Biomechanical Effect of Coronal Alignment and Ligament Laxity in Total Knee Arthroplasty: A Simulation Study

Abstract

The purposes of this study were to develop a cruciate-retaining total knee arthroplasty musculoskeletal model, which enables the adjustment of ligament length and implant alignment; validate the model; and evaluate the effects of varus/valgus alignment adjustment and unbalanced medial/lateral ligament laxity during gait. A cruciate-retaining total knee arthroplasty musculoskeletal model was constructed and validated against the in vivo contact forces. This model was transformed to 2° varus/valgus alignment of femoral or tibial replacement models and 2° medial/lateral laxity models. The contact forces and ligament tensions of the adjusted models were calculated. The contact forces in the model showed good agreement with the in vivo contact forces. Valgus replacement alignment with balanced ligament models showed a lower contact force at the medial compartment than at the neutral alignment model, whereas the varus replacement alignment with balanced ligament models showed a greater contact force at the medial compartment and medial/posterior cruciate ligament tension. The medial laxity with neutral alignment model showed a similar contact force with decreased medial ligament tension compared to the balanced neutral alignment model, whereas the lateral laxity with the neutral alignment model showed a greater contact force and decreased lateral ligament tension. The cruciate-retaining total knee arthroplasty model was validated using in vivo contact forces (r = 0.939) Two degrees of valgus alignment adjustment with balanced ligament or neutral alignment with 2° of medial laxity can be safe without increasing contact force or ligament tension compared to neutral alignment with a balanced extension gap. However, 2° of varus alignment adjustment with balanced ligament or neutral alignment with 2° of lateral laxity may be unfavorable due to the overloading of the joints and knee ligaments.

Learning curve of robot-assisted total knee arthroplasty and its effects on implant position in asian patients: a prospective study

“…Achieving proper lower limb alignment in the coronal plane is essential for successful TKA [ 26 ]. A neutral mechanical axis permits even contact force on the joint and maintains adequate ligament tension [ 27 ]. Thus, failure to restore the neutral mechanical axis leads to unfavorable clinical outcomes and prosthesis failure.…”

Learning curve of robot-assisted total knee arthroplasty and its effects on implant position in Asian patients: A prospective study

“…Achieving proper lower-limb alignment in the coronal plane is essential for successful TKA [21]. Neutral mechanical axis allows even contact force on the joint and maintains adequate ligament tension [22]. Thus, failure to restore the neutral mechanical axis leads to unfavorable clinical outcomes and prosthesis failure.…”

Effect of subscapularis repair on joint contact forces based on degree of posterior-superior rotator cuff tear severity in reverse shoulder arthroplasty

“…Quantitative assessments of the 6-DOF anatomical shoulder model were performed by evaluating the root-mean-squared error (RMSE) and Pearson’s correlation coefficient ( r ) compared to the human in vivo JCFs from 10° to 90° abduction ( Bergmann et al, 2011 ) and compared to previously predicted JCFs from 13° to 109° abduction ( Quental et al, 2016 ). Because of the lack of previously reported RMSEs and correlation coefficients corresponding to the intact glenohumeral JCFs, the calculated RMSEs and correlation coefficients were indirectly evaluated by comparing them with the previously reported values in the 6-DOF musculoskeletal model of total joint arthroplasty ( Chen et al, 2021 ; Ro et al, 2022 ).…”