rotational alignment in total knee arthroplasty (TKA) involves component positioning in the axial plane, a critical factor for patellar tracking and flexion gap stability. Despite the clinical significance of this "third dimension," controversy persists regarding optimal alignment targets. Malrotation remains a primary cause of early prosthetic failure, frequently manifesting as instability, stiffness, and patellofemoral complications.
Objective: This review evaluates current surgical philosophies for femoral and tibial rotational alignment, analyzes the impact of axial plane deformities, and describes evidence-based techniques for achieving balanced kinematics and component longevity.
Key Points: Femoral alignment techniques include measured resection, balanced gap, extension gap first, and kinematic alignment. While the transepicondylar axis (TEA) is the recognized compromise for the flexion axis, 3D imaging reveals significant variability in the posterior condylar angle across both varus and valgus phenotypes. For the tibia, alignment strategies are categorized into mechanical, functional, and self-rotational philosophies. Proximal tibial axial deformities, characterized by variable tibial tubercle positioning, complicate these approaches and may lead to tibiofemoral mismatch or patellar maltracking. The authors advocate for an extension gap first technique to align the femoral component parallel to the TEA, particularly in the presence of distal femoral torsional deformities. For tibial malalignment, functional derotation within the joint is utilized to align the extensor mechanism, effectively reducing the tibial tubercle-trochlear groove distance without the necessity of formal tubercle osteotomy.
Conclusion: Precise axial alignment is essential for successful TKA. Surgeons must identify pre-existing torsional deformities via clinical or radiographic assessment. Utilizing the TEA for femoral rotation and functional derotation for the tibia provides a reproducible framework for optimizing clinical outcomes.
