Component placement angles in total knee arthroplasty affect mid- to long-term clinical results: an average 8-year follow-up study

Introduction

Few studies have examined how the component placement angles in total knee arthroplasty (TKA) affect mid- to long-term clinical outcomes. This study investigated the influence of coronal and sagittal plane component placement angles on mid- to long-term outcomes in mechanical alignment TKA.

Materials and Methods

Forty-eight knees undergoing TKA using the FINE Total Knee System were evaluated for range of motion (ROM) preoperatively. Both ROM and clinical scores were evaluated at 3 and 5 years postoperatively and at the final follow-up (average 8-year). The valgus (alpha) and flexion (gamma) angles of the femoral component, and the varus (beta) and posterior tilt (sigma) angles of the tibial component were evaluated. Correlations between radiographic assessments, knee ROM, and clinical scores were assessed using Spearman's correlation coefficient.

Results

The alpha angle was negatively correlated with the knee flexion angle (r = − 0.323, p = 0.025) and ROM (r = − 0.352, p = 0.014), and the sigma angle was negatively correlated with the Knee Injury and Osteoarthritis Outcome Score (KOOS)-Symptoms at 3 years postoperatively (r = − 0.304, p = 0.036). The alpha angle was negatively correlated with the knee flexion angle (r = − 0.357, p = 0.013), ROM (r = − 0.337, p = 0.019), and KOOS-Sports and Recreation function (r = − 0.349, p = 0.015), and positively correlated with the Visual Analog Scare pain score (r = 0.307, p = 0.034) at the final follow-up. The beta angle was positively correlated with KOOS-Pain (r = 0.303, p = 0.036) and KOOS-Symptoms (r = 0.397, p = 0.005) at the final follow-up.

Conclusions

Valgus placement of the femoral component and varus placement of the tibial component in the FINE Total Knee System negatively impacted clinical scores at an average 8-year follow-up.