Dynamic ligament balance after total knee arthroplasty: a comparative finite element analysis

Abstract

Objectives: To compare postoperative gait biomechanics between patients aged ≤70 years and >70 years undergoing navigation- assisted total knee arthroplasty (TKA), integrating intraoperative navigation data with patient-specific finite element analysis

(FEA) to evaluate dynamic joint behavior and internal load distribution during gait. Methods: A retrospective analysis was performed on 402 primary unilateral TKAs implanted with the SCORE® prosthesis using the Amplivision® surgical navigation system. Intraoperative data acquisition included lower limb alignment expressed by the hip–knee–ankle (HKA) angle, dynamic ligament balance (GAP), coronal plane angular behavior (varus–valgus), femoral and tibial rotational kinematics, and implanted component dimensions. Postoperative gait biomechanics were reconstructed by interpolating joint positions recorded at 0°, 30°, 60°, and 90° of knee flexion. Patient-specific three-dimensional finite element models were developed to simulate physiological loading conditions throughout the entire gait cycle. Results: No statistically significant differences were identified between age groups with respect to lower limb alignment, coronal or rotational kinematics, or dynamic ligament balance during gait. In contrast, patients older than 70 years exhibited significantly higher contact pressures acting on the femoral component (p = 0.04) and a tendency toward increased stresses on the tibial component and polyethylene insert. Finite element simulations demonstrated that aging is associated with increased internal joint loading despite comparable postoperative kinematic patterns. Conclusion: Navigation-assisted TKA provides consistent restoration of postoperative alignment, kinematics, and ligament balance across different age groups. However, older patients experience higher internal articular stresses during gait, indicating that aging predominantly influences load transmission rather than joint kinematics. These findings highlight the importance of incorporating dynamic, load-based biomechanical assessment into postoperative evaluation, implant optimization, and long-term follow-up strategies in patients undergoing TKA.