Cruciate ligament force of knees following mobile-bearing unicompartmental knee arthroplasty is larger than the preoperative value

Kenichi Kono,Shin Sameshima,Sakae Tanaka,Tomofumi Kage,Hiroshi Inui,Darryl D D’Lima,Shoji Konda,Shuji Taketomi,Takaharu Yamazaki,Kohei Kawaguchi,Ryota Yamagami,Tetsuya Tomita

doi:10.1038/s41598-021-97655-z

Abstract

We analyzed the implantation effects on cruciate ligament force in unicompartmental knee arthroplasty (UKA) and determined whether kinematics is associated with the cruciate ligament force. We examined 16 patients (17 knees) undergoing medial UKA. Under fluoroscopy, each participant performed a deep knee bend before and after UKA. A two-dimensional/three-dimensional registration technique was employed to measure tibiofemoral kinematics. Forces in the anteromedial and posterolateral bundles of both the anterior cruciate ligament (aACL and pACL) and the anterolateral and posteromedial bundles of the posterior cruciate ligament (aPCL and pPCL) during knee flexion were analyzed pre- and post-UKA. Correlations between changes in kinematics and ligament forces post-UKA were also analyzed. Preoperatively, the aACL forces were highly correlated with anteroposterior (AP) translation of the lateral condyles (Correlation coefficient [r] = 0.59). The pPCL forces were highly correlated with the varus–valgus angulation (r = − 0.57). However, postoperatively, the PCL forces in both bundles were highly correlated with the AP translation of the medial femoral condyle (aPCL: r = 0.62, pPCL: r = 0.60). The ACL and PCL forces of the knees post-UKA were larger than those of the knees pre-UKA. Kinematic changes were significantly correlated with the cruciate ligament force changes.

Highlights

We analyzed the implantation effects on cruciate ligament force in unicompartmental knee arthroplasty (UKA) and determined whether kinematics is associated with the cruciate ligament force
The most important findings of this study were that the knees of the patients with OA showed a larger cruciate ligament force following UKA than that before UKA, and the cruciate ligament force was correlated with the varus–valgus angulation and AP translation
Mochizuki et al have reported that UKA does not completely recreate normal knee k inematics[7]

Summary

Introduction

We analyzed the implantation effects on cruciate ligament force in unicompartmental knee arthroplasty (UKA) and determined whether kinematics is associated with the cruciate ligament force. The PCL forces in both bundles were highly correlated with the AP translation of the medial femoral condyle (aPCL: r = 0.62, pPCL: r = 0.60). A previous study has reported that preoperative and postoperative femurs displayed external rotation with flexion, and that the anteroposterior (AP) translation of the medial and lateral sides indicated posterior movement with flexion[6]. One of the reasons near-normal kinematics are observed in UKA knees may be due to the preservation of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) during this procedure. Several studies have demonstrated that the cruciate ligament force following BCR-TKA was higher than that of normal k nees[10,11]. The independent relation between kinematics and the cruciate ligament force remains unknown as well

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