BETTER PERFORMANCE OF THE SQUAT AFTER INVERSE KINEMATIC ALIGNED TKA

Objectives: Higher satisfaction is reported in total knee arthroplasty (TKA) after inverse kinematic alignment (iKA) compared with adjust mechanical alignment (aMA). These findings need to be evidenced by biomechanical studies investigating gait and daily functional movements. The purpose of this
study was to compare the performance of the bipodal squat of an iKA cohort, with an aMA cohort.
Methods: At 2 years postoperative, 15 aMA and 15 iKA patients were analyzed. All patients were operated with robotically assistance using an identical perioperative protocol. As a control group, 15 healthy subjects were used, matched for age and sex. A 3D Vicon motion analysis system was used for the spatiotemporal and kinematic analysis of the squat, which was subdivided into 2 phases: descending phase from movement initiation to deepest knee flexion as possible and ascending phase from deepest knee flexion back to starting position. Data collection was done by a blinded investigator.
Results: The duration of the descending phase of the bipodal squat with iKA (58,0%) was comparable with the healthy controls (59,1%); with aMA the duration was shorter (53,0%). (Table 1) The duration of the ascending phase was longer with aMA (47,0%) compared to iKA (42,0%) and the healthy controls
(40,9%). Maximal knee flexion during bipodal squat was lower with aMA (77,0°), compared to iKA (85,2°) and the healthy controls (97,9°). (Table 1, Figure 4) Hip flexion during squat was reduced both in iKA (77,6°) and aMA (77,1°), compared to the healthy controls (90,7°). No difference was noticed in ankle
dorsiflexion.
Conclusions: At two years postoperative, the performance of the bipodal squat after iKA TKA was closer to the healthy control group, compared to aMA. Restoring native joint line obliquity might lead to better performance of loaded knee activities such as the bipodal squat.