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. 2023 Jul;143(7):4339-4347.
doi: 10.1007/s00402-022-04661-5. Epub 2022 Oct 25.

Influence of kinematic alignment on femorotibial kinematics in medial stabilized TKA design compared to mechanical alignment

L Bauer  1 , M Woiczinski  1 , C Thorwächter  1 , P E Müller  1 , B M Holzapfel  1 , T R Niethammer  1 , J-M Simon  2
Affiliations

Influence of kinematic alignment on femorotibial kinematics in medial stabilized TKA design compared to mechanical alignment

L Bauer et al. Arch Orthop Trauma Surg. 2023 Jul.

Abstract

Introduction: Worldwide more and more primary knee replacements are being performed. Kinematic alignment (KA) as one of many methods of surgical alignment has been shown to have a significant impact on kinematics and function. The aim of the present study was to compare KA and mechanical alignment (MA) with regard to femorotibial kinematics.

Materials and methods: Eight fresh frozen human specimens were tested on a knee rig during active knee flexion from 30 to 130°. Within the same specimen a medial stabilized (MS) implant design was used first with KA and then with MA.

Results: The femorotibial kinematics showed more internal rotation of the tibia in KA compared to MA. At the same time, there was a larger medial rotation point in KA. Both alignment methods showed femoral rollback over the knee bend.

Conclusion: Relating to an increased internal rotation and a more precise medial pivot point, it can be concluded that KA combined with a MS implant design may partially support the reproduction of physiological knee joint mechanics.

Keywords: Femorotibial kinematics; Kinematic alignment; Mechanical alignment; Total knee arthroplasty.

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Conflict of interest statement

PEM is a consultant for the Medacta shoulder system and an instructor for Medacta shoulder and knee system. This in no way influenced the results of this study. The authors declare that they have no conflicts of interest relevant to the content of this article.

Figures

Fig. 1
Fig. 1
Experimental setup for human specimen with the total knee prosthesis and markers for optoelectrical measuring system
Fig. 2
Fig. 2
Landmarks of the femur and tibia used for the calculation of femorotibial kinematics
Fig. 3
Fig. 3
Femorotibial kinematics of the knee joint with mechanical alignment, kinematic alignment and native situation. Mean values (n = 8) and 95% confidence interval of femorotibial kinematics of a medial stabilized prosthesis during flexion from 30° to 130°; a Tibial rotation, b Anterior-posterior central translation, c Anterior-posterior lateral translation, d Anterior-posterior medial translation, for kinematic alignment (orange), mechanical alignment (blue) and the native situation (black)
Fig. 4
Fig. 4
Boxplots of tibial rotation for 30°, 60°, 90° and 120° of knee flexion. Boxplots of tibial rotation showing the median (n = 8), first and third quartile, range and outliners for kinematic alignment (KA, orange), mechanical alignment (MA, blue) and the native situation (NatSit, gray); for a 30° of flexion, b 60° of flexion, c 90° of flexion and d 120° of flexion. Mean values are marked with ◇; Significant differences (p < 0.05) are marked with asterisks
Fig. 5
Fig. 5
Medial rotation points of the knee flexion with a total knee prosthesis. Mean value (n = 8) of the medial rotation point and horizontal/vertical standard deviation of a kinematic alignment 30–120° flexion, b mechanical alignment 30–120° flexion
See this image and copyright information in PMC

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