Cadaveric analysis of an accelerometer-based portable navigation device for distal femoral cutting block alignment in total knee arthroplasty

Abstract

Femoral intramedullary guides have been shown to be insufficiently accurate in creating a distal femoral resection perpendicular to the mechanical axis in total knee arthroplasty (TKA), as they make assumptions regarding the difference between the patient's femoral mechanical and anatomical angles. The aim of this cadaveric study was to validate the accuracy of a portable accelerometer-based navigation device for alignment of the distal femoral cutting block in TKA. Twenty-nine trials were performed on five cadaveric specimens (hip-to-ankle), in which the distal femoral cutting block was placed using the KneeAlign 2™ navigation device. For each specimen, a preoperative “target” was assigned for varus/valgus and flexion/extension alignment of the cutting block. The actual alignment of each cutting block was then measured using the ORTHOsoft Computer Assisted Surgery (CAS) system. The mean absolute difference between the preoperative target and the alignment of the cutting block was 0.83 ± 0.60° for varus/valgus, and 0.83 ± 0.83° for flexion/extension. The KneeAlign 2™ navigation device can set and align the distal femoral resection guide with the same accuracy as a large-console CAS system, thus demonstrating that portable accelerometer-based navigation can be used reliably in total knee arthroplasty.