Comparison of an Accelerometer-Based Portable Navigation System, Patient-Specific Instrumentation, and Conventional Instrumentation for Femoral Alignment in Total Knee Arthroplasty

Purpose The KneeAlign2 (KA2, OrthoAlign Inc.) accelerometer-based portable navigation system and patient-specific instrumentation (PSI; Signature, ZimmerBiomet) are widely used for ideal femoral component alignment in total knee arthroplasty (TKA). However, there has been no comparative study of the KA2 system, PSI, and conventional intramedullary instrumentation (CON). The purpose of this study was to compare the accuracy in achieving proper femoral component alignment and clinical features by using the KA2 navigation system, PSI, and CON. Materials and Methods We retrospectively compared the accuracy of femoral component alignment of 34 TKAs performed with the KA2 system for implantation of the femoral component, 32 TKAs with PSI, and 33 TKAs with CON. Results In the coronal plane, use of the KA2 system was more likely to result in optimal femoral component alignment than the CON and PSI (p<0.01). In the sagittal plane, use of the KA2 system was more likely to result in optimal component alignment than PSI, but the difference between the KA2 and CON was insignificant. Conclusions The portable accelerometer-based KA2 navigation system enabled ideal femoral implantation in the coronal and sagittal planes, as compared to the PSI or CON.