Length-Change Patterns of the Collateral Ligaments During Functional Activities After Total Knee Arthroplasty

S H Hosseini Nasab,A Trepczynski,W R Taylor,R List,P Damm,C R Smith,P Schütz

doi:10.1007/s10439-020-02459-3

Abstract

This study aimed to quantify the elongation patterns of the collateral ligaments following TKA during functional activities of daily living. Using mobile video-fluoroscopy to capture radiographic images of the knee in a group of six patients, each with an ultra-congruent knee implant, tibiofemoral kinematics were reconstructed throughout complete cycles of level gait, downhill walking, stair descent, and squat activities. Kinematic data were then used to drive subject-specific multibody knee models to estimate length-change patterns of the LCL as well as three bundles of the MCL. In addition, a sensitivity analysis examined the role of the attachment site in the elongation patterns. Our data indicate a slackening of the LCL but non-uniform length-change patterns across the MCL bundles (ranging from lengthening of the anterior fibers to shortening of the posterior fibers) with increasing knee flexion angle. Near-isometric behavior of the intermediate fibers was observed throughout the entire cycle of the studied activities. These length-change patterns were found to be largely consistent across different activities. Importantly, length-change patterns were critically sensitive to the location of the femoral attachment points relative to the femoral component. Thus, in TKA with ultra-congruent implants, implantation of the femoral component may critically govern post-operative ligament function.

Highlights

Knee extension through terminal swing phase resulted in continuous elongation of the LCL and posterior MCL (pMCL), together with shortening of the intermediate MCL (iMCL) and anterior MCL (aMCL)
Accurate tibiofemoral kinematics were reconstructed from imaging data captured using a moving fluoroscope throughout complete cycles of level gait, downhill walking, stair descent, and squat, and were used to drive subjectspecific multibody knee models for the estimation of length-change patterns of the MCL and LCL
Regardless of the activity, our results revealed a slackening of the LCL as well as non-uniform lengthchange patterns across the MCL bundles with increasing knee flexion angle

Summary

Introduction

To define the optimal ligament tension during TKA and avoid postoperative complications, a thorough understanding of the length-change patterns experienced by the collateral ligaments in natural and replaced knees during different functional activities is crucial. Such knowledge is extremely limited due to a lack of studies assessing their in vivo and dynamic functionality. The few studies that have assessed in vivo length-change patterns of the MCL and LCL have generally exploited image-based approaches, combining static video-fluoroscopy and 3D modelling of the knee joint in order to track the relative movement of the ligament attachment sites, and thereby estimate their length-change patterns.[29,37,38] Here, Park and co-workers measured healthy subjects per-

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