Abstract
The use of portable, accelerometer-based navigation (PN) devices for positioning of
the components of total knee arthroplasty (TKA) is emerging as an alternative to standard
extramedullary (EM) systems, which was needed to the image intensifier. The aim of
our study was to compare the accuracy of component positioning in TKA using an EM
and PN systems. Data from 100 consecutive primary TKAs, performed by multiple surgeons
in 87 patients between October 2010 and June 2015, were analyzed. Coronal and sagittal
plane alignments of the TKA components, relative to the mechanical axis of the limb,
were evaluated by radiography. The mean postoperative coronal alignment angle of the
femoral (α) and tibial (β) components was comparable between the groups (α: PN, 89.9
± 2.2 degrees; EM, 89.9 ± 1.6 degrees and β: PN, 90.1 ± 1.4 degrees; EM, 89.6 ± 1.3
degrees). Groups were also comparable with regard to mean postoperative sagittal alignment
angle of the femoral and tibial components (γ: PN, 2.3 ± 3.3 degrees; EM, 1.8 ± 1.7
degrees and σ: PN, 89.7 ± 2.5 degrees; EM, 90.1 ± 1.3 degrees). The incidence rate
of a component malalignment > 3 degrees in the coronal and sagittal planes of the
mechanical axis of the knee was comparable between the groups. In conclusion, the
coronal and sagittal alignments for the femoral components was less accurate compared
with tibial component alignment, especially in the PN group, and the sagittal alignment
of the femoral component was less accurate than coronal alignment for both groups.
Both the PN and EM systems provide satisfactory coronal and sagittal component alignments
in TKA. Further technical improvement of the PN system could further improve its application
for accurate component implantation in TKAs.
Keywords
total knee arthroplasty - extramedullary guides - portable navigation - coronal alignment
- sagittal alignment
