ISAKOS: 2019 Congress in Cancun, Mexico
ISAKOS

2019 ISAKOS Biennial Congress ePoster #933

 

Comparison of Anterior Stabilized and Posterior Stabilized Total Knee Arthroplasties in the Same Patients: A Prospective Randomized Study

Man-Soo Kim, MD, Seoul KOREA, REPUBLIC OF
Chulkyu Kim, MD, Seoul KOREA, REPUBLIC OF
Keun-Young Choi, MD, Seoul KOREA, REPUBLIC OF
Yong In, MD, PhD, Seoul KOREA, REPUBLIC OF

Seoul St. Mary's Hospital, Seoul, KOREA, REPUBLIC OF

FDA Status Cleared

Summary

Although there was greater static posterior displacement in AS TKA group, both AS and PS TKA groups showed similar dynamic stability under weight-bearing conditions and clinical outcomes at two years postoperatively.

Abstract

Introduction

A highly conforming, anterior stabilized (AS) insert is designed to provide anteroposterior (AP) stability of the posterior stabilized (PS) insert, without a post. AS insert acts as a PS device by allowing the femoral component to move within a deep-dish configuration. So AS insert provides the benefits of a PS component without sacrificing femoral bone to make a PS box cut. The purpose of this study was to compare the static and dynamic kinematics and clinical outcomes of AS and PS total knee arthroplasties (TKAs) in the same patients.

Methods

A prospective randomized controlled trial was performed in 45 patients scheduled to undergo same-day bilateral TKA. The mean age at time of index TKA was 70±6.9 years. One knee was randomly assigned to AS TKA and the other knee was assigned to PS TKA of the same Knee System. These two groups were compared for knee AP stability and clinical outcomes at two years postoperatively. Static AP stability was compared using anterior and posterior drawer stress radiographs at 90° knee flexion. Dynamic AP stability was evaluated using one leg standing lateral fluoroscopic images during range of motion. Clinical outcomes were compared using Knee Society score (KSS) and WOMAC score.

Results

There was significant difference in knee AP laxity at 90° flexion between the two groups (7.6 ± 3.9 mm in AS group vs. 2.2 ± 2.3 in PS group, p<0.001). However, there were no differences in dynamic AP stability under one leg standing fluoroscopic lateral images at 30° knee flexion (0.4 ± 0.9 mm in AS group vs. 0.3 ± 0.8 mm in PS group, p=0.732), 60° knee flexion (0.1 ± 0.2 mm in AS group vs. 0.1 ± 0.1 mm in PS group, p=0.764), and 90° knee flexion (-0.7 ± 1.1 in AS group vs. -0.6 ± 0.9 in PS group, p=0.679). The KSS (157.1 ± 18.1 in AS group vs. 156.5 ± 18.5 in PS group, p=0.641), and WOMAC scores (27.1 ± 18.6 in AS group vs. 26.6 ± 17.1 in PS group, p=0.582) were not significantly different between the two groups.

Conclusion

Although there was greater static posterior displacement in AS TKA group, both AS and PS TKA groups showed similar dynamic stability under weight-bearing conditions and clinical outcomes at two years postoperatively.