J Knee Surg 2018; 31(01): 092-098
DOI: 10.1055/s-0037-1602133
Original Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Comparative Study for Alignment of Extramedullary Guides versus Portable, Accelerometer-Based Navigation in Total Knee Arthroplasty

Kazu Matsumoto1, Hiroyasu Ogawa1, Masashi Fukuta2, Nobuyuki Mori3, Haruhiko Akiyama1
  • 1Department of Orthopaedic Surgery, Gifu University Graduate School of Medicine, Gifu, Japan
  • 2Department of Orthopaedic Surgery, Matsunami General Hospital, Hashima-gun, Gifu, Japan
  • 3Department of Orthopaedic Surgery, Gifu Munincipal Hospital, Gifu, Japan
Further Information

Publication History

30 July 2016

09 March 2017

Publication Date:
01 May 2017 (eFirst)


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.