Richard Hannan a, Matthew Free a,∗ , Varun Arora a , Robin Harle b, Paul Harvie a
a Department of Orthopaedics, Royal Hobart Hospital, 48 Liverpool St, Hobart, Tasmania, Australia, 7000
b Department of Medical Imaging, Royal Hobart Hospital, 48 Liverpool St, Hobart, Tasmania, Australia 7000
Introduction:
Evidence now exists advocating the use of computer navigation in total knee arthroplasty
(TKA). Despite the introduction of new navigation systems into clinical practice no evidence currently
exists showing independent verification of their accuracy. The aim of this study was to validate the in
vivo accuracy of the Exactech Guided Personalised Surgery (GPS) computer navigation system using a validated computed tomography (CT) measurement of alignment.
Method:
Consecutive patients who underwent TKA using the GPS Navigation System at our institution
were prospectively recruited. Intraoperative parameters of 3D alignment as measured by the GPS navigation system were recorded and compared against the postoperative measurements of alignment measured
using the Perth CT Protocol to assess the accuracy of the GPS navigation system.
Results: 29 consecutive patients (13 male, 16 female) who underwent TKA were prospectively recruited.
Overall, for all measures of 3D alignment the mean difference between intraoperatively recorded and
postoperative CT-measured alignment was 1.55° ± 0.22° (95% confidence interval). Individual measurement differences in the femoral prosthesis were: coronal alignment 1.64° ± 0.52°; flexion 2.07° ± 0.55°; rotation 1.38° ± 0.33° Differences in the tibial prosthesis were: coronal alignment 2.03° ± 0.53°; slope 1.14° ± 0.39° The whole limb coronal alignment difference was 2.34° ± 0.83°
Conclusion:
The Exactech GPS Navigation system is very accurate with a high concordance between intraoperative and postoperative measures of alignment and prosthesis positioning. We therefore confidently validate the system and support its continued use in clinical practice. Other navigation systems should undergo a similar validation process.