2023 ISAKOS Biennial Congress ePoster
The Effect of Minor Adjustments to Tibial and Femoral Component Position on Soft Tissue Balance in Robotic Total Knee Arthroplasty
Simon W. Young, MD, FRACS, Auckland NEW ZEALAND
Matthew Carter, Auckland NEW ZEALAND
Gavin William Clark, MBBS, FRACS, Subiaco, WA AUSTRALIA
Christina Esposito, PhD, Sydney AUSTRALIA
Matthew Walker, MBChB, FRACS, Auckland NEW ZEALAND
University of Auckland, Auckland, NEW ZEALAND
FDA Status Cleared
Summary
A high percentage of TKAs can be balanced without soft tissue release using minor adjustments to component position, from both MA and KA start points.
ePosters will be available shortly before Congress
Abstract
Introduction
Ideal goals for alignment and balance in total knee arthroplasty (TKA) remain controversial. Some authors propose balance and alignment targets that more closely approximate the native knee. We aimed to compare initial alignment and gap balance using mechanical alignment (MA) and kinematic alignment (KA) techniques, and to analyze the percentage of knees that could achieve balance using limited adjustments to component position.
Methods
Prospective data on 388 primary robotic TKAs (154 MA and 234 KA) was analysed. Medial extension, lateral extension, medial flexion and lateral flexion virtual gaps were recorded. A computer algorithm calculated potential solutions to achieve soft tissue balance, utilizing virtual angular and translational adjustments of the tibial and femoral components (±1°, ±2°, or ±3° from initial). The percentage of knees that could achieve balance without soft tissue release was compared. We also analyzed the effect of balance targets with greater lateral gap tolerances (1-3mm).
Results
Less than 5% of TKAs were initially balanced in both KA and MA cohorts. Limited adjustments to component position increased the percentage of TKAs that could be balanced in a graduated manner, with no difference between MA and KA start points: adjustments of ±1° (10% vs 6% p=0.39), of ±2° (48% vs 38% p=0.23) or of ±3° (64% vs 51% p=0.39). A higher percentage of TKAs could be balanced when a greater tolerance for lateral gap laxity (up to 3mm) was allowed, in both KA and MA cohorts (KA 51% vs 88%, P< 0.01; MA 64% vs 89% p< 0.01).
Conclusion
A high percentage of TKAs can be balanced without soft tissue release using minor adjustments to component position, from both MA and KA start points. KA positioning alone did not lead to a more balanced knee. Surgeons should consider the relationship between alignment and balance goals when optimizing component positioning in TKA.