No kinematical difference between ultra-congruent and medial-congruent total knee arthroplasty when implanted with mechanical alignment: an in vivo dynamic RSA study

Abstract

Purpose To explore in vivo kinematical behavior of the same total knee arthroplasty (TKA) cruciate-retaining (CR) femoral design with either medial-congruent (MC) or ultra-congruent (UC) inlay using model-based dynamic radiostereometric analysis (RSA). The hypothesis was that there would be comparable kinematics between the two groups. Methods A cohort of 16 randomly selected patients (8 MC Persona Zimmer, 8 UC Persona Zimmer) was evaluated through dynamic radiostereometric analysis (RSA) at a minimum of 9 months after TKA, during the execution of a sit-to-stand. The antero-posterior (AP) translation of the femoral component and the AP translation of the low point of medial and lateral femoral compartments were compared through Student’s t test (p < 0.05). Results Both groups showed a medial pivot behavior, with a significantly greater anterior translation of the Low Point of the lateral compartment with respect to the medial compartment (MC medial range: 2.4 ± 2.4 mm; MC lateral range: 7.7 ± 3.0 mm; p < 0.001 – UC medial range: 3.3 ± 3.3 mm; UC lateral range: 8.0 ± 3.2 mm; p < 0.001). A statistically significant greater degree of flexion was clinically recorded at follow-up visit in the MC group respect to the UC group (126° vs 101°—p = 0.003). Conclusion The present study did not show difference in the medial pivot behavior between ultra-congruent and medial-congruent total knee arthroplasty when implanted with mechanical alignment; however, the MC group demonstrated a greater degree of flexion. The MC design examined is a valid alternative to the UC design, allowing to achieve a screw-home movement restoration combined with a high flexion. Level of evidence IV.

Larger Medial Contact Area and More Anterior Contact Position in Medial-Pivot than Posterior-Stabilized Total Knee Arthroplasty during In-Vivo Lunge Activity

“…Multiple studies have reported superior clinical patient outcomes in MP-TKA compared to PS-TKA [ 1 , 15 , 16 , 17 , 18 ]. In contrast, some other studies have shown no difference between the two groups [ 2 , 19 , 20 , 21 ]. Also, the comparison of in-vivo six-degree-of-freedom (6-DOF) knee kinematic during daily activity such as gait [ 3 , 14 , 22 ], stair climbing [ 23 ], sit-to-stand [ 24 ] between MP-TKA and PS-TKA have shown inconsistent results.…”

“…First, only lunge activity was investigated to compare the difference between MP-TKA and PS-TKA. However, the kinematic differences in some daily activities, such as level walking or sit-to-stand, have been evaluated in previous studies [ 3 , 14 , 20 , 24 ]. Lunge activity was considered to evaluate the implant performance better, especially under high flexion.…”

PCL retention demonstrates better functional scores and gait patterns in total knee arthroplasty using a medial congruent insert—a prospective study

“…Several authors have reported on the rationale behind the evolution of the MC polyethylene insert design in providing a greater level of stability with minimum constraint [9, 18, 21]. Alesi et al [1]. reported no difference in medial knee kinematics on comparing Ultracongruent (UC) and MC knee arthroplasty.…”

Knee kinematics are not different between asymmetrical and symmetrical tibial baseplates in total knee arthroplasty: A fluoroscopic analysis of step‐up and lunge motions

“…The included number of TKAs in this study was chosen based on previous fluoroscopic experience, but lacking a proper sample size calculation. Studies with a similar primary objective and with a sample size calculation, comparing the kinematics of two variations of the Persona TKA, included fewer TKAs per study group [1,42]. Therefore, the results of this study are still of value.…”