Summary

Bi-cruciate stabilized total knee arthroplasties were similar to posterior-stabized total knee arthroplasties in knee biomechanics during gait.

Abstract

Introduction

Implant design is important to achieve appropriate knee biomechanics during gait following knee arthroplasty. Bicruciate-stabilized (BCS) total knee arthroplasty (TKA) attempts to replicate anterior stability and rotational facilitation. Several studies have investigated the effects of BCS implants on gait biomechanics. For example, it was reported that BCS TKA showed lower anterior–posterior acceleration than posterior-stabilized (PS) acceleration. BCS TKA guides axial rotation through the implant shape, which may reproduce better rotation. However, detailed information of gait biomechanics compared with other implant designs have not been analyzed so far. The purpose of the present study was to compare knee kinematics and kinetics among four different conditions including BCS TKA, posterior-stabilized (PS) TKA, unicompartmental knee arthroplasty (UKA), and normal knees.

Methods

A total of 51 subjects, including 12 BCS TKAs, 16 PS TKAs, 13 UKAs and 10n healthy subjects (controls), were enrolled in the present study. All subjects underwent unilateral procedures. All TKAs were done using same measured resection technique with same implant (Trimax, Posterior Stabilized, Ortho Development, Draper, UT, USA, and Journey II BCS system, Smith and Nephew Inc., Memphis, TN, USA) and all UKAs were done using Zimmer Unicompartmental High Flex Knee (Zimmer,Warsaw, IN, USA). Less invasive parapatellar approach was utilized as surgical exposure for TKAs and UKAs. At the time of the surgery, full extension was carefully confirmed to avoid flexion contracture for each surgery. All patellae were resurfaced in TKAs, and all components were fixed with bone cement for TKAs and UKAs. Patients underwent a standard rehabilitation program which consisted of early range of motion and weight-bearing exercises as tolerated. The mean follow-up period after arthroplasty was 11.0 months. Gait analysis system consisted of eight infrared cameras (120 frames/s, Oqus, Qualisys, Sweden), two force plates (sampling rate 600 Hz, ; AM6110, Bertec, Columbus, OH, USA), and 44 reflective markers. Three-dimensional kinematics and kinetics were assessed using the software (Visual3D, C-motion, Boyds, MD, USA) during level walking on a 5-m walkway for each subject. Comparisons among groups were conducted using the Kruskal–Wallis test, and post hoc analysis was performed for those parameters. Statistical significance was set at p < 0.05. The protocol was approved by the Institutional Review Board of our university. All participants provided written informed consent.

Results

No differences were found between the controls and UKAs. Knee extension excursion during midstance phase was smaller in BCS TKAs than in controls, and rotation excursion was smaller in BCS TKAs than in UKAs. Knee extension and internal rotation moments were also smaller in BCS and PS TKAs than in controls.

Discussion And Conclusion

BCS TKAs exhibited different biomechanical characteristics compared to natural knees and UKAs during gait. Ideally, BCS TKA has the function of anterior cruciate ligament (ACL), and thus, there is no stiffening strategy in the sagittal plane and no pivot shift avoidance phenomenon in the axial plane for BCS TKA. However, in these parameters, BCS TKAs were similar to PS TKAs.