In vivo kinematic comparison of bi-cruciate retaining total knee arthroplasty between mechanical alignment and functional alignment methods

Tomofumi Kage; Kenichi Kono; Tetsuya Tomita; Takaharu Yamazaki; Shuji Taketomi; Ryota Yamagami; Kohei Kawaguchi; Ryo Murakami; Takahiro Arakawa; Takashi Kobayashi; Sakae Tanaka; Hiroshi Inui

doi:10.1016/j.asmart.2024.09.002

In vivo kinematic comparison of bi-cruciate retaining total knee arthroplasty between mechanical alignment and functional alignment methods

Asia Pac J Sports Med Arthrosc Rehabil Technol. 2024 Sep 14:38:14-21. doi: 10.1016/j.asmart.2024.09.002. eCollection 2024 Oct.

Authors

Affiliations

¹ Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
² Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe-ku, Osaka, 559-8611, Japan.
³ Department of Information Systems, Faculty of Engineering, Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama 369-0293, Japan.
⁴ Department of Orthopaedic Surgery, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe City, Saitama 350-8500, Japan.

Abstract

Background/objective: This study aimed to clarify the kinematics of bi-cruciate-retaining (BCR) total knee arthroplasty (TKA) by comparing the mechanical alignment (MA) and functional alignment (FA) methods and to evaluate differences between the two alignment methods.

Methods: The in vivo kinematics of 20 MA TKA and 20 FA TKA knees were investigated under fluoroscopy during squatting using a two-to three-dimensional registration technique. Accordingly, knee flexion angle, axial rotational angle, varus-valgus angle, anteroposterior translation of the medial and lateral low contact points of the femoral component relative to the tibial component and kinematic pathway were evaluated.

Results: No difference in the knee flexion angle was observed between the MA and FA TKA groups. Femoral external rotation was observed in both groups and no significant difference was observed. Significant varus alignment from extension to early flexion range was observed in the FA TKA group. The posterior translation of the medial side was smaller in the FA TKA group than in the MA TKA group. Conversely, no significant difference in the anteroposterior translation of the lateral side was observed. In the kinematic pathway, a medial pivot motion from 0° to 20° of flexion and a lateral pivot motion beyond 20° of flexion were observed in both groups.

Conclusion: During squatting in BCR TKA, the FA TKA group significantly showed varus alignment and smaller posterior translation of the medial side than the MA TKA group from extension to early flexion range.

Keywords: Bi-cruciate retaining; Functional alignment; Kinematics; Mechanical alignment; Total knee arthroplasty.